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A Running Start - Apollo 17 up to Powered Descent Initiation

Corrected Transcript and Commentary Copyright © 1995 by Eric M. Jones.
All rights reserved.
Last revised 24 September 2010.

In a few pages, we will pick up the Apollo 17 mission at the time of Powered Decent Initiation (PDI), the beginning of the engine burn that took Cernan and Schmitt down to a landing at Taurus-Littrow. First, we will go back a few years to the point of definition of Apollo 17 and then, picking up at launch from Earth, summarize the mission up to PDI.

The mission that became Apollo 17 began life as Apollo 18. In the early years of the program, NASA had all that it could handle in getting the hardware designed and tested and it wasn't until late 1967 that NASA was in any position to sketch out a lunar program that included the possibility of missions past a first landing. In discussions with Congress, NASA Administrator James Webb indicated that the program would require 15 Saturn Vs and Command Modules and 14 LMs. This was enough hardware for the missions which were eventually designated Apollos 7 through 20. There was no way of knowing, of course, how much of the flight hardware would have to be used in test flights prior to the first landing and few would have predicted with confidence that the first landing would be accomplished as early as Apollo 11. The early success meant NASA had hardware for nine more landings and, on July 28, four days after the Apollo 11 splashdown in the Pacific, NASA announced a tentative schedule of flights up through Apollo 20. Apollo 12 was scheduled for November 1969; and, in general terms, Apollos 13, 14 and 15 were planned as missions using the same LM design flown on 11 and 12. Apollo 16, then planned for April 1971, would be the first of the missions to fly the advanced LM and the Lunar Rover. As mentioned previously, the latter type of mission was known as a J mission.

Crew Selection

A few weeks later, on August 8, 1969, NASA announced the crews for Apollo 13 and 14, the scheduled third and fourth landings. The backup crew for 14 included Gene Cernan as Commander, Ron Evans as Command Module Pilot, and Joe Engle as Lunar Module Pilot. In the normal scheme of crew rotation, Cernan, Evans, and Engle were expected to fly Apollo 17, then scheduled as the second of the J missions.

However, continued erosion of political support for Apollo forced NASA, on January 4, 1970, to announce the cancellation of Apollo 20 and, also, a stretchout of the schedule with Apollo 13 moved from March to April and Apollo 14 moved from July to an unspecified date in the fall. On March 26, NASA announced the selection of Scott, Worden, and Irwin as the Apollo 15 crew, with Dick Gordon serving as backup Commander, Vance Brand as backup Command Module Pilot, and Jack Schmitt as backup Lunar Module Pilot. No specific date was set for Apollo 15. NASA expected it to be flown about six months after the completion of Apollo 14.

In the absence of any further cutbacks, Gordon, Brand, and Schmitt would have been assigned to fly Apollo 18. At the time, Schmitt was the only geologist in the astronaut corps and it came as no surprise that he was the first of the scientist-astronauts to be assigned to a crew. As detailed by historian W. David Compton in his book, Where No Man Has Gone Before, the scientific community and some of the scientist-astronauts had long been lobbying for their assignment to crews and were upset that pilots with less seniority were getting seats while the scientists were relegated to support roles. Schmitt, in the meantime, devoted his efforts to learning the LM systems and other essentials of becoming a Lunar Module Pilot; and he also spent years making sure that the geology training for the pilots would actually be useful to them. There were strong arguments that, after only a few missions, Apollo was still very much an experimental program and, certainly, NASA was very aware that a failed or fatal mission could well be a political disaster. Thus, while it seems likely that lobbying by the scientific community contributed to Schmitt's assignment to the 15 backup crew, it is also likely that his own work as an astronaut was of far greater importance. Those who know Slayton well are adamant that Schmitt would not have flown had Slayton not believed that he was fully qualified to fly as a Lunar Module Pilot.

Unfortunately, in September 1970, Apollo 18 was relegated to the historical dustbin. A combination of the Apollo 13 accident in April and further budget tightening forced NASA to cancel the third H mission (then known as Apollo 15) and the fourth J mission (Apollo 19). The remaining three missions were then renumbered, with Scott, Worden, and Irwin inheriting the first of the advanced LMs and the first of the Rovers, This mission was to have been Apollo 16 but was renamed Apollo 15. Young and Duke would now fly the second J mission along with Ken Mattingly, who had been bumped from Apollo 13 and replaced by Jack Swigert because of possible exposure to German measles. With the renumbering, Apollo 17 would now be the third and last of the J missions; and, while Cernan, Evans, and Engle still had prospects of making that flight, it looked as though the Apollo 15 backup crew of Gordon, Brand, and Schmitt would be left out in the cold.

The scientific community was now faced with the possibility that none of the scientist-astronauts would get to the Moon and, as Compton discusses in his book, in the early months of 1971, they lobbied NASA hard. Ultimately, the decision was Slayton's and it is an open question whether the lobbying had any appreciable effect. Slayton certainly understood the logic of sending a geologist to the Moon and, with Schmitt as the geologist, the decision was probably not a difficult one. The announcement was made on August 13. Cernan, Evans, and Schmitt would fly on Apollo 17.

The following paragraphs have been derived from my February 21, 1994 conversation with Gene Cernan and deal with Gene's - and Jack's - road to Apollo 17. Readers should note that the Apollo 13 and 14 crews were announced in August 1969 and that the mission that would have been Apollo 20 wasn't canceled until January 1970. Further, the missions that would have been Apollos 18 and 19 weren't canceled until the following September.

"In 1969, I was approached by Deke about assigning me as Lunar Module Pilot with John Young on the backup crew for Apollo 13. Deke never gave any guarantees that you were going to rotate and get any flight. He never said the backup crew of Apollo 13 was going to fly Apollo 16. But the bottom line is that I told Deke I'd rather wait for an opportunity to fly in the left seat and have my own crew - even though I knew that opportunity might not come - rather than commit myself and eliminate all other possibilities, except maybe a flight in Skylab, to fly Apollo from the left seat. I just wanted my own crew. Basically, Deke had said 'Well, you know the chances are you're going to fly on a lunar landing mission if you're on the backup crew of Apollo 13. No guarantee. But the chances are you will.' And you know, flying with John would have been fine. But I just wanted to take my chances. So, in Deke's typical way, he said 'Fine. If that's what you want. But, you know, I'm not guaranteeing, number one, that I'll assign you the left seat (meaning to be the Commander) on any mission and if I do assign you the left seat on a mission, there's no guarantee that your backup crew would rotate and, besides, the first mission you could possibly get as the backup crew in the left seat would be 14.' And then he said 'You know, if you get 14 (backup), there may or may not be a 17, because 20 is already canceled and people were talking about other missions being canceled. So you may be talking yourself out of walking on the Moon.' That's what he said, in so many words. And I said, 'I'll take my chances.'"

