January 3

The Aerospace Safety Advisory Panel, at the request of the NASA Administrator, undertook an extensive review of the Skylab Program. Priorities in the review were given to the activities and systems deemed to he most critical to crew safety [291] and mission success:

• Contractor development and manufacture of Skylab modules and associated NASA management activities. (This included factfinding trips to principal contractor and NASA management Centers.)
• NASA management activities for the evaluation of design and hardware maturity and mission operations planning and preparation.

The Panel was satisfied with the technical management system for development and fabrication of the modules, spacecraft, and launch vehicles; the design and hardware acceptance reviews; and preparations for and execution of mission operations. They felt that the NASA/industry team was mature and that it was applying careful planning and responsible management to the hardware, software, and checkout operations. However, some mission operational areas, cluster change control, and integrated testing would require continued future emphasis. Some of these specific areas were contractor policies for joint operational activities; fire extinguishment and toxicity controls; and flammability of materials. Following the presentation of the written report, the Panel, by letter of 26 January 1973, was requested by George M. Low (NASA Hq) to continue the review and provide comments before each Skylab flight. This would include consideration of prelaunch activities, test, and checkout activities, mission preparations, and the areas identified in the study as warranting continued emphasis. The Panel would also review mission operations for each flight to assess the basis for confidence in mission operation for the next flight. In this area, the Panel conducted a comprehensive review of MSC operations activities on 12 and 13 March 1973.

Panel personnel were Carroll H. Dunn, chairman; Frank C. DiLuzio, Henry Reining, Jr., Bruce T. Lundin, John A. Hornbeck, and Harold M. Agnew, members; William A. Mrazek, consultant; and Gilbert L. Roth, Carl R. Praktish, V. Eileen Evans, staff.

Volume I, Summary Report to the Administrator by the NASA Aerospace Safety Advisory Panel on the Skylab Program, January 1973; letters, C. H. Dunn to J. C. Fletcher, NASA Hq, 4 January 1973; C. A. Berry, NASA Hq, to Director, Skylab Program, NASA Hq, "Skylab Between Mission Durations," 14 February 1973; memoranda, D. D. Myers, NASA Hq, to the Administrator, "Third Annual Report of the Aerospace Safety Advisory Panel," 27 June 1972; W C. Schneider, NASA Hq, to Associate Administrator for Manned Space Flight, "Comments on Third Report of the Aerospace Safety Advisory Panel," 26 June 1972; G. L. Roth to Manager, Skylab Program, MSC, "MSC Review," 14 February 1973; JSC (formerly MSC), "Skylab Program Office Weekly Activity Report," 16 March 1973.

January 10

At a Manned Space Flight Management Council meeting, William C. Schneider (NASA Hq) emphasized the mounting pressures from open work at KSC and the demanding schedule for integrated systems testing during February and March. As examples he cited the following areas:

February	ATM system verification
	AM/MDA/OWS end-to-end system test
	SL-2 (first manned Skylab launch) vehicle roll
[292] March	Stowage and crew compartment fit and function review
	SL-1 and SL-2 flight readiness test

Summary of Action Items, Manned Space Flight Management Council, 10 January 1973.

January 15

At a NASA general management review, Dale D. Myers summarized Skylab problems which were aggravated by a requirement to replace a control and display panel in the multiple docking adapter-one of the pacing program items. He told the general management review group that confidence in the ability to maintain an April launch date was slipping. Following the review, a decision was made to delay the launch of SL-1 and SL-2 until May 1973, with tentative launch dates of 14 and 15 May. An evaluation of launch intervals between SL-2 and SL-3 and between SL-3 and SL-4 was being made to determine if an approximate recovery date of 21 December 1973 could be maintained.

TWX, William C. Schneider, NASA Hq, to MSC, MSFC, KSC, and GSFC, "Skylab Planning," 22 January 1973; OMSF, "Summary of January Action Items " 10 February 1973; memorandum, Dale D. Myers, .NASA Hq, to the Administrator, "Rescheduling of Skylab I Workshop Launch," 24 January 1973.

January 17-19

A three-day mission planning simulation was conducted at MSC. Work was underway to resolve the problems identified during the simulation. Consideration was also being given to replacing the planned two-day on-orbit simulations with three-day simulations. A decision on this change would be reflected in a revised mission planning simulation schedule.

MSC, "Skylab Program Office Weekly Activity Report," 26 January 1973.

January 19

MSFC began implementation of a plan for preparation and storage of unassigned Saturn hardware, phaseout of the Saturn V production capability, and amendment of the facility operations contract at the Michoud Assembly Facility for minimum surveillance of stored hardware.

Letter, E. F. M. Rees, MSFC, to Dale D. Myers, NASA Hq, "January Management Council Meeting," 19 January 1973.

January 19

A design certification review was held at KSC. Primary and supporting Center responsibility was assigned for certain action items. Input from the supporting Center would be utilized by the Center having primary responsibility in generating the closeout information for the action. In the majority of the action items, KSC was assigned primary responsibility, with MSFC providing support.

Letters, William C. Schneider, NASA Hq, to MSFC, MSC, and KSC, "Launch Complex 39 Delta DCR and Integrated SWS and Launch Vehicle GSE/ESE DCR Action Items," 30 January 1973; William C. Schneider to Dist., same title, 22 February 1973; William C. Schneider to Associate Administrator for Manned Space Flight, "DCR Action Items," 22 March 1973.

January 19 - February 2

[293] KSC processing of SL-1 and SL-2 was progressing as planned. The Workshop and its associated modules were successfully stacked 29-31 January. No major problems were encountered in the SL-2 processing. Propellant loading and unloading, facilities, and ground support equipment tests were conducted on the Saturn IB launch vehicle at Pad B. Following tests, the vehicle was rolled back to the Vehicle Assembly Building. Prime and backup crews completed manned altitude chamber tests of the SL-2 command and service modules on 19 January, following which the spacecraft was moved to the Vehicle Assembly Building where it would be erected on the S-IB.

"Skylab Engineering Weekly Highlight Reports," 1, 8, and 16 February 1973; Manned Space Flight Management Council, "Summary of Proceedings," 14 February 1973.

January 22

An ATM calibration rocket systems launch was accomplished at the White Sands Test Facility in New Mexico. The launch was one of a series to qualify the calibration rocket program before the Skylab missions.

MSFC, "Skylab Weekly Activity Report," 23 January 1973.

January 24

An evaluation to determine the impact of changing the Skylab 1 and 2 launch dates indicated that the greatest impact was on the crew training activities. The evaluation indicated that the star charts aboard the Orbital Workshop were launch-date dependent. Changeout packages were being prepared for the star charts which would be carried in the command module. Changeout packages were also being prepared for the rendezvous book, the ATM systems checklist and data book, the flight plan, and the flight plan sequence for the activation and deactivation checklist.

MSC, "Skylab Program Office Weekly Activity Report," 2 February 1973; JSC, "Skylab Program Office Weekly Activity Report," 23 February 1973.

January 26

MSFC Director Eberhard F. M. Rees retired. He had served as Director since 1 March 1970. Rocco A. Petrone, NASA Apollo Program Director, became the new MSFC Director.

MSFC PAO; Marshall Star, 17 January 1973.

January 29-30

Checkout of the AM/MDA and ATM flight units was completed at KSC, and the units were mated to the launch vehicle.

MSFC, "Weekly Activity Report," 30 January 1973.

February 5

A customer acceptance readiness review for the Skylab television system was completed at Westinghouse Electric Corporation, Baltimore. The unit was being assigned to the qualification test program for testing.

MSC, "Skylab Program Office Weekly Activity Report," 9 February 1973.

February 12

The Manned Space Flight Management Council acting in the capacity of a design certification review board completed the following Skylab Program reviews:

Saturn launch vehicles	7-8 June 1972
Command and service modules and MSC experiments	10-11 Aug. 1972
Mission operations	15 Sept. 1972
MSFC modules and experiments	2-3 Oct. 1972
Cluster systems	19 Oct. 1972
Launch Complex 39 and integrated ground and electrical support equipment	19 Jan. 1973

The adequacy of the design performance requirements and verification programs for Skylab vehicles, spacecraft, modules, experiments, cluster systems, launch complex and ground support equipment, and mission operations planning were examined to certify that equipment and operational elements could safely accomplish the planned Skylab mission.

Memorandum, Dale D. Myers, NASA Hq, to the Administrator, "Skylab Design Certification Reviews," 12 February 1973.

February 14

At a Manned Space Flight Management Council meeting, William C. Schneider (NASA Hq) summarized the results of a Skylab study on launch interval options. The purpose of the study had been to assess the potential effect of reducing the interval between SL-2 and SL-3 by 5 days and between SL-3 and SL-4 by 10 days. The study indicated concern about launch abort lighting, night recovery, and circadian rhythm on SL-4 and about a reduction in the mission planning cycle between SL-3 recovery and SL-4 launch to 27 days. The Council accepted [295] Schneider's recommendation to retain the previously scheduled launch intervals shown below. Planning would proceed on that basis.

Mission	Launch	Recovery*
.
Skylab Workshop (SL-1)	May 14, 1973	-
First manned mission (SL-2)	May 15,1973	June 12, 1973
Second manned mission (SL-3)	Aug. 8, 1973	Oct. 3, 1973
Third manned mission (SL-4)	Nov. 9,1973	Jan. 4, 1974
------------------------------------
*No nighttime recoveries were planned.

Manned Space Flight Management Council, "Summary of Proceedings," 14 February 1973; TWX, William C. Schneider to MSC, MSFC, KSC, and GSFC, "Skylab Planning," 16 February 1973.

February 15

The North American Rockwell Corporation and Rockwell Manufacturing Corporation merged to become Rockwell International Corporation.

Telecon, R. Newkirk, Historical Services and Consultants Co., to Lyle Burt, Rockwell International, 15 October 1974.

February 17

The Manned Spacecraft Center at Houston, Texas, was officially redesignated the Lyndon B. Johnson Space Center in honor of the late President.

MSC Announcement 73-34, 17 February 1973.

February 19

Astronaut Robert A. R. Parker was designated Skylab Program Scientist and would be responsible for ensuring that the inflight Skylab science requirements to be implemented by flight operations elements were compatible with NASA and Skylab program requirements. John R. Sevier served as Assistant Program Scientist. Parker was assigned to Skylab Program Manager Kenneth S. Kleinknecht and during actual mission operations would respond to the directions of the Skylab Program Director and the MSC and MSFC Skylab Program Managers.

MSC Announcement No. 73-32, "Key Personnel Assignment," 2 March 1973.

February 20

The OWS high-fidelity mockup arrived at MSFC from McDonnell Douglas, Huntington Beach. It was updated for use as a systems engineering mockup along with an AM/MDA and the ATM dynamic test articles, which were modified at MSFC for this use.

MSFC, "Weekly Activity Report," 27 February 1973.

February 22-23

A customer acceptance readiness review for Skylab flight food was held at Whirlpool Corporation in St. Joseph, Michigan. Items of OWS were accepted. However, the CSM flight and backup food were not accepted because of lack of [296] stowage definition and the required stowage drawings in the data pack. This food would be accepted when the stowage arrangement in the CSM was defined.

JSC, "Skylab Program Office Weekly Activity Report," 2 March 1973.

February 27 - May 25

The Skylab 2 spacecraft, mated to its launch vehicle, was transferred 27 February from the KSC Vehicle Assembly- Building to Launch Complex 39B in preparation for launch. The SL-2 space vehicle consisted of the following major components: an S-IB (the first stage); an S-IVB (the second stage, which comprised the propulsion stages); an IU; a CSM; and an SLA. The next five paragraphs trace the SL-2 from the arrival of the component parts at KSC through liftoff.

The S-IVB stage had arrived at KSC' on 24 June 1971 and was placed in storage until 17 April 1972. The CSM arrived on 19 July 1972 and was immediately moved into the Operations and Checkout Building for systems testing. The S IB and the IU both arrived on 22 August 1972. On 5 September 1972 the S-IVB was mated to the S-IB. Three days later, 8 September 1972, the IU was mated to the S-IVB.

Since SL-2 was the first Saturn IB space vehicle to be launched from LC-39, it was necessary to verify the modified facilities and systems. Therefore, the SL-2,....

[297] ...with a boilerplate spacecraft, was moved to LC-39B on 9 January 1973. The mobile service structure was positioned on 12 January 1973, and the fit, function, and facility systems tests required in support of the SL-2 launch were performed. The Propellant Loading All Systems Test was performed on 29 and 30 January, 1973. The SL- 2 was then returned to the Vehicle Assembly Building.

On 9 February 1973 the SLA was mated to the CSM. The CSM/SLA was then moved to the Vehicle Assembly Building on 20 February 1973 and mated to the launch vehicle the following day. Transfer of the SL-2 to LC-39B was completed 27 February

The space vehicle Flight Readiness Test was completed on 5 April 1973. The Countdown Demonstration Test began on 25 April 1973. At 0:00 a.m. EDT 9 May 1973, the launch countdown for SL-2 was started.

Because of the meteoroid shield anomaly and failure of the solar wings to deploy on the Workshop, the SL-2 launch was scrubbed on 14 May 1973 at T minus 14 hours 35 minutes (9:10 p.m. EDT 14 May), and scrub turnaround procedures started. The countdown clock was then held at T minus 59 hours until countdown resumed at 10:30 p.m. EDT 22 May 1973. SL-2 was successfully launched at 9:00 a.m. EDT on 25 May 1973 (see 25 May 1973 entry).

KSC, "Skylab 2 Post-Launch Report," 21 June 1973, pp. 7-1, 7-2.

February 28

During a news conference in Washington, Charles "Pete" Conrad, first manned Skylab mission commander, reviewed activities that would be conducted during the SL-2 mission.

NASA News Release, "Press Conference with Pete Conrad," 28 February 1973.

March 1

MSFC Director Rocco A. Petrone initiated an MSFC flight hardware integrity review at MSFC and contractors' facilities. The purpose of the review was to ensure integrity of MSFC-developed hardware by examining in-depth specifications, design and design changes, failures, and test results of critical hardware components and systems associated with the activation sequences. The review was scheduled to be completed before the MSFC preflight readiness review meeting in mid-April.

MSFC, "Weekly Activity Report," 20 March 1973.

March 8

Following two lightning strikes on Apollo 12 while in flight and a strike on the launch umbilical tower while Apollo 15 was on the launch pad, an intra-Center telecon with participation from NASA Hq, KSC, JSC, and MSFC was held to discuss previous studies on lightning. It was determined that analyses and corrective actions accomplished since the strikes on Apollo 12 had reduced to a very low probability the chance of system damage to Skylab vehicles from lightning strikes.

[298] Memorandum for record, H. Wong, NASA Hq, "Lightning Strikes," 8 March 1973.

March 8

During a meeting of the Manned Space Flight Management Council, R. C. Hock (KSC) summarized the major test milestones completed and those remaining to be completed on SL-1 and SL-2 in order to meet the launch planning dates of 14 and 15 May 1973.

KSC Presentation Outline for MSF Management Council, 8 March 1973; Manned Space Flight Council, "Summary of Agreements and Action Items," 8-9 March 1973.

