Shuttle Laser Altimeter-01 Mission Status ReportThis page was last updated March 19th, 1996.Post-missionSLA-01 was deintegrated at Kennedy Space Center (KSC) in early February 1996. The two hard drives which provided onboard storage of all SLA-01 data were recovered. Overall, SLA-01 collected more than 83 hours of on-orbit data. For more information about SLA-01 data, please e-mail Doctor. Jack Bufton, SLA-01 Payload Manager Thermal Energy Storage-2 (TES) operated successfully. All Get Away Special (GAS) experiments operated successfully. The Sample Return Experiment experiment has been returned to Jet Propulsion Laboratory ( JPL) and will undergo analysis. January 19, 1996 (Flight Day 9)SLA-01 was deactivated today at 19/09:50 Greenwich Mean Time (GMT). G-459 was deactivated. January 18, 1996 (Flight Day 8)The SLA-01 payload has operated for over 62 hours resulting in over 2.2 million laser pulses transmitted. Of these pulses, on the order of 90 percent have resulted in valid range measurements from which the relief of the Earth's ocean surfaces, landscapes, and cloud tops have been imaged with outstanding vertical precision. Over relatively smooth surfaces, height variations of less than 2 meters in our preliminary data have been observed, attesting to performance of the instrument. Scientific highlight of the observations include measurement of the relief of gigantic mountains in the Southeastern Himalayas (Click here to see graph of measurements of the Himalyas relief here), (Hengduan Shan of China) where over 7 kilometer of topographic variation was observed. In addition, SLA-01 was able to acquire a cloud-free transect of an extensive variety of terrestrial landforms including shield volcanoes, rift zone escarpments, vegetated food plains (Amazon, south east Asia, Western Africa), longitudinal and barchan dunes, and even the subtle relief of interior sedimentary basins in both Australia and Africa. In some instances, only 5-10 meters of variation in the topography was observed. Perhaps most compelling about these initial SLA-01 measurements of the Earth's landscapes has been its ability to provide robust observations of topography in many inaccessible regions for which existing data are extremely scant. Orbital topographic remote sensing from SLA-01 currently complements the voluminous Earth surface imaging data sets already in hand as part of National Aeronautics and Space Administration's contribution to the Global Change research Program. Here is the ground track graph showing the areas of the earth that have been imaged by SLA-01 as of 18/06:00 GMT. January 17, 1996 (Flight Day 7)Following the successful completion of the Extra Vehicular Activity -2 (EVA-2), SLA-01 recommenced laser operations. Today's operations included tightening the orbiters dead-band (the stability at which the orbiter flies and hence the accuracy at which SLA-01 is pointed directly at the earth) from the +/- 1.0 degree down to +/- 0.1 degree deadband. This significantly increases the number of pulses of greatest return strength that are received back at the detector. Approximately 16 hours of this tight dead-band are currently being flown. Later in the Flight Day, the orbiter will perform several yaw maneuvers will allow us to downlink imaging data of targets not previously available to the SLA-01 team on the ground. Targets will include increased coverage of South America and Australia. January 16, 1996 (Flight Day 6)SLA-01 has resumed operations following the successful rendezvous/retrieval of (note: this link will open the page in a new browser) Office of Aeronautics and Space Technology-Flyer. During this observation period, SLA-01 reached and exceeded its minimum data requirement of 30 hours of lasing measurements. To date, approximately 1,050,000 laser pulses have been generated on orbit. Instrument status is nominal. Hitchhiker Avionics continues to perform well despite the loss of low rate data telemetry capability on Flight Day 3. Shuttle Laser Altimeter-0 will operate until deactivation of the laser and Hitchhiker motorized door assembly closure prior to EVA-2. A total of 12 hours of observations are planned for this Flight Day. Graph of a preliminary topographic profile of last nights pass over Australia depicts the western coast from Eighty Mile Beach, across the Great Sandy Desert, the MacDonnell Ranges and further eastward across the Simpson Desert and The Great Dividing Range just south