"Charlie Duke (who flew with Young on Apollo 16) doesn't know what I just told you. But it's history, and it probably ought to be written down. And so I took my chances and reluctantly did not accept what was told me might be my only opportunity to walk on the Moon."

"Subsequent to that conversation with Deke, I was assigned to backup 14. And probably, at that point in time, backing up Al Shepard was the greatest challenge that any human being could ever ask for. Because Al Shepard was still a stranger to most people. But, once he and I had a couple of very candid, up-front discussions, we became very best friends. I think that what happened was that, as his backup, I had to tell him and then prove to him that I was his equal. And I think I did that. And he accepted me. He has mellowed a lot since he flew Apollo 14; and we've become very good friends with, I think, a great deal of mutual respect. But, prior to that, I didn't know Al Shepard very well at all, in spite of the fact that he was my boss."

"So, Deke threw me into the fire. He said (in effect), "All right, you want a left seat backup (that is, be a back-up Commander assignment)? You got one!" In retrospect - and it was probably not too calculated on my part - it was the best pull-it-out-of-your-butt decision I made in my entire life. In turning down a chance to walk (on the Moon with Young) and then getting both the challenge and the opportunity of backing up Shepard, I put myself in the very vulnerable position of maybe never flying on Apollo again, much less ever landing on the Moon. But, I told Al that our crew was going to do our best to get his crew to the Moon and back safely, and that we were going to be better prepared to fly than he was. And, from that moment on, I gained his respect. And we had a ball. We enjoyed it."

"Now, how did the Apollo 17 crew finally get selected. Once we started backing up 14, it didn't take long to realize that the only thing that was obvious was that a geologist - and there was only one - was going to fly a mission to the Moon. And when 18 got canceled (in September 1970) it was like "Wow!" Jack was already on the backup crew to 15 (that announcement had been made in March 1970). When 18 got canceled, we all knew that there was a lot of political pressure to put Jack on a lunar mission. And there weren't any left except 17."

"Now, Deke was the kind of guy who could never have been pressured by anybody. Deke would have resigned. If the President of the United States had come to him and told him to fly somebody that Deke didn't think as qualified, he would have resigned. Deke would never, ever have put anybody on any mission who he didn't feel could Goddamn do the job and do it well. Deke would not have put Jack - nor would Deke have put me - on that flight if he didn't think we could handle it. And, once he decided you can handle it, and once he put you on that flight, he would defend you to Kraft or anybody and stick by his guns. That's just the way Deke was. Deke was a no-bullshit guy. A let's-get-on-with-it guy. He was the Godfather. He was the true, unflappable guy, the one who'd listen to all the stuff about why you can or can't get something done and then say, 'Let's get on with it.' When I got selected for the space program, I got a call from Deke and he said 'I've got a job for you down here, if you still want it.' It's not like 'Hey, Gene! Congratulations you've been selected!' And if I'd said 'Deke, I've change my mind', he would have said 'Okay. Listen, I'll look forward to seeing you again, some time.' That's the kind of guy Slayton was. He never forced anyone to do anything, and he never had anything forced upon him, other than his removal from flight status back in Mercury."

"So it became obvious that Jack was going to fly Apollo 17, and the thing we talked less and less about was what was going to happen to Joe Engle (who was then the Apollo 14 backup LMP). But the question was: who was going to fly as Commander? Deke never gave us any guarantees, never gave me a Guarantee One that I was going to rotate from 14 to 17. Not a one. And I knew what was going through Dick Gordon's mind at the time. All six of us - well, maybe Jack wasn't sure - but the rest of us were sure that Jack was going to fly on that mission. The question was whether Jack's going to take Joe Engle's place and we're going to rotate or whether they were going to take Jack's entire crew - the Apollo 15 backup crew - and put them on Apollo 17. Had Deke made that decision, he would have been well within his right to make it. There was enough time, they were well trained, they were capable and they worked together well and, quite frankly, I don't know what tipped the scale one way or the other. All those little factors add up. How well you performed in simulations and all the other things.

"It was probably a pretty non-political decision, although, I think there were two camps. I think there were people who wanted to see Gordon and his crew fly, and I think there were people who probably wanted to see me fly, not withstanding the fact that Ron Evans and I would fly without Joe Engle. Obviously, where I went, Ron Evans went. The question was on the table until October of 1971 when I got a call in Acapulco from Deke asking me how I'd like to fly Apollo 17 with Ron and Jack. I think Joe Engle knew the handwriting was on the wall. Because I wanted to keep my crew together, I had done some fighting for Joe to stay on the mission. And had a lot of sympathy and support from people. But only to the point where I was asked 'Are you telling me you will only fly with Joe? If you're telling me that, then it makes my decision a lot easier.' And I told Deke, 'No, I can't tell you that. I've fought too hard for the opportunity to have my own crew and to be in the left seat.' And it was not a question of Jack as an individual, it was just a case of wanting to keep your crew together, quite frankly. And I said 'No, I won't tell you that.'

"Now, I don't know how Deke came to the conclusion he came to. Maybe he took my background and experience - along with Ron's because Ron was a good pilot and had a good reputation with the simulation people and everybody else and studied geology hard - and put them up against Dick Gordon's and Vance Brand's capabilities and said 'Notwithstanding the fact that we're going to break up the Dick Gordon crew, this is our best combination.' I don't know how that decision was arrived at. I do know that there were people in Dick Gordon's camp and there were people in my camp. I say it probably wasn't a political decision, but I do have to believe that there were some strong supporters on both sides who made a difference. And if I had to pick two people who were on my side, I'd have to say that Stafford was one and Shepard was another. And I may never know. And if I had to pick, I'd said McDivitt was certainly in Gordon's corner, as was Conrad. And the reason Shepard would have been in my camp was because we did such a good job on 14. I mean, that was my key. I either flunked or passed the test on 14. And if I passed it, then I had to wait and see what was going to happen."

"There are always a lot of what-ifs that come up in talking about the Apollo crew selection. Had I chosen to fly the Apollo 13 backup crew and, eventually 16, who knows how it would have turned out on 17. Who would have backed up 14? And who would have flown 17? Just like the accident that killed Elliot See and Charlie Bassett in St. Louis that put Tom Stafford and I (the Gemini 9 backup crew) onto Gemini 9. If that accident hadn't happened, Buzz wouldn't have flown in Gemini; but it did and then, somehow, he found himself walking on the Moon. Who knows. He might have been a Command Module Pilot. Or he might have flown an early Earth orbit Apollo mission and have gotten a lunar flight later on. Who knows?" Readers interested in the what-ifs of Gemini/Apollo crew selections would do well to consult Mike Collins' excellent book, "Carrying the Fire". In brief, See and Bassett were in training as the prime crew for Gemini 9 when they were killed. That moved their backups - Stafford and Cernan - onto the flight and moved the Gemini 10 backup crew - Lovell and Aldrin - up to the Gemini 9 backup slot. That, in turn, gave them the assignment as the prime crew on Gemini 12, the last of the Gemini flights. In other words, if See and Bassett hadn't been killed, Aldrin might have drawn an early Apollo flight, and so on. My thanks to Journal Contributor Garry Kennedy for suggesting this explanation.

