[439] THE in-house research at Ames was becoming increasingly fundamental and an increasing proportion was of the pure variety aimed principally at satisfying human curiosity and having little relation to practical applications. Research objectives were, in fact, often intermingled. For example, applied aerothermodynamic research provided the practical knowledge required for the design of spacecraft to be used for the pure objective of exploring some foreign planet. Applied research thus represented the pillars on which pure research was mounted and often found useful applications beyond its original objective. Indeed these related practical benefits were frequently used as justification for the costs of the pure research, though such costs seemed much too heavy to be amortized by this means.¹ It is also of interest to note that a strong element of "pure" motivation existed behind much of the applied research-indeed behind the work of any man worthy of the appellation of research scientist or engineer.

The pattern of research at the Center had become very complex. The life-sciences, space-sciences, and project-management activities were getting into full swing. Aeronautical research represented no more than 20 percent of the total effort; the remaining 80 percent was devoted to a diversity of space problems. The interest in aerodynamic heating, ablation, and radiation continued strong during this period but the speed range of interest was outrunning the capacity of the test facilities. Aerodynamicists had turned to meteors as a source of information on aerodynamic heating at extremely high speeds. Indeed, for this and other reasons, a surprising interest had developed in these celestial bodies.

Research relating to aircraft, although a fairly small percentage of the Ames research effort during the period 1963-1965, still constituted a substantial volume. A significant amount of this research was in the nature of development studies of advanced military aircraft undertaken in behalf, and at the request, of the military services. This work, dealing with such aircraft as the Dynasoar, the B-70, the F-111, the YF-12A, and various other airplane and missile types, was generally classified. The Dynasoar, which as the X-20 was to have been the next major step beyond the X-15 in the research-airplane program, was canceled in December 1963 when the interests of the Air Force turned to a manned orbiting laboratory (MOL). The research-airplane program carried on with the X-15 and before the end of 1965 that airplane had attained speeds of over 4000 miles per hour and altitudes of over 65 miles.

Aside from the development work just mentioned, the remaining aircraft research conducted at Ames during this period was focused on the supersonic transport, on large subsonic transports several of which were being designed, and on various types of V/STOL vehicles.

Although airfoil research was a bit old fashioned in these days, certain specialized aspects of the airfoil problem invited study. One example was a theoretical study, made by Joseph Cleary and John Axelson and reported in TR R-202, of sharp and blunt airfoils in hypersonic flow; another was an analysis (TR R-201) by James Der of the performance of airfoils operating in air that, as a result of a shock wave, was in a state of disequilibrium.

Despite the vast amount of earlier work on wing planforms, there was still something to be learned on this subject. One of the more important wing-design concepts arising at this time, a scheme involving a nonlinear (S-curve) leading edge, came from Britain. The distinguishing feature of the OGEE wing, as it was called, was the leading edge of the inboard portion which not only was rather sharp but, more noticeably, swooped forward as it approached the fuselage. At the same time the leading edge of the tip section was rounded backward, thus completing the S-curve. The result was a planform not unlike that which was found in the vertical tail surfaces of earlier airplanes but which, surprisingly, had not before been applied to a wing. The action of the sharp, highly swept inboard sections (cf. dorsal) was to produce a strong vortex extending spanwise over the forward portion of the wing. Unexpectedly, perhaps, the vortex stabilized the flow over the wing and provided, in a simple efficient way, the benefits sought but not always achieved through the use of heavy, complicated lift-control devices. The OGEE wing was in 1965 applied experimentally to a Douglas F5D-1 airplane which was then tested by Ames engineers both in the 40- by 80-foot wind tunnel and in flight. The modification so improved the stability and control characteristics of the airplane that the pilot felt....

....safe in lowering the landing approach speed by 10 knots. The results of the F5D-1 tests were reported in TN D-3071 by Stewart Rolls, David Koenig, and Fred Drinkwater.

Design studies of the supersonic transport (SST) made by NASA and industry had by 1964 revealed two promising configurations: one a canard arrangement incorporating a delta wing, and the other having a wing the Sweep of which could be varied as required in flight. Ames gave some attention to the variable-sweep configuration but much more to the development [442] of the canard-delta design. In fact, Ames engineers were largely responsible for the successful development of the canard-delta SST configuration, an accomplishment for which they received some acclaim.

In 1963, as part of the SST program, the Ames Vehicle Aerodynamics Branch undertook a study of the effect of spanwise variations of leading-edge sweep on wing performance. This work, reported by Ray Hicks and Ed Hopkins in TN D-2236, led to considerations first of the OGEE planform and then of a more practical substitute-the "double-delta" wing. The double-delta, which provided the principal benefits of the OGEE planform, represented, in effect, the superposition of two delta planforms having different amounts of sweep. The double-delta planform was adopted by the Lockheed Aircraft Corp. for use in its SST proposal.

To provide the designers of the SST with requisite information, it was necessary to try to anticipate the flying qualities of the airplane. For this purpose, flight simulators were extremely useful. Flight-simulator studies of the SST, made during an earlier period by White, Sadoff, Cooper, and others, have already been mentioned. Further work of this kind, on the landing characteristics of a canard-delta SST configuration, was carried out and reported by Richard Bray in TN D-2251. In this study the known performance of the Boeing 707 was used as a reference for judging that of the SST.

Inasmuch as the SST was expected to involve a tremendous national investment, the need was evident for the utmost care in evaluating SST design proposals. The Federal Aviation Agency (FAA) established a Supersonic Transport Evaluation Team composed of specialists in all of the many aspects of aircraft design and operation. Heavily represented on this team were several NASA Centers including Ames. The work of the team won high praise from FAA and, for their contributions, certain NASA representatives, including several men from Ames, won honors from their own agency. Among those at Ames so honored were Edward W. Perkins, George E. Cooper, Maurice D. White, Adrien E. Anderson, Mark W. Kelly, and Norman E. Sorensen.

The Ames flight simulators also found use during 1963-1965 in studies of a number of special airplane flight problems. In one of these, reported by Tom Wempe in TM X-54,063, the Ames height control apparatus (attached to the side of the 40- by 80-foot tunnel) was used to investigate the probIems of a pilot who, as required by some military missions, attempts to fly very low over irregular terrain. The pilots performing the simulated mission "crashed" a number of times, thus demonstrating the importance of simulator studies. Another useful application of flight simulators at Ames during this period was a study of the serious situation that had occasionally occurred in the operation of commercial jet transports when severe turbulence was encountered, particularly during the climb to altitude. Under such conditions, a momentary loss of control arising from a burst of turbulence can lead to rather wide excursions of airplane attitude and possibly to....

[444] ....structural failure during attempted recovery. The technique for handling the airplane safely in such circumstances obviously can be studied much more safely in a flight simulator than in flight. The work of Ames pilots and engineers on this problem was very constructive. It was reported at an AIAA meeting in July 1965 in a paper (ref. C-29) entitled "Summary of NASA Research on Jet Transport Control Problems in Severe Turbulence," by Melvin Sadoff, Richard S. Bray, and William H. Andrews. From the study of this problem it became clear that a simulator providing wide ranges of translational, as well as angular, motion would be of much value.

V/STOL aircraft were becoming of increasing interest both at home and abroad and for commercial as well as for military applications. While normally thought of as applying to craft having only modest top-speed capabilities, VTOL principles had been used in some cases, such as the British Hawker P-1127, for high-speed fighter-type aircraft.

V/STOL aircraft offered a tremendous range of design possibilities- many, assuredly, no good but few so bad that they could be abandoned without wind-tunnel prototype flight tests. The diversity of V/STOL design was especially great with respect to the powerplant and the means by which engine power was used to produce both thrust and lift. The powerplant was far more important than in an ordinary airplane; indeed, it was the very heart of any V/STOL design. In VTOL types, other than helicopters, a power failure in flight almost inevitably spelled catastrophe. Ames pilots, it should be noted, were shocked by the ease with which glib proponents of dangerous and impractical VTOI, devices were able to sell their ideas.

Owing to the complexity, diversity, and in many cases impracticality of the design of V/STOL aircraft, their development seemed permanently to remain in the prototype stage. By 1965 a few of the simpler V/STOL schemes appeared ready for application to operational aircraft but the more radical ideas continued to be limited to highly experimental craft. In the development of V/STOL aircraft, analysis had played its part but there was no substitute for experimental confirmations obtained in wind tunnels and simulators and through prototype flight tests. A new V/STOL science had to evolve and in the generation of this science NASA played a leading role, working closely with the military services, the FAA, the industry, and even with foreign development agencies.

Ames, in particular, had by 1965 become a world authority on V/STOL aircraft. Its elevation to this role resulted in some degree from its interest in the V/STOL field but even more from its impressive background of flight-research experience and from its possession of a large wind tunnel and advanced simulator facilities. The counsel and assistance of Ames engineers and pilots were regularly sought by domestic and foreign agencies engaged in the development of V/STOL aircraft. Seth Anderson of Ames was in 1965 made chairman of a new international committee that was....

....formed for the purpose of dealing with the establishment and standardization of V/STOL handling requirements.

An example of the international cooperation provided by Ames was the Center s joint program with the French Air Ministry and the Breguet Aircraft Co. to investigate the handling qualities, stability and control and operational characteristics of the Breguet 941 (deflected slipstream) trans-[446] -port. One phase of this program was reported by Hervey Quigley, Robert Innis, and Curt Holzhauser in TN D-2231 (ref. C-30). As reported in TN D-2966 by Holzhauser, Innis, and Vomaske, Ames also collaborated with certain Japanese national and private organizations in a flight and simulator study of an experimental Japanese STOL seaplane.

On the domestic front, Ames investigated numerous V/STOL, configurations in the 40- by 80-foot wind tunnel. These included types involving ducted fans, propellers-in-wing, jet-helicopter rotors, deflected slipstream complicated jet flaps, and tilt wings. An example of this work was the tests of a large model of the four-engine, tilt-wing, Ling-Temco-Vought XC-142 reported in TN D-1857 by Wallace Deckert, Robert Page, and Stanley Dickinson.

In flight research the Bell X-14A variable-stability VTOL airplane proved very useful, as did the Lockheed C-130 equipped with boundary-layer control. The value of the C-130 for STOL stability research was considerably increased by the incorporation of certain variable-stability features in the airplane-a modification performed by Lockheed under contract with Ames. Though the powerplant may have been the heart of any V/STOL design, stability and control were certainly the crux of its operation. Inherent stability under landing and takeoff conditions was found very difficult to obtain, with the result that electromechanical stability augmentors ("black boxes") came to be regarded by many V/STOL designers as a practical necessity.

The critical recirculating problem of V/STOL aircraft was investigated at Ames in a special, outdoor, static test rig which allowed the distance between the test model and the ground to be varied. Recirculation, one of the more serious problems of hovering VTOL aircraft, occurs when the hot downwardly deflected jet of the lifting engines finds its way hack, through ground reflection or other influences, to the engine inlet. The recirculating....