of Brisbane. The Inset shows classical longitudinal dunes in the Great Sandy Desert of Western Australia. January 15, 1996 (Flight Day 5)The third observation period for SLA-01 was executed following the successful deployment of the Office of Aeronautics and Space Technology-Flyer yesterday. Early in this Flight. Day, approximately 700,000 laser pulses have been generated and instrument performance is nominal. All altimetry data continues to be recorded on- board the SLA-01 on hard disk, with data being transmitted to the ground when Ku-band coverage (providing medium rate downlink) is available. Observation highlights include night time passes of Africa and Southern China, and day passes over the Pacific. During the final Pacific Ocean pass, altimeter digitizer parameters were altered in order to acquire cloud- top and ocean surface elevations with a single laser pulse return echo. Broadening of laser pulse returns from land surfaces continue to resolve surface slope and vegetation canopy features. A quick-look SLA-01 cross-section of the Zagros Mountains in Iran documents the spectacular topography of this classic fold and thrust belt tectonic province where active thrust faulting is forming folds in the Earth's upper crust. Crew disable of Shuttle Laser Altimeter was performed prior to the Extra Vehicular Activity-1 (EVA-1). Later in the Flight Day, following the EVA-2 SLA-01 continued lasing operations. The highlight of this period included our first pass observation pass over the Australian continent, highlighted by a profile of the Great Sandy and Simpson Desert regions. Laser operations were terminated terminated after this observation in preparation for the upcoming Office of Aeronautics and Space Technology-Flyer rendezvous. Another graph of the preliminary topographic profile of Red Sea rift. The dunes highlighted in the figure show mega-dunes in the central Saudi Arabian desert observed with tens of meters vertical resolution. Such features are found only in the hyperarid desert regions in Northern Africa, Saudi Arabia, the Gobi and in the Atacama of Chile. Earlier in this pass, SLA-01 also observed vegetation in the rainforests of the Congo basin. January 14, 1996 (Flight Day 4)Laser operations continued from Flight Day 3 into Flight Day 4. Operations were terminated during the (note: this link will open the page in a new browser) Office of Aeronautics and Space Technology-Flyer deploy but will be resumed later in the Flight Day. To date, the SLA-01 instrument has successfully transmitted approximately 277,000 laser pulses resulting in ranging measurements off of terrestrial ocean and land surfaces as well as various types of clouds. Topographic cross- sections of important landscape targets in North Africa and Saudi Arabia were acquired. For example, a spectacular cross-section of the Red Sea rift extending west to east from Sudan across the Red Sea to Saudi Arabia on the East was collected which illustrates the classical geologic structure of a continental rift system. SLA-01 laser altimeter echoes were acquired for vegetated surfaces which suggest that aspects of the vertical structure of tree- covered land can be measured directly from Earth orbit using this technique. Finally, topographic data for central African desert regions confirms the relatively benign nature of sand-covered landscapes in these areas. The vertical resolution of SLA observations of oceanic surfaces is well within the anticipated 1-10 meter range. The following graphs depict quick-look (preprocessed) samples of raw data from SLA-01. Post mission processing of this data should provide horizontal and vertical resolution of under 10 meters. A graph of the preliminary topographic profile of the Red Sea rift as imaged by SLA-01. A graph of the preliminary topographic profile of Mauna Kea, Hawaii as imaged by SLA-01. Some additional highlights from Flight Day 3 observations: January 13, 1996 (Flight Day 3)Its been a challenging day for the SLA-01 team! Early this morning SLA-01 lost all low-rate telemetry capability, which provides housekeeping data on the Hitchhiker (HH) carrier system. Earlier in the mission, for the past two Flight Days, low-rate had been functioning properly. After some troubleshooting, it was theorized that the problem resided in the Pulse Control Modulation (PCM) unit in the Hitchhiker avionics, and that low-rate would be unavailable for the remainder of the mission. Uplink