Gene continues.

"Anyway, I know that there were people who thought that Jack had a lot to prove. He got the Apollo 17 assignment because he was a geologist and there were some people saying he wasn't an aviator, that he shouldn't fly, that he couldn't handle it. So Jack probably had a little cross to bear in proving to those people that, not only could he handle the geology - which came natural - but also that he could handle the other requirements of being a Lunar Module Pilot."

"Some time ago I told you that Jack was an 'adequate' pilot, and I want to clarify that. Jack in a T-38 was an adequate (airplane) pilot. He wasn't a great pilot, but he didn't have the experience to be a great pilot. And, quite frankly, I don't think he had the aptitude or the desire to be a great pilot. Jack flew airplanes in NASA because he had to fly. That was one of the squares to fill to get on the Moon. And that's not a knock. I flew with Jack in T-38's, and I think Jack was a safe and an adequate pilot. I don't think Jack thought he was the greatest pilot in the world. Most people who want to fly big-time or fly off aircraft carriers, if they're not a little arrogant and don't think they're the best pilot in the world, they should get in some other business. And, since we came back, Jack hasn't flown. To be a great pilot, you've got to think you can do it better than it had ever been done before. You know your limitations, but you have to be a little arrogant. I used to say, 'I dare the guidance system on the Apollo Saturn V to fail, because I can get us into orbit.' And if I didn't think I could get us into orbit, then I shouldn't have been there. And I knew I could land that lunar module closer than anybody else had done to their desired landing point. Whether I'm a few feet long or short, really didn't matter, but I had to go into that mission thinking that. It's the kind of arrogance - not egotism - that you have to have. And Jack didn't have that when it came to flying an airplane. Adequate is the word I used."

In a prior conversation, Jack and I discussed his flying abilities.
"I was a pretty good (airplane) pilot, as long as I was doing it. As long as I was proficient and was getting lots of time. But if I stopped getting time, my skills degraded faster than somebody who trained as a teenager. And I've always interpreted that primarily as coming at it late and as having some neuro-pathways developed because of scientific training where you get to focus on things longer than you can focus on them when you're flying an airplane. As long as I was doing it routinely, more or less daily and getting good-weather time, I was fine. I think I was as good as anybody. But if you put me into a situation where the skills of test-piloting, fighter-piloting, and formation flying are necessary, it was just outside my experience. Yeah, I would never stack myself up against those guys. But, routine flying of a T-38 - and, by that, I mean emergency or otherwise - and helicopters, I had no qualms."
Gene continues.
"Now, when it came to flying the lunar module, 'adequate' does not describe Jack's ability to fly in the right-hand seat of the lunar module. He was outstanding."
Readers who are not familiar with the duties of the Commander and the Lunar Module Pilot should note that, while the Commander actually flew the LM during the final approach - using the handcontroller to change targeting, attitude, horizontal velocity, and descent rate - the LMP monitored the computers and other spacecraft systems and provided information to the Commander. Consequently, the LMP's job was not the sort of thing that one normally associates with being a "pilot".

Gene continues.

"Jack knew the systems. He knew the AGS computer. He knew the PGNS computer. He knew the dynamics. He knew what we were going to be looking at. Now, when I say 'fly', Jack didn't have much of a chance to land it (in the simulators) and Jack didn't have much of a chance to fly the rendezvous, but that wasn't his job. He trained hard. He studied hard; and he worked hard. Jack was not an 'adequate' lunar module pilot; he jumped in with both feet and was an outstanding lunar module pilot. Now, contrast that with Joe Engle. Joe was born with a stick and rudder in his hand. Joe Engle is probably the finest stick and rudder aviator that I've ever flown with in my entire life. He could make an airplane do things that I don't have guts enough to make it do. So Joe was an outstanding aviator. In contrast, Joe was only an adequate lunar module pilot."
Jack continues.
"When Deke Slayton said 'Are you ready to go?', I said 'Yes'. I do know that, if he talked to flight controllers, if he talked to the systems instructors, if he talked to the simulator instructors, he would have gotten - I think - a very positive evaluation about my ability to operate the lunar module. Because I think I worked at it harder than anybody except Fred Haise. Fred probably knew more about the lunar module - both sides - than anybody. The other side of the coin is that, if I had not demonstrated the capability to operate the lunar module from the right side, I wouldn't have gone. I'm absolutely confident that Slayton would never have allowed anyone to dictate to him putting somebody who couldn't fly the lunar module on the mission. And I can think of some people that he probably would have fallen on his sword to keep from flying. Just for that reason. Because he didn't think he could trust them with the spacecraft."
Gene responds.
"The bottom line was that you had Deke's endorsement, you didn't need anybody else's. Period. I think the simulator instructors, and the flight controllers, and all those guys had a direct influence and input into everybody being selected to fly. Because that was your on-going, dynamic test. And if they didn't think you were cutting the mustard, they could see it from there and a lot easier than anyone else could. I'm sure that Deke used that input. Deke would have fought to his death against flying somebody if he thought he wasn't qualified. So Jack can sit back and relax. When you have Deke's endorsement, you don't need anybody else's. Period."

"People ask 'How'd you ever get selected for the space program?' And, quite frankly, I don't have the vaguest idea. Every time I went to Houston (during the selection process) there were half as many guys as there were the time before; and all the guys that had broken world speed records and altitude records weren't there. And there I was. I wasn't even qualified to be selected for the program. Didn't have enough jet hours. Didn't have all that test-pilot time that those guys had. Yet, somehow, when all was said and done, there were fourteen of us and I was one. (Group 3 was Aldrin, Anders, Bassett, Bean, Cernan, Chaffee, Collins, Cunningham, Eisele, Freeman, Gordon, Schweickart, Scott, Williams. Group 2 was Armstrong, Borman, Conrad, Lovell, McDivitt, See, Stafford, White, Young.) And as I look back, I don't know how all those other guys missed out. And when you get to crew selection, it's almost the same thing. It became a little bit more obvious towards the end of Apollo, perhaps. But you just did your best and let the chips fall where they may. And I did that all the way through backing up Apollo 14. I wanted a crew, but not so I could give orders. I just wanted the responsibility of my own squadron, which I never had in the Navy, and I wanted it on an Apollo mission. I don't know. Why do you want those things? Why did I go back to the Moon? If you risk your neck once, why do it the second time? Because I wanted to go back with my own crew. And it turned out to be the best Apollo crew there ever was, quite frankly. Building on other people's experience, we should have been better. But, had we had a chance to fly Apollo 11 or any of those other missions, we would have been just as good or better than anybody. There's no question in my mind."

