GeoPrep for the EVA-1 Traverse

Station 1 at Plum Crater

 

Traverse to Station 1

Corrected Transcript and Commentary Copyright © 1997 by Eric M. Jones.
All rights reserved.
Scan credits in the Image Library.
Video credits in the Video Library.
Except where noted, audio clips by Roland Speth.
Traverse strips and movie assembled by Ken Glover. Last revised 4 April 2014.

122:56:45 England: Okay, John. Our best guess is a heading of 274 for the first leg; 0.7 kilometers should take you past Buster there and just north of Spook.

122:56:58 Young: Okay. (Long Pause)

[The planned EVA traverse is shown in the Descartes EVA-I, II 1 of 2 map. The named features are shown in a detail from a Pan Camera frame. They plan to drive between Spook Carter and Buster Crater and proceed past Halfway Crater and park on the rim of Flag Crater a short way northeast of Plum Crater, a 40-m crater on the rim of Flag. For the broader context, see also, a larger detail in which the LM can be seen just above center near the right edge of the picture. North is up and the LM is in the bright area created by the engine exhaust on the west side of a small crater. Navigation details for the traverse can be found on the contour map, which was printed on the reverse of normal map.]

[See, also, an EVA-1 map based on LRO image nacr00000ad8 , taken 12 July 2009 19:04:51 UTC. The Sun was low in the west, so the LRV tracks don't show up. Brian McInall has sketched in the first 100 meters of the tranverse to Station 1 on the ALSEP Deployment Planimetric Map (10 Mb).]

[Duke - "The (contour) map was clipped right next to the DAC camera, so I could just reach up and pull it off and look at it. It shows that we were supposed to go out 280 for nine tenths and then off 270 basically on out to Plum for six tenths. But, you know, the maps are based on where you think you're landing, and they made a comment here in the tape that they thought we were farther west. We thought we were farther west than we normally were and, so, we started out, I think at 276...They wanted us to go 274 for seven tenths instead of nine tenths. That indicated that we were north of where we wanted to be and we were west of where we had originally thought we were. Whether that was right or wrong remains to be seen. To be honest, it was difficult to pick out Double Spot (a crater pair near the LM) and Spook and, as we go through this thing, you'll hear a lot of 'Well, I think that's it.' And 'No, maybe it's not.' And we were really unsure at first. You know, this is our first time driving and it's like a you-can't-see-the-forest-for-the-trees type thing."]

[John initialized the Nav system at the LM, which is near CB.1/80.6. They plan to park on the rim of Flag Crater at about CA.9/73.6. Had they landed at the planned spot, the planned parking place would have corresponded to a LM bearing of 096 and a range of 1.5 km. Because they landed about 200 meters NNW of their target, the planned parking place corresponds to a LM bearing of 88 and a range of 1.4 kilometers.]

122:57:30 Duke: Man, am I sitting up in the air! (Pause) Did you get your seat belt done? John?

122:57:46 Young: Yeah. Got it hooked to something, Charlie.

122:57:52 Duke: Okay, wait a minute.

122:57:56 Young: Okay, Houston. You want the readings, right?

122:58:00 England: Right.

MP3 Audio Clip ( 11 min 35 sec)

122:58:02 Young: Or do you? We got 118 ampere-hours, batteries are up to 90 and 90 (degrees F). The forward and rear motor temps are off-scale low; amps are zero; and the volts are 68. And we're on our way.

122:58:23 England: Outstanding. (Pause) Do you now have the Nav and range.

122:58:32 Young: Suppose we do. Okay. 033 is the bearing; the range is one-tenth.

122:58:44 England: Okay. We copy that.

122:58:45 Young: Hasn't changed any, has it (since John parked at the ALSEP site)?

122:58:46 Duke: No, it hasn't changed any. Okay, Tony. Looking off to the northwest there (means southwest), you can see South Ray Crater with just tremendous amount of blocks on it with some black streaks, and here we go. Heading 274, John.

122:59:06 Young: Okay.

[This is their current heading. As indicated on the contour map, they plan to drive 0.9 kilometers on a heading of 280 to reach Checkpoint 2 midway between Spook and Buster. At that spot, they expect to have a LM bearing of 100 and a range of 0.9. The landing offset will reduce both readings.]

122:59:08 Duke: And it's going to be a piece of cake taking pictures from here, Tony.

[Charlie plans to take Hasselblad pictures at intervals of about 50 meters to document the traverse. In fact, he takes 28 pictures during the 1.4 km drive and hits the 50-meter average interval exactly. Including a short stop, the trip takes about 24 minutes. Charlie's first picture is AS16-109- 17747, a view to the southwest showing South Ray Crater.]

[Although Jim Irwin took a few pictures from the Apollo 15 Rover on one occasion when Dave Scott stopped to take a brief rest during the EVA-2 traverse to the Apennine Front, documentation of the Apollo 15 traverses was to have made with the 16-mm DAC movie camera. That effort was not successful and, for Apollo 16, Charlie will take pictures at regular intervals to supplement/backup the DAC. Charlie's traverse photography will be so successful that the DAC will not used on the Apollo 17 Rover.]

