Apollo 15 Lunar Surface Journal

Irwin's Dunes

Corrected Transcript and Commentary Copyright © 1996 by Eric M. Jones.
All rights reserved.
Scan credits in the Image Library
Last revised 22 December 2010.

MP3 Audio Clip ( 15 min 22 sec ) by David Shaffer

164:47:36 Irwin: Okay. Rover readouts, Joe: 72 (on heading) 0 on bearing; distance (driven), 0.2; range (to the Nav initialization point), 0:0; amp-hours, 90, 95, 100, 105; and motor temps are still off-scale, low.

164:47:58 Allen: Thank you, Jim. Copied.

164:48:02 Scott: Okay. Ready?

164:48:03 Irwin: I'm ready, Dave.

164:48:05 Scott: Okay. Give me a heading.

164:48:06 Irwin: Give you a heading. Head west, man. We're heading towards Station 9. Head about, oh, I'd say 270, until they give us an update.

[As per cuff checklist page CDR-27, they are headed to either Scarp Crater, which is the 150-m crater at BS.5/66.8 or Rim Crater, which is the 10-m crater at the very edge of the rille at BS.2/65.4 on the EVA-3, Part B map. The LM is near BS.4/73.3 and Dave initialized the Nav system at the drill site - which is near BS.6/73.0 - at 164:06:24.]

[At 166:38:34, during the drive back to the LM from Station 10, Dave mentions that the Nav system has been biased "to the right" by about 8 degrees which suggests that the indicated bearings to the LM be decreased by 8 degrees.]

164:48:18 Allen: That sounds good,...

164:48:19 Scott: Okay. That's a...

164:48:20 Allen: ...Jim. 265...

164:48:21 Irwin: Head a little to the north...

164:48:22 Allen: ...to 270...

164:48:23 Irwin: ......

164:48:24 Allen: ...for about 1.8 clicks. And just enjoy it.

164:48:26 Irwin: Okay. And we're moving.

164:48:29 Scott: Yeah. We're going around the ALSEP, too.

164:48:33 Irwin: Yeah, let's not drive through the ALSEP.

164:48:35 Scott: Yeah. It's too bad the (16-mm) camera didn't work because there was some neat bumps there.

164:48:38 Irwin: Yeah. Oh, man! Look...Is that a glass ball right there?

164:48:43 Scott: Yeah. Right on top of the surface...

164:48:45 Irwin: Yeah.

164:48:46 Scott: ...about 2 inches or so.

164:48:47 Irwin: There's several here. Here's one over at 1 o'clock.

164:48:48 Scott: Yeah.

164:48:50 Irwin: Almost like a black spherule of glass.

164:49:01 Allen: We copy that.

164:49:02 Irwin: Okay. Right now we're swinging around more to the west. We're heading 270. Range (is) 0.1.

164:49:17 Allen: Roger, Jim. Copy. And shortly, you'll be...

164:49:21 Irwin: Man!

164:49:22 Allen: ...passing the Quark Triplet that's on your right, probably, and we'll be most likely be directing you back towards the western crater in that triplet for some mare sampling towards the end.

[The craters in the Quark Triplet are at BT.6/71.4, BT.8/72.2, and BT.3/72.6.]

[Scott - "A comment on Quark Triplet. That's another one of Joe's names, 'cause quarks had just been discovered. I remember one night, he was explaining quarks to us. So that's why we threw the name in there."]

[Jones- "There are also a lot of science fiction/fantasy names - like Durin's Bridge from the Lord of the Rings. Was Joe the science fiction reader?"]

[Scott - "There could be a whole chapter on the influence of science fiction on what everybody did. I think it's interesting because we, collectively, had an interest in using science fiction names."]

164:49:36 Irwin: I see them and they look rather fresh. There's a lot of angular light-colored fragments on the rim, Joe. So, mark our position here; we're (at) bearing 110 and range, 0.2.

164:49:59 Allen: Okay, fine. (Pause)

[They are near BS.9/72.2 or, if we use the 8 degree correction, BS.8/72.2. This close to the LM, the correction is inconsequential.]
164:50:08 Irwin: We dropped into a shallow depression there, and that was the Quark Triplet there on the northwest side of that shallow depression.

164:50:17 Scott: Oop, look at this nice, little, new fresh one.

164:50:20 Irwin: Yeah. But there're not too many fragments on the rim.

164:50:24 Scott: No. You're right. Oh, there's a...

164:50:27 Irwin: There's a very large depression ahead of us.

164:50:30 Scott: Yeah.

164:50:31 Irwin: We don't want to drive through that.

[This feature extends from 72.3 to 71.1 in the east-west direction and from BS.2 to BT.3.]
164:50:32 Scott: I don't know whether we do or not. Let's take a look at it. Ooh, hoo.

164:50:34 Irwin: Oh, I wouldn't think so, Dave.