March 19

Consideration was being given to the feasibility of a second set of Skylab missions (designated Skylab-B) during the interval between the Apollo-Soyuz Test Project in 1975 and the start of Space Shuttle operations late in 1979. The inherent worth of a Skylab-B was recognized, but officials were reluctant to recommend it, on the premise that it would be unwise to allow it to delay or displace the development of the Space Shuttle and other programs already included in the FY 1974 budget.

Letter, James P. Fletcher, NASA Hq, to Lowell P. Weicker, Jr., U.S. Senate, 19 March 1973; note, William C. Schneider, NASA Hq, to Dale D. Myers, NASA Hq, "Skylab-B Planning," 15 March 1973; memorandum, William C. Schneider to Deputy Director, Budget and Program Analysis, "Request for Answer Regarding Skylab-B," 19 March 1973.

March 20

To reduce the possibility of fire hazards onboard spacecraft, NASA adopted a rigid materials selection and control program based on elimination of flammable materials and substitution of nonflammable or self-extinguishing materials wherever possible. Where this was not possible, flame propagation paths were eliminated. In addition, a two-gas system was adopted, fire sensors were added to the caution and warning system, fire extinguishers were installed in all elements of the Skylab cluster, and crews were trained in fire-fighting and evacuation methods.

Memorandum, Dale D. Myers, NASA Hq, to the Administrator, "Full-Scale Flammability Testing on Skylab," 20 March 1973.

March 25-30

The Skylab flight hardware successfully completed the first total mission operations sequence during the mission simulation and flight readiness test at KSC. The test included the SL 2 astronaut crew participation in the simulated launches of SL-1 and SL-2, mission activation and operation, deactivation, data dump, and powerdown.

KSC Skylab Spacecraft Integrated Daily Schedule, 30 March 1973.

March 28

The USNS Vanguard, a part of NASA's Space Flight Tracking and Data Network, departed Port Canaveral, Florida, for temporary duty at Mar del Plata, Argentina. The ship would provide a two- way flow of information and communication....

[300] ...between Skylab and Mission Control Center in Houston via Goddard Space Flight Center. Upon completion of the Skylab Program, it would return to Port Canaveral. The Vanguard was originally designed to provide tracking and data acquisition for the Apollo flights. It played an important role in the Apollo Program.

GSFC News Release, "Vanguard Tracking Ship to Argentina for Skylab Support," 28 March 1973; Cocoa, Florida, Today, 28 March 1973, pp. 1B, 2B.

March 29

An agreement was published which provided for the optimum utilization of resources in programs and projects in which both JSC and MSFC had development roles. It would permit the direct application of each Center's institutional resources for the benefit of visiting members from the other Center.

"MSC (sic)/MSFC Inter-Center Agreement on Institutional Resources," 29 March 1973.

April 3

An ATM Naval Research Laboratory rocket calibration launch was unsuccessful due to two major discrepancies. l he guidance system failed to work properly and the recovery system failed. The launch was a qualification test flight of the rocket vehicle, science package, and support equipment which would he flown during the manned Skylab mission to calibrate the Naval Research Laboratory instrument in the ATM. This calibration would establish the amount of misalignment or degradation of the optics, if any, in the ATM instrument due to the launch environment or contamination. Investigations were initiated to determine the causes of the failures.

Memorandum, William C. Schneider, NASA Hq, to Associate Administrator for Manned Space Flight, "Skylab/ATM Calibration Rocket NRL Qualification Launch," 9 April 1973.

April 3

Studies were conducted to determine the feasibility of conducting a controlled deorbit of the Orbital Workshop. Three methods were considered: (l) using the CSM service propulsion system; (2) using the CSM reaction control system; and (3) implementing an S-II (Saturn V second stage) deorbit. The service propulsion system deorbit was assessed as not feasible; the reaction control system deorbit was considered technically feasible but, like the service propulsion system, it had an inherent program and crew safety risk associated with it. Implementation of an S-II deorbit would have serious time and cost impacts on the program. A 1970 study, which indicated that the probability of damage from the deorbiting Skylab was so small that changes which caused major impact in cost and schedule were not worth pursuing, was confirmed.

TWXs, William C. Schneider, NASA Hq, to MSFC and JSC, "OWS Deorbit," 2 March 1973; William C. Schneider to MSFC, JSC, and KSC, "SWS Deorbit," 30 March 1973; letter, Leland F. Belew and R. G. Smith, MSFC, to Director, Skylab Program, "SWS Deorbit," 12 March 1973; memoranda, William C. Schneider to Associate Administrator for Manned Space Flight, "SWS and S-II Deorbit," 3 April [301] 1973; Dale D. Myers, NASA Hq, to Administrator, "Deorbit of Skylab Elements," 2 May 1973; Dale D. Myers to Administrator, "Workshop Deorbit," 23 June 1973.

April 4-5

Reporters and commentators from the United States and several foreign countries attended a series of Skylab news briefings at MSFC. MSFC Director Rocco A. Petrone and MSFC Skylab Program Manager Leland F. Belew gave a general presentation on the program. They were followed by a series of presentations by specialists on the various systems, experiments, and research efforts connected with the Skylab missions. Tours of the high-fidelity mockup and the neutral buoyancy simulator were included during the two days.

MSFC PAO, Marshall Star, 11 April 1973.

April 5

The planning dates of 14 and 15 May 1973 were officially confirmed as the launch dates for SL-1 and SL-2, respectively. The launch planning date for SL-3 continued to be 8 August 1973; for SL-4, 9 November 1973.

TWX, William C. Schneider, NASA Hq, to JSC, MSFC, KSC, and GSFC, "Firm Launch Dates for SL-1 and SL-2," 5 April 1973.

April 13

A miniature, fast, analytical clinical laboratory developed by the Atomic Energy Commission's Oak Ridge National Laboratory for use on manned space stations was undergoing laboratory tests at JSC. It was expected that the new system would subsequently be used in clinical situations. The analyzer would provide a pediatrician with the capability of rapidly completing 12 simultaneous analyses of an infant through the use of only a drop of blood compared to as much as five cc's required by single analyzers. Tests would be performed in the doctor's office, with the results available within minutes. The same would apply for geriatric patients, emergency room patients, and accident victims where rapid multiple diagnoses with minimum blood samples were vital.

JSC News Release 73-37, "Analyzer Has Spinoff Potential," 13 April 1973.

April 16-19

Loading of the Apollo spacecraft's hypergolic propellants for a scheduled 15 May launch was completed at KSC. The next major milestone in preparing the Saturn IB/Apollo for launch would occur 23 April when the kerosene to fuel the Saturn IB booster's eight engines would be pumped aboard the first stage.

KSC News Release 75-73.

April 16 - May 13

The Skylab 1 spacecraft on its launch vehicle was moved to Launch Complex 39, Pad A, on 16 April. The SL-1 space vehicle consisted of two launch vehicle stages, an instrument unit, and the three major payload modules of the Saturn Workshop (SWS). The two launch vehicle stages and IU (S-IC, S-II, and S-IU) were identical to the first and second launch vehicle stages of the Apollo Saturn V space vehicle. The SL-1 payload consisted of the Orbital Workshop [302] (a converted S-IVB stage), airlock module/multiple docking adapter, Apollo telescope mount, payload shroud, nose cone, and experiments.

The S-II stage had been the first to arrive at KSC, on 1 April 1971, and was placed in storage. The stage underwent modifications for approximately one year. On 16 July 1972, the S-IC stage had arrived and was erected on Mobile Launcher 2 on 2 August. The S-II stage was mated to the S-IC stage on 20 September.

Both the ATM and the OWS arrived at KSC on 22 September 1972. The ATM was moved into the Operations and Checkout Building cleanroom, checked out, and moved to the Vertical Assembly Building. The OWS was moved to the Vertical Assembly Building and stacked on 29 September. On 26 October, the IU stage arrived at KSC; it was mated to the OWS on 1 November. The AM/MDA arrived at KSC on 6 October and was moved into the Operations and Checkout Building. Docking tests between the SL 2 CSM and the AM/ MDA were conducted. The AM/MDA was flight-mated to the fixed airlock shroud (FAS) and docking adapter (DA), and on the following day the AM/ MDA/FAS/DA was mated with the payload shroud. This section of the payload was then moved to the VAB and was mated to the OWS. The ATM was mated to the DA on 30 January 1973.

System testing began on the payload modules and the launch vehicle stages. Testing included both intra- and intermodule/stage testing, including SWS mission simulation flight readiness test and launch vehicle flight readiness test. The nose cone was installed on 8 April, and SL-1 transfer to Pad A was completed on 16 April.

High winds delayed the connection of environmental control system air and prevented internal access to the spacecraft until late on 17 April.

Skylab 1 countdown demonstration test started at T minus 123 hours at 7:00 p.m. EDT, 26 April. Final stowage of the ATM cameras and film in the MDA stowage locker and flight closeout of the MDA was completed on 27 April. Final closeout of the AM/MDA was completed on 1 May, and the EVA hatch was secured for flight.

Launch countdown began at 2:00 a.m. EDT, 9 May. A small amount of rain fell into the ATM area during a thunderstorm that day, but affected areas were temporarily covered. High winds prevented further weatherproofing of the payload shroud nose cap until 10 May. The Mobile Launcher 2 lightning mast was struck by lightning at 12:57 p.m. EDT on 9 May. Lightning retest operations on the launch vehicle and spacecraft were successfully completed. No anomalies attributed to the lightning were noted.

KSC, "Skylab 1 Post-Launch Report," 8 June 1973, pp. 7-1, 7-2.

April 17

[303] NASA Hq issued a policy instruction on accountability for experiment materials returned from the Skylab missions. The purposes of the instruction were to ensure the integrity of the experimental data in the returned material and to prevent loss, theft, or unauthorized use or disposition of such material.

Skylab Program Directive No. 61, "Skylab Policy on Accountability for Experiment Materiel Returned from the Skylab Missions," 17 April 1973.

April 17-20

The final NASA top management review and approval of the launch and mission readiness was completed in a flight readiness review at KSC. Items covered in the review ranged from modules and launch vehicles readiness to missions and operations support. Following the review, NASA Skylab Program Director William C. Schneider said, "We still have a few things to be closed out, but we have assured ourselves that the systems are all working with one or two minor open items and we're still ready to go for a 14 May launch of Skylab 1 and a 15 May launch of Skylab 2."

Transcript.

April 18

KSC and MSFC were directed by NASA Hq to implement a reduction in force of contractor personnel immediately following the launches of SL-1 and SL-2, but to maintain a sufficient complement for a backup launch capability through 30 September 1973.

TWX, William C. Schneider, NASA Hq, to KSC, MSFC, and JSC, "Post SL-1/2 Launch Manpower Planning," 18 April 1973.

April 25

Since the adjustment of the Skylab launch dates, KSC updated rescue response times. The new SL-R rescue response times are shown in the following table:

Letter, R. C. Hock, KSC, to Dist., "Skylab Rescue," 25 April 1973.

May 1

Individual and group behavioral evaluations, which were discontinued following the 14-day flight of Gemini VII , were being reinstituted for the Skylab flights because of the longer duration of the SL-2, 3, and 4 missions. Information obtained from these evaluations would provide additional data useful in future diversified crew selection and expected performance in future long-duration flights.

Letter, Dale D. Myers, NASA Hq, to Christopher C. Kraft, Jr., MSC, "Behavioral Evaluation of Skylab Crews," 1 May 1973.

May 3

Three types of private conversations were authorized for Skylab missions by the NASA Administrator: private phone calls from astronauts to their families once a week, conversations required by extreme operational emergency, and routine medical conversations. In the cases of operational emergency and medical conversations, bulletins would be issued to the news media. Bulletins or public announcements of crew member conversations with their families would not be made.

Memorandum, James C. Fletcher, NASA Hq, to the Associate Administrator for Manned Space Flight and the Assistant Administrator for Public Affairs, "Private Communications for Skylab," 3 May 1973; NASA News Release 73-110, "Fletcher Statement on Skylab Private Communications," 1 June 1973.

May 8

A fund of unsolicited cash contributions, which started in 1959 and contained $5548, would be used to defray the cost of equipment for student scientific experiments on Skylab. NASA was authorized by the Space Act of 1958 to accept unrestricted gifts.

NASA Hq News Release 73-98, "NASA Gift Fund Used for Skylab Student Experiments Program," 14 May 1973.

May 9

Lightning struck the Skylab 1 launch umbilical tower near swing arm eight at 1:00 p.m. Lightning retest plans were satisfactorily completed on the AM, MDA, and ATM. No significant anomalies due to the lightning static were revealed.

"Skylab Engineering Weekly Status Report," 9 May 1973.

May 14

Skylab 1, the unmanned Orbital Workshop (OWS) was launched from KSC Launch Complex 39A at 1:30 p.m. EDT. (See item for 16 April 13 May for countdown detail.)

An unexpected telemetry indication of meteoroid shield deployment and solar array wing 2 beam fairing separation was received 1 minute and 3 seconds after liftoff. However, all other systems of the OWS appeared normal, and the OWS was inserted into a near-circular Earth orbit of approximately 435 km altitude.

The payload shroud was jettisoned, and the ATM with its solar array was deployed as planned during the first orbit. Deployment of the Workshop solar [306] array and the meteoroid shield was not successful. Evaluation of the available data indicated that the following sequence of events and failures occurred:

Time from Liftoff (hr:min:sec)	Event
.
0:01:02.9	Meteoroid shield tension strap 2 separated.
0:01:03	Meteoroid shield tension strap 1 and 3 separated.
0:01:03	Solar array system wing 2 beam fairing separated.
0:01:30	Meteoroid shield temperatures went off-scale.
0:01:30	Partial deployment of meteoroid shield was indicated.
0:10:00	Thermal measurements on wing 2 solar array panels ranged from 345 K (161°F) to 389 K (240°F), rather than the expected temperature of about 300 K (80°F). Wing 1 temperatures remained normal.
0:55:55.9	Wing 1 beam fairing separated.

Solar array wing 1 was released, but there were indications that the wing had not fully deployed. Wing 2 was inoperative or had encountered structural failure. Temperature excursions in the OWS showed that the meteoroid shield was not affecting the temperatures as intended. The remainder of the planned Workshop system activation and deployment functions occurred as scheduled with transfer of attitude control from the instrument unit to the OWS approximately 41/2 hours after liftoff.

The OWS was maneuvered into a solar inertial attitude, with the plane of the solar arrays normal to the Sun for maximum electric power generation. The OWS area temperature then rose above operating limits. The Workshop was subsequently pitched up toward the Sun at 13 hours into the flight to reduce the solar incidence angle on the OWS area. This attitude further reduced the power generation capability which had already been severely limited by the loss of the Workshop solar array wing 2 and the failure of wing 1 to deploy. A continuing adjustment of attitude was necessary to keep the power and temperature within acceptable limits. Constraints to maintain adequate heat in other critical areas of the Workshop and to optimize the operation of the attitude control system in an off-nominal mode added further complications. This delicate balance continued for approximately 10 days.