[Because they are planning to use a full magazine of 16-mm film to document John driving the Rover when they get back to the LM at the end of the EVA, the DAC will not be run during the drive to Station 1 or on the drive back to the LM.]

[Photos for the first part of the traverse - 17747-68 - are available in a PDF album 13 Mb)

122:59:15 Young: I see it, but...

122:59:17 Duke: A deepy one over here. (Pause) Four clicks an hour Tony and...

122:59:25 Young: Charlie, you hit my arm.

122:59:26 Duke: Excuse me.

122:59:28 Young: I'll end up in that big crater. (Chuckling) Oh, man!

[John has the handcontroller in his right, inboard hand and, when Charlie hits his arm, the controller moves and the Rover swerves.]

[During the first few minutes of the traverse, Charlie takes AS16-109- 17748 to 17751. Frames 17747 to 17751 are combined in strip form.]

122:59:53 England: A heading of 274.

122:59:57 Young: 274, huh?

123:00:00 Duke: Now one thing I can't do is see the maps.

123:00:02 England: Okay, I'm not sure that heading is good. That was based on an earlier estimate of where ALSEP was, and your bearing now may make that wrong. It's pretty much if you go west you are going to hit Spook.

123:00:17 Young: That's what we're doing, going west. I'm not sure that's not it right there, Charlie.

123:00:25 Duke: Where?

123:00:26 Young: Right there. That couldn't be it, could it?

123:00:29 Duke: I don't see it. (Pause) Man, this is the only way to go, riding this Rover.

123:00:37 England: Right. Only way.

[Jones - "I believe you and John were supposed to have been the first of the Rover crews, back when they were first letting the contracts."]

[Duke - "Yeah, John and I were going to be the first ones. We started with all that; and we turned it over to Dave and Jim after a while. I remember a time of John and I going out to Santa Barbara and Seattle and going through some design reviews and the original prototypes and going out to Huntsville to ride a simulator at first. But then they moved that (schedule) all around and Dave Scott and Jim took it over. And we just concentrated on the training part."]

[According to the late Mitchell R. Sharpe, a Rover historian, NASA made the decision to design and build a Lunar Roving Vehicle on May 23, 1969, the day that the Apollo 10 crew performed a final rehearsal of LM operations in lunar orbit. Once the design team was chosen, a preliminary design review was held on January 18-19, 1970 at the Marshall Spaceflight Center in Huntsville, Alabama. John, Charlie, and fellow astronaut Gerald Carr attended that meeting. A final design certification review was held at Marshall on June 16/17. On September 2, NASA announced that Dave Scott and Jim Irwin had been given the first Rover mission although, according to the Apollo 15 training logs, Dave and Jim had their first session with a Rover mock-up on August 17.]

[Jones - "Do you remember anything about the initial discussion about the Rover. As an example, I remember reading that the initial design included the same kind of controller that you had in the Command Module: a pistol grip rather than the t-bar you ended up with."]

[Duke - "Well, it was apparent to us that that wouldn't work. We needed a t-bar. There were some minor things. When I first looked at it, I didn't understand how the wheels were going to work. I mean, they were wire and you could see through 'em. But I'm glad they didn't ask me to design the wheels, 'cause I wouldn't have done it that way. But it worked great. We had some discussion about the seat design, I remember."]

[Jones - "In what regard?"]

[Duke - "Just make sure we could get in it and get out of it easy. And the seat belts. We went through a couple of iterations on that, (to make sure) we could work it in the suit and the one-sixth gravity - make sure we could lock ourselves in and then adjust it. And, in fact, after Apollo 15, they had to go back and we had to re-design. We had a big, over-center handle that we put on it so that we could lock ourselves into the seat. It was really important to do that."]

[Jones - "Because it was a bouncy ride?"]

[Duke - "Yeah. And it was like driving on ice, a lot. The back end kept fishtailing, at least for us. And, then I think we had some problem with switch guards and stuff like that with the big, fat gloves. We had a little, minor change with those."]

[Jones - "How about the circuit breakers?"]

[Duke - "You'd have to ask John. You know, that was basically his job: driving it, getting it configured right."]

[Jones - "Did you talk with the engineers about configuration of the console and things like that?"]

[Duke - "Well, we looked at it, of course, and it seemed to be a pretty logical layout. We didn't have any major complaints, so that was basically left as is. If I remember, we had a rear-view mirror at first, so we could see behind us to back up. But they took that off. We had reverse; but I don't remember us ever using reverse. Generally, John just did U-turns. Or we just picked it up and turned it around."]

[Jones - "I think Dave used reverse once (at Station 6a). Any discussions you remember about the tool gate on the back and the operation of that."]

[Duke - "No. You know, those things were pretty standard: the rakes and core tube holders and the little ratchet like you'd see on plumbers' trucks. We had one of those to get the core apart. There wasn't really many changes on the Rover! They changed the pallet a little bit because we had some different experiments, so the brackets had to be changed. But, basically, that went pretty well. That was a good machine. I really thought it was well designed; as quickly as they built it, it was remarkable, I think."]

[Jones - "And NASA took a lot of undeserved heat over cost overruns."]

[Duke - "I know."]

[Jones - "Some people didn't understand that, when you're only making three of a thing, they're going to be expensive."]