164:50:36 Scott: Let's take a look at it. Look at the big boulder there, Jim.

164:50:41 Irwin: Yeah. I saw that one.

164:50:42 Scott: About 3 feet, angular.

164:50:43 Irwin: A very large depression here. I'd say, let's go north of it.

164:50:45 Scott: Yeah. I think you're right.

164:50:47 Allen: Roger. We agree.

164:50:50 Irwin: Oh, yeah. I really can't tell how wide it is, but at the very deepest portion of it, it looks like there's a crater.

[Scott, from the 1971 Technical Debrief - "(To Jim) Why don't you comment on what you saw of the terrain, because I was just pretty much trying to drive and avoid the big holes."]

[Irwin, from the 1971 Technical Debrief - "There was just a gradual drop down (into the depressions). We drove through one or two of those depressions. I would not say 'shallow' depressions; because, actually, the bottom was probably 150 feet (45 meters) below the general surface of the plains."]

["It was about a 5-degree angle into the bottom. I remember one, in particular, that seemed like (it had) a fairly fresh crater in the very center of it, with no rock debris, no ejecta, on it."]

164:51:01 Scott: I get the idea that it looks collapsed north to south, doesn't it? Sort of looks elongate.
[Dave is suggesting that the north-south diameter is less than the east-west diameter. On the EVA-3, Part B traverse map it is difficult to tell exactly where the rim is except on the east side where the early-morning shadow starts at about BS.8/73.3]
164:51:11 Irwin: I don't (know)...Look at our map here. (Pause)

164:51:17 Scott: Take just a little...

164:51:19 Irwin: Sure can't pick that up.

164:51:21 Scott: No, sure can't.

164:51:25 Irwin: Let's see, we're going about 8 clicks. (Pause) And we're kind of dropping down as we go around the (depression). And we're heading 320; we're on the northeast rim of this very shallow depression. By "shallow", (I mean that) the slopes are probably 3 degrees. And I guess, at the deepest part there, it's probably, oh, 200 feet (60 meters) deep. (Pause) Right now, we're on the north side of that depression.

[Jim has provided us with two estimates of the inner slope and depth. A 5-degree slope and 45-m depth gives a radius of about 515 m. A 3-degree slope and 60-m depth gives a radius of 1160 m. Because of the shallow slope, Wolverine does not show up in overhead photography taken with the Sun more than a few degrees above the horizon. LROC image M117467833R was taken on 7 January 2010 at 01:42:46 UTC, The Sun was 7.1 degrees above the western horizon. Consequently, the eastern half of the depression will tend to be slightly brighter than the surrounding surface and the western half will be slightly darker. A possible outline of Wolverine is sketched on a detail from the LROC image. The crater at the deepest point that Jim noted at 164:50:50 is labeled, as is a candidate for the boulder they noted at 164:50:36. The range from the boulder to the nav initialization point is about 230 meters and the bearing about 99.]
164:52:10 Scott: Hang on.

164:52:11 Irwin: Yeah. (To Houston) And we're swinging around to the west, heading, 270. Heading right towards Bennett Hill. (Pause) Dave, I'm going to call that big crater "Wolverine".

[The name honors the University of Michigan Wolverines.]

[Scott - "All three of us - Jim and Al Worden and I - went to Michigan."]

[Jim and Al earned M.S. degrees from Michigan. Dave entered the University of Michigan on a swimming scholarship but left after one year because he had been accepted by the U.S. Military Academy at West Point.]

164:52:32 Scott: Oh, that's a good name. Good name for a big crater.

164:52:42 Irwin: Okay, bearing is 113, and we're at 0.6.

[They are near BT.5/70.8, or, if we apply the 8-degree correction, near BT.2/70.7]
164:52:47 Scott: There's another big one (meaning another large depression), Jim. Whoo, and look at that rock over there.

164:52:51 Irwin: Oh, yeah.

164:52:52 Scott: Look at that one!

164:52:53 Irwin: Sitting right on the surface...

164:52:54 Scott: Yeah.

164:52:55 Irwin: ...a block angular frag on the northwest side about one-quarter of the way down...

164:53:03 Scott: Yeah.

164:53:04 Irwin: ...into the crater. But, a very subdued crater. That block is...

164:53:09 Scott: Isn't that something? We've got to drive right by it, anyway. (Pause)

164:53:15 Allen: And, Jim, don't hesitate to fire off pictures right and left here. We've got lots of film.

164:53:22 Irwin: Oh, I wish I could, Joe! (Pause)

[Because Jim's camera is broken, only Dave can take pictures.]
164:53:28 Scott: Right there.

164:53:31 Irwin: Okay, we've stopped.

164:53:32 Scott: Just for a second, though.

164:53:33 Allen: Okay.

164:53:35 Scott: Getting it. (Pause) Got it.