The electrical power available from the ATM solar array was further reduced by the requirement to cycle certain power regulator modules on and off to [307] prevent the overheating caused by unplanned vehicle attitudes. Although considerably below the total design capability of approximately 8500 watts, the power was sufficient for the critical loads. Many components and systems were turned off or were cycled as required to remain within the power generation capability.

The high internal temperatures that were reached in the Workshop could have caused outgassing of some materials which would have been hazardous to the crew. Therefore, before crew arrival, the habitation area was depressurized and repressurized four times with nitrogen to purge the outgassing products. The final repressurization was with the proper oxygen/nitrogen mixture for the crew.

Maneuvering into and out of the various thermal control attitudes and maintaining attitude hold and control during several docking attempts caused a much larger use of the Workshop thruster propellant than predicted. Sufficient propellant remained, however, for the three manned missions.

JSC, Skylab Mission Report First Visit, JSC-08414, August 1973, pp. 2 and 4; JSC, "Skylab Program Office Weekly Activity Report," 18 May 1973.

May 22

A Skylab 1 Board of Investigation was established to investigate the anomalies that occurred during the launch and Earth orbit of SL-1. Bruce T. Lundin (Lewis Research Center) was named chairman of the Board.

Letter, James C. Fletcher, NASA Hq, to Bruce T. Lundin, "Skylab 1 Investigation Board," 22 May 1973; memorandum, James C. Fletcher to Associate Administrator for Manned Space Flight, "Investigation of Skylab 1 Anomalies," 22 May 1973; NASA Notice 1154, "Skylab 1 Investigation Board," 22 May 1973.

May 23

NASA Administrator James C. Fletcher briefed members of the Senate on the anomalies that occurred during liftoff and orbit of Skylab 1. Fletcher summarized as follows:

1. We encountered unexpected problems with the micrometeroid shield and the workshop solar arrays.

2. These problems led to overheating and reduced power.

3. We believe we can control the heating by one of several fixes executed by the crew of Skylab 2.

4. We will try to improve the power situation, but even if we can't, there is enough for nearly normal execution of the 28- and 56-day missions.

They are going to look at the condition of the solar panels. They are not going to spend too much time on that because we have enough power. If it looks like an easy thing to do, if one of the panels, which is missing here, is partially deployed and is hung Up on something and all it needs is a little tug, we will put a loop of twine around the end of it, play it out 50 that we are well away from the panel in case it starts to deploy, and give a little tug on the twine. If it deploys, fine; but if it does not, we will go on without it.

[308] But we are not going to spend too much time on that fix. There are too many uncertainties and we do not really need the power.

5. We will be unable to carry out some 3 out of the planned 87 experiments. This is normal for almost any test of this complexity. Usually we aren't able to complete the large number of experiments that are planned. In this particular case we estimate that three of them will not be able to be carried out. Those are primarily the ones that would have come out of the airlock. If there is a sunshade over the airlock you can't do very many experiments from it.

The remaining experiments, in our judgment, fully warrant going ahead with the repair activity and then executing as much of the fully planned program as possible.

6. There will be no relaxation of safety considerations in the conduct of the replanned Skylab missions.

7. We have established a Skylab I investigation board whose findings will be reported to the committee as soon as available.

In closing, let us say that the crew, the Skylab team, and NASA management are cautiously confident-some more than others, hut all are optimistic-that the Skylab 2 mission will be a historic one and that it will permit us to meet almost all of the major objectives of the Skylab program.

U.S. Congress, Senate, Committee on Aeronautical and Space Sciences, Skylab: Hearing on Status of Skylab Mission, 93d Cong., 1st sess., 23 May 1973, pp. 4-17.

May 23-24

A design certification review was held for the revised Skylab 2 mission. The review board determined that a "Skylab parasol," with a strengthened ultraviolet resistant material, deployed through the scientific airlock would be the prime method for the deployment of a thermal shield on the Orbital Workshop. A "twin pole" thermal shield and a standup extravehicular thermal sail would be flown as backup methods. Following final assessment of mission readiness with favorable recommendations, a certification of flight worthiness for the new hardware was executed.

Letters, William C. Schneider, NASA Hq, to SL-1 and -2 Flight Readiness Review Board, "Confirmation of Flight Readiness for SL-2 Launch," 31 May 1973; William C. Schneider to Dist., "Skylab Design Certification Review of New or Changed Equipment and Procedures for Revised SL-1/SL-2 Mission," 11 June 1973.

May 25

At 9:00 a.m. EDT, Skylab 2 lifted off from Pad B, Launch Complex 39 at KSC. The vehicle was manned by astronauts Charles "Pete" Conrad, Jr., Joseph P. Kerwin, and Paul J. Weitz.

Skylab 2 , consisting of a modified Apollo CSM payload and a Saturn IB launch vehicle, was inserted into Earth orbit approximately 10 minutes after liftoff. The orbit achieved was 357 by 156 km and, during a six-hour period following insertion, four maneuvers placed the CSM into a 424 by 415 km orbit for...

...rendezvous with the Orbital Workshop. Normal rendezvous sequencing led to stationkeeping during the fifth revolution followed by a flyaround inspection of the damage to the OWS.

The crew provided a verbal description of the damage in conjunction with 15 minutes of television coverage. The solar array system wing (beam) 2 was completely missing. The solar array system wing (beam) 1 was slightly deployed and was restrained by a fragment of the meteoroid shield. Large sections of the meteoroid shield were missing. Following the flyaround inspection, the CSM soft-docked with the OWS at 5:56 p.m. EDT to plan the next activities. At 6:45 p.m. EDT the CSM undocked and extravehicular activity was initiated to deploy the beam 1 solar array. The attempt failed. Frustration of the crew was compounded when eight attempts were required to achieve hard docking [310] with the OWS. The hard dock was made at 11:50 p.m. EDT, terminating a Skylab 2 first-day crew work period of 22 hours.

JSC, "Skylab Mission Report First Visit," JSC-08414, August 1973, p. 2-1; R. V. Gordon, JSC Skylab News Center, "Skylab 1/2 Quick Look Reference," 2 July 1973, p. 3.

May 26

The second manned day of the Skylab mission was focused on entry into the OWS and deployment of the Skylab parasol. The crew removed and inspected the docking probe and drogue. They then entered the MDA to activate the airlock module and MDA systems. The crew entered the OWS at 3:30 p.m. EDT. The atmosphere, although hot, was habitable, and the crew was able to work in the environment for 10- to 15-minute intervals. At 5:00 p.m. the crew began deployment of the parasol; the task was completed at 7:30 p.m.

The parasol provided thermal shielding for the area of the Workshop exposed to the Sun because of the missing meteoroid shield. The parasol concept, design, development, construction, and delivery to KSC was completed in seven days by JSC. Two other thermal protection devices were also devised and delivered during this same time period. One was a sail, produced by JSC and designed to be deployed by an extravehicular crewman standing in the command module hatch while the spacecraft was being flown in close to the OWS. The other, called a twin-boom sunshade and produced by MSFC, was designed to be deployed by extravehicular crewmen from the ATM station.

The parasol provided a thermal protective device which was simple, and deployment could be accomplished from within the OWS in a shirt-sleeve environment. The system was capable of being jettisoned.

The parasol concept made use of a spare experiment T027 (ATM contamination measurement) canister which was designed to interface with the solar scientific airlock. The seal design used in the back plate of the experiment canister was incorporated into a new back plate required for the parasol. This allowed the use of deployment rods which were of the same type used for experiment deployment, and also allowed use of the experiment T027 photometer ejection rod, if jettisoning became necessary.

Major components of the parasol, other than the modified canister, were a 6.7 by 7.3-m aluminized Mylar/nylon laminate canopy that was partially opaque to solar thermal energy, a canopy mast, a mast hub with deployment springs, four telescoping deployment rods, seven extension rods, and the experiment T027 canister support tripod.

Deployment was accomplished through the solar scientific airlock by attaching the extension rods to the mast and pushing the rod assembly outward. As the mast hub was extended to 4.9 m above the opening of the airlock, the telescoping deployment rods became fully extended and locked and the tip retainers....

....for the telescoping rods were released. The mast hub was then extended to 6.4 m above the outer surface of the OWS, allowing the rod tips to swing free of the solar scientific airlock opening and deploy the canopy. The parasol was then retracted to its final position a few centimeters above the OWS outer surface During the retraction process, the long extension rods were removed, and the short extension rod was left in place.

OWS temperatures started dropping immediately upon parasol deployment. The initial temperature drop for the outer wall exceeded 36 K (65°F) per hour. Temperatures within the OWS, though dropping at a much slower rate, were below 311 K (100°F) within a day of deployment. The inside temperature continued a steady decline until stabilization was reached somewhat below 297 K (75°F). At the end of the first visit, the temperatures increased because of the increase of daytime exposure for the orbital plane at that time of the year.

R. V. Gordon, JSC Skylab News Center, "Skylab 1/2 Quick Look Reference," 2 July 1973, p. 3; JSC, "Skylab Mission Report First Visit," JSC-08414, August 1973, pp. 2-2, 3-1, and 3-6; abstract, J. A. Kinzler, JSC, "The Skylab Parasol," ca. January 1974.

May 27

A Skylab Program Director's meeting was held to identify further actions required for the SL 2 mission and actions required for the SL-3 mission. The following agreements were reached:

• The parasol installed on the OWS would not be jettisoned until a replacement thermal shield was on board, if a twin-boom thermal shield had not been deployed during the SL-2 mission.
• The twin-boom sunshade and the JSC sail would be retained in the OWS at the end of the SL-2 mission.

"Minutes of Skylab Program Director's Meeting," 27 May 1973.

May 27 - June 22

[312] Following the successful deployment of the parasol, the Skylab-2 crew began to transfer and store equipment and activate experiments. On 29 May, everything in the OWS was turned on for the first time. The crew checked out the EREP and the ATM.

On 7 June astronauts Conrad and Kerwin performed an EVA to free the undeployed OWS solar array. EVA began at 11:15 a.m. EDT. At 2:01 p.m., the strap restraining the solar wing was severed, the beam was fully deployed, and the three panels had begun to deploy. The 3-hour 25-minute EVA was completed at 2:40 p.m. By 8:55 p.m., all the solar array system solar power sections were deployed, and the OWS power crisis had abated.

At 3:22 a.m. EDT, 18 June, the crew of SL-2 broke the space flight record of 570 hours 23 minutes set by the Soviet Soyuz 11 flight in June 1971.

During the SL-1/SL-2 mission, the following experiments were conducted:

• Medical-all medical experiments were successfully conducted with a completion range of 80 to 100 percent.
• Apollo telescope mount-82 hours of manned viewing time and 154 hours of ground commanded data gathering were accomplished.
• EREP-11 passes with a full range of instrument operation and task site assignments were completed. (Prelaunch planning called for 14 passes.)
• Corollary-56 hours of crew time were devoted to these experiments. (Prelaunch planning called for 64 hours.)

A breakdown of the actual crew time allocation for experiments as opposed to the preflight plan is shown in the following chart.

[313] TWX, G. S. Lunney, JSC, to American Embassy Science Attache, Moscow, U.S.S.R., 22 June 1973; R. V. Gordon, JSC Skylab News Center, "Skylab 1/2 Quick Look Reference," 2 July 1973; NASA Hq Post Launch Mission Operations Report No. M 960-SL-1/SL-2, 14 July 1973.

May 30

The following editorials were typical of those evoked by the launch of Skylab I with its attendant anomalies. The first editorial quoted is from the Los Angeles Times.

The men of NASA at Cape Kennedy and Houston were getting ready to pass another miracle, but there had been so many-the first men on the moon followed by a succession on moon landings-that the success of the latest adventure in space was taken for granted. Even the crowd of spectators on the cape was less than a quarter of the million persons who watched the last of the Apollo moon missions Dec. 7.

The launch went smoothly, as Skylab, an 85-ton vehicle perched atop a Saturn 5 rocket, ascended majestically May 14 from a roaring flame and disappeared into the heavens on its journey into orbit 270 miles above the earth. "Everything looks super-good so far," Mission Control in Houston reported, and Skylab, the largest weight ever thrust into space, began to respond to radio signals.

Minutes later, the $2.6 billion project was in trouble. Two solar panels failed to deploy. The launching of three astronauts, scheduled to dock in space with Skylab the next day, had to be postponed. Skylab 2 was recycled for five days until May 20 and again for May 25, last Friday. What was needed was a simple little plan to shield the space laboratory from the sun-something like an umbrella.

An umbrella. Why, of course, Jack Kinzler, a NASA technician with a reputation as a fix-it man, started thumbing through the Yellow Pages. He found what he was looking for-fishing poles that would telescope down to 18 inches. Using the poles as ribs, he and other technicians constructed an umbrella with a 24-by-28 foot expanse of coated nylon, designed so that the collapsed umbrella could be projected through an 8-by-8 inch airlock passage and deployed over the laboratory.

It was packed, handy-like, in a small metal box and placed in Skylab 2 when the three astronauts were launched into space for their delayed rendezvous with Skylab 1. The astronauts poked the umbrella through the airlock in careful stages. The gadget worked. [A more sophisticated version of Kinzler's idea was produced and flown.]

It wasn't much, really. Just a few fishing poles and a spread of nylon. In all, a modest little miracle, but enough. Enough to save Skylab and enough to give a lift to the spirit of all who followed the latest human drama enacted in space.

The following editorial is taken from Test magazine.

IN OUR PRESENT pre-occupation with consumer products and problems, it is easy to forget the miracles of our great space projects. Skylab's failures tend to bring space and space testing back into focus.

It is possible to speculate, as some authorities are doing already, that the damage done to Skylab on its way into orbit was due either to (a) the unanticipated [314] effects of vibration in the Saturn rocket or (b) the under-design of the failed Skylab components or (c) a combination of both.

In any event, it would seem likely that insufficient testing was done in the effort to live within what is generally considered to be a too-tight budget. After the vast achievements of Project Apollo, one would think that the accumulated knowledge of NASA as to how to achieve the essential near 100% reliability in a space flight would have caused NASA managers to throw out enough stern warnings to Congress and to the public about underfinancing and possible failures. In a project running to two and one-half billion dollars, perhaps another $250 million (10%), for example, for more testing and redesign might have made the difference. At this writing, three highly intelligent, highly trained, highly motivated men are out there trying with all their ingenuity and that of NASA to salvage some part of this all-important basic Skylab mission. Of course, their success in this attempt is fervently prayed for by everyone.

"A Modest Little Miracle," Los Angeles Times , 30 May 1973; R. H. Mattingley, Editor's Page, Test Magazine, June 1973.

May 31

During a Manned Space Flight Management Council telecon, four agenda items were discussed: an early launch date for SL-3; plans for an EVA solar array system repair; deorbiting of the Skylab cluster; and lengthening the SL-2 mission.

The Council decided to go for a 27 July launch date, with the possibility of a further acceleration on a crash effort basis to 22 July if possible degradation of hardware because of unexpected thermal stresses required an earlier launch. Decisions on the other three agenda items were deferred pending further study.

"Minutes of Management Council Telecon," 31 May 1973; memorandum, Dale D. Myers, NASA Hq, to Associate Administrator through Deputy Administrator, "Launch Date for SL-3," 8 June 1973.