[Duke - "Plus a short time fuse and working three shifts a day. And there's a lot of unknowns in that kind of stuff and it's hard to plan for it."]

[This may be the boulder shown in AS16-109- 17752.]

123:01:40 England: Very good.

[Readers should note the map shows a featured named Eden Valley south of Flag Crater and well west of their current position. Eden Valley also shows up nicely on the detail from the Pan Camera frame and probably represents one or more very old, eroded craters. There is another depression southeast of Spook and south of their current location. This is probably the 'valley' Charlie is seeing, although the name 'Hidden Valley' does not appear on any of the maps I have seen.]

123:01:54 England: Do you have a speed amp?

[Tony is asking for their current speed and the ampere reading.]

123:02:03 Young: What did he say?

123:02:04 Duke: I don't know.

123:02:05 England: Could we have the speed and the amps?

123:02:09 Duke: Okay, you're 5...(Pause)

123:02:15 Young: We got to go around this, Charlie.

123:02:16 Duke: Yeah, you're 5 kilometers an hour, and the amps are oscillating about...between 10 and 20.

123:02:24 England: Okay. (Pause)

123:02:36 Duke: How's it driving, John? Pretty easy?

123:02:38 Young: Darn good.

123:02:40 Duke: Hey, man. We could just go, babe. I'm really cinched into this moose.

[Jones - "Was most of the ride like what we saw in the film last night of John doing the Grand Prix?"]

[Duke - "Yeah. It was bouncy. That's why I made the comment that we could really let her go because we were cinched in. You never felt like it was going to turn over on you but you got this fishtail action a lot. The steering was real sensitive and, in the light gravity, it tended to fishtail on the back end a lot."]

[Unidentified speaker from the 1972 Technical Debrief - "Say something about Rover driving out there in zero phase."]

[Young, from the 1972 Technical Debrief - "Man, I'll tell you, that is really grim. I was scared to go more than 4 or 5 kilometers an hour. Going out there, looking dead ahead, I couldn't see the craters. I could see the blocks alright and avoid them. But I couldn't see craters. I couldn't see benches. I was scared to go more than 4 or 5 clicks. Maybe some times I got up to 6 or 7, but I ran through a couple of craters because I flat missed (seeing) them until I was on top of them. And, I don't recommend driving in zero phase (which is the direction directly opposite the Sun). (Pre-flight) they kept saying they wanted it included in the traverse, and I specifically cautioned them not to include it on the traverse. But, there is no way for us to get to Flag Crater without driving in zero phase. It sure is grim. The other direction (on the way back to the LM) was about twice as good. I saw my tracks on the way back. We were doing 7, 8, 9, and 10 clicks. It wasn't any good during the traverses where we were going down-Sun. I was tacking a lot of times. But, when you got to a ridge, you couldn't tell if it was a drop-off, or whether it was a smooth, shallow ridge. In a couple of cases, you couldn't see there was a ridge. I didn't care for that much. It's kind of like landing an airplane aboard ship where you're looking right into the Sun and you can't see what you're doing. You just go ahead and land it anyway. It is not normal but, on occasion, you have to do it. But you'd just as soon not."]

[The almost complete lack of detail at zero phase is due, in part, to objects hiding their own shadows and, most importantly, to a dramatic brightening caused by the phenomenon of Coherent Backscatter.]

123:03:20 England: Okay. We copy that.

[The formal definition of 'cobble' is a piece of rock between about 6.4 cm and 25.6 cm.]

[Duke - "Looking, later, at the pictures, that was a high estimate (of surface coverage)."]

[Charlie's pictures on this part of the drive may be AS16-109- 17753 to 17755. Frame 17755 gives a good indication of the small scale, local undulation of the terrain. The fact that we can see the shadows of both helmets means that the Rover is pitched down considerably. This is one of only a few pictures of this kind in the Apollo collection. Photos 17752 to 17755 are combined in strip form.]

123:03:27 England: And we're right on the timeline.

123:03:28 Duke: We see some small fresh craters, meter size, that show some very fresh...at least...Perhaps it's indurated regolith. That's what it looks like, because the little hard clods are the same inside the craters as on the rim.

123:03:57 England: Okay.

[Charlie is describing a piece of regolith breccia, which is also known as 'instant rock'. These are clods of dirt which are formed by an impact in soil. Apollo 17 photo AS17-133- 20208 shows a dramatic example of a small crater covered with regolith breccia.]

[These may be the craters in AS16-109- 17756.]

123:04:29 Young: Charlie, you hit my arm.

123:04:32 Duke: I'm not sure, Tony. I think they were breccias, but they were really dust covered, so I couldn't tell you, really.

123:04:40 England: Okay, understand. And have you seen any rocks that you're certain aren't breccias?

123:04:50 Young: (Annoyed) Quit hitting my arm!

[Duke - "I was moving around, taking pictures and reaching for maps and stuff like that; and, as I moved around in my seat, I'd keep hitting John's arm and it would knock him over. And, when I hit his arm, it would move the handle and it would turn the vehicle. And he was getting a little frustrated with me, for which I don't blame him. But it's really hard to stay out of his way. You had plenty of room as far as fore and aft goes; but, side-by-side, we were sort of shoulder-to-shoulder and it was difficult to stay out of his way. If we had it to do again, maybe we ought to design the Rover a little bit wider so the passenger wouldn't be knocking the guy's arm."]