Site Selection

Selection of a specific Apollo 17 landing site got under way in early November, 1971, shortly after the completion of Apollo 15. The effort was led by Noel Hinners, with guidance from Rocco Petrone, the Apollo Spacecraft Program Manager, and his successor, astronaut Jim McDivitt. Schmitt and USGS (U.S. Geological Survey) geologists like Bill Muehlberger were also deeply involved. As with all of the Apollo missions, site selection was strongly influenced by operational considerations. The crews needed to land soon after local dawn in order to have good shadow definition of the terrain, and that dictated a short launch window that opened no more than once a month for each site. Further, because of the tilt of the Moon's orbit relative to the terrestrial equator, the tilt of the initial spacecraft orbit due to the latitude of the Florida launch site, and various constraints imposed by the possibility of an in-flight launch abort, the farther a potential landing site was from the lunar equator, the less likely it was that an acceptable trajectory existed for an arbitrary launch month. Beyond these constraints, the flight planners wanted a site far enough from the eastern limb that they would have at least 12 minutes of flying time - and preferably 15 minutes - between AOS (Acquisition of Signal) and the start of the final descent. The twelve-minute limit meant that acceptable sites could be no farther east than a lunar longitude of 34E and, as McDivitt made clear in a November 23, 1971 memo, only in the case of extraordinary scientific merit should a site between 34E and 43E be considered. Irrespective of flight dynamics, it was essential that there be a fair amount of reasonably level ground within the landing ellipse and no large areas of unacceptable ground. And, finally, it helped if there was good, high resolution photographic coverage so that the selection committee and the EVA planners could be reasonably sure that a particular site offered a substantial scientific return.

In its effort to sort out lunar geologic history, the scientific community was interested in very old, crustal materials - such as the Imbrium ejecta breccias returned by the Apollo 14 crew from the Fra Mauro formation and by the Apollo 15 crew from Mt. Hadley Delta - and, also, materials that might be the product of recent volcanism. In general, it was felt that the lunar mare had been thoroughly sampled on Apollos 11, 12, and 15 and, certainly, there were now plenty of samples in hand from the Imbrium impact. During the Apollo 16 site selection process - which ultimately focused on the problem of young volcanics - considerable interest was expressed in such sites as (1) the mountains that lie between the Serenitatis and Crisium basins in the northeast part of the Nearside; (2) the Crater Gassendi which, because of its great size, has a central mountain peak produced by rebound of the rocks pushed downward in the impact; (3) the Crater Alphonsus which was the target of the Ranger 9 mission because of its complex structure and lava fill; (4) the prominent, lava-flooded crater Tsiolkovsky on the Farside (a choice Schmitt vigorously tried to promote for Apollo 17); and (5) a variety of other sites such as the Crater Copernicus, the Davy Crater Chain, Crater Tycho, Crater Alphonsus, and Marius Hills (a potential volcanic site) which had all been of long-standing interest. As Schmitt discusses in his commentary, the added cost and risk of the otherwise-exciting Tsiolkovsky mission meant that the proposal never made any real headway and, as Hinners details in the Apollo 17 Preliminary Science Report, scientific and operational considerations trimmed the list to two candidates: Alphonsus and Taurus-Littrow.

Apollo 15 was the key to the 17 site selection. The high resolution cameras carried in the 15 Command Module had produced very high quality images of the mountainous region along the ground track between Crisium and Serenitatis and it soon became apparent that Taurus-Littrow was a very interesting site. The mountains that frame the valley would provide an opportunity to sample ejecta from the Serenitatis and Crisium impacts and there was even the landslide that had put South Massif materials out on the valley floor within easy reach. Apollo 15 had carried X-ray and gamma ray spectrometers, and data from those instruments indicated that the Massif materials were different in composition from the mountains at Hadley. That result certainly justified the original interest in the general area. In addition, there was also evidence of young volcanics and, as described in a February 16, 1972 site selection press release, the prospect had the geologists licking their lips.

"The targeted landing point itself will be on the other prime sampling objective (other than the mountains) which is the very dark, non-mare material filling the valleys between the mountains. On occasion, the dark material is found in small troughs on the mountain sides, indicating that it once thinly covered the mountains but has eroded off the steep slopes. This observation, plus the presence of volcanic-looking cinder cones, first reported by Apollo 15 Command Module Pilot Al Worden, indicates to lunar scientists that the dark material is an explosively-produced volcanic ash. The apparently low crater density in the area covered by the dark material also leads geologists to believe it to be among the youngest lunar volcanics. The explosive nature of the volcanism indicates a relatively high content of volatiles or gases, both of which have been exceedingly rare in all lunar samples seen thus far. If the Moon, as the preferred models indicate, had indeed cooled from the outside in, these youngest lunar volcanics should be derived from the greatest depths and may give the first good samples of the deep lunar interior."
As we have already seen in the summary of Apollo 17 surface operations, the original interpretation of the dark material was flawed, if only in the assumption that it had been produced by recent volcanism. Predominantly, the valley fill is mare basalt and dark coloration is the product of ancient, rather than modern, volcanism. Nonetheless, in pre-flight analysis, the site looked to be very interesting and, as the mission proved, that interest was fully justified.

There was one final obstacle that had to be overcome before the selection of Taurus-Littrow could be made. Houston's Mission Planning and Analysis Division (MPAD) had estimated a landing ellipse that was three kilometers long and two kilometers wide and, therefore, too large to fit into the valley without including portions of the North Massif and/or some of the larger craters. After much debate between MPAD and Hinners' site selection team at NASA Headquarters, techniques for the refinement of the LM guidance were agreed on that shrank the landing ellipse to a circle 1 kilometer in diameter. Taurus-Littrow would be the site of the last Apollo moon landing.

The Launch of Apollo 17

Assembly of the Apollo 17 flight hardware by the manufacturers had begun in February and March of 1971. The Lunar Module, which the crew later named Challenger, was shipped to the Cape on June 14, 1971 while the Command-and-Service Module, later named America, was shipped on March 24, 1972. In August 1972, the components of the Apollo 17 stack were fitted together and, then, were rolled out to the launch pad for three more months of checkout. As had been the case throughout Apollo, no significant problems were encountered and Apollo 17 remained on track for a December 6th launch.