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[447] ....air may carry debris from the ground to the inlet and, being relatively hot, will reduce the power of the engine and perhaps actually cause it to stall. Ames studies indicated that, as a result of recirculation, the use of the deflected-slipstream principle for VTOL aircraft was questionable.

Because of manpower limitations and other factors, Ames found it desirable, in the 1963-1965 period, to let contracts for certain V/STOL investigative work. Contracts were let with Boeing for a number of flight studies designed to exploit the special capabilities of the Boeing 367-80 prototype airplane. This airplane was one of the 707 class which had been so modified (BLC and special high-lift devices added) as to give it an unusually low landing speed and further so modified as to provide lateral-directional variable-stability characteristics. With this airplane, Boeing in 1965 undertook two studies for Ames. One was a study of the landing-approach characteristics of a large swept wing STOL transport; the other was an investigation of the flight characteristics of the huge C-5A cargo-transport airplane in which the Air Force had recently become interested.

In addition to carrying on its own V/STOL contracting work, Ames in 1964-1965 was collaborating with the FAA and industry in a design study aimed at the development of a short-haul, STOL commercial transport airplane. The general requirements of such an airplane were investigated at Ames and the results of the study were presented in 1964 at a meeting of the AIAA as a paper entitled "Design and Operating Considerations of Commercial STOL Transports," by Curt A. Holzhauser, Wallace H. Deckert, Hervey C. Quigley, and Mark W. Kelly. Additionally, Ames was proceeding on research leading to the ability to land aircraft under conditions of zero visibility which would have obvious application to STOL transports; flight investigations of a Convair 340 airplane, equipped for blind landings, began in this period. Following these efforts, NASA let contracts with Boeing, Ling-Temco-Vought, and Lockheed for feasibility studies of various V/STOL concepts applicable to the short-haul transport. These studies were under way as 1965 ended and were to be completed in time for results to be presented at a general V/STOL conference at Ames in 1966.

The importance of the pilots' role in the V/STOL work at Ames can scarcely be overemphasized. Their evaluations, in simulators and in flight, of the performance of V/STOL types were particularly valuable in view of the meagerness of existing knowledge and experience relating to the operation of such craft. In this pioneering work, there was obviously much danger. The Ames pilots most deeply involved were Fred Drinkwater and Bob Innis, both of whom luckily escaped serious injury in their flight tests of V/STOL aircraft. The staff at Ames was more than pleased when, in 1964, both pilots won the coveted Octave Chanute Award for their V/STOL work For significant contributions to the safety and efficiency of flight testing, Fred Drinkwater also, in 1965, won the Richard Hansford Burroughs Test Pilot Award.

The desire to land instrument packages and human beings safely on foreign celestial bodies stimulated an interest in the means for attenuating the landing impact. A primary requirement, of course, was that the weight of the shock-absorbing material be as small as possible. Thus the factor "specific energy absorption" (SEA)-energy absorption per pound of weight of the absorbing material-became an item of interest. In seeking the highest value of SEA, research engineers considered many forms of energy absorption. These included (1) gas compression (air bags), (2) acceleration of masses, (3) friction, and (4) cutting, crushing, extrusion of materials, or other forms of materials deformation. Processes resulting in a rebound were considered undesirable. One interesting method of energy absorption with which Ames engineers experimented was the pulling inside out of an aluminum tube. Another one was the cutting or crushing of a mass of plastic foam. The plastic (polystyrene) would be carried compactly as a fluid and then "blown up" in time to harden just before impact.

SEA, it was soon realized, was by no means the only important factor in the design of a lunar or planetary landing system. It was also necessary that the supporting elements of the landing gear provide stability, so the spacecraft would not tip over, and have broad feet so as not to sink into the lunar dust. The gear also had to be stowable in a small space for launching. With all these requirements, the design of a spacecraft landing system [449] offered room for the exercise of a great deal of ingenuity. It also represented a natural field of activity for the Ames Structural Dynamics Branch. The work of the Structural Dynamics Branch in this field is best represented, perhaps, by the paper published in 1965 by the American Society for Testing and Materials, entitled "Materials Needs for Energy Absorption in Space-Vehicle Landings" (ref. C-31), by R. W. Warner and D. R. Marble.

Although there had been earlier work on materials at Ames, the materials research effort began to take on significant proportions only in 19631965. The sputtering work, which had been instituted by Mike Bader and Fred Hansen, was continued during the early part of this period by Tom Snouse, whose work appeared as TN D-2235, "Sputtering at Oblique Angles of Ion Incidence." In the meantime, Ames materials research engineers had become interested in the effects on certain spacecraft materials of the hard vacuum and ultraviolet radiation encountered in space. One phenomenon investigated was the welding that sometimes takes place between two pieces of metal which are brought together in a high vacuum. This study was reported in TM X-56,334, "Solid Phase Welding of Metals under High Vacuum," by William Gilbreath and H. T. Sumsion.

Strangely enough, it was also found that the vacuum of space affected the mechanical properties of metals-particularly single crystals of certain metals. For example, it was possible to produce a single crystal of magnesium so large that it could be machined into a cylindrical tensile test specimen. When the specimen was pulled beyond the yield point in various degrees of vacuum, its cross section remained circular, as expected, as long as the air pressure was greater than 10-6 mm of mercury. At lower air pressures, however, the cross section became oval and the material showed increasing ductility. These characteristics suggested that under normal conditions the ductility of a test specimen is greatly affected by the oxide film which immediately forms on the surface of virgin test-body material as it is exposed by stretching. In a high vacuum, the oxide film does not form fast enough to lend its strength to the stretching material. The study of this phenomenon by Ames engineers was reported by Dell Williams and Howard Nelson in the paper, "Effect of Vacuum on the Tensile Properties of Magnesium Single Crystals," published in the AIME Transactions in July 1965.

In spacecraft design, plastics were used quite extensively for heat shields, thermal-control coatings, etc. Unfortunately, under a space environment, many plastic materials tend to evaporate, be clouded by ultraviolet radiation, be eroded by micrometeoroids, or suffer other detrimental effects. To study these effects in a fundamental way the Materials Branch undertook what it referred to as its "polymer program." Out of this program by the end of 1965 had come several research reports, one being TM X-54,030 by John Parker and Hermilo Gloria on "The Kinetics of the Vacuum Weight Loss of a Composite Comprising a Subliming Solid in an Inert [450] Polymer Matrix." There was also a series of papers on the mechanical properties of polymers, an example of which was TM X-54,020, "An Analytical Method for Evaluating the Effects of Radiation in Vacuum on the Mechanical Properties of Rigid Plastics," by Jerome J. Lohr and John A. Parker. Additionally, a study of the degradation of plastic materials exposed to ultraviolet radiation was being made in 1965 by Ronald Reinisch.

The Gasdynamics Branch was also much interested in certain materials problems. Carr Neel of that branch had for several years been investigating performance degradation, produced by the environment of space, of painted "thermal control" panels. The development of ablation materials was by 1965 becoming a rather sophisticated science, and it now seemed feasible to synthesize new ablation materials by altering the molecular structure of existing plastics in such a way as to make them more suitable for ablation purposes. So that such investigations could be pursued more effectively, a fine new chemical laboratory was being established in 1965, within the Gasdynamics Branch. John Parker, a well-known polymer chemist whose work has already been mentioned, was in charge of the new laboratory.

The studies of spacecraft configurations and airflows undertaken at Ames during this period seemed to fall into four categories: theoretical or experimental studies of (1) basic airflows, (2) conical reentry bodies, (3) Apollo-type capsule configurations, and (4) lifting reentry bodies, in particular the M-2 configuration which originated at Ames.

In the first category, the analysis of the familiar blunt-body flow problem was continued in a study reported in TR R-204 by Harvard Lomax and Mamoru Inouye. At the same time, a less formal and very practical analytical approach to the blunt-body flow problem was made by Elliott Katzen and George Kaattari and reported in a paper entitled "Inviscid Hypersonic Flow around Blunt Bodies," which in 1964 was presented at a meeting of the American Institute of Aeronautics and Astronautics (AIAA) .

In another phase of the basic-flow work, several studies were made of the effects of ablation on the aerodynamics of reentry bodies. This work is well represented by two important papers prepared in 1965 but not published until the following year. One of these, presented at an AIAA meeting in January 1966, was entitled "Free-Flight Aerodynamics of a Blunt-Faced Reentry Shape With and Without Ablation," by Lionel L. Levy, Jr., and Leroy S. Fletcher (ref. C-32). Special interest attached to this study because it employed the free-flight test method which had recently been developed by the Gasdynamics Branch for use in the vertical arc-jet tunnel. The second paper, prepared for an AGARD meeting in Brussels in May 1966, was entitled "Boundary Layer Separation and Reattachment With and Without Ablation," by Donald M. Kuehn and Daryl J. Monson. [451] This work represented an extension of studies of boundary-layer separation on reentry bodies which Don Kuehn had been making for several years.

Also in the first category were two studies of a somewhat different type. One was TN D-2135 by Maurice Rasmussen and Don Kirk, which dealt with the pitching and yawing motions of a spinning symmetric missile. This study represented an extension of earlier work by both authors on the application of nonlinear analytical methods to the analysis of free-flight (HFF) model tests. The second study was TM X-54,045, "Electric Drag on Satellites-Theory and Experiment," by William C. Pitts and Earl D. Knechtel, which in April 1964 was presented at an AGARD meeting in Marseilles, France. This study evaluated the extremely small resistance to motion (drag) encountered by a satellite as a result of its passage through a flow (solar flux) of electrically charged particles. In determining the lifetime of a high-flying satellite, this "electric drag," though minute, may nevertheless be important.

The second category, the study of conical reentry bodies, is perhaps best represented by the work of Peter Intrieri and particularly his report TN D-3193 (ref. C-33) entitled, "Experimental Stability and Drag of a Pointed and a Blunted 30° Half-Angle Cone at Mach Numbers from 11.5 to 34 in Air." Another worthwhile study was made by Joe Cleary and reported in TN D-2969, "An Experimental and Theoretical Investigation of the Pressure Distribution and Flow Fields of Blunted Cones at Hypersonic Mach Numbers."

In the third category, the Apollo configuration, the work undertaken was quite extensive. Included in this effort was a study, reported by Louis Stivers in TM X-1081, in which measurements of forces and moments on an Apollo capsule were made at high air speeds and at angles of incidence ranging from -30° to + 185°. There was also, as reported by Jack Mellenthin in TM X-1203, an investigation of an Apollo capsule model at Mach numbers up to 21.2 in a helium tunnel. Additionally, a particularly interesting study of the Apollo capsule was made in the 14-inch helium tunnel and reported by Joe Kemp in TM X-1154 (ref. C-34) . This study, in which afterbody pressures of free-flying models were transmitted by telemetry, represented the first application of the free-flight testing technique in the helium tunnel. Out of the hypervelocity free-flight facility came another important study dealing with the Apollo capsule. Reported in TM X-1086 by Robert Sammonds, it was an investigation of the force and moment characteristics of the Apollo capsule at Mach numbers up to 35 in air. The effects of changing the corner radius of the capsule were investigated as one element of this study.