[Jones - "The T-handle was really in the center, wasn't it?"]

[Duke - "Right in the center. Yeah. Either one of us could drive. I could have driven with my left hand. We didn't do it that way; but we had trained a little bit where I could drive it, too."]

123:04:58 England: Okay.

[Charlie's photos taken during this part of the traverse are AS16-109- 17757 to 17761. Frames 17756 to 17761 are combined in strip form.]

[Duke, from the 1972 Technical Debrief - "I think the whole way out there, we were in this series of rays from South Ray."]

[Young, from the 1972 Technical Debrief - "You couldn't tell where one took up and the other left off."]

[Jones - "There's a nuance here that I don't get. You were talking along and then you said, 'Go ahead, John.' And there was certainly no verbal cue that he had something he wanted to say."]

[Duke - "I don't know whether he nudged me or whether I saw him looking over to the left."]

[Jones - "Could you have seen him in the seat? Did you have enough peripheral vision that you could see him?"]

[Duke - "Yeah."]

[Jones - "Did you ride with the Gold Visor down?"]

[Duke - "Yeah, the Gold visor was down, but the opaque side-blinders weren't down."]

[Jones - "Could you see him?"]

[Duke - "Yeah, I think so."]

[Jones - "That is, through the helmet and you could see where he was looking."]

[Duke - "No, I couldn't do that. Now that I think of it, when he turned, he would just turn inside the helmet and he would still be facing forward (meaning that the suit wouldn't have moved). So I don't know what I was thinking about, here."]

123:05:36 Duke: It could be.

[At Charlie's last report, they were at a bearing of 091 and a range of 0.5 km. The LM is near CB.1/80.6 and they are currently near CB.1/78.1. They are about 100 meters from the northwest rim of Spook. See the Descartes, EVA-I, II; 1 of 2 map.]

123:05:42 Duke: No, Spook's about...Let's see. (Pause) At 0.6 we should be at Spook, huh? Let's see. (On the contour map) Spook is at (a bearing of) 100 at 0.9 (km range from the planned landing site). Not there yet. We're only 0.6, Tony.

[Duke - "If we were landed two hundred meters farther west, it would be 100 at point seven. But, but I make the comment here, 'No, we're only at point six.' So I failed to make that deduction (in the sense of 'subtraction'). I think we figured it out in a little bit."]

[Duke, from the 1972 Technical Debrief - "We felt as if we'd landed a little bit west of where we were supposed to, and that the distances (meaning the ranges to the LM along this traverse) would be shorter (than shown on the map)."]

[Young, from the 1972 Technical Debrief - "They didn't turn out to be."]

123:06:13 England: Right. That summary you got there, Charlie, (on the map)...

123:06:15 Duke: John's just doing great driving this moose.

123:06:17 England: ...is the point by Buster; you should be coming up to the edge of Spook. The eastern edge of it.

123:06:28 Duke: Okay. Turn left, John, and let's go look down over there. Boy, Tony, there is some excellent little secondaries with the indurated regolith in 'em and on the rim. The biggest one is a couple of meters.

123:06:44 England: Very good.

123:06:50 Duke: You know that might have been Spook right back there. That was a pretty big crater.

123:06:56 Young: It sure was.

123:06:57 Duke: Right back there, John. Boy, it's really hard (to navigate). There's an interesting rock. A layered (rock), really dust covered, like a regolith (breccia)...I mean a...Turn left, John. There's a crater over there, a big one. (Pause)

123:07:18 Young: Boy, that is a biggie.

[Photos taken during this part of the drive may be AS16-109- 17762 to 17764. these frames are combined in strip form.]

[Jones - "Was there any emphasis in training on making sure you were describing what you were doing?"]

[Duke - "Oh, yeah. Especially on the way with the Rover, because we didn't have any TV camera. And so I was sort of the running travel guide, taking pictures and describing the terrain as we traveled across, you know, from point A to point B. Going out to Plum, and then going up to Stone Mountain. As John drove, I was navigating, describing the terrain we were going over and taking pictures every few meters."]

[Jones - "Now, Jim didn't take pictures. Do you remember any explicit discussions during planning for this one..."]

[Duke - "Yeah. The geologists realized they were going to get a lot of terrain that they weren't going to get to see what it was like without pictures. So we budgeted, in the film budget, pictures during the traverses. I didn't realize Jim didn't do it. That was the first mission with the Rover, and they just hadn't thought about it. So, as they drove, they just realized, 'Man, we got a lot of gaps in our coverage, here.' If we were going to go from wherever to wherever, you know, it might be two kilometers and we'd like to see what that looks like. So we drove and took pictures and described."]

[In 1996, I asked Bill Muehlberger if he remembered "any discussions that led to the decision to have Charlie take Hasselblad pictures during the traverses. Was it because of doubts about the performance of the 16mm camera? Or did somebody say 'Hey, film doesn't weigh much and having the LMP take pictures doesn't cost us anything?'"]

