THE APOLLO YEARS

YOU'RE WELCOME, ED coolly termed it a "non-catastrophic failure" and we all went back to work. After touched down on the moon astronaut Ed Mitchell called back Fortunately this sort of drama was rare, but the past decade was nevertheless an to Mission Control and said, "Tell those exciting time for all of us. Success pro- guys at MIT thanks. . .they saved the vides its own excitement and the re- mission". This appreciative comment warding triumphs are too numerous to referring to the efforts of a handful of list here. Hundreds of people here at the - Draper people in the wee hours of the Draper Laboratory, who have partici- morning is one of the high points of the pated in what is probably the greatest , but it should not over- achievement of their lifetime, can be shadow the ten-year effort by all. Special APOLLO Edition Jan 73 proud. We have been privileged to be It has been a long trip. part of a great team, and we can look APOLLO: THE WAY IT WAS back at this program with a glow of ac- Draper engineers and technicians were complishment. As Doc told us, "You're The following reflections on the Apollo pro- already working on Apollo back when no longer saying that you are going 10 gram were written by five men intimately Alan Shepard sat inside a tin can atop a involved in the moon effort. The pieces are do it-YOU DID IT!" critical, whimsical and sentimental, but all Redstone and waited for a bunch of en- represent the feelings of the Draper five who gineers who had never sent a man into And we'll do it again. With the ap- held prime responsibilities for APOLLO. space before to touch it off. We were in proaching SKYLAB missions and the beginnings of the Shuttle work we can RALPH RAGAN: on the ground floor back in the days see that not only is the space program THE GOOD OLD DAYS when NASA had few experts but plenty of money, and we have watched while here to stay, but the Draper Laboratory It is difficult to judge a painting when that situation slowly reversed. is in it to stay. Perhaps we can even look you stand close to it. Likewise, it has forward to a time when Draper Labora- been difficult to judge the Apollo pro- Draper Laboratory was a key part of tory technicians and engineers ascend to gram while being involved in it from the this effort when, during Jim an orbiting space station to field-test inside. We, at the Draper Lab, have al- Lovell drawled, "ah,. . . we've their equipment. ways been dedicated and interested in got a problem". He didn't know just Astronaut Eugene Cernan paused before the challenging technology that it has how bad his problem was, with a large entering the command mod- been our fortune to have. So it was not part of the butt end of his vehicle blown ule and said, ". . .Any part of Apollo 17 surprising to see our people apply them- out taking with it many of the con- or any part of Apollo that has been a selves eagerly to the most difficult tech- sumable~. Draper experts participated success is for the most part due to the nical task of guiding manned spacecrafts with NASA in the crucial decisions thousands of people in the aerospace to the moon. However, as the program necessary to bring the crew back safely. industry who have given a great deal. . . gained momentum, many found that A unique corrective burn by the lunar to make it all reality. I would just like their favorite solution to a complex module's descent engine sent the cold, to thank them. . .God bless you and technical problem had to be compromi- nearly-dead spacecraft around the moon thank you." sed to interface with a schedule, a cost and back to earth. The aborted mission restriction, or an associate's needs. became a triumph of sorts and Houston Gene, Baby-it's been a pleasure. My most poignant memories of the pro- gram will be of watching the many young outstanding engineers who faced this conflict for the first time and suc- cessfully met the challenge. Time and again I saw our people dig in to tedious and tiresome tasks which restricted the creativity of the individual concerned - maybe it was coding someone else's equations, or maybe it was making a reliable circuit with unreliable relays when it was obvious that better equa- tions and better relays were wanted. cont pg 2