In the fourth-lifting-body-category, the work was a continuation of studies under way at the Center since 1957. Indeed, Ames from the first had been a major advocate of the lifting-body principle for spacecraft. In the press of competition the nonlifting body had been adopted for the first U.S. [452] man-in-space operation, but the advantages of the lifting reentry body be came increasingly apparent and increasingly important as more advanced space missions came under consideration. It became clear that, as compared with a simple drag body, a lifting reentry body would widen the entry corridor, simplify the entry navigation task, and provide some control over entry heating and accelerations. It would also offer some latitude in choice of a landing site and permit a landing on solid earth, if desired, rather than at sea. The design of a lifting reentry vehicle was, however, a much more difficult and time-consuming task than the design of a nonlifting body and required a great deal of preliminary research. By the end of 1965, this research effort, being pursued elsewhere in the country as well as at Ames, had reached a fairly advanced state.

Among the major contributors to the lifting-body research work at Ames was the team of George Holdaway, Joe Kemp, and Tom Polek. As reported in TM X-1029 and TM X-1153, this trio investigated experimentally the control characteristics and horizontal landing capabilities of a variety of blunt, lifting reentry bodies. Among the many other contributors to the liftingbody studies during this period were John McDevitt, John Rakich, Gene Menees, Jack Mellenthin, John Axelson, Leland Jorgensen, George Kenyon, and Ronald Smith. In TN D-3218, Rakich and Menees reported on a series of tests in the 3.5-foot tunnel of flared bodies at incidence, while in TM X-950 Gene Menees and Willard Smith described reentry body tests made alternately in air, carbon dioxide, and argon-the last two gases being regarded as likely constituents of the atmosphere of Mars.

The lifting-body configuration that Ames engineers considered most promising was one for which Al Eggers and his 10- by 14-inch-tunnel staff had laid down general design principles in 1957. This configuration-essentially a blunt, flat-topped semicone-was later, when fitted out with control and stabilizing surfaces, cockpit, and landing gear, given the name of M-2. Much effort was spent at Ames developing a practical configuration which would provide the necessary amount of lift, stability, and control while at the same time resisting the ravages of reentry aerodynamic heating. Toward this end development test work was conducted in the 11-foot, the 12-foot, the 3.5-foot, the 6- by 6-foot, and the 8- by 7-foot wind tunnels.

These tests provided the information required for the construction of a flying prototype, called the M2F1. The M2F1, made of plywood with a steel-tube frame, was a glider designed to be towed aloft by a DC-3 airplane and released. It, in large part, was built by the Briegleb Sailplane Corporation of America under contract with NASA. It was thoroughly tested in the 40- by 80-foot tunnel, and was then flight-tested at the NASA Flight Research Center at Edwards. The information gained from these and other tests was utilized in the design of a second, larger, more refined flight prototype, the M2F2, which the Northrop Aircraft Corp. built. The M2F2 was made of aluminum and, like the X-15, was designed to be carried aloft for....

....launching by a B-52 airplane. In 1965 it was undergoing checkout tests in the 40- by 80-foot tunnel in preparation for later flight tests.

While Ames was concentrating its efforts on the M-2, considerably different reentry-vehicle configurations were being developed by the NASA Langley Research Center and the Air Force. Langley's design, called the HL-10, was shaped something like a high-pronged flat-bottom boat. In 1965 Northrop was building a flying model of the HL-10 for flight-testing at Edwards. It was planned that both the M2F2 and the HL-10 would later be fitted with 8000-pound-thrust engines. The flight tests of the M2F2 and the HL-10 were expected to provide a comparison of the low-speed, maneuvering, and landing characteristics of the two configurations but not of their high-speed reentry performance. The Air Force, however, was preparing to evaluate its design, called the SV-5D, at high speed by means of rocket-launched test flights.

Late in 1964 four members of the Ames research staff received special recognition from NASA Headquarters for their conception and development of the M-2 reentry vehicle. The four men were Alfred J. Eggers (who had recently joined the Headquarters staff), Clarence A. Syvertson, George G. Edwards, and George C. Kenyon.

Spacecraft reentry techniques and problems had been fairly well examined in earlier years; nevertheless, a few additional studies, relating to very high entry speeds, were made during this period. One of these, reported in TN D-2818 by Henry Lessing and Robert Coates, described an entry guid-....

....-ance scheme appropriate for lifting-body entries made at speeds up to 50,000 feet per second. A second study was reported by Robert Carlson and Byron Swenson in a paper, "Maneuvering Flight within Earth-Entry Corridors at Hyperbolic Speeds" (ref. C-35), which in January 1965 was presented at a meeting of the AIAA. This study looked into the question of how much the entry corridor, already narrow because of the high entry speeds, might be further restricted by the probable imprecision of the onboard knowledge regarding entry angle, velocity, and altitude. It thus dealt with a very practical problem relating to manned spacecraft returning from interplanetary missions.

Devices that control the attitude of a vehicle in space generally utilize power generated by gas jets, inertia wheels, or other means. These devices may be made to operate automatically or, if a pilot is present, they may be controlled manually. The design and efficient use of a manually controlled jet system were matters of some interest to Ames engineers and there was a question of how well a pilot could control the attitude of his spaceship in the vacuum of space. Out of this interest came TN D-2068, ''simulator Studies of the Manual Control of Vehicle Attitude Using an On-Off Reaction Control System," by Armando Lopez and Donald W. Smith.

The possibility of using gravitational force to stabilize a space vehicle and keep it pointed at the earth was at this time well understood in principle, but much remained to be learned about the practical application of such a scheme. The problem was studied by Bruce Tinling and Vernon Merrick, who then prepared a paper on "The Status of Passive-Gravity-Gradient Stabilization" for presentation in June 1965 at the International Federation of Automatic Control Symposium in Stavanger, Norway.

[455] A substantial number of the spacecraft flight studies undertaken at Ames during this period were aimed at solving the guidance and control problems of the Apollo spacecraft. This work came under the surveillance of a special Apollo Guidance and Control Team established at Ames under the leadership of Merrill Mead in September 1961. The principal matters to be considered by this team were (1) the problems of midcourse navigation, and (2) how best to use a human pilot in reentry. Among the studies bearing on the problems was one reported in TN D-2697, "Application of Statistical Filter-Theory to the Interplanetary Navigation and Guidance Problem," by John S. White, George P. Callas, and Luigi G. Cicolani. Studies were also made of the feasibility of using handheld sextants for space-navigation purposes. Several important papers were written on this subject, one of which was TN D-2844, "Investigation of a Manual Sextant-Sighting Task in the Ames Midcourse Navigation and Guidance Simulator," by Bedford A. Lampkin and Robert J. Randle. The sextant used in this case was one which Ames scientists had modified and specially adapted for space navigation. Plans were being made in 1965 for experiments with the sextant in space during the projected flight of Gemini XII.

Early manned space flights had been controlled largely by automatic means but, as more experience was gained in such flight operations, an increasing interest was taken in the abilities of the pilot and crew to guide and control their spacecraft. The sextant sighting study just mentioned was one of many attempts to investigate this matter at Ames. One of these, amply described by its title, was TN D-2807, "Evaluation of Pilot's Ability to Stabilize a Flexible Launch Vehicle during First-Stage Boost," by Gordon H. Hardy and James West. In this study the Ames five-degrees-of-freedom flight simulator proved very useful. Another investigation of the same general character was reported in TN D-2467 (ref. C-36), "A Study of the Pilot's Ability to Control an Apollo Type Vehicle during Atmosphere Entry," by Rodney C. Wingrove, Glen W. Stinnett, and Robert C. Innis. This study, also performed with the five-degrees-of-freedom simulator, brought the reentry task down to a very personal and practical level. Wingrove's work in the reentry field had been quite outstanding and included the paper, delivered in June 1965 in Norway, on "Guidance and Control in Supercircular Atmosphere Entry."

Pilot performance under conditions of stress-such as might be encountered in space flight-was also investigated at Ames. Representative of this work is the study described in TN D-2710, "Effect of Combined Linear and Oscillatory Acceleration on Pilot-Attitude Control Capabilities," by C. B. Dolkas and John D. Stewart. The physical limitations of the pilot with respect to the withstanding of accelerations was a critical matter in space flight. Accordingly' a great deal of effort was spent in devising special restraining harnesses, or suits, that would enable the pilot better to withstand acceleration loads. At Ames a very promising restraining harness and suit were....

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[457] ....developed by Hubert C. Vykukal and E. Gene Lyman. As 1965 ended, the evaluation of this equipment was about to begin. Vykukal had been working On such matters for years and in 1963 had been accorded recognition for the design and development of a "universal pilot restraint suit."

During this period a number of Ames engineers received honors and awards for their work in space-flight guidance research. In 1963, John White and Rodney Wingrove jointly won the Dr. Samuel Burka Award of the Institute of Navigation for their analysis of guidance and navigation problems connected with manned missions to the moon. In 1965, Rodney Wingrove was chosen to receive the AIAA Lawrence Sperry Award for his contributions to controlled reentry and precise landings of U.S. manned spacecraft. Also in 1965 Gerald L. Smith was honored by his agency for having developed a computer analysis which resulted in a NASA decision to give ground-based navigation a primary role during Apollo lunar missions.

Much interest existed during this period in the exploration of neighboring planets-particularly Mars, since that planet was reasonably accessible, had surface features which had long intrigued astronomers, and seemed more likely than any of the others to harbor some form of life. The Mars landing, it was felt, would probably be made first by an instrument package and, much later, by human beings. Before even an instrument package could be landed safely, it would be desirable, Ames engineers realized, to obtain much more information about the atmosphere of the planet.

Al Seiff, on giving thought to this matter, concluded that much could be learned about the structure and chemical composition of the atmosphere of a planet from the dynamic response and gas-cap radiation of an instrumented probe vehicle as it penetrated the planet's atmosphere in a crash landing. The structure (pressure-density-altitude relationship) of the atmosphere could be deduced from the motions of the probe-telemetered back to earth-and the chemical composition might be revealed by the gas-cap radiation measurements-also telemetered back to earth. The technique as conceived represented a wholly new approach to the study of planetary atmospheres and Seiff realized that it might well provide the basis for a useful planetary probe mission. His thoughts regarding such a mission were developed in 1962 and published in April 1963 as TN D-1770, "Some Possibilities for Determining the Characteristics of the Atmosphere of Mars and Venus from Gas-Dynamic Behavior of a Probe Vehicle." This paper was followed by others, including one, "Defining Mars' Atmosphere-A Goal for the Early Missions" (ref. C-37), which Al Seiff and Dave Reese prepared in 1964 for presentation to the AIAA.