[Muehlberger, from a 1996 letter - "As I remember - albeit poorly - because we were landing in an area with visible rays from South Ray Crater, we wanted to know how much of the surface was really covered. The 16mm camera was fixed in the direction of the Rover, whereas the LMP could move his body to get the best possible pictures. So, use an intelligent observer who could take pictures close enough together that we could locate each shot relative to the previous one and then make a map of relative rockiness on the line of travel. See our report for the results. Horribly time consuming and amazingly - to me, at least - low percentage of visible rocks."]

[The results of this study are presented in Figure 6-6 from the Apollo 16 Preliminary Science Report. Along the EVA-1 traverse, typically only 3 to 4 percent of the surface was covered with rocks larger than 2 cm.]

123:07:27 England: Outstanding.

123:07:28 Duke: Boy, that is a biggie. (To Houston) Okay, here is Spook; and it's 089 at 0.7.

123:07:36 England: Okay.

[They are near CB.1/77.1 on the north rim of Spook. AS16-109- 17765 is probably a picture of the interior of the crater. Spook is about 350 meters across. On the way back to the LM, they will do a geology stop at Buster/Spook and AS16-109- 17820 to 17827 is the part of Charlie's Station 2 pan showing Spook.]

123:07:41 Young: We're not...We're looking...We're almost completely past it; we're not right even with it. Where'd you say Buster is?

123:07:48 Duke: I thought it was right over here, John.

123:07:51 England: Is the rim of Spook rocky?

123:07:52 Duke: Right straight ahead here. (Answering Tony) Negative, it's real subdued, Tony.

123:08:01 England: Okay, do you see any ledges or anything in the inside of Spook?

123:08:09 Duke: No, we sure didn't. We're driving on, now. I think we're coming up on the (southeast) rim of Buster, and we've got a real good boulder field around Buster.

123:08:21 England: Okay, good show.

[In a frame from Charlie's first Station 2 pan, AS16-109-17814, the tracks they made as they drove up close to the rim of Buster are visible beyond the Rover.]

123:08:45 Young: That is a big crater.

[During the stop on the way back to the LM, Charlie takes a partial pan of Buster, AS16-109- 17828 to 17836).]

123:08:51 Young: 40 meters (diameter).

123:08:53 England: About 40 meters.

123:08:54 Duke: That's bigger than Buster.

123:08:56 Young: That's Buster. 50 meters. It's 150 feet, Charlie.

123:09:01 Duke: Okay. That's Buster, then.

123:09:03 Young: Yep, sure is.

123:09:04 Duke: And, Tony, we've got some 5-meter boulders in the bottom of it. Some real big ones. The biggest, 5 meters, and the whole bottom is covered; we're going downslope now.

123:09:19 England: Okay, there should be a scarp around there someplace.

[Tony is discussing the feature mapped at CA.7/77.0 on the Descartes EVA-I, III 2 of 2 map.]

[Young, from the 1972 Technical Debrief - "You know, we never encountered any of these features on the geology map. They were mapped at scarps of steep features that they said we were going to have to drive around or over of maybe we could pick up outcrop. We just never ran into those. And I think that's because those (pre-flight) photo analysis guys were reaching for and pulling out features that weren't there. I mean, I looked for these things and sure enough, if you really imagined it, you could see something there. But, I think with that scarping we had (on the map), they were reaching for it. Because they sure weren't there in the real world. If they were (there), they looked like every other slope that was around there."]

[The following is taken from a December 8, 1986 conversation between Andrew Chaikin and John Young. My thanks to Chaikin for providing this material.]

[Chaikin - "Do you remember being particularly surprised by any geologic aspect of the EVAs? Was there any one thing that stands out to you as a surprise?"]

[Young - "Well, the whole Descartes thing was sort of a surprise in some areas and sort of not in other areas, in terms of the technical aspects of it. Driving down-Sun, you can just barely see where you're going when you've got a sun angle that's low right over your shoulder. And our first EVA was all down-Sun, so you had to be very careful how fast you went. It was very tricky."]

["Well, the sad part of that was there had been some studies by some people that had said there were 3- to 5-meter scarps all over this area, because we didn't have very good...The best photography we had was, I think, 20 meters. Stu (Roosa, the Apollo 14 CMP) shot this in the (Apollo 14 CSM) cockpit, and it was good photography, but you just couldn't get any better than 20 meters. So here we are driving down-Sun. You can't see a darn thing and we're supposed to go over a 5- or 3-meter scarp, and I was very nervous about that. But they just weren't there."]

MP3 Audio Clip ( 9 min 42 sec )

123:09:36 Young: What's the heading from here to...(Pause) Oh, man.

123:09:41 Duke: Okay, we want to head...Just keep going west.

123:09:44 Young: 26 something, Charlie.

123:09:46 Duke: (As per the contour map) we want to get 100 degrees at about point...That's Station 2. Wait a minute; we want (a bearing of) 96 at (a range of) 1.5 (at Station 1. It's (a heading of about) about 280. I'm about to freeze. I have to turn my (cooling) water down. (Pause) Okay, Tony. Most of the rocks that we've seen look breccias to me. We're making good time at about 7 kilometers an hour. Off to the right, what I thought was a scarp turned out to be a crater on the side of a ridge that runs east-west.

[Although Charlie can't turn the suit very much while seated, he can turn is head inside the bubble helmet and, consequently, gets at least a 180-degree view.]