D-NOTES is published for the personnel of the Laboratory, Cam- bridge, Massachusetts. News and contributions should be addressed to D-NOTES and for- warded to Publications, Room DL141 1, 68 DL7 on December 19th, just before the splashaown of Apo~lo17-members of the Albany Street, Cambridge, Massachusetts 02139 press share the excitement with the SCAMA Room crew. Telephone: (6171-258-3547. THE WAY IT WAS cont Lunar landing accuracies were specified which were exceeded in every mission But year after year our people worked to be within 0.5nm of a specified landing by the combined use of the spacecraft the long hours required to overcome site. At that time it was felt that this GNCS and earth-tracking systems. was the maximum distance an astronaut these obstacles and to meet the overall It is seldom that a large project such as could walk on the moon and then return objectives. For many the tasks were not the Apollo program, with its extensive to the LM. With , a "pin-point" fun, but they did what they had to do public exposure, exceeds its design ob- landing within a few hundred feet of a and most can now look back and say, jectives in such a spectacular manner. Surveyor Spacecraft was achieved, and "Those were the good old days." The Draper Laboratory should be proud this type of performance later became of the major role it played in supporting routine. such a national program. Again, in the early design phase of the program, lunar orbital rendezvous ap- RICHARD BATTIN: peared to be a major GNCS performance PRETTY HEADY STUFF problem since several of the first earth orbital rendezvous missions on the Gem- While the flight director called out the ini program were difficult to complete increasing velocities during the trans- and required more propellant than was lunar insertion burn of , an desired. eerie sensation crept over me as I gradu- ally began to realize that men .were No less than six guidance and naviga- actually going to the moon. We had tion systems were designed for this phase of the mission; three on the LM Deputy Director for NASA Programs (PGNCS, AGS, and CHARTS); two on the CSM (PGNCS and CHARTS); and It was clear to me that the motivation finally the earth-trackingsystem. to bear this drudgery was the thrill of participating in the great adventure of The Lab'stwo primary GNCS of the LM the Apollo program. We all felt it. We and CSM performed so well from the are convinced that centuries from now first Apollo 7 rendezvous, using only the Apollo program will be judged the optical sightings, that all subsequent great achievement of the twentieth cen- rendezvous became routine. It reached iun/. There are others not so intimately the point of lunar mission crews failing involved who agree with us. Even some to report, until post-mission debriefing of the younger members of our families, sessions, mid-course correction man- who are now questioning how tech- RlCHA RD BA TTIN: euvers performed on the far side of the Director of Mission Development nology should be used, think so. We are moon. Some of the most impressive fortunate to have received so much rec- worked many years toward this event camera and television pictures taken ognition in real time. but, somehow, the reality of the Apollo during the program were those of the program had not struck me fully until terminal phases of the lunar rendezvous. then. NORMAN SEARS: JUST1 FIABLY PROUD Personally, I had already been to the moon via equations and simulations and In looking back over the past ten years meetings many times during the pre- of the Apollo program, I believe that the vious eight long years. I had been re- Draper Laboratory can be justifiably sponsible for the flight computer soft- proud of its major role in the design of ware of Apollo even before the word the Apollo Guidance, Navigation and "software" was coined. Schedules, de- Control system (GNCS)-one of the velopment plans, manpower estimates most sophisticated subsystems involved -these things were reality. Flying to the in the program. moon was only the goal-pretty heady stuff to be sure-but too many things The continued support of the GNCS had to work, too many pieces had to throughout the operational missions to fall into place. It was all an enormous the moon was an equally significant fantasy. achievement for the Lab. But to my mind, the most impressive accomplish- On the other hand, a host of analytical ment was the performance of this sys- NORMAN SEARS: problems in guidance, navigation and Director of Systems Development tem in both the CSM and the LM control had been solved at MIT during spacecraft, with respect to reliability those eight years. We could take final Another mission phase providing its and accuracy. solace in that. At least now we knew share of spectacular television coverage how it could be accomplished even if we Early in the program, many of the per- was the earth entry and splashdown. never really did it. formance requirements specified seemed Here again, original performance require- difficult, if not impossible to achieve. ments called for 5 to 1 Onm accuracies BATTIN cont pg 4 ELDON HALL: The attempt to limit the design had We who have been working on Apollo RELIABILITY THE QUESTION advantages, but as the project developed since it started in the Lab in 1961 have the requirements continued