Seiff's enthusiasm for the Mars probe project aroused the interest of Others and considerable research bearing on the project was undertaken.

Attempts to devise engineering models of the Mars atmosphere were made by the team of G. M. Levin, D. E. Evans, and V. I. Stevens,² and also by H. E. Bailey. These efforts were reported in TN D-2525 and SP-3014. Also, as reported by Victor Peterson in TN D-2669 and TR R-225, techniques for determining the structure of planetary atmospheres through probe operations were devised and evaluated for accuracy.

The application of the probe method of planetary atmosphere determination required more theoretical and experimental information on the flow properties of gas mixtures than was then available. Accordingly, tests involving the use of various gases were instituted in several facilities including the 1-foot shock tunnel and the 3.5-foot tunnel. Some of these tests have already been mentioned. Theoretical analyses were also instituted. One of these is reported in TR R-222, "Equations for Isentropic and Plane-Shock Flows of Mixtures of Undissociated Planetary Gases," by Victor Peterson.

The dynamic stability of the Mars probe was also a matter of serious concern to Ames engineers. This was investigated in a general way by Murray Tobak and Victor Peterson. This team produced two reports, one of which was TR R-210, "Angle of Attack Convergence of Spinning Bodies Entering Planetary Atmospheres." The other was TR R-203 (ref. C-38), "Theory of Tumbling Bodies Entering Planetary Atmospheres With Application to Probe Vehicles and the Australian Tektites." In addition, the general aerodynamics problem of the Mars probe was covered in a paper by Leland Jorgensen, "Aerodynamics of Planetary Entry Configurations in Air and Assumed Martian Atmospheres," published by the AIAA in 1966.

While the Mars atmosphere probe, owing to its early feasibility, [459] absorbed much attention at Ames, interest continued at the Center in landing a man on Mars. The manned Mars mission was analyzed by the Ames staff and also, in greater detail, by several commercial aerospace companies operating under NASA contracts. One of the Ames studies is reported in TN D-2225 (ref C-39), A Parametric Study of Mass-Ratio and Trajectory Factors in Fast Manned Mars Missions," by Duane W. Dugan. Another study, which related to both the manned Mars and the Mars probe missions, was reported by Robert McKenzie in TN D-2584, "Some Effects of Uncertainties in Atmospheric Structure and Chemical Composition on Entry Into Mars."

Also to be mentioned was the development of the Venus Swingby technique, whereby the braking effect of the gravitational attraction of Venus would be used to slow the reentry speed of a space vehicle returning from a mission to Mars. Analysis had shown that Mars-mission reentry speeds, which might otherwise amount to 75,000 feet per second, could be reduced through the use of the Venus Swingby technique to 50,000 feet per second or less. Work on this important development was led by Harold Hornby of the Ames Mission Analysis Division and carried out under contract with Ames by the Thompson Ramo Wooldridge Corp.

Research in the general field of aerodynamic heating, radiation, and ablation continued in 1963-1965 to represent a substantial portion of the effort of the Ames Research Center. The work was quite diverse but seemed to fall roughly into four categories: (1) physics of gases, (2) convective heat transfer, (3) ablation, and (4) radiation. There was, of course, considerable overlapping between these categories.

The work on physics of gases was carried on by the Magnetoplasmadynamics Branch of the Thermo- and Gasdynamics Division as well as by the Physics Branch of the Vehicle Environment Division. The Magnetoplasmadynamics Branch was using the arc-jet in studies of the chemistry and thermodynamics of high-temperature gases. This work was of fundamental significance and also contributed to further arc-jet development. The efforts of the Physics Branch were concentrated by the end of 1965 in the fields of chemical kinetics, atomic collisions, and vacuum ultraviolet radiation. Ultraviolet radiation was now of interest to Ames research people inasmuch as the frequency of radiation produced by a reentry body moved into the ultraviolet range as reentry speeds increased and gas-cap disturbances became more violent.

Representative of the numerous technical papers that resulted from physics-of-gases work at Ames during this period was TN D-2611, "A Critical Evaluation of Existing Methods for Calculating Transport Coefficients Of Partially and Fully Ionized Gases," by Warren F. Ahtye. There were also [460] TN D-2794, "The Vacuum Ultraviolet Radiation from N⁺ Electron and O⁺ Electron Recombination in High Temperature Air," by G. Hahne, and a paper by Leroy Presley and Charles Chackerian, "Chemical Kinetics Studies of CO in an Arc Discharge Shock Tube," which in 1965 was presented at a meeting of the American Physical Society. Additionally, there was TIN D-2678, "Effects of Uncertainties in the Thermal Conductivity of Air on Convective Heat Transfer for Stagnation Temperatures up to 30,000° K," by John T. Howe and Yvonne S. Sheaffer.

The studies of convective heat transfer undertaken during this period were often concerned with the tremendously high reentry speeds of vehicles returning to earth from planetary missions or with the aerodynamic heating that would be encountered by a vehicle penetrating the atmosphere of a foreign planet such as Mars or Venus. Under consideration at this time were reentry speeds of up to 70,000 feet per second and stagnation temperatures of up to 24,000° K-up to four times the temperature of the surface of the sun. At these speeds and temperatures, the heating of a blunt reentry body would come primarily from radiation; but Allen and others had shown that the radiation component could be greatly reduced, and the aerodynamic heating confined largely to convective heating, if the front face of the reentry body was made in the shape of a cone the included angle of which was decreased as the entry speed increased. Thus, even at the highest reentry speeds, convective heating remained a very important factor as did also the condition of the boundary layer-laminar or turbulent-upon which convective heat transfer is strongly dependent. Moreover, it was now clear that, owing to the threat of radiation, convective heating could be controlled only by ablation and not, as in days of yore, by body blunting.

Among the many studies of convective heat transfer made by Ames engineers, those described in the following papers might be taken as representative: TN D-2463 (ref. C-40), "Theoretical Laminar Convective Heat Transfer and Boundary-Layer Characteristics on Cones at Speeds to 24 Km/Sec" (nearly 80,000 feet per second), by Gary T. Chapman; TR R-224 (ref. C-41), "Convective Heat Transfer in Planetary Gases," by Joseph G. Marvin and George S. Deiwert; TN D-3017, "Pressure and Convective Heat Transfer Measurements in a Shock Tunnel Using Several Test Gases," by Joseph G. Marvin and Clifford M. Atkin; TN D-2871 (ref. C-42), "FreeFlight Measurements of Stagnation-Point Convective Heat Transfer at Velocities to 41,000 Ft/Sec," by Dale L. Compton and David M. Cooper; and TM X-1096, "Free-Flight Measurement of Heat Transferred to the Apollo Afterbody With and Without Ablation," by Layton Yee. The measurement of heat transfer in free-flight facilities was difficult at best and novel methods were devised for its accomplishment. Thus Compton and Cooper in their study determined stagnation temperatures and corresponding heat transfer at test speeds higher than had ever before been obtained by observing the [461] point in the trajectory at which melting of aluminum models began to occur.

Numerous studies of ablation were undertaken during this period. Ablation had become the generally accepted method of protecting spacecraft against the rigors of reentry heating; but the more the ablation process was studied' the more complex it appeared. The process was particularly difficult to treat analytically. Mathematical description of gas-cap conditions, at best almost impossible, became still more difficult with the addition of chemically reactive ablation products to the gases normally present. Moreover, the ablation process itself, and the thermal protection it provided, were quite complex. It was known that an ablation material changing in state, in a nonchemical reaction, from a solid to a liquid to a gas would absorb heat and that the relatively cool ablation gases flowing along the body would fend off the hot gases in the gas cap, thus reducing convective heat transfer to the body. It was also known that under certain conditions some of the melted ablation material would be swept away in waves and thus would fail to complete its cooling mission.

There was, however, much more to the ablation process than the effects just noted. In ablators of current interest, such as those which were made of phenolic nylon, the aerodynamic heating would cause a chemical reaction, a pyrolysis, in the plastic and the resulting vapor would then itself often react chemically (sometimes burn) with the gas-cap gases. The reaction, or pyrolysis, zone in the ablator would gradually work inward from the surface leaving a porous char layer through which the ablation vapors would percolate. If the gas-cap atmosphere contained oxygen (not present in the Mars atmosphere), the ablation vapors and the char-layer surface would tend to burn, thus adding to-not subtracting from-the heat load. However, the char-layer surface would get very hot and dissipate some of its heat by radiation. Thus the whole pattern of convective and radiative heating in the gas cap was materially affected by the ablation process as was also the character of the boundary layer.

The action of the ablator, in all of its ramifications, was difficult of comprehension, but experimentation had confirmed its effectiveness in protecting space vehicles. Of all of the beneficial actions of an ablator, the most important, perhaps, was the fending off of the hot gases by the ablation vapors. The radiation of heat by the char layer had also been found to be important.

A group of six research papers may be cited as representative of the ablation studies at Ames during the period 1963-1965. One was TR R-207 (ref. C-43), "Mass Addition in the Stagnation Region for Velocity up to 50,000 Feet per Second," by John T. Howe and Yvonne S. Sheaffer. In this paper, Howe and Sheaffer undertook the difficult analysis of gas-cap flow to which ablation by-products had been added. Another paper was TN...

....D-2437, "Heat Transfer Measurement for Binary Gas Laminar Boundary Layers with High Rates of Injection," by C. C. Pappas and Arthur F. Okuno. In the work described here, the authors injected gas into the boundary layer to evaluate the major benefit of ablation which arises from fending off the hot gases. This effect could not be determined in tests made with a solid ablator inasmuch as it would be obscured by chemical, and other, reactions produced by the ablator. Another paper in this group, one which was presented at an AIAA meeting in July 1965, was entitled "Generalized Ablation Analysis With Application to Heat Shield Materials and Tektite Glass," by Fred W. Matting and Dean R. Chapman. A useful computer program for ablation analysis was developed in this study.

Additional papers in the group on ablation included one, published in a 1964 issue of the AIAA Journal, entitled "Effect of Gas Composition On....

....the Ablation Behavior of a Charring Material," by Nick S. Vojvodich and Ronald Pope. Another paper published in the AIAA Journal in 1965 was "Experimental Investigation of a Charring Ablative Material Exposed to Combined Convective and Radiative Heating" (ref. C-44), by John H. Lundell, Roy M. Wakefield, and Jerold W. Jones. Finally, a review of Ames work on ablation was prepared by Brad Wick and presented in a paper entitled "Ablation Characteristics and Their Evaluation by Means of Arc Jets and Arc Radiation Sources." In June 1965 Brad delivered this paper before the Seventh International Aeronautical Congress held in Paris.