June 1

William C. Schneider, NASA Hq, expressed regret that certain experiments would be deleted from the Skylab Program because of loss of the micrometeoroid thermal control shield and the subsequent deployment of the parasol. Schneider also requested that Principal Investigators wishing to make changes in their experiments' protocol submit proposed changes by 5 June 1973, in order that the changes might be reviewed by the Skylab advisory group for experiments.

TWX, William C. Schneider to JSC, MSFC, Dudley Observatory, Naval Research Laboratory, Martin Marietta Corporation, Denver Div., and Westinghouse Electric Corporation, Pittsburgh, "Deletion of Change in Protocol for Certain Experiments on Skylab Missions," 1 June 1973; memorandum, William C. Schneider to Associate Administrator for Manned Space Flight, "Experiments Deleted from Skylab SL-1/ SL-2 Mission-Costs, and Alternate Approaches for Operation on SL-3/SL-4 Missions," 22 June 1973.

June 4

Testing began on 1200 OWS flight food samples and 5 cu m of ground test analytical food samples. They would be exposed to a thermal profile simulating that on the OWS, to verify that the food safety and quality had not been [315] compromised by the 17 days of high temperature to which the OWS had been subjected.

JSC, "Skylab Program Office Weekly Activity Report," 15 June 1973.

June 11 - July 28

The Skylab 3 space vehicle was moved to KSC Launch Complex 39, Pad B, on 11 June in preparation for launch. The space vehicle consisted of a Saturn IB launch vehicle S-IB-207 first stage, S-IVB-207 second stage, and a S-IU-208 instrument unit; a CSM; and a spacecraft lunar module adapter. The SL-3 crew consisted of commander Alan L. Bean, science pilot Owen K. Garriott, and pilot Jack R. Lousma.

On 6 June, the SL-3 launch date had been changed from 8 August to 27 July; the launch date was subsequently changed to 28 July to optimize the rendezvous conditions. The prelaunch checkout was accelerated accordingly.

The S-IVB stage had arrived at KSC on 26 August 1971 and was placed in storage until 28 November 1972. The CSM arrived on 1 December 1972 and was moved into the Operations and Checkout Building for systems testing. The S-IB stage arrived 30 March 1973 and was erected on Mobile Launcher 1 on 28 May. The IU arrived at KSC 9 May.

The S-IVB and IU were mated to the S IB 29 May. On 7 June the CSM/ spacecraft lunar module adapter was moved to the Vehicle Assembly Building and mated to the launch vehicle the following day. SL-3 transfer to LC-39B was completed on 11 June.

On 17 June, the mobile launcher and mobile service structure sustained several lightning strikes. The damaged parts for the CSM, mostly instrumentation, were replaced and retested or waived. The damaged ground support equipment parts were replaced and retested. The launch vehicle lightning retest revealed no related failures or effects on the launch vehicle or ground support equipment.

The flight readiness test was completed on 29 June. The final countdown began at 7:00 a.m. EDT 25 July in preparation for a 28 July launch (see 28 July entry).

KSC, "Skylab 3 Post-Launch Report," 20 August 1973, pp. 7-1, 7-2.

June 15

A review was conducted at NASA Hq to determine whether the astronaut maneuvering unit and foot controller maneuvering unit could be safely used within the confines of the OWS. It was concluded that the units could be safely operated, and approval was given for scheduling their use. Previously, a decision to operate the units had been deferred until a more thorough briefing could be provided. Concern over their use had been based on the Aerospace Safety Advisory Panel Report on Skylab.

Memorandum for record, R. A. Aller, NASA Hq, "Deputy Administrator Briefing on Skylab Experiments M509/T020," 21 June 1973.

June 20

A recommendation to jettison the docking ring and probe assembly on SL-2 while the crew was unsuited was reaffirmed. Major considerations in arriving at the recommendations were that a suited landing was unacceptable, the additional risk of performing the operation unsuited was extremely low, and the crew had trained premission and in flight using the proposed timeline for an unsuited jettison of the docking ring and probe assembly.

Memorandum, Dale D. Myers, NASA Hq, to the Deputy Administrator, "Separation of Docking Ring and Probe Assembly," 20 June 1973.

June 22

At 9:49 a.m. EDT, Skylab 2 splashed down in the Pacific Ocean 9.6 km from the recovery ship, U.S.S. Ticonderoga , and 1320 km southwest of San Diego. At 10:28 a.m., the crew and spacecraft were aboard the Ticonderoga.

The objectives of the SL-1/SL-2 mission were to establish the Orbital Workshop in Earth orbit, obtain medical data on the crew for use in extending the duration of manned space flight, and perform inflight experiments. A summary...

The photograph above, left, shows central Florida and was taken from an altitude of 432 km by the Skylab 2 crew on 13 June 1973. The outlines of the Green Swamp area are (1) Zenith Acres; (2) Groveland Ranch Estates; and (3) Groveland Ranch Acres. The city of Orlando is at center right. Above right is an overhead view of the Skylab space station as photographed from the Skylab 2 CSM during its final flyaround inspection.
Above is a photo of a significant solar flare reproduced from a frame of flight film recovered from the Hydrogen Alpha telescope No.1 and returned on Skylab 2. The solar flare occurred on 15 June 1973.

....assessment of the mission objectives indicated a very high degree of completion, particularly when the reduction in experiment time due to parasol deployment, solar array wing deployment, and OWS system anomalies were considered. Primary mission objectives were accomplished, and a majority of the assigned experiment-detailed objectives were completed.

The following conclusions were drawn from the SL-1/SL-2 mission:

• Resolution of the seemingly insurmountable system difficulties that occurred on the flight demonstrated the advantage of having man on board space vehicles.
• The flight demonstrated that for long-term manned and unmanned space flight, provisions needed to be made for unforeseen inflight repair and [320] maintenance in the form of accessibility, handholds, tools, facilities, materials, and hardware appropriate for interior and exterior operation.
• There were no operationally significant physical or psychological health problems associated with the space vehicle environment for the 28-day visit. There were no findings that would preclude longer duration visits.
• The habitability provisions were satisfactory and contributed to the ability of the crew to work effectively for a visit of this duration. No factors were identified to preclude longer duration visits.
• Operation of the command and service module systems in a semiquiescent state was demonstrated for the 28-day period. No factors were identified which precluded operation for longer periods.
• Extensive scientific data were returned in all planned experiment disciplines
• The methods and techniques employed in the daily flight planning provided the flexibility to react to major departures from preflight plans and constraints. This ability was an important factor in optimizing the scientific return.
• The various experiment groups were organized effectively within each discipline and functioned well as a unit. In addition, with the excellent cooperation between the various experiment groups, flight planning techniques were effective in resolving interdisciplinary conflicts and integrating the diverse experiments program.
• Long-duration flight with sophisticated multidiscipline experiments generated large amounts of data requiring ground data handling and processing capabilities.
• Overall objectives of the visit were accomplished.

Memorandum, Dale D. Myers, NASA Hq, to Administrator, "Skylab Mission SL-1/ SL-2," 10 July 1973; Post-Launch SL l/SL-2 Mission Operation Report No. M-960-73-01102, 14 July 1973; TWX, G. S. Lunney, JSC, to Science Attache, American Embassy, Moscow, 22 June 1973; JSC, Skylab Mission Report First Visit, JSC-08414, August 1973, pp. 14-7 and 18-1.

July 2

NASA Hq issued guidelines for the preparation of a Skylab mission evaluation report that would consist of a unified set of individual reports or sections. The report, which would be prepared by NASA Hq and the three manned spacecraft Centers, would cover such areas as summary and objective assessment, Skylab vehicle description, Orbital Workshop, command and service modules, crew equipment and activities, experiments, pilots' report, and operations.

Letter, William C. Schneider, NASA Hq, to Dist., "Guidelines for Preparation of Unified Skylab Mission Evaluation Report," 2 July 1973; JSC, "Skylab Program Office Weekly Activity Report," 13 July 1973; Skylab Program Directive No. 35, "Skylab Mission Evaluation Requirements," 22 April 1971.

July 3

The launch date for Skylab 3 was officially established as 28 July 1973. The launch window would open at 7:08 a.m. EDT for 10 minutes and would provide for a rendezvous in five revolutions. Recovery of SL-3 was planned for 22 September 1973.

TWX, William C. Schneider, NASA Hq, to JSC, KSC, and MSFC, "SL-3 Launch Date," 3 July 1973; memorandum, Dale D. Myers, NASA Hq, to the Administrator, "SL-3 Launch Date," 5 July 1973.

July 5

William H. Rock was appointed Acting Manager of the Apollo-Skylab Programs at KSC. He succeeded Robert C. Hock, who was named Acting Director of Executive Staff. Rock would also continue to serve in his previous position as Manager, Science and Applications Project Office.

KSC Announcement, "Mr. William H. Rock Named Acting Manager, Apollo-Skylab Programs," 5 July 1973.

July 12

Joint Skylab 3 flight readiness reviews and thermal shield design certification reviews were held at KSC. A comprehensive series of center reviews were completed before, and in preparation for, the flight readiness reviews.

"Minutes of the Skylab SL-3 Flight Readiness Review and the Thermal Shields Delta DCR," 12 July 1973.

July 13

Premature deployment of the meteoroid shield during the Skylab 1 launch interjected additional factors in the consideration of the OWS deorbit. (Reference entry of 3 April 1973.) Because of the additional uncertainties and complications....

....deriving from these factors and the inherent crew and mission risks involved in the OWS deorbit even under expected conditions, the decision was taken to terminate all OWS deorbit efforts.

Letter, William C. Schneider, NASA Hq, to JSC and MSFC, "SWS Deorbit," 13 July 1973

July 17

Testifying before a joint Congressional Committee hearing, astronaut Charles "Pete" Conrad, Jr., stated:

....I like to think of it as the Pete Conrad private citizen approach-as an overall systems design, tie all of these things we talk about with different satellites into a big picture.

Through something like the shuttle vehicle you maintain a space orientation that allows you to do communications, weather, Earth resources. And there are many other things I can conjecture about such as typing computers and telemetry from airplanes for air traffic control. There are all kinds of things you can get into. But I feel that these little niches we are making with the data we brought back from the Moon gave us a system that allowed us to, in a relatively inexpensive manner, fly a space station for the flight that we flew. And it will fly several more flights. And the future says that we have a tremendous capability to help mankind, if it is developed. And I feel it has to be developed in a profitable nature. And that is something this country can do under the free enterprise system. It is the payloads of the future and how they are integrated into the system that will give us all of these benefits, Earth resources, solar technology and many of the other things that are being done by the unmanned satellites. I think man is a necessary link in this system because he has to repair it, maintain it and operate it. That means not only on the ground but also in the air. I could go on forever with what I think....

 

 

....some of the systems could be. But I think we are giving enough data to the citizens of this country that they should appreciate that there is a place for using this system that we have developed that will really bring benefits to many, many people....

U.S. Congress, Senate Committee on Aeronautical and Space Sciences and House Committee on Science and Astronautics, Testimony from Skylab Astronauts: Joint Hearing, 93d Cong., 1st sess., 17 July 1973, p. 10.

July 25

Twice-weekly experiment planning meetings were being instituted for the 59-day Skylab 3 mission. The purpose of the meetings was to formulate a balanced set of experiment requirements for each upcoming week based on a consideration of plans for the remainder of the mission.

Letter, William C. Schneider, NASA Hq, to Principal Investigators, "Second Skylab Mission," 25 July 1973.

July 28

[324] Skylab 3 lifted off from Pad B, Launch Complex 39, KSC, at 7:10:50.5 a.m. EDT. The vehicle was manned by astronauts Alan L. Bean, Owen K. Garriott, and Jack R. Lousma.

The space vehicle, consisting of a modified Apollo command and service module payload on a Saturn IB launch vehicle, was inserted into a 231.3 by 154.7 km orbit. Rendezvous maneuvers were performed during the first five orbits as planned. During the rendezvous, the CSM reaction control system forward firing engine oxidizer valve leaked. The quad was isolated. Station-keeping with the Saturn Workshop began approximately 8 hours after liftoff, with docking being performed about 30 minutes later.

JSC, Skylab Mission Report Second Visit, JSC-08662, January 1974, p. 2-1.

July 28 - September 25

The Skylab 3 crewmen experienced motion sickness during the first three visit days. Consequently, the Orbital Workshop activation and experiment implementation activities were curtailed. By adjusting the crew's diet and maintaining a low workload, the crew was able to complete the adjustment to space flight in five days, after which flight activities returned to normal.

On 2 August the service module reaction control system engines were inhibited, and the isolation valves closed because of another leak. Acceptable control modes and deorbit and entry procedures were defined, consistent with the constraints imposed by the two reaction control system problems.

The first extravehicular activity was delayed until 6 August because of the crew's motion sickness. The EVA lasted almost six and one-half hours during which time the crew changed the Apollo telescope mount film, deployed the twin-pole sun shield (see 6 August entry), inspected and performed repair work on the S055 (ultraviolet spectrometer) experiment, deployed the S149 (particle collection) experiment, and installed the calibration shield from experiment S230 (magnetospheric particle composition).

A second EVA was performed on 24 August. It lasted 4 hours 30 minutes. The tasks accomplished included installation of a rate gyro package, deployment of a thermal shield material sample, retrieval and replacement of the ATM work station film, temporary stowage of the experiment S149 in the fixed airlock shroud and redeployment at the Sun end, and removal of the aperture door/ramp latch from two ATM experiments.

A third EVA was accomplished in 2 hours and 45 minutes on 22 September. Its purpose was to retrieve the expended film on the ATM solar experiments and experiments S230 and S149.

Earth resources experiment package activities included 39 passes with a total of 930 minutes of data. All experiment coverage was normal with the exception [325] of the loss of experiment S193 (microwave radiometer/scatterometer and altimeter) when the antenna failed to operate during data pass 29.

A series of medical experiments was accomplished which assessed the effect of a 59-day space mission on the crewmen. Included were a hematology and immunology program, a mineral balance assessment, an evaluation of the changes in hormonal and associated fluid and electrolyte parameters, the extent of bone mineral loss, the cardiovascular effects utilizing the lower body negative pressure experiment and the vector-cardiogram, and an assessment of metabolic activity.

Four astrophysics experiments were successfully performed: experiment S019 (ultraviolet stellar astronomy); experiment S063 (ultraviolet and visible Earth photography); experiment S149 (particle collection); and experiment S230 (magnetospheric particle composition). Data were obtained for studies of the habitability and crew quarters and crew activities and maintenance. In addition, several experiment M509 (astronaut maneuvering unit) sequences were performed. The chart below gives a comparison of the actual crew time devoted to experiments as opposed to that allocated in the preflight plan.

On 25 September, the command module was reactivated and the crew performed the final OWS closeout. Following undocking and separation, the command module entered the atmosphere and landed in the Pacific Ocean approximately 300 km southwest of San Diego. Splashdown was at 6:20 p.m. EDT. The recovery ship, U.S.S. New Orleans, retrieved the command module and crew 42 minutes after landing. The total flight time was 1427 hours 9 minutes 4 seconds.