123:10:27 Duke: It is, isn't it?

123:10:29 Young: It's really bad.

[Duke - "Well, you can see it from the photographs. We've already talked about it a little bit; but zero-phase just basically washes everything out - the craters, the slope, and, also, the smaller rocks."]

[Jones - "So you would only see things as you got close enough..."]

[Duke - "And then they would start coming through the glare. It was like looking at a glare. The rocks just reflected a lot and the surface just reflected a lot of the Sun into your eyes and, so, it got real bright down zero-phase. Whether we were walking or driving or taking pictures, when you looked down-Sun, it was real bright."]

[Jones - "Did John try tacking at all on this..."]

[Duke - "We did a little bit; but nothing significant."]

[Jones - "This was the only zero-phase driving you did, I think."]

[Duke - "Yeah. Most of the time we were cross-Sun. Traverse 2 and 3 we were cross-Sun. There were a little going down-Sun and into the Sun going up to North Ray Crater. You would think going into the Sun was harder, but it wasn't."]

[The brightness of zero-phase is chiefly due to a process called Coherent Backscatter, which is discussed by Bruce Hapke in the journal Science vol. 260, pages 509-511, 23 April 1993. My thanks to Ron Wells for the reference.]

123:10:36 England: Okay.

123:10:39 Duke: (To John) And you're making great time, though.

[They left the ALSEP site at about 122:59:06 and have covered a straight-line distance of a kilometer in about 11.5 minutes. Their net speed, therefore, is a cautious 5.2 km/hour. Because they have had to maneuver to get around craters, they have probably driven about ten percent farther than a kilometer and their typical speed over short distances has probably been closer to 6 km/hour.]

[The photos taken during this part of the traverse are AS16-109- 17766 to 17768. These three images are combined in strip form.]

[They may have run through an unseen crater or turned suddenly to avoid one.]

[Charlie is mistaken. As he mentions in a moment, the bearing to the LM is 088 and is the range is 1.0 km. They are near CA.9/75.6 on the eastern rim of an anonymous crater immediately south of Halfway crater. As can be seen on the LRO-based EVA-1 map.]

123:11:07 Duke: We are here!

123:11:08 England: Well, congratulations.

123:11:09 Duke: Okay, 088 at 1.0 is...(Stops to listen to Tony) Okay, we stop, John, about 40 meters from Plum.

123:11:23 Young: Okay, now, I don't see Plum.

[Plum is a 40-meter crater on the southeast rim of Flag at CA.6/73.4. See the sketch map on CDR-32 and LMP-22. See, also, the LRO-based EVA-1 map.]

123:11:26 Young: That's Plum?

123:11:28 Duke: Yeah!

123:11:30 Young: That ain't even on the rim.

123:11:32 Duke: Well, it is; it's...Yeah, it is. It's right...We're...The rim is right here. We're on top of the rim.

123:11:39 Young: Okay.

123:11:40 Duke: Hey, stop. It's going to be terrible walking on this thing. Why don't we go turn around and go back up on the rim where it's level?

123:11:49 Young: Suits me.

123:11:53 Duke: This is a steep slope here. (Pause) Okay, Tony. It didn't seem like there was that much distance between (Buster and Flag) (Pause) 300 meters is Flag. That's not 300 meters. Is that 300 meters right there?

123:12:14 Young: Charlie, you got me. I can't tell.

123:12:18 England: Okay. Could we have another range and bearing, please?

123:12:24 Young: Okay. 087 at 1.1. (Pause)

123:12:36 Duke: Well, that's a big crater anyway.

123:12:38 Young: Yeah, it looks to me like we're due north of South Ray Crater right now. I can look down there, and I feel like I'm bisecting it. No, we're not due north of it, not according to shadow.

123:12:50 Duke: Get the map out here. (Long Pause)

[They are near CA.8/75.1. The anonymous crater has a diameter of 35 meters, comprable to that of Plum. It is roughly in the same location relative to Halfway as Plum is to Flag, but the diameter of Halfway is only about one third of Flag's 300 meters.]

123:13:14 Duke: Okay, it was 0.6 between Buster and...That's got to be Buster.

123:13:24 Young: Back there, huh? That...(Pause)

123:13:34 Duke: That...(Pause) Okay...

123:13:35 Young: That's a 40-meter crater.

123:13:36 Duke: Over here?

123:13:37 Young: Yeah.

123:13:38 Duke: Yeah; that's what I'm thinking.

123:13:39 Young: It'll do...Let's not waste any more time thinking about it.

123:13:42 Duke: Okay, let's do it. Okay, Tony. We're going to call this Flag.

123:13:48 Young: Let me park the thing...

123:13:50 Duke: Okay.

123:13:51 Young: ...heading south (as per CDR-32). You want to get off?

123:13:52 Duke: No, go ahead.

123:13:57 England: Okay. (Pause) And...(Stops to listen)

123:14:03 Duke: It has all the characteristics (of Flag). We must have landed...(Stops to listen)

123:14:08 Young: (Garbled)

123:14:14 England: When you're brushing off the LCRU there, would you get the TV lens, please?