Radiation, as produced by reentry vehicles, also received much attention at Ames during these years. Radiative heating was known to decrease very rapidly with the backward inclination of the bow shock wave. Thus, by using a pointed conical body, which produced an inclined shock, it could be kept under control. The trouble was that the normal ablation processes rapidly blunted the conical point and when that occurred, a vertical (normal) shock would form in front of the blunted portion. Control of radiative heating thus depended on the designer's ability to ensure that all portions of the bow shock wave maintained a backward tilt.

While many radiation studies were made in the arc-jet facilities at....

...Ames, gas-cap radiation could be truly represented only in the hypervelocity free-flight facilities. It was thus not surprising that much of the radiation research effort was concentrated in the HFF Branch headed by Tom Canning and Bill Page. Indeed the HFF radiation team, headed by Page, was believed to be one of the most knowledgeable groups of reentry radiation experts in the country.

Although the HFF facility was able to reproduce gas-cap radiation phenomena, it did not, for obvious reasons, lend itself to easy radiation measurements. Much ingenuity was therefore exercised in devising methods for measuring the radiation, and the distribution of radiation, in the gas caps of fast-flying models. When it came to measuring ultraviolet radiation, which is absorbed by air, the problem of measurement in the HFF facilities seemed almost insurmountable. Almost it was, but not quite. Dale Compton, one of the clever chaps in the HFF radiation team, solved the problem by using the ultraviolet radiation detector as the target for the speeding test model. Thus the detector, in the barest instant before being struck by the model, was reading the true value of ultraviolet radiation.

A number of the technical papers resulting from the research performed by the HFF radiation group bear mentioning. Among these is TM X-X52, "Measurements of Spatial Distribution of Shock Layer Radiation for Blunt Bodies at Hypersonic Speeds," by John Givens, Thomas N. Canning, and Harry Bailey. Another, published in the Journal of Quantitative Spectroscopy arid Radiative Transfer, is entitled "Oscillator Strengths for the N₂ Second Positive and N₂+ First Negative Systems From Observations of Shock Layers About Hypersonic Projectiles," by Victor H. Reis. Still another important document was TR R-193 (ref. C-45), "Shock-Layer Radiation of Blunt Bodies at Reentry Velocities," by William A. Page and James O. Arnold. In addition to these, there was a study, reported by Jack [465] Stephenson in TN D-2710, of the radiation emanating from the glowing wake of ablating blunt bodies.

Some very fundamental theoretical studies of radiation phenomena were made by such men as Max Heaslet, Franklyn Fuller, Barrett Baldwin, W. P. Jones, and Walter Pearson. Out of their work came a number of reports of which two are representative: TN D-2128, "On the Direct Solution of the Governing Equation for Radiation-Resisted Shock Waves," by Walter E. Pearson; and TN D-2515 (ref. C-46), "Approximate Predictions of the Transport of Thermal Radiation Through an Absorbing Plane Layer," by Max A. Heaslet and Franklyn B. Fuller.

A surprising interest in meteors developed at Ames. It was related in part to practical matters but also to broad philosophical questions-such as the origin of the solar system. Meteor impact was of interest in connection with the damage it might do to spacecraft; meteor flight was of interest because it provided a means of studying aerodynamic heating and ablation at speeds (up to 50 miles per second) so far unattainable in the laboratory; and meteor composition and shape were of interest because of what they might reveal about the composition and origin of our solar system. All told, meteors provided Ames scientists with a very satisfying and rather open-ended field of study.

The meteors that had produced the large craters on the moon were obviously large as were also a few that had left evidence on the earth. It appeared, however, that the overwhelming majority of such bodies were small -their size ranging down to, or less than, that of a small marble. In substantial part, therefore, meteor studies were concerned with small objects, essentially cosmic dust.

Most meteorites,³ it appears, fall into two broad classes depending on composition. Stony meteorites, the first and more common class, are composed of stony or rocklike materials. One variety, the chondrites, contain tiny globular occlusions (chondrules) which may have been formed by condensation from a primordial solar nebula. Iron meteorites, the second class, are in large part composed of iron and nickel and are about twice as dense as the stony variety. In addition to the two main classes, there are also tektites, composed of siliceous glass of somewhat lower density than the stones. Finally, although none has been found on earth, there is some evidence of the existence of a very low-density variety of meteoroid which at Ames was identified by the name "fluffy."

Although the speed of meteoroids was beyond the capabilities of Ames test facilities, Ames engineers had, as earlier reported, been able to use the Ames impact range to assess the threat to spacecraft arising from meteo-[466] -roid impacts. During 1963-1965, the Ames impact range proved useful for investigating the impact characteristics of certain man-made meteoroids as well as for further generalized studies of the impact phenomena. Two papers relating to this work may be cited.

One of these reports is TN D-1981, "Investigation of the Impact of Copper Filaments into Aluminum Targets at Velocities to 16,000 Feet per Second," by C. Robert Nysmith, James L. Summers, and B. Pat Denardo The filaments used in the experiments were very fragile threads of copper, a few thousandths of an inch thick and three-quarters of an inch long. They resembled the filaments which, as contemplated in the Air Force's "West Ford" project, were to be orbited by the billions into a radio-wave-reflecting band around the earth. The study reported in TN D-1981 suggested what might happen to a fast-traveling spacecraft that encountered such man-made projectiles in space. The copper filaments were far too fragile to be hurled down the impact range at the target. Instead, one was supported on threads in the range and the target, an aluminum sphere, was hurled at it. The tests showed that the filament, hit end on, would at speeds of 16,000 feet per second penetrate the aluminum sphere to a depth of about four-tenths of an inch.

The second report to be mentioned is TN D-3369 (ref. (C-47), "Penetration of Polyethylene Into Semi-Infinite 2024-T351 Aluminum up to Velocities of 37,000 Feet per Second," by B. Pat Denardo. This study was parti-...

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[467] ....-cularly notable because it established a world speed record for guns. Never before had a projectile been hurled so fast by a gun. The advances made by Ames in gun development were evident. In this case, the gun used a 125-gram powder charge exploding behind a 100-gram polyethylene deformable piston to compress hydrogen gas which drove the projectile out of the barrel. The projectile was photographed by cameras operating with exposure times, as controlled by Kerr-cell shutters, of 5 billionths of a second. The impact with the target was made at a speed well above that (25,000 fps) at which the target material became fluid and confirmed the earlier established relationship that the penetration of a spherical projectile into a target, and thus the volume of material ejected, varies as the two-thirds power of the projectile velocity expressed as a fraction of the speed of sound in the target material. This speed criterion was thus in the nature of an impact Mach number.

While the work just mentioned was going on in the impact range, Donald Gault and William Quaide of the Space Sciences Division were intently pursuing their studies of impact cratering in materials considered representative of the surfaces of the earth and the moon. The new vertical impact range proved very useful in these studies though it could not reproduce the highest meteor speeds and there were also some questions about scale effect. The speed of the vertical gun was, nevertheless, such that it could at least reproduce the lower end of the lunar primary impact velocities and the full range for the secondary impacts produced by ejecta from primary meteor impacts. Regarding scale effect Gault, Quaide, and Verne Oberbeck obtained reassuring evidence from craters produced at the White Sands Proving Ground by the impact of missiles.

The White Sands evidence also confirmed the impact-range observations that an impact in sand, regardless of the angle of missile approach, would produce a circularly symmetrical crater-in top view. Impact in rock, however, produced a different result which, at least at the lower speeds (of secondary impacts), depended very much on the strength of the target material. Owing to the natural fractures in rock, impacts in such material often produced a squarish crater.

In 1965, Gault and his colleagues were using a new technique for studying the flow of material in impact craters. In this technique, targets having strengths as desired are made from quartz sand bonded by thermosetting cement. The sand is laminated in thin horizontal or vertical layers, each layer being stained with a different color. After the target has been impacted, it is carefully sectioned by sawing. The distortion of the different strata can thus be easily observed and measured. Through the use of this technique, it has been possible at Ames to reproduce in the laboratory many of the peculiar structures found in natural craters. Credit for the method of building the targets goes to Andre Bogart and his coworkers of the Model Construction Branch.

In their cratering work, Gault and his staff had cooperated closely with people of the U.S. Geological Survey office in nearby Menlo Park. Together they had become a team of world authorities on impact cratering. In behalf of the International Astrophysical Union, three of this team-Don Gault, Bill Quaide, and Verne Oberbeck-undertook an interpretation of the photographs of the lunar surface taken by Ranger IX. The study was reported in a paper entitled "Interpreting Ranger Photographs from Impact Cratering Studies."

Gault's cratering studies had involved considerations of the physical nature of the cratering process as well as of the character and trajectories of the material ejected. He had concluded that material was regularly escaping from the moon as a result of impacts of meteor showers-remnants, perhaps, of comets-and that some of it, together with material from remoter origins, was reaching the earth. These considerations encouraged an interest among members of his staff in the nature of the extraterrestrial material and in the possibility that scientifically interesting information could be obtained from it. Interest in these matters led to a fairly intensive study of the composition, origin, and probable thermodynamic history of meteoritic materials.

In 1964-1965, the Space Sciences Planetology Branch participated in the Luster project, an operation in which meteoric particles in space were collected by means of a space probe. Part of the collected material was subjected to chemical analysis at Ames as were also certain meteorites that had been found years earlier on the surface of the earth. The particles examined were often very small, which would have made chemical analysis difficult had it not been for the recent commercial development of an instrument called an electron microprobe. This instrument was capable of nondestructive chemical analysis of a particle only a few thousandths of a millimeter in diameter. The technique was to bombard the specimen with a finely focused beam of high-energy electrons whereupon the specimen would emit X-rays [469] in a pattern of wavelengths and intensities characteristic of the materials present. The emitted pattern was analyzed by means of an X-ray detection system.

Leader of the analytical work on meteorite composition was Dr. Klaus Keil, a brilliant NAS Fellow from Germany who later became a permanent Ames employee. While examining a stony meteorite (enstatite chondrite) which in 1926 had fallen near the Pakistanian village of Jajh deh Kot Lalu, Keil and his colleagues discovered within the meteorite an occlusion of a new material, silicon oxynitride (Si2N2O). The new mineral, which they chose to call "sinoite," had only recently been produced in a laboratory by a team of Swedish scientists; it had never before been discovered in a natural state on earth and presumably could not have been generated in any recent earth environment.

The finding was first reported in the October 9, 1964, issue of Science by its discoverers, Christian A. Andersen of the Hasler Research Center, Goleta, California, Klaus Keil of Ames, and Brian Mason of the American Museum of Natural History, New York. More details of the finding were given in a paper (ref. C-48) entitled "Electron Microprobe Study of the Jajh deh Kot Lalu Enstatite Chondrite," by Klaus Keil and Christian Andersen.

Keil's studies of chondrites led him to believe that they may have come from small planetary bodies which condensed directly from the solar nebula at about the same time-perhaps 4 1/2 billion years ago-that the earth was formed. Inasmuch as the earth's rocks have since remelted one or more times, the chondritic material appeared to be a billion or more years older than the oldest rocks discovered on earth. Meteorites thus provide clues, otherwise unavailable on earth, of the primordial materials and environment that existed during the formation of our solar system.