R. V. Gordon, "JSC PAO Skylab Activities Summary," September 1973; JSC, Skylab Mission Report Second Visit, JSC-08662, January 1974, pp. 2-1, 2-2, and 15-2.

July 30

[326] Lewis Research Center Director Bruce T. Lundin, who served as chairman of the Skylab 1 Investigation Board, presented the findings of the board and the recommended corrective actions in congressional testimony:

'.. . the Board developed 14 findings, quoted directly herein as contained in o~ report to the Administrator of NASA.

 

1. The launch anomaly that occurred at approximately 63 seconds after liftoff was a failure of the meteoroid shield of the OWS.

2. The SAS-2 wing tie downs were broken by the action of the meteoroid shield at 63 seconds. Subsequent loss of the SAS-2 wing was caused by retrorocket plume impingement on the partially deployed wing at 593 seconds.

3. The failure of the S-II interstage adapter to separate in flight was probably due to damage to the ordnance separation device by falling debris from the meteoroid shield.

4. The most probable cause of the failure of the meteoroid shield was internal pressurization of its auxiliary tunnel. This internal pressurization acted to force the forward end of the tunnel and meteoroid shield away from the OWS and into the supersonic air stream. The resulting forces tore the meteoroid shield from the OWS.

5. The pressurization of the auxiliary tunnel resulted from the admission of high pressure air into the tunnel through several openings in the aft end. These openings were: (1) An imperfect fit of the tunnel with the aft fairing; (2) an open boot seal between the tunnel and the tank surface; and (3) open stringers on the aft skirt under the tunnel.

6. The venting analysis for the tunnel was predicated on a completely sealed aft end. The openings in the aft end of the tunnel thus resulted from a failure to communicate this critical design feature among aerodynamics, structural design, and manufacturing personnel.

7. Other marginal aspects of the design of the meteoroid shield which, when taken together, could also result in failure during launch are:

a. The proximity of the MS [meteoroid shield] forward reinforcing angle to the air stream.

b. The existence of gaps between the OWS and the forward ends of the MS.

c. The light spring force of the auxiliary tunnel frames.

d. The aerodynamic crushing loads on the auxiliary tunnel frames in flight.

e. The action of the torsion-bar actuated swing links applying an outward radial force to the MS.

f. The inherent longitudinal flexibility of the shield assembly.

g. The nonuniform expansion of the OWS tank when pressurized.

h. The inherent difficulty in rigging for flight and associated uncertain tension loads in the shield.

8. The failure to recognize many of these marginal design features through 6 years of analysis, design and test was due, in part, to a presumption that the meteoroid shield would be "tight to the tank" and "structurally integral with the S-IVB tank" as set forth in the design criteria.

9). Organizationally, the meteoroid shield was treated as a structural subsystem. The absence of a designated 'project engineer" for the shield contributed to the lack of effective integration of the various structural, aerodynamic, aeroelastic, test, fabrication, and assembly aspects of the MS system.

10. The overall management system used for Skylab was essentially the same as that developed in the Apollo program. This system was fully operational for [327] Skylab; no conflicts or inconsistencies were found in the records of the management reviews. Nonetheless, the significance of the aerodynamic loads on the MS during launch was not revealed by the extensive review process.

11. No evidence was found to indicate that the design, development, and testing of the meteoroid shield were compromised by limitations of funds or time. The quality of workmanship applied to the MS was adequate for its intended purpose.

12. Given the basic view that the meteoroid shield was to be completely in contact with and perform as structurally integral with the S-IVB tank, the testing emphasis on ordnance performance and shield deployment was appropriate.

13. Engineering and management personnel on Skylab, on the part of both contractor and Government, were available from the prior Saturn deployment and were highly experienced and adequate in number.

14. The failure to recognize these design deficiencies of the meteoroid shield, as well as to communicate within the project the critical nature of its proper venting, must therefore be attributed to an absence of sound engineering judgment and alert engineering Ieadership concerning this particular system over a considerable period of time.

'These findings led the Board to offer the following four corrective actions, again quoted directly from our report to the Administrator.

1. If the backup OWS or a similar spacecraft is to be flown in the future, a possible course of action is to omit the meteoroid shield, suitably coat the OWS for thermal control, and accept the meteoroid protection afforded by the OWS tank walls. If, on the other hand, additional protection should be necessary, the Board is attracted to the concept of a fixed, nondeployable shield.

2. To reduce the probability of separation failures such as occurred at the S 11 interstage second separation plane, linear shaped charges should be detonated simultaneously from both ends. In addition, all other similar ordnance applications should be reviewed for a similar failure mode.

3. Structural systems that have to move or deploy, or that involve other mechanisms, equipment or components for their operation should not be considered solely as a piece of structure nor be the exclusive responsibility of a structures organization.

4. Complex, multidisciplinary systems such as the meteoroid shield should have a designated project engineer who is responsible for all aspects of analysis, design, fabrication, test, and assembly."

U.S. Congress, Senate, Committee on Aeronautical and Space Sciences, Skylab-Part 2; Hearing on Report of Skylab 1 Investigation Board, 93d Cong., 1st sess., 30 July 1973, pp.25-26; U.S. Congress, House, Subcommittee on Manned Space Flight of the Committee on Science and Astronautics, Skylab 1 Investigation report: Hearing, 93rd Cong., 1st. sess., 1 August 1973, pp. 29-30; memorandum, G.M. Low, NASA Hq, to Program Associate Administrators, "Skylab 1 Investigation Board Report," 19 July 1973.

July 30

In a letter to the White House, NASA Administrator James C. Fletcher summarized the Skylab 2 mission:

....A situation that was bleak indeed on May 14, and for several days thereafter, improved to, a point well beyond our most optimistic forecasts at that time. 'This of course was due to a courageous crew and a dedicated team of government and industrial contractor personnel, whose dedication and ability cannot be over emphasized.

[328] Not only was the crew able to accomplish the great majority of the technical and scientific objectives established for this first Skylab mission, but they were able also to repair the Skylab space station and leave it in a condition which will allow the satisfactory completion of nearly all that we desired from the overall Skylab Program, with the unexpected additional accomplishments of demonstrating the ability to respond to adversity and demonstrating the flexibility provided by the use of man and his faculties in a hostile environment....

Letter, James C. Fletcher to the President, 30 July 1973.

August 1

Skylab 2 postflight medical debriefings indicated the desirability of minimizing crew exposure to recovery ship motions for both crew reconditioning and postrecovery medical evaluations. In order to provide the Skylab 3 crew with this minimum exposure, mission duration was extended to 59 days. This allowed for a splashdown closer than 550 km of San Diego, and a crew stay time aboard the recovery ship of only 17 hours.

Letter, William C. Schneider, NASA Hq, to Associate Administrator for Manned Space Flight, "SL-3 Mission Duration," 1 August 1973.

August 2

During weekly medical briefings scheduled to begin on Thursday, 23 August, JSC would provide the Skylab Program Director with an in-depth review on all medical experiments and a consolidated systems-type clinical summary on crew health status. Where possible, a projection of anticipated crew performance would also be presented.

Letter, Kenneth S. Kleinknecht, JSC, to Skylab Program Director, "Medical Review of SL-3 Results," 2 August 1973; TWX, William C. Schneider, NASA Hq, to JSC Manager, Skylab Program, "Medical Status," 26 July 1973.

August 6

During EVA by crew members of Skylab 3, a twin-boom sunshade, developed by MSFC, was deployed over the parasol of the OWS. A redesigned and refined thermal parasol had been launched with Skylab 3. However, its use would have required jettisoning the parasol deployed by crew members of Skylab 2, with the possibility of creating the same thermal problems that existed on the OWS prior to the parasol deployment. Following erection of the twin-pole sunshade, the cabin temperature stayed at a comfortable 293-297 K (67.7°F-74.9°F).

JSC, Skylab Mission Report Second Visit, JSC-08662, January 1974, pp. 3-1 and 10-37.

August 6

Anomalies that had occurred during micrometeoroid shield testing were summarized:

A series of deployment tests were conducted on the micrometeoroid shield during the course of two years prior to launch. Only one component actually failed during this testing. This failure was the rupture of an ordnance expandable tube which did not affect its intended function of breaking the tension strap, but did allow contaminants in the form of explosive residue to be released. Redesign was accomplished and no further problems were encountered.

[329] Other anomalies that occurred which precluded the tests from being successful were misalignment of deployment latches and failure of latches to engage. All deployment tests were successful from the standpoint of deploying the micrometeoroid shield to a position which would have been acceptable for orbital operations.

A second micrometeoroid shield component failure occurred during ultimate pressure testing of the dynamic test article. Three of twenty-four hinges that connect the micrometeoroid shield to the straps which run under the main tunnel yielded. The straps were subsequently redesigned to provide greater strength and no further problems were encountered.

The decision to utilize solar panels instead of fuel cells or some form of generator was not made because of economical reasons. Fuel cells had originally been considered; however, due to extension of the mission to 240 days total, and the continued increase in power requirements, the fuel cell concept became inadequate. The solar panels were developed to satisfy the extended mission and high power requirements.

Memorandum, W. K. Simmons, Jr., MSFC, to G. C. Hunt, MSFG, "Skylab Micrometeoroid Shield Inquiry," 6 August 1973.

August 7-15

A meeting was held at MSFC to define a viewing program for the comet Kohoutek during the SL-4 mission. Representatives from NASA Hq, MSFC, GSFC, and JSC attended. Results of a feasibility study for viewing the comet were presented to the NASA Administrator on 15 August. It was agreed that observations of Kohoutek would he made at appropriate times during the SL-4 mission.

JSC, "Skylab Program Office Weekly Activity Reports," 10 August and 23 August 1973; TWX, William C. Schneider, NASA Hq, to MSFC, JSC, and KSC, "SL-4 Mission Schedule," 16 August 1973.

August 13

NASA decided to delete the Skylab backup Saturn V Orbital Workshop launch capability effective 15 August. All work associated with the completion, checkout, and support of Skylab backup hardware, experiments, software, facilities, and ground support equipment would be canceled immediately, except for the work that would directly support SL-3, SL-4, and rescue missions.

Memoranda, Dale D. Myers, NASA Hq, to James C. Fletcher, NASA Hq, "Cancellation of Skylab Back-up Saturn V Workshop Launch Capability," 8 August 1973; James C. Fletcher to Dale D. Myers, same subject, 13 August 1973; TWX, William C. Schneider, NASA Hq, to JSC, MSFC, KSC, LaRC, and ARC, same subject, 15 August 1973.

August 14 - November 16

The Skylab 4 space vehicle was moved from the KSC Vehicle Assembly Building to Launch Complex 39, Pad B, on 14 August. The space vehicle consisted of a Saturn IB launch vehicle-S-IB-208 first stage, S-IVB-208 second stage, and S-IU-207 instrument unit; a CSM-118; and a spacecraft lunar module adapter. The SL 4 crew was made up of commander Gerald P. Carr, science pilot Edward G. Gibson, and pilot William R. Pogue.

[330] The S-IVB stage had arrived at KSC on 4 November 1971 and had been placed in storage until 15 December 1972. The CSM arrived on 10 February 1973 and was moved into the Operations and Checkout Building for systems testing. The S-IB stage arrived on 20 June 1973 and was erected on Mobile Launcher 1 on 31 July 1973. The IU arrived at KSC on 12 June 1973. The S-IVB and IU were mated to the S IB on 1 August 1973.

The processing schedule was accelerated on 3 August to a seven-day, 24-hours-per-day workweek to make SL-4 ready for a possible early flight to rescue the orbiting SL-3 crew, which was having serious leakage problems in their service module reaction control system. This accelerated schedule would support a launch on 9 September. As a better understanding of the SL-3 problem was obtained, the SL 4 checkout flow was adjusted on 13 August to support an earliest launch date of 25 September, which allowed a complete spacecraft integrated systems test to be conducted. With this schedule, hypergolic loading, anticipated for 9 September, would he a decision point for a rescue need with earliest launch readiness of a rescue mission nine days from commitment to hypergolic load. Upon completion of the hypergolic loading preparations on 10 September, the space vehicle remained on a launch minus nine days status until the splashdown of SL-3 on 25 September, when the schedule was readjusted for a 10 November launch.

On 15 August, the mobile launcher sustained several lightning strikes. Damaged components of the CSM, mostly guidance system units, were replaced and retested. The launch vehicle lightning retest revealed no related failures or effects on the launch vehicle or ground support equipment.

Cracks in an S-IB upper "E" beam forging were found on 27 August; repairs were completed on 3 September.

The flight readiness test was completed on 5 September. Processing of the space vehicle continued until 9 September, at which point it was ready for start of hypergolic loading. The space vehicle remained in this mode until 25 September, when the SL-3 astronauts splashed down successfully. Scheduled processing began immediately for a standard mission November launch.

A rerun of the flight readiness test was completed on 11 October Space vehicle hypergolic loading was completed on 19 October. On 23 October, two S-IB fuel tank domes were inverted due to a partial vacuum pulled on the tanks; two days later a tank pressurization returned the tanks to their original configuration.

As on SL-3, the countdown demonstration test was combined with the countdown into one function, with a launch countdown-wet (LCD-wet) followed by securing and 42 1/2 hours of final countdown tasks. The LCD-wet began at 10:00 p.m. EST on 28 October and finished at 11 :40 a.m. EST on 2 November.

Discovery and repair of cracks in the S-IB fins caused a five-day postponement of the launch date, and one additional day was needed to inspect the S-IVB [331] structure. These delays moved the scheduled launch date to 16 November. The final countdown began at 2:30 a.m. EST on 14 November with launch at 9:01 a.m. EST, 16 November (see 16 November entry).

KSC, "Skylab 4 Post-Launch Report," 10 December 1973, pp. 7-1, 7-2; Astronautics and Aeronautics, 1973 (NASA SP-4018), Washington, D.C., 1975, p. 244.

August 16

A telecon was held to discuss the guidelines to be used for SL 4 planning. The key points resulting from this discussion were:

(1) The normal mission launch would be scheduled to allow the first fifth orbit rendezvous opportunity occurring on or after 9 November 1973. Current estimates indicated an 11 November launch.

(2) The mission would be planned for a nominal 56- to 59-day duration. Splashdown date would be adjusted so that a return to port would be accomplished within 24 hours after recovery.

(3) There would be no primary recovery ship utilization planned for other than a normal end-of- mission recovery.

(4) KSC would continue the present rescue vehicle flow through 9 September 1973 (readiness for hypergolic loading), at which time a hold mode with a nine-day launch capability would be maintained. The decision to load hypergolics would be made by the Program Director.

(5) A review to examine the Workshop systems fully would be held on 17 September 1973, at which time the capability of the Workshop to perform the normal scheduled mission on the scheduled date would be established. For planning purposes, a minimum of 21 days' preparation would be allowed for an orderly launch acceleration if the review showed such a necessity.

(6) At SL 3 splashdown, the SL-4 KSC flow would revert to the normal mode. Retesting and additional tests would be performed as necessary.

(7) The SL-4 mission was not to be predicated on the availability of the S201 far ultraviolet camera. However, attempts would be made to accomplish its development.