123:14:19 Young: You bet. (Pause)

[In a few moments, John and Charlie decide that they are near Halfway and decide to drive on. Shortly after they re-mount the Rover at about 123:17:24, Charlie takes AS16-109- 17769. Note the footprints at the front of the Rover, which indicate that the picture was taken during this brief stop. A comparison of this picture with Figure 6-15 in the Apollo 16 Preliminary Science Report indicates that 17769 shows an unnamed, 40-m crater immediately south of Halfway Crater. Note the telltale dimple crater in the south rim. This 40-m crater is about the same size as Plum and is in about the right location relative to Halfway to be mistaken for Plum. The major difference in the two settings is the fact that the size ratio between Halfway and this 40-m crater doesn't match to size ratio of Flag and Plum.]

[The remaining frames in the traverses - 17769-74 - are available in a PDF album (4 Mb).]

123:14:31 Young: Yeah, I should have gone to Minimum cooling.

123:14:33 Duke: Me too.

123:14:34 Young: I forgot all about it. (Pause) Okay.

[Because of a strategically-placed cut-out in the Rover seats, they are able to reach the controls on the bottom of the PLSS while seated.]

[Charlie really isn't sure they are at Flag/Plum.]

123:15:20 England: All right, our...(Stops to listen)

123:15:22 Young: This one here?

123:15:23 Duke: Yeah, this one right here.

123:15:25 England: Our measurements say that...

123:15:26 Duke: Say again.

123:15:27 England: ...you should be pretty near Halfway.

123:15:31 Young: Okay, why don't we get back (on the Rover) and try some more, Charlie?

123:15:34 Duke: Okay, I agree. (Pause)

[They are going to climb back on the Rover.]

[Duke, from the 1972 Technical Debrief - "We got to a crater that turned out to be Halfway Crater."]

[Young, from the 1972 Technical Debrief - "It was a really big crater."]

[Duke, from the 1972 Technical Debrief - "We weren't to Flag...(and) the reason we realized we weren't there was because the distance was only about three quarters (of the expected distance from the LM)."]

[Young, from the 1972 Technical Debrief - "(On the map), Halfway Crater looked as if it was 100 meters across."]

[Duke, from the 1972 Technical Debrief - "The craters all looked bigger (than they really are)."]

[Young, from the 1972 Technical Debrief - "Flag Crater is 300 meters across. What we're saying is we couldn't tell the difference between a 100- and a 300-meter crater. And that's the truth."]

[Duke, from the 1972 Technical Debrief - "I think it's the sharpness of the land and the degree of the subduing of the craters."]

[Young, from the 1972 Technical Debrief - "You know, I would have been willing to buy that for being Spook Crater (probably means Flag). But it wasn't."]

[Duke, from the 1972 Technical Debrief - "When we got to Flag, there was no question. 'Man, this is a big crater.' It was a lot bigger than the one where we stopped first."]

[The locking pin on John's purge valve has pulled out.]

123:15:44 Young: Pulled out the thing. Get that for me, Charlie?

123:15:51 Duke: Yeah. (Pause)

123:15:59 Young: I know what it is; every time I put the...

123:16:03 Duke: Belt on, huh?

123:16:04 Young: Belt on (and) tighten down the belt, it pulls my...

123:16:09 Duke: Can you push against me?

123:16:10 Young: Yeah.

123:16:11 Duke: No, wait. Just stand up. Let me get downslope, and you get upslope.

123:16:17 Young: Okay; be careful. (Pause) Backing up. (Pause)

123:16:27 Duke: You're moving away from me. Can you prevent that? Okay, it's back in. (Long Pause)

[We can hear Charlie's breathing. He is probably getting up off his knees.]

123:16:52 Young: Sure does. (Long Pause)

[Here, Charlie is commenting on the difficulty of judging sizes and distances. There is little to distinguish the individual craters, at least at first look.]

[We hear John and Charlie huffing, puffing, and grunting as they get seated.]

123:17:32 England: Okay. It looks like Plum Crater would be almost due west of you about 200 meters.

123:17:42 Duke: Okay. I'm hooked, John. (To Tony) Roger. (Pause)

123:17:54 Young: Well, I'm not.

123:17:55 Duke: You're twisted a little bit. Turn it clockwise, counter-clockwise. Other way. There you go.

123:18:02 England: I'd loop around Halfway to the south.

123:18:03 Duke: That got it.

123:18:05 Young: (Responding to Tony) That's what we're doing.

123:18:07 Duke: I think that's what we're doing. We got a little depth-size problem here and I think we'll figure it out here in a little bit.

123:18:19 England: Very good. Understand.

123:18:24 Duke: And this crater here is probably South...Correction: Halfway, with a smaller one on the side.

123:18:37 England: Rog.

123:18:39 Duke: I tell you that is a bigger crater than that, though.

123:18:44 Young: Okay.

123:18:46 Duke: You in? (Pause) Excuse me, John. (Pause) Okay, we're underway again, Tony.

123:18:55 England: Okay. (Pause)

[They have been stopped for about 7 minutes.]

[After John starts forward, Charlie takes AS16-109- 17770 which shows the west side of the 40-meter crater south of Halfway.]

[Duke - " 17769 and 17770 is sort of a little stereo pair which shows us, in the near foreground, on the edge of a crater with another crater on the south rim. And you're looking across the TV camera to the western side of South Ray. And you begin to get a pretty good view of Cinco below the high-gain antenna. That's the Cinco area." These two images are combined in strip form.]