Keil and his associates also examined iron and stony meteorites to determine from their grain structure the rate at which the material cooled following the solidification process. The cooling rate suggests the depth to which they were buried in the planetary bodies of which, presumably, the meteorite was originally a part. For the meteorites examined, the indications of this analysis are that the burial depth was fairly shallow-150 miles or less.

In the meantime, and throughout the period 1963-1965, Dean Chapman continued his scientific search for the origin of tektites-those grasslike pellets which in great numbers had been discovered in the Australasian region from Tasmania to the Philippines. Dean's detective work had by 1965 become one of the most fascinating displays of scientific virtuosity in the annals of the Ames Research Center. Helping him in this work were Howard Larson, Fred Matting, Frank Centolanzi, and others. The best record of Chapman s tektite studies during this period exists in his paper (ref. C-49) entitled "On the Unity and Origin of the Australasian Tektites," published in Geochimica et Cosmochimica Acta, 1964.

Through careful measurements made on thousands of tektites, Dean [470] and his colleagues determined that despite the variation in physical appearance of tektites from different parts of the Australasian area, they were nevertheless of common age and common origin-which he was convinced was the moon. Their age since last solidification, as determined by both the argon-potassium and the uranium-fission age-dating processes, was 700,000 years. These were by far the youngest tektites found on earth. Tektites found in Czechoslovakia were about 15 million years old and others found in the United States (Georgia and Texas) were still older-about 35 million years.

The youth of the Australasian tektites no doubt accounted for the fact that the ablation pattern, produced by their entry into the earth's atmosphere, had not been worn off in all cases by chemical and physical erosion occurring on earth. And from the ablation pattern and other clues, Dean was able to deduce their entry speed (about 7 miles per second) and entry angle. He was also able to explain the differences in shape of the Australasian tektites-why those that fell in southeast Australia were often nice round little buttons, while those from areas farther north tended to be irregular blobs. If the tektite material had been splashed from the moon, the buttons would come from the hotter, less viscous, central part of the splash and the stringy blobs from the cooler, more viscous, outer portions. The spray of Australasian tektites, Dean concluded, had moved from south to north.

Opponents of the lunar-origin theory pointed out that, from the moon, the earth blocks out only 1/15,000th of the celestial sphere; thus the probability that a splash from the moon would ever hit the earth would be very small, and if it did, they said, it would sweep over the whole earth and not just Australasia. But Dean, with the help of his colleagues at Ames, and an IBM 7094 computer, made trajectory studies which showed that, because of the earth's gravitational pull, the probability that a lunar splash might hit the earth was much greater than the I in 15,000 cited by the objectors and was indeed about 1 in 200-as an average for all possible points of origin on the moon.

Then from lunar photographs, Dean selected 10 of the youngest (700,000 years considered very young) craters-ones in which the rays of ejected material were still clearly visible-and made trajectory studies to determine whether some narrow stream of molten ejecta from any one of the craters could have reached the earth and, if so, what its landing pattern would have been. He found that the probability of an earth hit from most of the craters, including one on the back side, was quite high (as high as I in 60 in one case) but that from only one, Tycho, would the landing pattern correspond to the distribution of Australasian tektites. Tycho, a crater over 50 miles in diameter located in the lower left quadrant of the moon, had in some past millennium been formed by a cataclysmic event of such....

[472] ....appalling magnitude that it might be likened to the ramming several miles into the earth of the combined city and suburbs of Los Angeles.

The spurts of ejecta from a crater, as evidenced by the lunar rays and as observed in impact tests at Ames, are very narrow and the dispersion of those coming from a lunar crater would be further restricted by the focusing effect of the earth's gravitational field. It was clear from the trajectory analysis that the landing pattern of a stream of ejecta from the moon might well be restricted to a fairly small portion of the earth's surface. The analysis had, indeed, indicated the exact angle at which a spurt of ejecta would have had to emerge from Tycho if it were to produce the observed pattern of Australasian tektites. Chapman set his protractor at that angle and laid it on an enlarged photograph of Tycho. Under the protractor's edge lay a prominent ray!

Many simplifying assumptions had been required in making the trajectory analysis and Dean offered no assertions that the Australasian tektites came from Tycho. He remained firmly convinced, however, that they came from the moon. A few of the scientists who earlier opposed this view had yielded a little in the face of Chapman's convincing evidence. As 1965 ended, however, the Nobel Laureate appeared to be holding his ground in opposition.

In October 1963, at a ceremony in which Vice President Lyndon B. Johnson was principal speaker, Dean was presented with NASA's highest scientific award, its Medal for Exceptional Scientific Achievement. He was the first man at Ames to receive this award.

Harvey Allen shared in the general interest in meteors that prevailed at Ames during this period. His special concern with the subject, however, was to gain information on aerodynamic heating that might be useful in the de-...

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[473] ....-sign of some future space vehicle. That, at least, was the nominal objective; but scientific curiosity, unrelated to practical application, was certainly one of the influences which each year led him more deeply into the subject. By the end of 1965 he had become an authority on meteor flight and kept in touch with meteor observation groups in the United States, Canada, and Europe.

The difficulties of increasing the speed potentialities of laboratory test facilities had become so great that the thoughts of Ames engineers had turned to meteors as a possible source of information on high-speed heating effects. Meteors were known to travel at speeds from 7 to 50 miles per second, and their flashing entry into the earth's atmosphere was a common and readily observable occurrence. Astronomers had in fact been making photographic records of meteor trails for many years. Unfortunately for the purpose of their study, most meteors are very small and only a few of the larger ones reach the earth and are recovered for inspection. Moreover, as Allen pointed out, the visible flight of most meteors occurs at an altitude at which the air is too tenuous to act as a continuous medium or to form a shock layer, or gas cap, ahead of the meteor. Much of the meteor evidence is thus lacking in practical value for the aerodynamicist. Nevertheless, it was felt at Ames that useful information was obtainable from the evidence provided by the rather few large meteors that fall, and the Center encouraged the observatories to obtain more and better information on future events of this kind.

The evidence of meteor flight regularly obtained by the observatories consists of precisely timed photographs obtained by two cameras separated by a known distance, and also of photometric measurements of the luminous intensity of the meteor throughout its visible flight path. The camera data provide altitude, flight-path angle, and a time history of velocity and deceleration. Such data also allow the calculation of the rate of ablation- the change in diameter of the meteor-if the density is known. However, unless the meteorite is recovered, its density is difficult to determine. The luminosity data can be used to estimate the rate of mass loss; and Allen, through the use of a rather devious procedure, was able to show that the density could also be estimated. It was clear to Ames engineers that the interpretation of meteor observations could be greatly aided by a program of laboratory tests aimed at the evaluation of such factors as the luminous efficiency and the ablation characteristics of meteoritic materials.

Allen had gone into the meteor-analysis methods with some thoroughness in the report TN D-2068, "Prospects for Obtaining Aerodynamic Heating Results from Analysis of Meteor Flight Data," by H. Julian Allen and Nataline A. James. Along another tack, he and his colleagues, aided by a large electronic computer, calculated the performance of four series of hypothetical meteors, each series composed of a different material (stone, iron, pumice, and tektite glass) and covering a range of meteoroid diameters (0.4 [474] to 0.000001 inch) and a range of entry speeds (7 to 45 miles per second). This very interesting study was reported in TN D-2872 (ref. C-50), "Effect on Meteor Flight of Cooling by Radiation and Ablation," by H. Julian Allen, Barrett S. Baldwin, Jr., and Nataline James. The report provided answers to a number of pertinent questions, such as: (1) At what size does melting occur and over what range of altitudes does the molten state exist? (2) Under what conditions will a nonrotating body with a molten front face have a solid rear face? (3) When will the dynamic pressure overbalance the surface tension and break up a molten drop? (4) How does the size of a meteorite vary with the initial size of the meteoroid? (5) At what altitude does the speed fall to a negligible value? And (6) what is the behavior of the luminosity of these bodies with respect to both maximum magnitude and magnitude variation with altitude?

Meteor evidence obtained by astronomers had revealed certain anomalies such as sudden changes in luminous intensity and sudden drastic reductions in density of the meteor body. Fragmentation of the meteor or peculiarities in surface radiation had been offered as possible causes. Why the density of a meteor of stone should suddenly fall by an order of magnitude was, nevertheless, rather difficult to explain. One possible answer appeared in the course of a major study which Howard Stine and his Magnetoplasmadynamics Branch staff in 1965 were making on meteors and their hazard to spacecraft. This study included measurements of radiation spectra from meteor models in arc-jet facilities and in particular it involved the determination of their luminous efficiency-a factor which heretofore had been largely guessed at but which was needed for an accurate interpretation of flight observations.

In the course of the study just mentioned, a stone meteorite model, containing some moisture, was tested in an arc-jet at very low pressure. In this high-enthalpy, low-pressure environment, the stone bubbled up, becoming frothy or fluffy. Its density fell quickly to a low value. The environment to which the test model was subjected corresponded to high-altitude meteor flight-but would moisture be present in a stone meteoroid? Possibly, Allen thought, if it were of cometary origin. No fluffy meteorite had yet been found on earth but an object of this kind would not, until this time, have been recognized as a meteorite. Henceforth, however, meteorite hunters would be on the lookout for such an object.

The composition and structure of the planets were subjects which were open to a surprising degree of analytical treatment, and such studies received attention from Ames space scientists during the period 1963-1965. Representative of this effort is a paper (ref. C-51) entitled "Models of Uranus and Neptune," by Ray T. Reynolds and Audrey L. Summers, which was....

....published in the January 1965 issue of the Journal of Geophysical Research. The major effort of the Ames space scientists during this period, however, was devoted to investigations of phenomena that were closer to home and more accessible to our spacecraft. These included the magnetic fields of the earth, moon, and nearby planets but related mostly to the flow of solar particles (solar wind) and its interaction with the earth's magnetic field.

The solar wind was known to be composed largely of hydrogen and helium nuclei, heated to a temperature of at least 100,000° K, which flow out from the sun in all directions sweeping over the earth and far beyond at speeds of a million, or more, miles per hour. The earth's magnetic field resists this earthward flow of charged particles and fends them off along a boundary which is about 10 earth radii out from the earth on the solar side but which trails backward, closing behind the earth far downstream. The enclosed, elongated area within the boundary, an area in which the magnetic field is dominant, is called the magnetosphere. The magnetosphere is obviously of vital consequence to human beings for it protects life on earth from damaging, if not deadly, radiation.

The boundary between solar plasma and the magnetosphere is never steady, for the defensive power of the magnetosphere is continually being tested by great surges of particle flux coming from the sun during "solar storms." It is a boundary of conflict between opposing forces, where temperatures rise to a million or more degrees Kelvin as the raging particles from the sun struggle to reach the earth. It is a boundary of great scientific as well as practical interest.