(8) Onboard consumables would be reserved for comet observations. Film was to be budgeted to ensure that an ample quantity was available for the comet viewing period. Mission planning would assume no additional film or tapes beyond those currently baselined.

(9) Three EVAs would be baselined for conduct of scientific experiments. However, expendables to enable one unscheduled EVA for system contingencies would be provisioned. Mission planning would reserve those expendables.

(10) Comet observation would be given the highest priority over other experiment activities during the period from 16 December 1973 to the end of the mission.

(11) One maneuver per day would be baselined for comet observation, with a goal to conduct an added maneuver to meet established experiment objectives . Maneuvers would be constrained as outlined in the systems management criteria document.

[332] (12) Funding for the experiment modifications would be the responsibility of the development center after 16 August 1973.

TWX, William C. Schneider, NASA Hq, to JSC, KSC, and MSFC, "SL-4 Planning," 17 August 1973.

August 30

Guidelines were issued by NASA Hq for release, disposition, and storage of all unneeded Skylab Program equipment. Two Saturn Vs, two Saturn IBs, three command and service modules, the backup Skylab cluster, and appropriate spares would be placed in minimum cost storage as soon as program requirements permitted.

Letter, William C. Schneider, NASA Hq, to MSFC, JSC, and KSC, "Storage and Disposition of Skylab Hardware and Associated GSE,' 30 August 1973; TWX, William C. Schneider to KSC, MSFC, and JSC, "Teleconference on Storage and Disposition of Excess Skylab Hardware and Associated GSE," 26 September 1973.

August 31

The results of solar radiation tests on the Skylab parasol material was released by LaRC. The accelerated testing indicated more severe degradation than would be experienced had the tests been conducted in real-time conditions. However, even with the severe degradation rate, the samples retained over 50 percent of their original tensile strength and elongation and showed no signs of delamination after the equivalent of 3316 solar hours of exposure.

Letter, Wayne S. Slemp, LaRC, to S. Jacobs, JSC, "Results of Tests on Skylab Parasol Material," 31 August 1973.

September 6

At the request of the Space Shuttle Program Manager, equipment had been carried aboard a Navy salvage vessel (a part of the launch abort contingency task force) for the purpose of monitoring the sonic booms created by Skylab 1 and 2 launch vehicles. However, the necessary data were not obtained from the SL-2 launch because the ray pattern was distorted away from the salvage ship by a high-altitude inversion layer. Therefore, it would be necessary to obtain sonic boom data from the SL-4 mission. Action was being initiated to accomplish this.

Memorandum, M. S. Malkin, NASA Hq, to Director, Skylab Program, "Obtaining Sonic Boom Data During Skylab Launch," 6 September 1973; TWX, William C. Schneider, NASA Hq, to Kenneth S. Kleinknecht, JSC, "Langley Research Center Sonic Boom Tests for Skylab 1/2," 7 May 1973.

September 6

At a Kohoutek status meeting, JSC w as requested to determine if additional ultraviolet eye protection would be required by the Skylab 4 astronaut while performing Kohoutek operations. A study indicated that no additional eye protective devices would be required for either intra- or extravehicular viewing of the comet. The use of the existing space suit sun visors would be required during extravehicular viewing.

JSC, "Skylab Program Office Weekly Activity Report," 21 September 1973.

September 13

[333] Discussions confirmed that there was reasonable assurance that an Apollo-Soyuz Test Project (ASTP) revisit to Skylab in mid-1975 was feasible. However, such a dual mission would create a significant planning problem for the operations team and would introduce many new considerations to the inflight planning and execution because of uncertainties in the orbital mechanics.

Memorandum, William C. Schneider, NASA Hq, to the Program Director ASTP, "ASTP-Skylab Revisit," 13 September 1973; letter, G. S. Lunney, JSC, to Program Director, ASTP, "Skylab Revisit," 26 November 1973.

September 15

The Director of the Skylab Program, in offering his counterpart in the ASTP some advice in establishing an ASTP television program, stated: " . . . I ascribe at least two of my many ulcers to television. It's an emotional subject because everyone is an expert on requirements. If you can get:

a. The groundrules stated,

b. The requirements from the senior man who feels responsible,

c. Then treat it like any other requirement,

d. Put a discipline in the system more rigorous than I did,

e. Take the requirements people out of the day-to-day implementation, you may only get only one TV ulcer."

Memorandum, William C. Schneider, NASA Hq, to Director, Apollo-Soyuz Test Project, "Skylab Television Experience," 15 September 1973.

September 18

Fish and embryo that were part of a Skylab science demonstration would be returned to JSC by Skylab 3, provided that one or more of the fish were still alive at the time of deactivation. Upon return to the recovery ship, the fish would be photographed and observed to determine any reaction to the one-g environment. They would then be returned to JSC for comparison with the backup fish and embryo which were being held in the JSC laboratory. Later histological observations and examinations of their vestibular apparatus would be performed to determine any changes between the two groups.

Memorandum, William C Schneider, NASA Hq, to Associate Administrator for Manned Space Flight, "Return of Fish and/or Embryo and SL-3," 21 September 1973

September 18

More high-quality solar data were recorded by the SL-1/2 mission than all previous solar research efforts combined. This was achieved with the ATM-a configuration of high-resolution instruments on a single platform with a wide range of spectral coverage pointed simultaneously at specific targets. In addition, man was integrated as a scientific observer, operator, and repairman to ensure maximum return of data.

Letter, R. Ise, MSFC to Dist., "ATM Results," 18 September 1973.

September 21

The final Earth resources experiment package pass for Skylab 3 ended. In all, 39 Earth-oriented passes, six solar inertial passes, two Earth-limb surveys, and two lunar calibration sequences were completed.

The 15 hours of data acquisition was about 40-percent higher than the premission flight plan and included 15 780 photographs and 28 000 m of magnetic tape. Data were acquired over the United States, Central and South America, Europe, Africa, Japan, and Southeast .Asia. Special observations were made of tropical storm Christine, the Sargasso Sea, the African drought area, and the Pakistan flood area. Oblique and nadir photography was obtained for most of Paraguay as part of a joint U.S./IAGS (Inter-American Geodetic Survey) Paraguay mapping experiment.

Memorandum, T. L. Fischetti, NASA Hq, to Dist., "SL-3 Summary and EREP Program Status," 26 September 1973.

September 25

All primary mission objectives for Skylab 3 were accomplished with the safe recovery of the crew and vehicle. These objectives were to

(1) Perform unmanned Saturn Workshop operations by obtaining data for evaluating the performance of the unmanned Saturn Workshop and obtaining solar astronomy data through unmanned ATM observations.

(2) Reactivate the orbital assembly in Earth orbit by operating the orbital assembly (Orbital Workshop plus command and service module) as a habitable space structure for up to 59 days after the launch of the second-visit spacecraft and obtaining data for evaluating crew mobility and work capability during both intravehicular and extravehicular activities.

(3) Obtain medical data on the crew for use in extended duration manned space flights by obtaining medical data for determining the effects on the crew of a space flight of up to 59 days' duration and obtaining medical data for determining if a subsequent Skylab mission of greater than 59 days' duration is feasible and advisable.

(4) Perform inflight experiments by obtaining ATM solar astronomy data for continuing and extending solar studies beyond the limits of Earth-based observations; obtaining Earth-resources data for continuing and extending multisensor observation of the Earth from low-Earth orbit; and performing the assigned scientific, engineering, technology, and Department of Defense experiments.

A summary of the objectives accomplished showed a very high degree of completion, especially considering the reduction of experiment time early in the mission caused by the motion-sickness problems. After the first few days, the crew quickly caught up and, during the remainder of the mission, exceeded the preplanned workload. For many experiments, the baseline requirements were exceeded, and a number of experiments planned for the third visit were accomplished. (See chart in entry for 28 July--25 September 1974.)

From the successful completion of the Skylab 3 mission, the following conclusions [336] were reached:

(1) The ability of the crew to correct systems difficulties by actions such as deployment of the twin-pole sunshield, replacement of the rate gyro package, repair of the teleprinter, and repair of the ATM experiment door enabled the second visit to proceed as planned and again demonstrated the advantage of having man on board the vehicle.

(2) Revisits provided the opportunity to correct hardware problems, restructure objectives, and revise replaceable commodities based on actual experience.

(3) Psychological and physical conditions resulting from the 59-day mission indicated no constraints for longer duration flights.

(4) Ordinary hand tools could have been used effectively in place of special tools in the zero-g environment when making repairs and adjustments.

(5) The limitations of noncontinuous ground station coverage imposed restrictions on data return, systems management, and uplink information.

(6) The skills learned in underwater training were almost identical to the skills used in actual performance of tasks during EVA and, if instructions were adequate, a crewman could perform extravehicular tasks for which he had not specifically trained. Tasks were somewhat easier to perform in zero-g than in underwater training.

JSC, Skylab, Mission Report Second Visit, JSC-08662, January 1972, pp. 14-1, 14-2, and 18-1; memorandum, William C. Schneider, NASA Hq, to the Administrator, 15 October 1973.

October 4

An ad hoc committee was established to analyze the vestibular problems which occurred in previous manned space flights and to make recommendations concerning prevention and control on future flights. Particular emphasis was placed on the experiences of the Skylab 3 crew. As a result of the committee meeting, it was recommended that the crewmen of SL-4 take anti-motion-sickness medication immediately upon orbital insertion and follow this with periodic doses for the first three days of flight.

Memoranda, S. B. Vinograd, NASA Hq, to the JSC Director of Life Sciences, "Ad Hoc Committee on Skylab Vestibular Effects," 4 October 1973; C. A. Berry, NASA Hq, to Director, Skylab Program, "Use of Anti-Motion-Sickness Medication for SL-4 Launch," 5 November 1973; Kenneth S. Kleinknecht, JSC, to Skylab Program Director, "Medical Action Items," 6 November 1973; William C. Schneider, NASA Hq, to JSC Skylab Program Director, "Skylab Action Items," 9 November 1973.

October 5

All elements of the Skylab organization (NASA Hq, JSC, MSFC, and KSC) would prepare documentation of significant Skylab experiences. Preliminary drafts of these "Lessons Learned" would be circulated to other Centers and Headquarters for review and comment prior to final publication. It was anticipated that the reports would be ready for final publication about the time of the SL-4 splashdown.

[337] Letters, William C. Schneider, NASA Hq, to MSFC, JSC, and KSC, "Documentation of Significant Skylab Experiences," 5 October 1973. William C. Schneider to Ames Research Center, same subject, 6 December 1973; JSC, "Skylab Program Office Weekly Activity Report," 7 December 1973.

October 20

The crew of Skylab 4 began a 21-day prelaunch isolation period. Established prelaunch procedures required each Skylab flight crew to begin a health stabilization program 21 days before liftoff.

JSC News Release 73-138, "Astronauts to Begin Isolation Period," 23 October 1973.

October 24

A review of Skylab 3 medical data and SL-4 mission planning was conducted by the NASA Administrator. Among the items covered were a plan for measuring both the pre- and postflight cardiac outputs of the SL-4 crew; elimination of all activities in the deactivation sequence not absolutely required; and a plan for accommodation of the circadian shift necessary for missions of various durations.

TWX, William C. Schneider, NASA Hq, to JSC, MSFC, and KSC, "Skylab Mission and Medical Review," 25 October 1973.

October 30

Because of an extension in mission duration and changes in mission requirements, publication deadlines would not be met for a final flight plan for Skylab 4. Therefore, summaries were in preparation that would incorporate all known changes in mission requirements. These would be available for limited distribution prior to liftoff.

Memorandum, J. W. Bilodeau JSC, to' Dist., "SL-4 Flight Plan," 30 October 1973.

October 30 - November 6

Two vials, each containing 500 gypsy moth eggs, were hand carried to JSC from the Department of Agriculture. After being loaded in flight containers, they were hand carried to KSC. The eggs would be launched on Skylab 4 and then transferred to the OWS sleep compartment area where they would be monitored during the course of the SL-4 mission. The eggs were being carried at the request of the Secretary of Agriculture.

JSC, "Skylab Program Office Weekly Activity Reports," 3 and 9 November 1973.

November 6

A shift in the Skylab 4 launch schedule was required in order to replace eight cracked fins on the S-IB. The hairline cracks were discovered during a postcountdown demonstration test inspection. Initial indications were that the 14 cracks were caused by load stress or salt air, or possibly a combination of both.

"Minutes of Manned Space Flight Management Council Meeting," 7 November 1973.

November 6

A high-energy food bar was added to the menu of the Skylab 4 astronauts. The 72 kg of additional food placed aboard the SL-4 command module included 39 kg of high-energy food bars and would supply sufficient food for an extension [338] of the mission to 85 days, plus an additional 10 days' supply for a rescue capability. The food bars, which contained 300 calories each, would be used by the crewmen every third day of the mission in combination with the normal Skylab food. There were three kinds of energy bars-chocolate chip, crispy, and flake. Each was coated with one of three flavors- vanilla, chocolate, or strawberry- making nine different varieties. The bar, a modification of a commercially available Pillsbury food stick, was all offspring of a bar developed jointly by NASA, the U.S. Air Force, and the Pillsbury Company.

JSC News Release 73-143, "New Food for Third Skylab Mission," 6 November 1973.

November 14

A launch readiness review was held at KSC. From the review and closeout of action items, the Skylab 4 vehicle was determined to be ready for launch on 16 November 1973. Other reviews included the KSC flight readiness review, 18 October; the JSC Director's flight readiness review and the JSC command and service module flight readiness review, 11 October; the MSFC review of the Skylab Workshop systems capabilities, 17 September; and the KSC SL-4 launch readiness review, 15 October 1973.

Letters, W. C. Schneider, NASA Hq, to Skylab 4 Flight Readiness Review Record, "Confirmation of Flight Readiness for Skylab 4," 14 November 1973; W. H. Rock, KSC, to JSC Skylab Program Manager, "SL-4 Launch Readiness Review," 4 October 1973; memoranda, W. C. Schneider to Dist., "Skylab L-2 Day Readiness Review for SL-4," 17 October 1973; W. C. Schneider to JSC, MSFC, and KSC, "SL-4 Planning," 4 October 1973; W. C. Schneider to MSFC and JSC, "Mission Planning for SL-4," 26 September 1973; W. C. Schneider to Dist., "Skylab Systems Status Review for SL-4 Launch Planning," 19 September 1973; TWXs, W. C. Schneider to JSC, MSFC, KSC, and GSFC, "SL-4 FRR and DCR Schedule," 7 September 1973; L. F. Belew, MSFC, to NASA Hq, KSC, and JSC, "SL-4 Pre-Mission Planning and SWS Systems Status Review," 7 September 1973; "Minutes of JSC Flight Readiness Review for Skylab 4," 16 October 1973; "Minutes of JSC Flight Readiness Review Board CSM 118/SLA 24," 11 October 1973.

November 16

Skylab 4 was launched at 10:01:23 a.m. EDT from Pad B, LC-39, at KSC. Planned duration of the mission was 56 days, with the option of extending it to a maximum of 84 days. The crewmen were Gerald P. Carr, Edward G. Gibson, and William R. Pogue.