[Jones - "Just below that white patch on the hillside."]

[Duke - "And then, the right-hand photograph shows a good view of South Ray off in the distance. As you can see, we've got no real problems here. There are no big, major blocks out there, so John can just let her go."]

[As John mentions in a moment, the poor visibility is holding him back.]

123:19:04 Duke: Can you go to the right, John? There's a pretty fresh batch, dead ahead. That's about a tenth of a kilometer across there, though; that's a big crater right there.

[If Charlie is looking at Halfway, his estimate is excellent.]

123:19:35 Duke: I feel real faith in this thing (meaning the Rover); open her up a little bit.

123:19:42 Young: I can't see where I'm going, Charlie. (Pause)

123:19:49 Duke: Here we go. Okay, Tony, we left that Halfway, and we're now en route to...Halfway and Buster looked about the same size. Is that right according to y'all's calculations?

123:20:03 England: That's right, Charlie.

123:20:04 Young: That's right, Charlie. Halfway...(Stops to listen)

123:20:05 England: That's just about right.

123:20:09 Duke: Okay. Well, that's what that was. That was Halfway.

123:20:13 England: Okay.

[During the next part of the traverse, Charlie takes AS16-109- 17771 and 17772. These two images are combined in strip form.]

123:20:27 Duke: Okay, Tony, we're at 086, 1.2. We're coming into another block-ray field up ahead of us about 50 meters or so, with angular blocks. The area we have here now is almost cobble free, except perhaps less than 1 percent of the surface.

[AS16-109- 17773 probably shows the block field Charlie is describing here.]

123:20:51 Duke: And now we're...There's another ray we're coming in out of South Ray, which (is) definitely out of South Ray, you can see it trending right on in to South Ray.

123:21:00 England: Outstanding. (Pause)

123:21:06 Young: Yeah, that's that big South-Ray-Crater ray, down here, I think.

123:21:13 England: Right.

123:21:15 Duke: You can see Hidden Valley. You can see partially into Stubby. The Cinco Craters are very visible up there on the side (of Stone Mountain).

[These features are labeled in various maps that can be found in the USGS Apollo 16 Professional Paper, for example, in the chapter on Traverse Planning and Field Procedures.]

123:20:25 Duke: Got to go back right, John, to get (garbled).

123:20:27 Young: I know it.

123:20:27 England: ...when you're in a ray or just the cobbles (about 64 mm to 256 mm) and boulders (bigger than about 256 mm)?

123:20:25 Young: No, it's albedo.

123:21:37 Duke: There is no mistake in your mind when you're in a ray because of the blocks.

123:21:42 England: Okay.

123:21:43 Duke: And the surface is a little bit lighter - the regolith. Blocks are very angular.

123:21:53 Young: I'd like to sort of tack. I can see a lot better. Just a little north or a little south.

123:21:59 England: Do you see both the white (brecciated anorthosite) and the black and white (breccia), here?

123:22:05 Duke: It's mostly gray, Tony, with a...There's a big crater over there, John.

123:22:10 Young: That's it.

123:22:11 Duke: Okay, that's it.

123:22:12 Young: Yeah.

123:22:13 Duke: We're coming into the south of Plum. (Pause)

[AS16-109- 17774 may be showing ejecta from Plum and Flag over the top of the TV camera.]

[A labeled detail from a Pan Camera frame shows the locations of Plum and Flag.]

[Duke, from the 1972 Technical Debrief - "Plum was smaller than Buster. Plum and Buster were supposed to be the same size; (but) Buster was gigantic compared to Plum."]

[Young, from the 1972 Technical Debrief - "I expected Plum to have a bright rim around it like it has in the photos. It didn't have a bright rim around it; but, when we dug down 2 inches, there was all this white material."]

[They will discover the white subsurface material at 123:50:59.]

123:22:36 England: Okay, did you notice that scarp that's mapped, that you should have driven across?

[This fictitious scarp crosses the traverse path at about CA.5/74.2 in the Descartes EVA-I, III; 2 of 2 map.]

123:22:49 England: Okay, do you notice a trend to the scarps? (On the pre-mission maps) they all seem to be (trending to the) northeast.

123:22:57 Duke: Yeah, that's probably pretty close, northeast. (Pause) Okay, that's got to be it, John. But I don't see Plum. Unless this is it right here.

123:23:13 Young: This is it, Charlie.

123:23:15 Duke: We are on the rim of it.

123:23:16 Young: (Chortling) Yeah.

123:23:18 Duke: Okay, we got to park on the other side about 40 meters up. Do a 180 left. (Pause) Well, Tony, we finally found it at 087 and 1.4.

123:23:29 England: Good show. That's where it should be.

[These (readouts) indicate they are near CA.7/73.6 which, indeed, is where they are parking - give or take 20 meters or so.]

123:23:38 Young: Man, you can't believe this territory.

123:23:44 Duke: It's all up and down. We're gonna be a little close here (to Plum), John, but that's okay.

123:23:54 Duke: Okay. (Pause) Tony, we're parking right on the rim of Plum. Dismounting.

123:24:02 England: Okay.