The theoretical attacks on the boundary problem which had begun earlier were continued during this period. Representative of the more recent work in this field was the study reported in TR R-206, "On the Stability of the Boundary of the Geomagnetic Field," by John R. Spreiter and Audrey L. Summers. A contribution was also made by Vernon Rossow in a paper [477] "Magnetic Compression of Collision-Free Plasmas with Charge Separation," which in 1965 appeared in the Journal of the Physics of Fluids. Additionally, the assaults on the boundary produced by solar storms were studied by Joan Hirshberg and reported in a paper, "Recurrent Geomagnetic Storms and the Solar Wind," which in November 1965 was published in the Journal of Geophysical Research.

The opportunities for carrying out experimental research in space were relatively few and the cost of such research was exceedingly high. Accordingly, there was much competition among scientists in the matter of devising experiments so promising that they would be chosen for inclusion in a spaceflight program. To be chosen, not only must the experiment be well conceived but the instruments with which the experimenter proposes to carry out his mission must also be of the highest quality and reliability. This was the sort of business in which Charles Sonett's Space Sciences Division was extensively engaged and much of it was the responsibility of the Electrodynamics Branch headed by John Wolfe. Wolfe had come to Ames in 1960, had become involved in spaceflight research while working in the Physics Branch, and then became the first Ames staff member to join the Space Sciences Division when it was formed. The Space Sciences Division had not long been in operation and had remained painfully short of manpower, yet its performance in the highly competitive field of space research had been noteworthy. Its experiments had been chosen for the following space missions:

Numerous papers were written by Space Sciences Division personnel on studies of magnetic fields and solar-plasma flows. Two papers may be cited as being representative of this work. One (ref. C-52), published in the March 1966 issue of the Journal of Geophysical Research is entitled "Observations of the Solar Wind During the Flight of IMP I," by John H. Wolfe, Richard W. Silva, and Marilyn A. Myers. The second was the paper entitled "Evidence for a Collision-Free Magnetohydrodynamic Shock in Interplanetary Space," by C. P. Sonett, D. S. Colburn, L. Davis, E. J. Smith, and P. J. Coleman, Jr. This paper, which was published in Physical Review Letters in August 1964, contained material included in the book Solar Wind (general editors: Robert Mackin, Jr., and Marcia Neugebauer), published in 1966 by Pergamon Press of New York.

[478] Space-physics experiments were also being devised by individuals in other divisions of the Ames Research Center. Experiments to determine the effects of space radiation on thermal-control coatings had been prepared by Carr Neel of the Gasdynamics Branch and flown in 1962 in OSO 1. Similar experiments prepared by Carr were flown in OSO II, which was launched in 1965. In both cases the experiments were successful, and those in OSO I yielded the additional information on reflected earth radiation reported in TM X-54,034, "Albedo and Earth Radiation From Emissivity Sensors on the First Orbiting Solar Observatory," by John P. Millard and Carr B. Neel

In space research a tremendous premium was placed on the design of accurate, lightweight, reliable instruments, and much ingenuity was demon strafed in the development of such equipment. For his work in devising instruments for the OSO I and II flights, Carr Neel received an award of excellence from the Instrument Society of America. Among the other noteworthy space-research instruments devised by Ames research engineers were a plasma probe, originally developed by Mike Bader and Fred Hansen but later improved by Roger Hedlund, Tom Fryer, and others of the Instrument Research Division, and an excellent magnetometer in the design of which major contributions were made by Charles Sonett, William Kerwin, John Dimeff, and others.

Another useful instrument which attracted much interest was an impulse balance for measuring the momentum of micrometeoroids striking a spacecraft. This instrument, designed by Vernon Rogallo for use in Project Pioneer, was so sensitive that it could detect the heartbeats of a chicken embryo in an egg 4 days old. The instrument found numerous uses such as for measuring the thrust of laser and ion beams, and in 1965 it was being considered by the Food and Drug Administration as a possible means of evaluating the effects of drugs and chemicals on heart action.

Of particular concern to the life-sciences people at Ames was the effect of the environment of space on the performance of the whole man and on the functioning of his organs. Of particular concern were the physiological and psychological stresses peculiar to space flight and the ability of a man to withstand these stresses. Human test specimens were used whenever feasible, but in many cases the severity of the test conditions dictated the use of animals, such as rats, mice, cats, dogs, chickens, and monkeys. Much of the work that related to the performance of man as a whole fell under the jurisdiction of the Biotechnology Division under Steven Belsley, while most of that concerned with the more detailed organic and physiological effects was the responsibility of the Environmental Biology Division under Eric Ogden.

The psychological part of the program had largely to do with the measurement of certain sensory perceptions which might well be important to....

....the crew of a spacecraft. The perceptions evaluated included the judgment of signal duration, pattern recognition, and visual responses to bright objects such as might be seen in space. For the exploration of the last-mentioned problem, a new high luminance vision laboratory was being installed in 1965 as a facility of the Biotechnology Division. Published papers representative of the psychological work at Ames include TM X-54,058, "Intersensory Judgments of Signal Duration," by Trieve A. Tanner, Jr., R. Mark Patton, and R. C. Atkinson; "Methods of Confusion in a Pattern Matching Task," by James A. Duke; and "Visual Problems of Space," by R. Mark Patton. Among other contributors in this particular field of endeavor w ere Ronald Kinchla and Richard Haines.

Effects of the immediate cabin environment on the mental and physical well-being of a spacecraft crew were also studied extensively. Some of this work was aimed specifically at the Apollo lunar mission and some also at longer space missions. One of these studies was an examination of the performance of two human beings (one being Ames test pilot Glen Stinnett) during confinement in an Apollo-size capsule for 7 days. Carried out in 1962, this investigation resulted in two reports, one of which, published in 1963, was T N D-1973 (ref. C-53), "Behavioral Testing During a 7-Day Confinement: The Information Processing Task," by Rollin M. Patton.

The nature of the cabin atmosphere-its composition and pressure- was a matter of grave importance in spacecraft design. In the Mercury and [480] Gemini flights, NASA had used an atmosphere of pure oxygen at about 5 pounds per square inch pressure and was planning to continue this practice in the Apollo. Questions arose about the physiological implications of prolonged exposure to a pure oxygen atmosphere, and this was the subject of at least two investigations conducted with animal subjects. One of these investigations was reported in a paper (ref. C-54), "Effects of Prolonged Exposure of Animals to Increased Oxygen Concentrations," by G. A Brooksby, Robert W. Staley, and Robert L. Dennis, presented in November 1965 at the Third International Conference on Hyperbaric Medicine at Duke University. The second study, yet unreported, was made by Jorge Huertas. In this case a monkey was installed in a special "hypobaric hyperoxic chamber" where he was exposed for periods up to a month to an atmosphere of pure oxygen at 5 pounds per square inch pressure. During the prolonged exposure, observations were made of numerous physiological and behavioral factors to detect any abnormalities arising from the environment.

Aside from claustrophobia and the effects of an unusual atmosphere, there were many other stresses to which a spacecraft crew would be subjected during a long space journey. One was a tendency toward dehydration. A study of this matter at Ames, conducted on human subjects, was reported in the paper, "Voluntary Dehydration in Man," by John E. Greenleaf, published in the July 1965 issue of the Journal of Applied Physiology. Another important cabin stress would arise from the malfunction of the gastrointestinal system during the close and prolonged confinement in a spacecraft. A study of this problem made at Ames is reported by Carl J. Pfeiffer in a paper, "Space (Gastro-enterology-An Appraisal of Gastro-Intestinal Function....

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[481] ...as Related to Space Flight," published in the Medical Times, September 1965.

The metabolism of fats and carbohydrates, and food-energy sources for space flight, were the subjects of extensive investigations at Ames. A major contributor to this effort was Donald Young. Representative of the numerous papers published on the subject was "Carbohydrate and Fat Metabolism During Prolonged Physical Work" (ref. C-55), by Donald R. Young. This paper was presented in March 1965 at the Symposium on Survival Nutrition, at the Arctic Aeromedical Laboratory in Seattle.

Spacecraft-crew requirements for air, food, and water were all under study in 1965, as was the problem of gastrointestinal function and waste disposal. For very long flights such as a trip to Mars, closed ecological systems, involving the complete recycling of all wastes, were being considered. Leading the work on such systems was Phillip Quattrone.

Among the more obvious stresses to which spacecraft crews would be subjected were those which would arise from changes in the force of gravity. A constant gravitational force has been a basic factor in man's evolutionary history and thus, in anticipation of space travel, there was good reason to question his tolerance of changes in gravitational environment, particularly of prolonged exposure to unusual conditions. There was interest not only in the effects of altered gravitation on organic function but also on the processes of reproduction and the physical and behavioral characteristics of offspring conceived and born under such conditions.

At Ames a study of these matters was undertaken by a group of scientists headed by Jiro Oyama. The subjects used for the investigation were rats and mice, and the vehicle for simulating the gravity variations was the centrifuge. The rat cages were hinged so that the combined centrifugal and gravitational force acted normal to the bottom of the cage. The rats were whirled for periods of one or more years at speeds simulating gravity forces of 2.5, 3.5, and 4.7 g. They mated and the babies were born and grew to full maturity while whirling on the centrifuge. The effects of acceleration on behavior, mating practice (discouraging above 3.5 g), metabolism, body weight and size, food consumption, organ development, and other physiological factors were determined. The effects of reducing the acceleration to 1 g (removing rats from centrifuge) after long exposure to high acceleration were also noted. Numerous papers were written on this study, one of which, "Effects of Prolonged Centrifugation on Growth and Organ Development of Rats,, by J. Oyama and W. T. Platt (ref. C-56), was published in April 1965 in the American Journal of Physiology. One interesting effect noted in the centrifugation of rats was the large deposits of fat in the livers of rats that had been exposed to fairly high (4.5 g) accelerations for as little as 3 hours. This phenomenon was examined in some detail and reported in a number of papers, among which was "Chemical and Metabolic Changes of....

....Hepatic Lipids From Rats Exposed to Chronic Radial Acceleration," by D. D. Feller, E. D. Neville, J. Oyama, and E. G. Averkin (ref. C-57) .

Space-cabin environment was expected always to be abnormal in some degree, and the effects on heart function of such conditions as high temperature and abnormal atmospheric-gas composition were considered worthy of study. Among the resulting papers was one by Eric Ogden entitled "Temperature Change and Oxygen Deficit as Determinants of Cardiac Power." It was presented at the 23d International Congress of Physiological Sciences in Tokyo in 1965.