The space vehicle consisted of a modified Apollo CSM and a Saturn IB launch vehicle. All launch phase events were normal, and the CSM was inserted into a 150.1- by 227.08-km orbit. The rendezvous sequence was performed according to the anticipated timeline. Stationkeeping was initiated about seven and one-half hours after liftoff, and hard docking was achieved about 30 minutes later following two unsuccessful docking attempts.

JSC, Skylab Mission Report Third Visit, JSC-08963, July 1974, p. 2-1.

November 17 - February 7

During 17 and 18 November, Orbital Workshop activation was accomplished by the crew of Skylab 4. The reactivation included the reservicing of the airlock module primary coolant loop.

The commander and pilot experienced symptoms resembling motion sickness during the initial three days of the visit, and flight plan activities were adjusted accordingly. Crew health was good thereafter. The medical experiments conducted during the first and second visits were continued during the third visit to assess the effects of the space visit on the crewmen. Some changes were made, and many new medical detailed test objectives were added.

EREP observations were conducted throughout the visit. Thirty-nine data passes were performed with the full complement of instruments operating, and several additional data passes were made for special purposes such as instrument calibration. Although the data acquisition sites were mostly concentrated in the United States, Mexico, and South America, data were also obtained while over Europe, Africa, Asia, and Australia. In addition to the EREP observations, about 850 visual observations were made, and more than 2000 photographs were taken by the crew using hand-held cameras to document specific areas of interest on Earth.

The Apollo telescope mount was operated by the crew for a total time of approximately 519 hours, with over 337 hours of solar, stellar, and Comet Kohoutek data being obtained. Some of the significant accomplishments were obtaining coverage of the Comet Kohoutek, a solar eclipse, the brightest coronal transient observed during the Skylab Program, and two solar flares which included flare rise.

Twenty-eight experiments in the fields of astrophysics, engineering, and technology were included in the third visit, and 235 crew man-hours were devoted to their...

Top, left, is a view of the Comet Kohoutek from Skylab 4 on 25 December 1974, when its halo was about 2.6 million km in diameter. At top right, on the same day Kohoutek's tail was approximately 4.8 million km long. Above right, is a 19 December 1973 photo of the most spectacular solar flare yet recorded (upper left), spanning more than 588 000 km across the solar surface. The darkened areas at top and bottom are polar areas. At right is a near-vertical Earth view, showing about 30 percent of Wyoming and small portions of Montana and Idaho; the dark area at left is Yellowstone National Park. Above is view of the ice-filled mouth of the St.Lawrence River in Canada; Anticosti Island is in the center.

[341] ....performance. More than 200 man-hours were devoted to Comet Kohoutek observations, with six special experiments plus the ATM instruments.

Orbital activities included four periods of EVA totaling approximately 221/4 hours. The first EVA was accomplished 22 November and lasted 6 hours 34 minutes. The primary purpose of the activity-installation of film magazines in the ATM cameras-was accomplished satisfactorily. Other tasks accomplished included performing corrective maintenance on the experiment S193 (microwave radiometer/scatterometer and altimeter) antenna, deploying panels of experiment D024 (thermal control coatings), deploying impact detectors of experiment S149 (particle collection), deploying detector modules of experiment S228 (trans-uranic cosmic rays), and deploying collector assemblies of experiment S230 (magnetospheric particle composition).

The second and third EVAs were conducted on Christmas day and 29 December to take photographs of the Comet Kohoutek; prior to and after perihelion. The instruments for experiments S201 (extreme ultraviolet camera) and T025 (coronagraph contamination experiment) were used for this purpose. Experiment S020 (X-ray/ultraviolet solar photography) was also conducted on the second and third EVAs. Other tasks performed during the extravehicular activity consisted of replacing film magazines in the ATM cameras, pinning open the door of experiment S082A (extreme ultraviolet spectroheliograph), manually repositioning the filter wheel on experiment S054 (X-ray spectrographic telescope), and retrieving experiment S149 (particle collection) impact detectors. The duration of the second EVA was 6 hours 54 minutes; the third 3 hours 29 minutes.

The fourth and final EVA was performed on 3 February 1974. The major tasks accomplished consisted of retrieval of the ATM film, an additional performance of experiment S020, and performance of experiment T 025. Other tasks consisted of retrieval of modules, panels, assemblies, and samples that were to be returned to the ground for analysis, and deployment of cassettes and panels for potential retrieval in the future. The duration of the fourth EVA was 5 hours 19 minutes.

The actual allocation of crew time to experiments, as opposed to the preflight plan, is shown in the following chart:

[342] R. V. Gordon, JSC PAO, "Skylab 4 Events," February 1974; JSC, Skylab Mission Report Third Visit, JSC 08963, July 1974, pp. 2-1, 2 2, and 14-2.

November 26

The Skylab rescue mission hardware was on schedule, and vehicle rollout to the launch complex was scheduled for 5 December. Integrated testing and the flight readiness test would be completed about 13 December. Flight readiness review dates would only be established if a rescue launch was required.

JSC, "Skylab Program Office Weekly Activity Report," 26 November 1973.

December 10

The Skylab Program organization at NASA Hq would be disestablished in March 1974. A small group headed by T. E. Hanes would be retained to manage the Skylab closeout. In addition to administering the equipment disposition and contract closeout activities, the group would lead and coordinate activities related to exploitation of the Skylab experience and scientific data. Arnold D. Aldrich was named Skylab Program Manager, and W. D. Wolhart would handle these special activities on a full-time basis at JSC. By mid-February, MSFC would also name an individual for the Skylab follow-on activities. In the meantime, Leland F. Belew would be the Center contact.

Letters, Dale D. Myers, NASA Hq, to Center Directors of JSC, KSC, and MSFC, "Close Out of the Skylab Program," 10 December 1973; Rocco A. Petrone, MSFC, to Dale D. Myers, same subject, 21 December 1973; memorandum, G. S. Lunney, JSC, to JSC Director, same subject, 2 January 1974.

December 10

A message of congratulation was read to the Skylab 4 crewmen for the tremendous contribution they were making toward procuring medical data which would provide the base for future manned space flight efforts. The message was from the Soviet delegation of the joint working group in space biology and medicine.

Letter, John H. Disher, NASA Hq, to JSC Skylab Program Manager, "Message to SL-4 Crew," 10 December 1973.

December 26

The AP's top 1973 news stories in order of balloting were Watergate, Spiro T. Agnew, end of war in Vietnam and the release of prisoners, the economy, war in the Middle East, the energy crisis, the slaying of 27 boys in Texas, the death of Lyndon B. Johnson, Skylab space missions, the revolution in Chile.

Memorandum, W. W. Pomeroy, NASA Hq, to Associate Administrator for Manned Space Flight, "Editors Rank Skylab in Top 10 News Stories," 26 December 1973.

January 3

Flexibility to conduct a second Skylab mission would be retained until such time as NASA planning for the FY 1976 budget was complete. To accomplish this, NASA issued the following guidelines.

• Launch umbilical tower 2 would be retained in its present status for possible Skylab usage until a decision was made to prepare for a Skylab launch or to begin modifications for the Shuttle Program.
• [343] Action would be continued to place in storage existing hardware (including appropriate backups and spares) required for conduct of a Skylab mission.
• The Skylab Program would fund the activities required to place the hardware in minimum cost storage and the storage costs through June 1974.

Letter, Dale D. Myers, NASA Hq, to the Directors, MSFC, JSC, and KSC, "Retention of Skylab II Capability," 3 January 1974.

January 10

Studies had been conducted to determine an end-of-mission configuration for the Orbital Workshop and for maintaining the option of an OWS revisit at some future date. MSFC assessed the special deactivation requirements for the AM, MDA, and the Workshop required to establish a satisfactory, economical configuration. JSC made an evaluation of ground support monitoring and control options. The OWS would be left in a configuration that would permit a revisit at some future date without reactivation.

"10 January 1974 Manned Space Flight Management Council Summary of Agreements and Action Items," 4 February 1974.

January 15

A series of engineering tests on the Orbital Workshop was authorized following completion of the Skylab 4 mission provided that only tests which would result in significant engineering knowledge would be performed; no compromise would be made to the desired end of mission configuration by conducting the test (10 January 1974 entry); the vehicle would be left in the final configuration no later than 15 February 1974; and only a minimum of overtime and shift operation would be expended to obtain the data.

Memorandum, Dale D. Myers, NASA Hq, to the Skylab Program Director, "End of Mission Configuration of Skylab," 15 January 1974.

January 24

Significant repair and maintenance accomplishments of the three manned Skylab missions were reported:

• For the first 11 days, ground operations control kept the Skylab alive and allowed time for planning and hardware manufacturing necessary to salvage the mission.
• The first manned crew deployed the parasol which brought the OWS internal temperatures down.
• On the 13th mission day, beam 1 and its solar array were deployed to provide adequate power for normal mission.
• The crew succeeded in reactivating a malfunctioning battery, providing additional power. (This was accomplished by whacking it with a hammer during EVA.)
• The first crew performed a variety of repairs and fixes on experiments, such as disassembly and repair of the S019 (UV stellar astronomy) mirror gear drive mechanism; replacing M074 (specimen mass measurement) electronics package; clearing jammed film plate on S183 (ultraviolet panorama); manual opening of [344] stuck S054 (X-ray spectographic telescope) door; camera/magazine changeout for S082 (extreme ultraviolet spectograph/spectroheliograph); clearing particle contamination from S052 (white light coronograph) occulting disc.
• The second manned crew installed a larger thermal canopy over the parasol which provided long-duration thermal protection.
• A complex package of six ancillary rate gyros was installed and provided the needed control and backup control for pointing the Skylab.
• The second crew pressurized and flushed the condensate lines and replaced the discharge assembly, thus allowing normal use of the waste water management system.
• Detailed inspection and checkout of the primary and secondary airlock module coolant loops to determine internal and external leakage were performed, and the information relayed to ground for analysis.
• The second crew also corrected significant experiment and support system problems, such as jettisoning T027 (Apollo telescope mount contamination measurement) to clear scientific airlock; replacing video tape recorder and teleprinter head; removing ATM door ramps to improve door closing and opening operations; repairing Mark I exerciser; correcting S019 (ultraviolet stellar astronomy) articulating mirror malfunction; checking out and restoring lighting control; replacing defective TV monitor and TV power cable; replacing and analyzing causes for malfunctioning tape recorders; correcting seal problem on M092 (inflight lower body negative pressure); hooking up the sensor down-link data cable assembly of the Earth resources experiment package for ground data diagnosis.
• The third manned crew successfully replaced the malfunctioning ATM TV monitor in the control and display panel; this restored the display redundancy critical for effective ATM solar pointing.
• The depleted primary AM coolant loop was reserviced using the coolanol servicing kit resupplied on SL-4, thus ensuring continued thermal control of a critical internal Skylab system.
• An automatic timer and cable was launched on SL 4 and installed by the crew on the ATM control and display console to correct erratic exposure operation resulting in loss of S082 experiment data.
• During SL-4 EVA 1, the crew performed troubleshooting and inspection of the inoperative S193 (microwave radiometer/scatterometer radar and altimeter) antenna and then locked the antenna in a position to permit continued operation of the experiment.
• The crew installed replacement units and provided an operational TV system to replace the system which failed on SL-3.
• The "noisy" multispectral scanner hardware was corrected by replacing a modified attenuator and the sensitivity of the unit was improved by installing a modified detector/coder/dewar assembly.
• Successful crew investigation and rerouting of dumpline into the waste tank eliminated venting disturbances.
• Other experiment and support system repairs performed by the third crew included installation of liquid crystal thermometers for rate gyro 6-pack assembly; [345] replacement of S009 (nuclear emulsion) drive assembly; pinning of H-alpha door; S019 (ultraviolet stellar astronomy) mirror replacement; S 190B (Earth terrain camera) clock replacement.

Attachment to letter, William C. Schneider, NASA Hq, to Leland F. Belew, MSFC, Kenneth S. Kleinknecht and P. J. Weitz, JSC, "AIAA Skylab Session," 21 January 1974.

January 25

Although the probability was remote that the Apollo-Soyuz Test Project mission would not be flown, it was necessary that an alternate mission plan be considered. Minimum effort and funds would be expended in the planning and preparation of an alternate mission.

Letter, C. M. Lee, NASA Hq, to JSC and MSFC, "ASTP Alternate Mission Revisit to Skylab," 25 January 1974.

February 8

Skylab 4 was undocked from the OWS at 6:28 a.m. EDT. A flyaround inspection of the OWS was made following undocking. Because of a suspected propellant leak on command module reaction control system 2, reentry was made using only system 1. The command module landed in the Pacific Ocean 289 km southwest of San Diego at 11:16:54 a.m. EDT, for a flight duration of 84 days 1 hour 15 minutes 31 seconds. The crew and the command module were taken aboard the recovery ship U.S.S. New Orleans approximately 40 minutes after landing.

With the third-visit landing, the Skylab mission was concluded. The total flight time for the three visits was 4117 hours ]4 minutes 24 seconds, during which the nine crewmen accrued a total of 12 351 hours 43 minutes 12 seconds of flight time.

JSC, Skylab Mission Report Third Visit, JSC 08963, July 1974, p. 2-3; R. V. Gordon, JSC PAO, "Skylab 4 Events," February 1974.

February 8

KSC was directed to discontinue plans for the Skylab rescue capability and to move the rescue vehicle (SA-209 and CSM-119) back to the Vehicle Assembly Building. Upon completion of this action, Headquarters responsibility for the SA-209 and CSM-119 would be transferred to the Program Director of the Apollo-Soyuz Test Program.

TWX, Director, Skylab Program to KSC, MSFC, and JSC, "Skylab Rescue Vehicle," 8 February 1974.

February 8-22

Following the successful completion of the Skylab Program, a series of news conferences was conducted at the Skylab News Center, JSC.

Skylab 4 Post-Recovery Briefing, 8 February 1974; Skylab Review, 21 February 1974; Skylab 4 Post-Flight Crew Conference, 22 February 1974.

February 9

All primary mission objectives of Skylab 4 were reported accomplished. The specific mission objectives were to

(1) Perform unmanned Orbital Workshop operations.

• Obtain data for evaluating the performance of the unmanned OWS.
• Obtain solar astronomy data by unmanned Apollo telescope mount observations.

(2) Reactivate the OWS in Earth orbit.

• Operate the orbital assembly (OWS plus command and service module) as a habitable space structure for a period of 56 days, with the option of extending to 84 days after the third-visit launch.
• Obtain data for evaluating the performance of the orbital assembly.
• Obtain data for evaluating crew mobility and work capability in both intravehicular and extravehicular activity.

[347] (3) Obtain medical data on the crew for use in extending the duration of manned space flights.

• Obtain medical data for determining the effects on the crew which result from a nominal space flight duration of 56 days, with the option of extending to 84 days.
• Obtain medical data for determining if a subsequent manned space flight mission of greater duration than the duration of the Skylab third manned visit is feasible and advisable.

(4) Perform inflight experiments.

• Obtain Apollo telescope mount solar astronomy data for continuing and extending solar studies beyond the limits of Earth-based observations.
• Obtain Earth resources data for continuing and extending multisensor observation of the Earth from the low-Earth orbit.
• Perform the assigned scientific, engineering, technology, and Department of Defense experiments.
• Obtain Comet Kohoutek data for continuing and extending studies of comets beyond the limits of Earth-based observations.