to expand. spent over eleven years on one program. The development of the Apollo hard- Fortunately the design,was conservative That's a large fraction of one's profes- ware presented many challenges, to its enough to tolerate several increases in sional career. I have never regretted a designers. In the case of the computers capacity. The outside experts discovered moment of it. Rather, it was something for the of the LM and many points to criticize, but offered few to enjoy. At least in retrospect, i enjoyed CM spacecraft, the challenge had many constructive ideas. In retrospect, their it. Many times the urgency and pressure technical aspects. It was also necessary contribution was mainly as a catalyst of major problems seemed to consume to convince the pi-ogram managers that which kept the D-Lab designers alert. all my available energy and enthusjasm. it was feasible to design and to build a If many more outside experts had been But these things are solved and pass on. digital computer of the required capa- available, their criticisms and alternate The memory saves the pleasant parts city which would still meet the program approaches may have led to complete most vividly. requirements of schedule, cost, relia- confusion. bility, size, weight and power. In the early 1960's the technology base The subject of reliability represented a was rather shaky. The application of real significant question since in the early time digital control computers was in 1960's no one would accept the fact its infancy. In general, control compu- that a computer could be made to op- ters were very limited in computational erate error-free for about two weeks. capacity, quite large and noted for poor This point is even difficult to accept to- reliability. day. The approach used by Apollo at- tempted to eliminate the source of The very demanding requirements for transient and hard failures. abundant computational capacity with very little penalty in terms of size, weight, The design provided methods of detec- power, and reliability required a signifi- tion and recovery from transient failures. cant advancement in digital computer DA VlD HOAG: The solution to the hard failures was Director of the Apollo Program technology. Even now, ten years after attacked by very careful design, by its development, there are very few, if maximum use of standardized compo- But I still remember, during times of any, aerospace computers with its com- nents, by working with component ven- strain, when everything seemed to be putational capacity and none which are dors to improve reliability, and by well- going wrong, the unselfish dedication also low power, small size and reliable. controlled fabrication techniques, and and effort of my colleagues in meeting To meet the Apollo requirements the subsequently by the development of very major and trivial problems. This part of computer designers advanced the state special procedures for monitoring the my memory is particularly cherished. of the art by the application of new quality of components and assembly These people I worked with are friends technologies in areas such as integrated processes during manufacturing. and admired engineers and technicians circuits, large capacity read-only mem- of outstanding competence. I am proud ories, welded cordwood construction, etc. One important ingredient should not be to be part of that team. underestimated-the motivation of all Because the Apollo requirements were From the beginning I wondered if we the people working on the program so demanding, program management ap- really were going to land men on the from the Draper designers to the com- plied pressure to limit the compensa- moon. The technology was possible and ponent manufacturers, the assembly line tional requirements and called in many the country's commitment was suf- workers and others. The challenge of outside experts to evaluate the design ficient, but there was something in- the Apollo Mission provided the addi- approach proposed by the Draper Lab. credible and mysterious about the auda- tional motivation which contributed sig- city of it that transcends description. nificantly to the success of the com- No one had ever left the narrow bounds puter. of earth in millions of years. Why should it happen now? Why should I be a par- ticipant? And now that the landings are DAVID HOAG: behind us, I still sometimes suddenly ask DID IT REALLY HAPPEN? myself: Did it really happen? Before Apollo, while I was working on The end of the program brings mixed the Polaris program, I was convinced emotions. It was as inevitable as was my that the first successful Polaris shot youth passing by or my children growing from Cape Canaveral was the pinnacle up. The one compensation is that, with of my experience. I could not imagine