Apollo 17 was the first-ever nighttime launch of an American space crew, a circumstance dictated by the extreme northeastern location of Taurus-Littrow and a desire to fly a heavily-ladened LM. The launch was scheduled for 9:53 p.m. Eastern Standard Time, December 6, 1972; but, because of a malfunction of the automatic countdown sequencer, the launch computer stopped the count with only thirty seconds to go. While the problem was being fixed, the flight dynamics team re-designed the launch trajectory and the translunar coast so that the crew would arrive in lunar orbit at the pre-planned time.

After a two hour and forty minute delay, the crew of Apollo 17 finally had a launch and were on their way. It was 33 minutes after midnight, December 7. In later years, Navy veteran Gene Cernan was always mindful that this last Apollo lunar voyage started on an anniversary of Pearl Harbor Day.

The launch was flawless. During training, Cernan had spent time in the simulators so that, in the event of a guidance system failure, he would be able to reach orbit by flying the Saturn stack manually. During the actual launch, he checked to see whether or not he could see stars and the horizon but, because the cabin lighting was set high enough that they would not be blinded at the moment of ignition and, thereby, be unable to see the instruments, Cernan could see no stars. In the post-flight Pilot's Report, he stated "it is the Commander's judgment that the abort (to orbit) would only have been marginally successful because of the small amount of night adaptation the crew were able to acquire in-flight." He went on to conclude that, because it would take multiple failures to force a manual abort to orbit, it was more important to have adequate lighting in the cabin.

As usual, once the crew reached orbit, they and NASA took time to thoroughly check the health of the spacecraft before committing to the lunar journey. Twice the crew orbited Earth and, then, just before their third sunrise over the Atlantic, they reignited the S-IVB, the Saturn's third stage, for the 351-second burn that accelerated them to nearly escape speed. A half hour later, Evans separated the CSM from the spent S-IVB and turned around so that they could examine the LM and then dock with it. Schmitt reported that he could even see the Rover and that it seemed to be in good shape, still snugly stowed against the Descent Stage.

The docking went smoothly, even though the crew was bothered by occasional soundings of the Master Alarm system. They suffered intermittent alarms throughout the first two days of the mission; but, because there were no accompanying warning lights, they concluded that the problem was probably due to an intermittent short in one of the instrument panels. It was a nuisance that could be ignored.

The Outbound Journey

Almost immediately after docking with the LM, Cernan got down into the short tunnel leading toward the lander and removed the covering CSM hatch to check the latches holding the two spacecraft together. He found that three of the ten were not fully set but was able to close them manually. He then got out of the tunnel and replaced the hatch. They were now ready to pull the LM out and away from the S-IVB. Cernan fired the explosive bolts that held the LM in place, and then Evans fired the CSM thrusters to pull themselves away. Schmitt ran the movie cameras to record these events and, eighteen minutes later, once they were safely out of the way, Houston put the S-IVB on a trajectory toward a planned lunar impact at a point picked to maximize the scientific return from the Apollo 12, 14, 15, and 16 seismometers. While they waited for the S-IVB burn, Cernan reported that, while he knew "we're not the first to discover this, but we'd like to confirm, from the crew of Apollo 17, that the world is round." In the two hours since the TLI burn, they had moved out far enough - about 16,600 miles - that they could see the whole Earth. Because of the Moon's position in its orbit, they were south of the terrestrial equator, over the southern tip of Africa, and had no trouble seeing Antarctica. The Earth was nearly full and, at 30,000 miles, they took a stunning portrait of the planet.

Throughout the outbound journey, they had a good view back toward Earth. Schmitt, in particular, provided lengthy and detailed weather reports, complete with predictions. His first report, given while Cernan and Evans were getting out of their suits, went on for a full half hour and, as the Earth turned beneath them, he could update his predictions for various parts of the world. Later in the mission, CapCom Gordo Fullerton told him, "You're a regular human weather satellite."

Nine hours into the mission, they were ready to sleep. Cernan wore a headset in case Houston needed to talk; and he also wore biomedical sensors so that the flight surgeon could watch his heart rate and other vital signs. On this first night, none of them got more than about three hours of sound sleep but, for the next few days, the work load would be relatively light and there would be plenty of time to get adequate rest.

On the morning of this second day, Houston was ready to discuss a reset of the mission clocks so that when they got to lunar orbit at the pre-planned time, the clock time would agree with the times printed in the flight plan. In essence, they needed to add two hours and forty minutes to the actual elapsed time and Houston was looking for a spot in the flight plan where the reset could be done without significant disruption. Their first thought was to do the whole correction at 65 hours. However, the choice would shorten that work day from 16 hours to 13 1/3 hours and, after some thought, Houston decided that it would be best to modify the schedule in two stages and avoid any more disruption of the sleep/wake cycle than was already necessary. Between 46 and 65 hours after the actual launch, they would move all activities up one hour. That is, they would do the activities scheduled at 52 hours at 51 hours of elapsed time. Then, at 65 hours they would set the clocks forward to 67:40. It was a bit confusing, even to the crew, but it avoided two clock changes and, because there were to be relatively few things going on between 46 and 65 hours, there would be only a few pencil changes in the flight plan.

About six hours after their first wake-up in space, Schmitt got down under one of the couches and, by holding onto one of the struts, was able to get some exercise by running in place on the bulkhead of what was called the Lower Equipment Bay. Before starting, his heart rate had been about 60 beats per minute and, much to the surgeon's pleasure, he was able to get his rate up to about 140. What is more, the engineers reported that he shook the spacecraft hard enough to stir the liquid oxygen in the Service Module tanks. Each of the tanks contained a fan and, when the fan wasn't running, heat losses at the walls created temperature gradients in the tank, a circumstance that the engineers wanted to avoid. By exercising, Schmitt had saved them the trouble of turning on the fan, thereby saving a little spacecraft power.

The second day was purposefully short. The landing was scheduled for about 2:30 p.m., Florida time, and the crew was then going to do a full EVA before getting to bed. They wanted to wake up on landing day at about 7:30 a.m., Florida time, and it had been decided that, after the disruption of their sleep cycle caused by the night launch, it would be best to get back to a morning wake-up as early in the flight as possible. After launching, they hadn't gotten to sleep until it was about dawn at the Cape, and then their first wake-up came at about 3:30 in the afternoon. However, by having only a ten-hour second day, they were asleep by 1:30 a.m. Florida time and could wake up at 9:30 a.m. with most of the adjustment already made and with three more sleep periods to go before landing day. With the help of a Seconal sleeping tablet, each of them got 7 1/2 hours of sound sleep on their second night in space and awoke feeling well rested and ready to go.