Although not a primary mission objective, a requirement to obtain documentary motion picture photography of scenes to present the human story of Skylab was considered to be of paramount importance. Approximately 95 percent of the desired crew activity scenes were filmed.

The planned requirements were not only met, but were exceeded for almost all experiments. Also noteworthy were the large number of candidate experiments that were performed.

There were 70 telecasts during the third visit. Premission planning for this visit made provisions for the development of telecast requirements which would be timely and would not be a repeat of subjects covered during the earlier two visits. This planning included three flight-data-file "TV Numbers" which were for television on a variety of subjects. These numbers were TV-77, general purpose intravehicular activity telecast; TV-78, Earth surface features; and TV-81 optional crew day- off activities.

The following conclusions were based on Skylab 4 activities.

(1) Crew refresher exercises in spacecraft operational modes and procedures were needed during long missions.

(2) Free and open discussions between the crew and the ground were necessary for the expeditious resolution of sensitive issues. When one party felt that the other was at fault, the existence of a routine private communications loop, less restricted use of existing capabilities for special private conferences, or less reluctance on the part of the crew and the ground to use the open communications loop to critically discuss sensitive subjects would expedite the solution of problems.

[348] JSC, Skylab Mission Report Third Visit, JSC-08963, July 1974, pp. 13-1, 13-2, and 17-1.

February 21

MSFC published a summary of Skylab operations:

The Skylab space station was launched May 14, 1973, from the NASA Kennedy Space Center by a huge Saturn V launch vehicle, the Moon rocket of the Apollo Space Program. Sixty-three seconds after lift-off the meteoroid shield-designed also to shade Skylab's workshop-deployed inadvertently. It was torn from the space station by atmospheric drag. This event and its effects started a ten-day period in which Skylab was beset with problems that had to be conquered before the space station would be safe and habitable for the three manned periods of its planned eight-month mission.

When the meteoroid shield ripped loose it disturbed the mounting of workshop solar array "wing" two and caused it to partially deploy. The exhaust plume of the second stage retro-rockets impacted the partially deployed solar array and literally blew it into space. Also, a strap of debris from the meteoroid shield overlapped solar array "wing" number one such that when the programmed deployment signal occurred, wing number one was held in a slightly opened position where it was able to generate virtually no power.

In the meantime, the space station had achieved a near-circular orbit at the desired altitude of 435 kilometers.... All other major functions including payload shroud jettison, deployment of the Apollo Telescope Mount ( Skylab's solar observatory) and its solar arrays, and pressurization of the space station occurred as planned.

Scientists, engineers, astronauts and management personnel at the NASA Marshall Space Flight Center and elsewhere worked throughout the first ten-day period of Skylab's flight to devise the means for its rescue. Simultaneously, Skylab-seriously overheating-was maneuvered through varying nose-up attitudes that would best maintain an acceptable 'holding' condition. During that ten-day period and for some time thereafter, the space station operated on less than half of its designed electrical system which, in the partially nose-up attitudes, was generating power at reduced efficiency. The optimum condition that maintained the most favorable balance between Skylab temperatures and its power generation capability occurred at approximately 50 degrees nose-up.

Skylab's achievements are a summary of the accomplishments of many groundbased persons as well as its three separate crew-e who were launched in Apollo-type command modules by Saturn IB vehicles on May 25, July 28 and November 16, 1973. In Skylab, both the man-hours in space and the man-hours spent in performance of extravehicular activities (EVA) under zero-gravity conditions exceeded the combined totals of all the world's previous space flights.

By deploying the parasol-type sun shield through Skylab's solar scientific airlock and later releasing workshop solar array wing number one during EVA, the first crew made the remainder of the mission possible. The second crew, also during EVA, erected another sun shield, a twin-pole device.

The effectiveness of Skylab crews exceeded expectations, especially in their ability to perform complex repair tasks. They demonstrated excellent mobility, both [349] internal and external to the space station, showing man to be a positive asset in conducting research from space. By selecting and photographing targets of opportunity on the Sun, and by evaluating weather conditions on Earth and recommending Earth Resources opportunities, crewmen were instrumental in attaining extremely high quality solar and Earth oriented data.

All three crews demonstrated their technical skills for scientific, operational and maintenance functions. Their manual control of the space station, their fine pointing of experiments and their reasoning and judgments throughout the manned periods were highly effective.

The capability to conduct longer manned missions was conclusively demonstrated in Skylab, first by the crew returning from the 28 day mission and, more forcefully, by the good health and physical condition of the second and third Skylab crews, who stayed in weightless space for 59 and 84 days respectively. Also, resupply of space vehicles was attempted for the first time in Skylab and was proven to be effective.

During their time in space all three crews exceeded the operational and experimental requirements placed upon them by the pre-mission flight plan and schedule. In addition, the third crew performed a number of sightings of Comet Kohoutek which were not initially scheduled.

Prior to departure, the third crew gathered samples of hardware, food and other general items which they placed in a bag and left in the Multiple Docking Adapter. In the event of a Skylab revisit, the bag will be retrieved to determine the effects on the samples of long term storage in the space environment.

Following the final manned phase of the Skylab mission, ground controllers performed some engineering tests of certain Skylab systems-tests that ground personnel were reluctant to do while men were aboard. Results from these tests will help to determine causes of failures during the mission and to obtain data on long term degradation of space systems.

Upon completion of the engineering tests, Skylab was positioned into a stable attitude and systems were shut down.

It is expected that Skylab will remain in orbit about eight years before entering the atmosphere and burning up.

MSFC PAO, "Skylab Operations Summary," 21 February 1974.

February 25

A group of five documents was prepared by NASA Hq, JSC, KSC, and MSFC. These "lessons learned" documents reflected the experience gained in the Skylab Program. They were intended for use by personnel in other programs who were familiar with the disciplines covered. The "lessons learned" documents are subjective and represent individual opinions; therefore, they should not be considered as official NASA policies or statements of NASA positions.

Letter, William C. Schneider, NASA Hq, to MSFC, JSC, and KSC, "Foreword for Lessons Learned Documents," 25 February 1974.

March 5

[350] Following completion of the Skylab Program, NASA Hq was reorganized. The primer! objectives of the reorganization were to consolidate under one senior line official--the Associate Administrator the planning and direction of the Agency's research and development plans; and to consolidate under one senior line official- the Associate Administrator for Center Operations-the overall planning and direction of Center operations.

NASA Hq Special Announcement, "NASA Reorganization and Key Personnel Appointments," 5 March 1974.

July - During the month

A JSC report summarized Comet Kohoutek's relationship to Skylab operations:

Comet Kohoutek was discovered on 7 March 1973, three months before the launch of Skylab. Preliminary feasibility studies indicated that there was insufficient time to send a suitably instrumented spacecraft to observe and study the comet at close range. However, other manned and unmanned observations were planned, with the most significant to occur during the third visit to the orbiting Skylab. Unique scientific data were obtained by the third-visit crew, helping to make Kohoutek the most comprehensively studied comet in history.

Because of the flexibility and adaptability of the manned program, changes were made in the plans for the third visit to Skylab to take additional equipment and film for ultraviolet and visible light photography. Imagery data were obtained with the extreme ultraviolet electronographic camera experiment (S201K) using special film, and a synoptic history of the comet was made with a series of visible light photographs in the Kohoutek photometric photography experiment (S233K). Existing Apollo telescope mount experiments such as white light coronagraph (S052), X-ray spectographic telescope (S054), and extreme ultraviolet and X-ray telescopes (S056) were used to obtain white light photographs and data in the ultraviolet and X-ray spectra.

Man was not only an invaluable scientific observer studying a comet for the first time from outside the Earth's atmosphere, he was required as a necessary link in the chain of experiment operations. The Skylab crew sketched the form of the comet and described various colorations, characteristics, and light intensities. Some of the preliminary findings were

• A sunward spike was discovered that was formed of relatively heavy particles released earlier from the comet.
• The tail was observed to be extremely long as the comet passed around the Sun, and water vapor within the tail was identified. An increase in the intensity of violet color in the tail was described as the comet went away from the Sun.

As data from the third-visit crew's unique observations and measurements were analyzed and correlated with data from unmanned probes and ground observatories, scientific knowledge of the composition and behavior of comets would be increased substantially.

JSC, Skylab Mission Report Supplement 3, JSC-08963, "Flight Crew Contributions to the Skylab Mission," July 1974.

July - During the month

JSC reported the Skylab program had fulfilled all program objectives. The performance of the crews and their ability to correct system problems permitted the program to continue, allowed the extended period third visit, and resulted in a bonus of information returned. The following conclusions were either related to the Skylab program objectives or had a general application.

Advancement of the Sciences

Objective: To increase knowledge of medicine, astronomy, Earth meteorology, physics, and other fields, including the effects of space and solar-system phenomena on the Earth environment.

(l) The methods and techniques employed in the daily flight planning provided the flexibility to react to major departures from preflight plans and constraints. This ability was an important factor in optimizing the scientific return.

(2) There were no operationally significant physical or psychological health problems associated with the space vehicle environment for the 84-day visit.

[352] Findings showed that longer duration visits would be unconstrained. However, longer missions would require periodic medical monitoring.

(3) The food and sleep requirements on a long-duration mission were essentially the same as they were on Earth. However, the maintenance of an established level of physical conditioning required more programmed exercise.

(4) Long-duration flight with sophisticated multidiscipline experiments generated large amounts of data which required ground data handling and processing capabilities.

(5) The Skylab Program demonstrated the advantage of scientist astronauts in providing effective data discrimination and optimization.

(6) Complex scientific experiments should be designed for automatic sequencing to allow a more effective utilization of the scientist astronaut's time for making additional data observations, performing analyses, and applying scientific evaluation.

 

Practical Applications

Objective: To perfect sensing and data systems for use in agriculture, forestry, oceanography, geography, geology, water and land management, communications, ecology and pollution-control applications, and to develop zero-g manufacturing techniques.

(1) The practical application aspects of the Skylab program would require many months of data evaluation. There were no immediate results which would support the accomplishment for this objective. However, the data were of good quality, and preliminary evaluations indicated that practical applications would be possible in a number of the objective areas. One set of examples suggests that a mineral deposit has been identified near KIN ~ Nevada-that existing data can be used for an inventory of vegetation patterns; that the Puerto Rican trench depression is about 20 m below the mean sea level; and that pollution has been identified off the coast of Puerto Rico. Another pair of examples from the visual observations experiment indicated that new data on red plankton bloom occurrence might be of aid to biologists and that repetitive observations and photographs of snow accumulation and melting phenomenon would be useful in the study of snow as a water resource.

(2) The success of the visual observations experiment indicated the usefulness of a well-designed visual observations facility.

Durability of Man and Systems in Space

Objective: To determine the ability of man, materials, and systems to maintain their qualities and capabilities during a long period of weightlessness.

(1) The Skylab Program demonstrated that man could perform major assembly and repair tasks in the zero-g environment. Extravehicular crewmen could perform any task that could be accomplished in a one-g suited environment, provided that he was furnished with adequate tools, restraints, and training. The [353] design of spacecraft could take full advantage of man's capability to modify and repair. The ability of the crew to correct systems difficulties by actions such as deployment of the Workshop solar array, deployment of the parasol and sunshield, replacement of the rate gyro package, reservicing the coolanol loop, and repairing the teleprinter allowed the Skylab Program to exceed the original expectations.

(2) The Skylab Program reconfirmed that the timeline should indicate a relaxed activity at the beginning of the mission to allow the crew to become acclimated to the zero-g environment.

Spaceflight Effectiveness and Economy

Objective: To improve spaceflight technology in order to develop long-duration mission capability for future programs.

(1) The habitability provisions were satisfactory and contributed to the ability of the crew to work effectively for visits of these durations, and no factors were identified to preclude longer duration missions.

(2) The skills learned in underwater training were almost identical to the skills used in actual performance of tasks during an EVA, and, if instructions were adequate, a crewman would be able to perform extravehicular tasks for which he had not specifically trained. Tasks were somewhat easier to perform in zero-g than in underwater training.

(3) Ordinary handtools could be used effectively in place of special tools in the zero-g environment when making repairs and adjustments.

(4) Skylab revisits provided the opportunity to correct hardware problems, restructure objectives, and revise replaceable commodities based on actual experience from the first two mannings.

(5) Regularly scheduled meetings of individuals involved in experiments planning who were managed by the program scientists were effective in optimizing science data return. Additionally, the Skylab flight planning system allowed day-by-day planning with the flexibility to make adjustments to take advantage of special opportunities noted by the crew and ground personnel.

(6) Direct communication during the visits between the crew and some of the experimenters proved to be a useful capability. However, the limited air-to-ground coverage and the need to devote most of this time to operational subjects left little time for scientific discussions.

General

A number of noteworthy program conclusions that were not directly applicable to program objectives were

(1) Extensive training is required for a productive visual observations program. The crew must be trained, premission, to recognize selected areas on the ground and to discriminate important features within the areas. This requires that adequate maps and charts be provided for orientation in flight. In addition, several passes over a selected site are required for the attainment of complete data.

[354] (2) All work areas within a spacecraft should be provided with a suitably designed work station, with minimal considerations being adequate restraint (triangular grid floor or otherwise), workbench (where required), stowage provisions, writing provisions, and an orientation scheme that is indigenous to the local work area.

(3) Relocatable handholds should be provided to allow the crew to tailor work and maneuvering areas in order to optimize inflight activities.

(4) To optimize time utilization, data station design required automatic recording of a number of parameters which had been reported by crews in previous programs. Examples were pointing position of experiment hardware, frame count of recording instruments, f-stop position, shutter speed, magazine or cassette being used, lens identification, and filter identification.

(5) Planning should allow for crew judgment in order to obtain data over Earth sites that may be obscured by cloud cover.

(6) A shopping list would provide crews with a selection of activities to utilize when not constrained by the timeline.

(7) The existence of a dedicated communications loop for the program scientist would have been a significant asset.

(8) Underwater simulations and training were not required for intravehicular tasks unless a crewman was to be operating in a pressure suit.

JSC, Skylab Mission Report Third Visit, JSC-08963, July 1974, pp. 17-I through 17-5.

August 20-22

The American Astronautical Society and the University of Southern California's Institute of Safety and System Management hosted a symposium on the definitive results of the entire Skylab Program. Among the subjects covered were the program's evolution, accomplishments, and application to future NASA programs; design and test philosophy; payload integration; living and working in space; Skylab management; crew views of Skylab; flight operations; Skylab to Shuttle (lessons learned); student science program; launch operations and Skylab technology; and science demonstrations.

[355] Brochure from the American Astronautical Society on the Skylab Results, undated; papers on the subject matter listed above.

October 30 - November 1

A conference was held by the American Institute of Astronautics and Aeronautics and the American Geophysical Union at MSFC. A series of papers on Skylab scientific experiments was presented.

Letter, Marion I. Kent, MSFC, to Ivan Ertel, Historical Services and Consultants Co,. 4 November 1974.