Stresses such as those to which space crews are subjected were known to cause the breakdown of proteins in the body and the release of certain enzymes which might affect body functions. The Life Sciences Directorate had excellent biochemical and endocrinology laboratories and was thus well equipped for enzyme studies. Leaders in this work were J. Ken McDonald and Stanley Ellis. Representative of their work was the study reported in the paper "Properties of a Dipeptidyl Arylamidase of the Pituitary," by J. Ken McDonnald, Stanley Ellis, and Thomas Reilly, published in September 1965 in the Journal of Biological Chemistry.

One of the major efforts of the Ames Environmental Biology Division was a study of the pathological effects, on animals, of radiation such as that to which space travelers might be exposed. This radiation included protons [483] (perhaps the most serious threat), alpha particles, X-rays, and gamma rays. The radiation work at Ames was carried on with the assistance of the University of California Radiation Laboratory by an exceptionally competent team headed by the internationally known neuropathologist, Webb Haymaker, and including Jaime Miquel, J. F. Estable-Puig, R. D. de Estable, Tom Taketa, and others.

The subjects used in the radiation studies included fruit flies, rats, cats, and rhesus monkeys; in some cases the whole body was exposed, and in others only the brain. In all cases, the animals were examined very carefully for pathological changes resulting from the radiation. Brain damage resulting from radiation was evidenced by many cellular changes and by an accumulation of glycogen in the brain. The fruit flies were used for studies of chromosomal changes produced by simulated cosmic ray primaries.

The papers issuing from the radiation studies at Ames, of which Haymaker is an author of a dozen or so, are rather large in number. An example is the paper, "Glycogen Accumulation in Monkey and Cat Brain Exposed to Proton Radiation," by J. Miquel and W. Haymaker (ref. C-58). It was presented at the International Congress of Neuropathology in Zurich in 1965. A second example of the radiation work at Ames is a paper entitled "Effects of Acute Doses of High Energy Protons on Primates," by S. Tom Taketa, C. A. .Sondhaus, B. I,. Castle, W. H. Howard, C. C. Conley, and W. Haymaker (ref. C-59).

Ames benefited from the services not only of Webb Haymaker but also from those of his wife, Dr. Evelyn Anderson, a distinguished endocrinologist who contributed greatly to the establishment of the Ames endocrinology laboratory Dr. Anderson also headed a team which was responsible for developing a method for detecting a hitherto unknown stress hormone in the blood stream. In 1964 she was one of six recipients of the Fourth Annual Federal Woman's Award.

Although the life-science and the physical-science groups at Ames had little in common, mutual benefits occasionally arose from their being together Along the common boundary of their activities, either group could benefit from the expertise of the other. One area in which the physical scientists were able to help the life scientists was in instrument design. Tom Fryer, Gordon Deboo, and Joseph Zuccaro of the Instrument Research Division were particularly active in this field. The work of Zuccaro is indicated by the title of a paper, "Pioneering Work in Bioinstrumentation for Flight Experiments and Flight .Simulation," which in 1965 he presented at a national meeting of the IEEE. Fryer and Deboo wrote a number of papers on bioinstrumentation among which was one entitled "A High-Performance Miniature Biopotential Telemetry System" (ref. C-60). The instrument described in this paper had created widespread interest and had been used quite extensively by C.M. Winget of the Ames Life Sciences Directorate for Studies of circadian rhythms in animals. It was particularly useful for mea-....

....-suring such physiological factors as body temperature, brain waves, and heart action under conditions in which direct wire connections to the subject were not feasible.

Aside from developing bioinstruments, Ames physical scientists Occasionally undertook to apply their special knowledge of fluid flows to the solution of some life-science problem. An example of such application is [485] reported in the paper (ref. C-61) by John Howe and Yvonne Sheaffer on "An Analysis of Recent Hypotheses of Plasma Flow in Pericapillary Spaces."

Perhaps the most stirring prospect in space research is the possibility that life may be discovered on some celestial body other than earth. One might suppose that if an intelligent manlike creature existed on some remote planet, his discovery by earth men would shake the foundations of our Society A much more likely discovery might be of some rudimentary form of life; but even this would be of tremendous scientific interest. The life form discovered might well, indeed, lie in that hazy zone between the inanimate and the animate through which life on earth, in its evolution, passed several billions of years ago. In their search for extraterrestrial life, space scientists, it is clear, must know what kind of evidence to look for, must know how to detect it in a foreign environment, must know how to recover it by means of a remote-controlled vehicle, must know how to nurture any life forms discovered to facilitate later studies and, if such discoveries are returned to earth, must know how to protect the foreign and the domestic life forms from each other. These, then, were some of the problems that faced the Exobiology Division of the Ames Life Sciences Directorate.

The Exobiology Division was headed by Richard Young, who had started the life-science activity at Ames in February 1961. The division in 1965 was comprised of a Chemical Evolution Branch directed by Cyril Ponnamperuma, a Biological Adaptation Branch directed by Robert Painter, and a Life Detection Systems Branch directed by Vance Oyama. The work of the division was of a very basic nature. Most of it was conducted in-house, none with human subjects, and little with animal subjects other than micro-organisms, eggs, and frogs. Indeed the evidence of life that was being sought was so subtle as to be easily obscured by the bacterial "filth" with which all humans and other animals on earth are laden. The experimental work of the Exobiology Division was mostly performed in its own, excellent laboratories though some of it was being carried out in space through experiments placed on space vehicles. Experiments devised by Richard Young and his colleagues were scheduled for inclusion in Gemini flights and the Biosatellite program.

If life forms have developed on other celestial bodies, it is assumed that they did so through a general evolutionary process which began with a primordial, hydrogen-rich environment,⁴ and proceeded first through numerous organic chemical phases, then through biological stages of increasing sophistication The crux of the process is the step, or steps, from the chemical to the biological stage, and it is assumed that this step would not take place [486] unless the chemical environment were favorable. The nominal purpose of the Chemical Evolution Branch was to investigate some of the chemical steps in the evolutionary process; however, if this effort proved successful, the Branch staff could be expected to press on, with great joy and gladness, to the early biological phases. The prospective task was enormous, for it was recognized that in nature the crucial "step" from chemical to biological may well alone have occupied millions of years and been so subtle as to defy any subsequent human effort to demonstrate that, through it, life had truly been produced. Some workers in the field of molecular biology seemed to feel that life is but a property of matter in a certain state of organization and that, if the proper molecules and their organization could be arranged in a test tube, the awesome phenomenon of life would automatically appear. Much work had been done in this field by scientists around the world and, while amazing progress had been made, life had not yet been produced in the laboratory nor was there any solid basis for guessing when this objective might be achieved.

Living matter is largely made up of specialized proteins, each assembled from a variety of amino acids contained in the cells. The amino acids so assembled are connected together, chainlike, in a pattern which is specific for each particular protein. The pattern for the amino-acid chain comes from a gene, also a chain, contained in the cell nucleus. The gene chain is composed of nucleotides each composed of three chemical compounds-a sugar, a phosphate, and any one of four nitrogenous bases. It is, however, the pattern of the bases in the gene chain that determines the pattern of amino acids in the protein.

Clearly the sugars, phosphates, and bases of the gene chain are essential chemical building blocks of life. They are produced in living animals and plants by a chemical breakdown of food or by photosynthesis. The questions Dr. Ponnamperuma and his staff undertook to answer was whether the individual building blocks could be synthesized in the laboratory, whether they could then be combined into nucleotides, and finally whether the nucleotides could be induced to form a gene chain-hopefully self-replicating. If they could demonstrate in the laboratory the chemical steps which led to the origin of life on earth several billions of years ago, this development would then lend much weight to the common presumption that life has also evolved elsewhere in the universe. The results of such work might also suggest what to look for in the search for extraterrestrial life.

In proceeding toward the goals just mentioned, Dr. Ponnamperuma and his associates had, by the end of 1965, synthesized under conditions representing a primitive earth environment, some of the bases (adenine and guanine), sugars (ribose and deoxyribose), sugar-base combinations (adenosine and deoxyadenosine), and nucleotides (such as adenosine triphosphate) contained in the gene chain, as well as some of the amino acids used in protein construction. Still in the early stages, however, were their [487] attempts, through the use of catalytic enzymes and other means, to encourage nucleotides to form a chain.

The work of Ponnamperuma and his associates was reported in numerous papers. One of these (ref. C-62) is entitled "Synthesis of Adenosine Triphosphate Under Possible Primitive Earth Conditions," by Cyril Ponnamperuma, Carl Sagan, and Ruth Mariner. Another, which in May 1965 appeared in Science, is entitled "Nucleotide Synthesis under Possible Primitive Earth Conditions," by Cyril Ponnamperuma and Ruth Mack.

Dr. Ponnamperuma had come to Ames in June 1961 as the first NAS Fellow stationed at the Center. He later became a permanent member of the staff. In recognition of his outstanding work, he was in 1964 presented with the NASA Sustained Superior Performance Award.

In the detection of life, extraterrestrial or otherwise, it is first necessary to establish the criteria by means of which the existence of life will be judged. Inasmuch as the boundary between the animate and the inanimate is rather hazy, there has been some disagreement in scientific circles as to what the criteria should be. Though not in full accord on the subject, scientists generally agree that living matter: (1) is of organic composition, (2) metabolizes (uses up energy and rejects a byproduct substance), (3) grows and reproduces. The first criterion is not conclusive in itself and, while the addition of the second is very reassuring, the matter is really clinched only when the third one is also present.

In view of our total ignorance of the life forms that may exist on foreign bodies, the Exobiology Division assumed that useful related knowledge might be obtained from an investigation of the tolerance of earth life forms to extreme conditions of temperature, pressure, atmosphere, moisture, radiation, salts, and gravity such as may be found naturally, or produced artificially, on earth. This work, which comes under the surveillance of the Biological Adaptation Branch, was still, in 1964, in an early stage.

The detection of life on celestial bodies other than the moon will presumably first be accomplished by remotely controlled, unmanned instrument packages (automated chemical laboratories) that are landed on the body. The development of life-detection procedures had, indeed, been studied extensively by the Exobiology Division as had also the design of automated chemical laboratories for life-detection purposes. Additionally, life-detection field studies were made in Death Valley in 1964.

A number of papers on life-detection problems had, by 1965, been written by members of the Exobiology Division. The best summary of the subject was perhaps to be found in NASA Special Publication SP-75 (ref. C-63) entitled "An Analysis of the Extraterrestrial Life Detection Problem" by Richard S. Young, Robert B. Painter, and Richard D. Johnson. The subject was also treated in Dr. Young's book, Extraterrestrial Biology, published by Holt, Rinehart &- Winston in 1966.

² G. M. Levin of the Goddard Space Flight Center, D. E. Evans of the Manned Spacecraft Center, and V. I. Stevens of the Ames Research Center were members of an Ad Hoc Planetary Atmospheres Committee established by the NASA Office of Advanced Research and Technology.

³ A meteorite is what remains of a meteor or meteoroid that has come to rest on earth.

⁴ An atmosphere presumably containing methane, ammonia, water vapor, and hydrogen, but no free oxygen.

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