By now, they were a bit over half way to the Moon, about 125,000 miles out from Earth and the spacecraft was working beautifully. They had been consuming maneuvering fuel, water, oxygen, and electric power at very close to the predicted rates; and they were being conscientious about eating and drinking enough to keep the surgeon happy. After Schmitt reported on the weather for southern Africa and Argentina, Fullerton read a news summary that included items such as the ongoing negotiations in Paris between the United States and North Vietnam, the medical condition of former President Harry Truman, and the start of the Texas state high school football playoffs.

The first big event of the day was a midcourse trajectory correction which came about two hours after wake up, an exceedingly modest two-second burn of the Service Module Engine. Four hours later, they pressurized the LM, opened the connecting hatches, and, for the first time, powered up the LM systems for a 2 1/2 hour checkout. Once they and Houston were satisfied that, with the exceptions of some minor problems with the comm system, the LM was in good shape, they powered down the spacecraft, crawled back into the CSM and closed the hatch. With all of the hardware - hatches and docking probes and the like - to be moved around, it was a time-consuming process but, at this stage of the mission, there was plenty of time and there was no point in hurrying. After finishing with the LM, the astronauts ran a small, self-contained, heat-flow-and-convection experiment which proved to be so fascinating that Houston had to remind them to take care of some other items in the checklist. Schmitt thought that it was the best Saturday afternoon matinee he'd seen in a long time and wished that they'd had some popcorn. And then it was time for another weather report - this one from the Commander - another exercise session, an evening meal, and then another good night's sleep. Once again, each of them took a Seconal.

For this third rest period, Houston gave the crew of Apollo 17 a full eight hours and, for the first time in the mission, Fullerton had to wake the crew out of a sound sleep. As a wake-up call, he used the stirring strains of the Jayhawk Fight Song, in honor of Ron Evans' alma mater, the University of Kansas. It was going to be another quiet day and Schmitt thought their only problem was going to be keeping Evans from going back to sleep. After breakfast, the news from Earth, the weather report from space, and a little bit of housekeeping, Schmitt got back in the LM and powered it up for about a half hour so that Houston could take a look at the telemetry system. He made another brief check of the comm system and, as Houston had expected after thinking about things overnight, the previous day's problems were confirmed as being problems on the ground, rather than in the spacecraft. Cernan, who had been detained by an urgent call of nature, joined Schmitt for the last few minutes of the LM checkout. Then, once the LM checkout was completed, all three of them got into their suits, just to make sure they wouldn't have any trouble doing so once they got to lunar orbit. Cernan and Schmitt then got out of their suits and got out of the way while Evans, still suited, made sure that he could get the probe re-installed and the hatch closed as he would have to do prior to separation for the descent.

While they got ready for lunch, Cernan took a look back at Earth, conscious that this would be the last trip anyone would make out this far for some time to come. He told Houston "You can look right down at the Cape area - that's the Cape that we know, in Florida - and it's a little disheartening because the last time I was up here (on Apollo 10) looking back from this angle, they were moving another Saturn V for another Moon trip out on the pad already."

The preparations for lunch took a bit longer than usual and the reason was that Evans couldn't find his scissors. The food, much of it dehydrated, was sealed in tough plastic bags. Each of them carried a pair of good quality surgical scissors so that they could cut the bags and get at the food. Without his scissors, Evans would get mighty hungry and his one hope, short of finding his own, was that Cernan or Schmitt would lend him a pair while they were down on the surface. After some joking about his predicament, they agreed to leave a pair behind.

After lunch, it was time to reset the clocks. Fullerton read them an explanation written for the press by the Public Affairs Office and, if possible, it was worse than what I wrote for this summary. Certainly Fullerton and the crew had a good chuckle over it. The important point was that, after lunch, they were 65 hours into the mission but had completed all the planned activities up to 67:40. Now, they could change the clocks and, from then on, behave as though they had launched on time.

The next item on the Apollo 17 agenda was an experiment called ALFMED or Apollo Light Flash Moving Emulsion Detector. On early missions, various astronauts had reported that, with their eyes closed, they sometimes saw brief streaks of light. The most reasonable explanation is that their retinas were being triggered by cosmic rays and, to test the hypothesis, Evans donned a helmet that covered his eyes and also contained slowly-moving plates of photographic film that would record any cosmic rays entering his head. He wore the detector for an hour and reported all of the flashes that he saw. These were later compared with the film record. As a control, Cernan wore a blindfold and also reported any light flashes he saw. It took Evans and Cernan about fifteen minutes to get sufficiently dark adapted that they began seeing flashes. Thereafter, they reported events about once every 2 1/2 minutes. The experiment was repeated on the trip back from the Moon, this time with all three of them wearing blindfolds. On that occasion, none of them reported any flashes. Readers may want to note, however, that the surgeon reported that the LMP seemed to be asleep during much of the homeward-bound experiment. ("My heart rate was very low anyway.")

Into Lunar Orbit

On Day 5, the crew of Apollo 17 was to enter lunar orbit. The night before, CapCom Bob Overmyer told them that he wanted to give them fair warning "in case you all feel a bump there when you're about ready to go to sleep there. At 73:17:45 (hours after the planned launch time), you'll cross that magic line into the lunar sphere of influence." Ever since TLI, the Earth's gravitational pull had been slowing them down but, now that they were getting close to the Moon, they were speeding up again. Their slowest speed, relative to the Moon was 2354 feet per second and, thereafter, they "started hauling the mail".

Cernan was the first up on Day 5. Houston had decided to give the crew an extra half hour of rest, but the Commander was awake before Houston could send a wake-up call. On this night, he hadn't taken a Seconal and had still managed about 5 hours of good sleep. Schmitt had taken a tablet in order to get to sleep and had slept soundly for over seven hours. Evans had also taken a Seconal but said that he thought he'd tossed and turned most of the night. However, the surgeon said that, although his periods of restlessness had been evident in the biomed data, none had been any longer than about ten minutes and it looked as though he'd gotten about 7 hours of good sleep.

As on Apollos 15 and 16, the Service Module's Scientific Instrument Module (SIM) Bay contained a variety of scientific instruments designed to scan the lunar surface passing beneath the orbiting spacecraft. There were photographic cameras for high-resolution mapping; an infrared scanner to map variations of the surface temperature which would allow inferences about the variations of density and thermal conductivity of the surface layers; a radar designed so that it would not only measure variations in the height of the terrain passing beneath the CSM but also detect variations in the electrical properties and, hence, the structure to a depth of roughly a kilometer; and an instrument to detect emissions from the extremely tenuous lunar atmosphere. During launch from Earth and during the coast out to the Moon, the SIM Bay had been covered with a protective panel; but, now that the spacecraft was approaching lunar orbit, the experimenters were eager to get data and it was time to jettison the SIM Bay door. After breakfast, a urine dump, an update of data for an emergency abort procedure, the news, the weather, and a variety of other routine chores, the astronauts oriented the spacecraft so that, once they fired the explosive bolts to push the door away, it would move off far enough and in the right direction that, when they fired the Service Module engine to enter lunar orbit, they wouldn't run into it.