command capability was still intact as verified by sending commands to open and then close the Hitchhiker Motorized Door Assembly (HMDA). Video downlink showed the Hitchhiker motorized door assembly open and close, demonstrating command receipt. This also demonstrated that the Hitchhiker avionics still was powered. The ASC was powered up and medium-rate telemetry was successfully transmitted from SLA-01 via the Hitchhiker avionics to the ground. Since the science data is recorded on hard drives onboard the ASC as well as telemetered to the ground, science objectives could be met with medium-rate telemetry alone. A joint Goddard Space Flight Center (GSFC)/Johnson Space Center (JSC)team concluded that nominal operations should proceed. The SLA-01 Hitchhiker motorized door assembly was opened and at 13/16:48 GMT (02/07:07 mission elapsed time) the laser was commanded on. Good data was received showing land forms, layered cloud cover and vegetation. An early highlight was an overflight of the Island of Hawaii, showing Mauna Kea and cloud cover off the coasts. Operations will continue throughout this Flight Day including overflights of south and central Africa, the Himalayas, southeast Asia, the Andes and Amazon basin. Data cross-sections will be posted later in the mission on the SLA-01 Home Page. TES-2After a successful status polling of the National Aeronautics and Space Administration (NASA)-Lewis Research Center's TES-2 payload on Flight Day 1, the TES-2 experiment operated for 22.5 hours. This operation included a 7.75 hour warm-up period, a 10.75 hour period including 4 heat-up and cool down cycles, and a 4 hour cool down period. The TES-2 experiment was commanded off by the shuttle crew at 13/12:11 GMT. (2/02:30 mission elapsed time after about 28 hours of operation. The data to be retrieved from the TES-2 payload after landing will be used to further validate the Thermal Energy Storage Simulation (TESSIM) computer software code. The TESSIM predicts the migration of voids and the resulting thermal behavior of SD receiver canisters. TES-2 is the second in a series of 4 experiments designed to provide data for understanding the long duration microgravity behavior of thermal energy storage salts that undergo melting and freezing. The first Thermal Energy Storage experiment was successfully flown on Space Transportation System-62 (STS-62) in March 1994. GASG-740, the Pool Boiling experiment, from NASA's Lewis Research Center, was powered off, completing its experiment operations. January 12, 1996 (Flight Day 2)SLA-01 Altimeter Support Canister (ASC) operated for approximately 2 hours today performing system checkouts. ASC performance is nominal. The SLA-01 team is ready to support the first laser operations planned for 02/05:10 mission elapsed time (9:51 Ante Meridiem Eastern Standard Time. January 11, 1996 (Flight Day 1)SLA-01 was launched aboard the shuttle Endeavour on Thursday, January 11, 1996 at 11/09:40:59.979 GMT (4:41 Ante Meridiem Eastern Standard Time.). The ASC has been powered up and successfully commanded by the Hitchhiker Payload Operations Control Center (POCC) at GSFC. All systems are functioning nominally. SLA-01 has been coordinating payload bay video camera views of the ground track with INCO to assess optimum camera settings for supplementing laser operation. Over the next two days SLA-01 plans to continue with system checkouts, temperature monitoring, and correlation between the Hitchhiker Avionics and SLA-01 electronics thermistors in preparation for the first laser operations on Flight Day 3. Get Away SpecialG-342 has completed experiment operations. G-459 was activated during ascent and confirmed "on" during Flight Day 1. G-740 was activated during ascent and confirmed "on" during Flight Day 1. The experiment phase was initiated by an internal timer at 14 hours after launch. As a back-up to the timer, the experiment was commanded on late in Flight Day 1. Thermal Energy Storage-2After a successful status polling of the TES-2 payload on Flight Day 1, the TES-2 experiment was activated today at 12/07:50 GMT, (00/22:17 mission elapsed time).The TES-2 experiment will operate for 22.5 hours. The experiment is to complete operations at approximately 01/20:45 mission elapsed time followed by deactivation by the crew at around 02/01:10 mission elapsed time. |
Overview | Mission
Status Comments and suggestions regarding the content of this web
site, please contact SSPP. |