luck, I will be working on new programs anything beating that Now I am sobered which, although not as spectacular, will by the thought that by luck, or what- provide new challenges. But just as im- ever it was, I have been given a second portant, I look forward to the oppor- peak. Why was it that Iwas permitted to tunity to work with the same respected ELDON HALL: play a role in such an important and colleagues who shared with me the Director of Digital Development successful program as Apollo? Apollo years. THE JOY OF IT ALL formed every measurement task asked of of dense Basal tic.rock perhaps as much it, in an almost flawless manner. as three or four kilometers in thickness. The TGE was originally proposed to show What Ifound particularly exciting during what a portable, automated gravimeter and immediately following Apollo 17 was could do in terms of defining the under- seeing how the data from various experi- ground structure beneath an area on the ments sucj! as surface geology, the active moon traversed by a vehicle seismic portion of ALSEP, and orbit per- (LRV). This was the first time a series of turbations of the CM began to fit to- precise measurements of the moon's gra- gether and define the underground struc- vity had been made on the surface of the ture and history of the moon in com- planet itself. plete agreement with the gravimeter data. Needless to say, the picture of the This extremely sensitive device is able to moon's interior, as well as how its outer resolve gravity differences as little as 0.035 mgal on the moon and is also able to measure the earth gravity field equal to about 980,000 mgals. It was hoped that the gravity readings would help solve the puzzle regarding the geological structure of the Sea of Serenity, which is near Taurus Littrow.

During the three EVA'S of Apollo 17, 21 gravity readings were taken at ten dif- ferent qeolo~ically- - significant locations. The direct gravity reading variations cov- SHE1 DON BUCK: Technical Director, ered a range of 49.5 mgals. By having Traverse Gravimeter Experiment 'By all the gods, you did it! You are Astronauts Cernan and Schmitt get off wnderful and smart people-I drink to layers were possibly formed, are now on the LRV in order to obtain an additional much firmer ground than any one single what you have done." Standing atop a measurement between stations 2 and 3 in table in the smoky SCAMA Room at experiment could possibly provide. DL 7, Charles Stark Draper toasted the the second EVA, the existance of a steep or large gravity gradient was verified, and Apollo program and the people who had BA TTIN cont made the great adventure possible. the three readings near the base of the South Massif will be of great help in de- Seconds after the splashdown, Dr. Draper But they were doing it! The S4B engine mounted the table to applause, cheers terminingthe nature of the underground had shut down on schedule and they and the popping of champagne corks. boundary between the material of the were on the way. It was Christmas, Massif and that of the Valley. 1968, just eleven years since the Russian And afterwards, there was time for talk Sputnik. of the long hours and the unbelievable According to Columbia University's Dr. deadlines. . .the challenge of it all. . . Manik Talwani, the principal investigator It is now fifteen years since the first something to tell one 's grandchildren. . . for the TGE, preliminary conclusions of man-made object orbited the earth. Who another frontier conquered. the future. . . the traverse gravity measurements indi- could have guessed that twelve men on cate that the material under the valley six different occasions would spend floor of Taurus Littrow is much denser many long hours and days exploring the GRAVIMETER A SUCCESS than that of the North and South Massif. moon? Incredible! But now it has been In January, 1970, Sheldon W. Buck became The gravity values w~llsupport the hy- done and the truly incredible thing is the Technical Director of the Traverse Gravi- ~othesisthat the vallev subfloor consists that it mav never hamen aaain. meter Experiment (TGE) at the Draper Lab- oratory. On December 7,1972, the gravimeter became the first piece of equipment designed, developed and built at Draper to be sent to the moon.

SHELDON BUCK: ON FIRMER GROUND I was sorry to see it go, as the traverse gravimeter headed for the lunar horizon after being hurled by Apollo 17 Com- mander Cernan; but the instrument had completed its mission of measuring local gravity variations across the valley of Taurus Littrow and had made an accurate earth-moon gravity transfer measurement. Milt Trageser (at left), whose MARS Reconnaissance Plan was the basis for In fact, this prime flight unit had per- the APOLLO proposal, toasts the APOLLO 17 splashdown.