By later standards, the on-board Apollo computers were fairly primitive. The crew sometimes had to enter data (called Nouns) manually on a keyboard and then tell the computer what actions (called Verbs) to take. Memory was limited, although there was room for enough information that the computer could fly the nominal flight plan without minute by minute instructions from the crew. Houston could feed data for normal flight procedures directly into the computer when the crew set it up in Program 00 (called "pooh" for short) and put it in the Accept mode. For emergency purposes - say if they had to abort the mission and had lost communications with Earth - Houston occasional read up data "pads" which Schmitt then wrote into the appropriate blank spaces in the Flight Plan book. Because of the launch delay and the usual slight deviations of the trajectory from the planned path, Houston had a great deal of data to read up. Thanks to long hours of repeated practice, Schmitt and the ground team got the work done smoothly and without error. Slowly, Fullerton would read up a block of data and then Schmitt would read back what he had written before they moved on to the next block.

All through the journey out from Earth, the crew had gotten a good view of Earth. As we have discussed, during the early hours of the mission they had been treated to a nearly full Earth. By now, their trajectory had carried them to a point where the Earth was about two-thirds full. Most of the time, they had been flying the spacecraft with its long axis oriented perpendicular to the Sun, slowly rotating around that axis so that all parts of the spacecraft would be heated uniformly. Informally, this was called the Barbecue mode or, in formal NASA-ese, the Passive Thermal Control (PTC) mode. There were five windows: one over each of the seats that gave a view more or less at right-angles to the long axis, and two others that gave a view forward for use during rendezvous and docking. For about two-thirds of each spacecraft rotation they had a good view of Earth. During the other half of each rotation, they had, in principle, a view of the Moon. However, because they were going to be landing at an eastern site just after local dawn, the Sun had been behind the Moon throughout most of the flight out from Earth. Therefore, the side of the Moon that they could see, the Nearside that always faces Earth, was in darkness and it wasn't until they got close that the perspective changed enough to see any of the sunlit portions. At a mission time of 86:46 - according to the reset clocks - Cernan reported their first view of the Moon.

"I've got the limb of the Moon...got it out the center hatch (the main hatch in the side of the vehicle, rather than the one leading to the LM) and we're just barely seeing the horizon of the Moon. But, boy, is it big."

It was, Evans said, just a tiny sliver of sunlit Moon, "a sliver of a sliver".

They were only about 5000 miles out and the Moon looked so big that Cernan had the impression that they were "coming right down on top of it". Half jokingly, he asked Fullerton if the tracking people were sure that they were going to miss the edge. Was the low point really going to be 73 miles as planned?

"Roger," said Fullerton. "That's about right. Don't worry, you'll miss it."

"I just wanted to hear you say it," Cernan replied, "because I'm going to hold you to it."

They had to shield their eyes to see the Moon because, at the moment, the Sun was sitting right on the lunar horizon. But it was worth the effort.

"Gordy, it's a sight to remember. Not just because of the uniqueness of the view, but because we've all got to ask ourselves if we really know where we are and what we're really looking at right this moment."

A few moments later, Cernan added "Gordy, it doesn't look like I'll have a chance to go to church today; but, under the circumstances, I guess it'll be okay. Next time you see the good father, you might have him put in a good word for us."

"Okay. I'll do that."

Although Cernan had been to the Moon before, on the Apollo 10 approach the western Nearside limb had been in darkness and the final hours hadn't been so visually dramatic. Cernan remembered that, on Apollo 10, he'd been impressed with how fast they seemed to be climbing away when they left lunar orbit for the trip home and, also, that he'd wondered what it would be like coming in that fast toward a surface he could see. Now he knew. Fortunately, there was plenty of work - and a great deal of pure professionalism - to protect him and the others from the full psychological impact of their seeming headlong rush.

"If you guys could get an idea down there," Cernan told Fullerton, "of the needle you're threading when you shoot for 50 miles at a quarter of a million miles, you'd be mighty proud of yourselves. I'll tell you, we are."

During our review of this summary, Jack Schmitt said that, "until I was going through my set of pictures, that I eventually gave to the University of New Mexico, and saw some pictures that Gene had taken, my memory was that we didn't see the Moon during the final approach. And I still don't have a personal recollection of looking at the illuminated edge of the Moon. Not a strong one, anyway. But I think that's because Gene was in the seat to do that. We were not in barbecue. We were in the attitude-hold mode. And he was in the position to see it and I wasn't. I may have glanced at it once. In fact, the more I talk about it, the more I think I remember him saying 'Come over and look at this'. But, for a long time, I didn't have any recollection of seeing any part of an illuminated Moon as we came in."

Gene replied, "Jack and Ron, never having had the opportunity to see what I saw on Apollo 10, can't appreciate the approach to the Moon that we had. I don't think anybody in any of the missions had this approach. I think everybody, starting with Apollo 8, went into darkness in the shadow of the Moon, and got on their back and, at a predetermined time, fired the CSM engine - in darkness and upside down and going backwards - and then, all of a sudden - maybe five minutes, maybe ten minutes later - we'd come out of darkness at fifty miles or thereabouts above the surface and it's 'WOW! Look at those craters. There it is. Man.' It's just like instant sunlight and we're THERE! I mean, it's like we've been flying in the darkness to rendezvous with this thing we can't see (meaning the Moon) - and we know we're close because we're in the shadow - and all of a sudden, WHAM, someone turns the lights on. And then the next major thing is to come around and see the Earthrise. Now, on Apollo 17 - and nobody told me it was going to happen - we went through the darkness and came out into sunlight before we got to the Moon. And we were coming in on this damn target and we were seeing, to start with, just a sliver, just a slice of the Moon. And then we started to see more of it as we snuck around behind it. And it's getting big so fast you can't believe it. And I'm telling you, you talk about rolling over on your back and making a dive bombing run at some point some 50 or 60 miles above the surface! That was the most spectacular entry into lunar orbit. And I don't think anyone appreciates it! Except me! I don't think any of the other flights ever saw that. And I don't think Jack and Ron appreciated because I've got a feeling they thought it was supposed to be like that all the time."

Now they were only 2660 miles out and had been accelerated by lunar gravity to 5000 feet per second. Cernan had the monocular out and, when the Moon was in view, got a good look into some of the larger craters on the illuminated edge. But then it was time to change the spacecraft orientation so that the big Service Module Engine would be pointed in the right direction when they swept down to their low point over the Farside.

Half an hour before lunar gravity swept them around the west limb and out of radio contact with Earth, they had the linked CSM/LM re-oriented. Looking back past the LM, they could see the Earth. LOS (loss of signal) came at 88:43:21 and, eleven minutes later, the LOI (Lunar Orbit Insertion) burn to put them in a lunar orbit with a low point of 53 miles and a high point of 170 miles.

On their first pass over the landing site, the area was in darkness and, because they had just gone through the dawn terminator a few moments before and still had the Sun shining in the spacecraft windows, Earthlight was of no help. By the time they came around again, the Sun would be up at Taurus-Littrow; but, first there was another burn to perform to put themselves in the proper orbit for the next day's descent. On this first pass over the Nearside and on the next as well, Houston took a careful look at the tracking data so that the burn parameters could be fine-tuned.

While Houston was busy, the crew had an opportunity to admire the view and, throughout most of the Nearside pass, Schmitt gave a running commentary about the lunar surface below. Because they were near the high point of their initial orbit as they passed over the landing site, the Sun didn't go below their horizon for another ten minutes. But soon, thereafter, they began to pick out detail in the Earthshine. Because the Earth was virtually overhead throughout most of the Nearside pass, there weren't any Earthshine shadows to delineate the hills and holes until they had completed most of the Nearside pass. However, even without Earthshine shadows, they could see differences in albedo, differences in the degree to which the surface materials reflected the Earthshine. As an example, the bright rays emanating from the young crater Copernicus stood out quite well.

By the time the crew re-emerged from behind the Moon again, Houston had the new data ready. Cernan configured the computer so that it could accept the uplinked data while Schmitt copied additional information that Fullerton read up. There was a great deal to be copied and Schmitt and Fullerton didn't finish until just before the second pass over the landing site. Down below, the shadows were very long. The North Massif was almost completely shadowed by the Sculptured Hills and there was little that was visible out on the valley floor. The only exception was the section of the Scarp near the crater Lara which, because it is highly reflective and was sloped toward the Sun, stood out quite prominently.

For the rest of the orbit, the crew of Apollo 17 kept busy preparing for the burn that would put them in what was called the Descent Orbit. On the early missions, the CSM flew a 60-mile-high circular orbit and LM fuel was used to take the lander down, first, into a 15 by 60 mile orbit and then to the surface. However, beginning with Apollo 14 and in preparation for landing the heavy J-mission LMs, the mission profile was changed so that, prior to separation, CSM fuel was used to put both spacecraft in the 15 by 60 mile orbit. Consequently, at the end of their second orbit, when they were once again down to about 53 miles above the lunar surface, the crew of Apollo 17 fired the Service engine and changed the orbit from 53 by 170 to 59 by 15, with the low point now just east of the landing site.

For the rest of the day, the crew did some more sightseeing and did some landmark tracking to help Houston fine-tune the tracking data. They ran some of the instruments in the SIM Bay, took pictures out the window, ate some dinner and copied down some more data, including a few football scores. Evans had still not found his scissors and, by the end of the day, was talking about taking the spacecraft apart until they were found. Fortunately, Cernan and Schmitt agreed to leave him one of their pairs so that he wouldn't go hungry and wouldn't have to destroy the Command Module in looking for his own pair. The crew said goodnight to Houston at a mission elapsed time of 95 hours 47 minutes, not long after their fifth pass over the landing site. From fifteen kilometers, Cernan had seen quite a bit of detail in the area around his target point and said that "if we're anywhere near it (at pitchover), we'll recognize it, I think, without question."

Landing Day

Landing day was not only going to be a big day for the crew of Apollo 17, it was going to be a long day as well. If all went well and they got down on time and got the EVA started promptly, it was still going to be a 22 1/2 hour day from wake up to bedtime. Cernan and Schmitt had decided that there would be no point in a short landing day and a sleep period before going out. They were well-rested and fit. And there was no doubt that the Moon would hold their interest.

The wake-up call for landing day was the John Denver version of the Steve Goodman song, The City of New Orleans, with its chorus of "Good morning, America, how are ya?" It is a happy song that had been suggested by people on the night shift in the press room - a song that matched the mood of the crew and, indeed, country-music-fan Schmitt requested a replay while he and the others finished waking up. Each of them had taken a Seconal; and Cernan and Schmitt, at least, had slept very soundly.

LOS at the end of the ninth orbit came only ten minutes after wake-up and, by the time Apollo 17 had re-appeared forty five minutes later, the astronauts were getting the tunnel cleared and were getting into their suits. They'd had a very quick breakfast.

Check out of the LM went quickly and smoothly; and, not long after AOS (Acquisition of Signal) on the eleventh orbit, Evans was in his suit and was busily sealing up the tunnel in preparation for undocking. As one of the last items, all three of them donned their helmets and gloves and performed pressure checks. They would perform the maneuvers unpressurized for the simple reason that their dexterity was limited in an inflated suit. However, they wanted to make sure that, in an emergency, the suits would inflate and stay inflated as long as necessary.

Separation of the Spacecraft

As planned, the crew undocked the two spacecraft during the Farside pass at the beginning of the 12th orbit. For the next hour and a half, the two spacecraft flew close to one another so that the astronauts could make visual inspections and perform final checks of systems. Later in the orbit, just before LOS, Evans fired the Service Engine to boost himself back up into a 60-mile circular orbit so that, in the event of an aborted landing, he would be in an optimal position for a rendezvous. As seemed usual in Apollo, the crew had a little trouble getting contact with Earth through the LM's steerable, high-gain antenna but, otherwise, Challenger was ready for the landing.

At 110:57, Cernan and Schmitt pressurized the propellant tanks and, a few minutes later, made their last pass over Taurus-Littrow prior to the descent. Evans had not yet made his circularization burn and was ahead and slightly below them. It was a spectacular, oblique view of the valley. They were less than fifteen miles away, and the LM crew took a couple of color pictures. Cernan was particularly interested in the small group of craters that surrounded his target point, and he called out the names as he found them.

"Houston, I can see Poppie, right where we're going to set this baby down. As a matter of fact, I can see the triangle: Rudolph, Frosty, and Punk. Man, Gordo, this is absolutely spectacular."

At 111:57, Evans did his circularization burn and, five minutes later, the LM crew did a more modest burn to move the low point of their orbit down to 10 1/2 miles over a point east of the landing site. At AOS on the 13th orbit, Evans reappeared first and confirmed that the LM burn had gone well. And then, once Houston had a bit more tracking data with which to update the LM computer, everything was ready for the landing.

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