[Dave has just taken AS15-82- 11065. In compiling photo captions for the Journal, I have relied heavily on the work of Bailey and Ulrich in "Apollo 15 Voice Transcript Pertaining to the Geology of the Landing Site" and have had few disagreements with their association of particular photographs with particular parts of the dialog. However, in the case of this picture, I do not agree with their suggestion that it was taken at 165:00:10. My reason for thinking that it was taken here is that Dave and Jim have clearly stopped to take a look at a rock and Dave says he is "getting it", meaning he is taking a picture. Frame 11065 is certainly taken from Dave's side of the Rover. Jim's camera is jammed. In addition to the rock, note the small, fresh crater at the left side which has produced a significant amount of regolith breccia.]
164:53:48 Irwin: Okay, we're moving.

164:53:49 Allen: Roger.

164:53:51 Scott: Hey, that's something, isn't it? I bet it chipped that hole, Jim. It went right in...It came from that...It made that crater there. And it come from 250, (correcting himself) I mean (laughing) 070. That angular projectile about a foot across, Joe, had made a secondary about a meter across, and it came from a 070 heading. I bet you anything, because the...Oh, that was neat! One part of the frag was covered with glass, and the central part of the crater was covered with glass. Obviously a secondary, and obviously made by that angular frag.

[See, also, the discussion at 123:36:42. The question is whether the rock dug crater and, by implication, the glass in the crater was left there when the rock hit or they are not associated and the glass in the crater was the result of the impact of a small, high velocity object.]

[Scott - "With somebody's help - and I don't remember who - I wrote a paper on that: 'Glass in the bottom of small lunar craters,' (published in the Geological Society of America Bulletin, vol. 83, June 1972) I think it was Gerry Schaber (who helped with the paper)."]

[During much of the deepcore recovery, Dave's voice was uncharacteristically subdued. He sounded tired and discouraged. Now that he and Jim are out doing geology, he is far more animated. Geology has revitalized him.]

164:54:32 Irwin: Dave, we've got another shallow depression here up ahead. And I don't know whether...I'd say, we'd be better off staying to the north, wouldn't you?

164:54:39 Scott: I don't know. We're making good time.

164:54:40 Irwin: Okay. Let's...

164:54:41 Scott: Why don't we...

164:54:42 Irwin: ...let's go through it then.

164:54:43 Scott: There's a big...

164:54:45 Irwin: A fresh one (meaning a fresh crater) out at 1 o'clock.

164:54:46 Scott: Yeah.

164:54:47 Irwin: It looks like a large fresh one. There are a lot of angular, light-colored blocks on its rim. You going to try going through here, huh?

164:54:59 Scott: Well, to go around it...

164:55:00 Irwin: Yeah.

164:55:01 Scott: We're making good time.

164:55:02 Irwin: Okay.

164:55:03 Scott: Down here to the left, it looks pretty flat.

164:55:04 Irwin: Okay, we're heading through another shallow depression, similar to the last large depression that we described.

[This could be the feature extending from 69.2 to 70.4 and BS.4 to BT.7.]
164:55:14 Irwin: What's that fragment at 12 o'clock to us? Another piece of glass, I suppose.

164:55:17 Scott: That shiny one? Yeah.

164:55:18 Irwin: Yeah. (Pause) Another glassy fragment, angular, about 3 inches long, sitting right on the surface.

164:55:31 Scott: And, you know, the surface is smooth, but it's pretty rough out here. Smooth on a small scale, and there's lots of...

164:55:42 Irwin: You really could get lost here.

164:55:45 Scott: Yeah. Up and down.

164:55:47 Irwin: Up and down. Yeah. It was great going uphill. Going up to the Front, you could always look back and see the LM. Here, it's like driving over the big sand dunes in the desert.

164:56:01 Allen: Roger, Jim...

164:56:02 Irwin: Pretty rough on the one you're seeing now. We'll walk...

164:56:05 Allen: ...Pretty description. And you're looking for Nav readings of 1.8 clicks at 088, when you're at Station 9.

[The corresponding map location is about BS.4/65.8 which is essentially the originally-planned Station 9 location. The difference is probably due to uncertainty - on Houston's part and mine - as to where Dave initialized the Nav system.]
164:56:13 Scott: (To Jim) Hang on.

164:56:15 Irwin: Okay, we're 1.0 now on range. Bearing, 101. And now there's another very large shallow depression. And, Dave, they're all about the same size!

164:56:26 Scott: Yeah, you're right. Go around the south of this one.

[They are near BT.4/69.1 or, if we apply the 8-degree correction, near BS.8/69.0. The eastern part of this feature may be the shadow centered at BS.8/68.3.]
164:56:31 Irwin: I think they're, you know, the first really shallow depressions or very subdued craters we've seen. And there are just three in a line that run east-west.

164:56:40 Scott: Yeah, I'd say they're probably about 100 meters across and maybe, what, 10, 15 meters deep?

164:56:48 Irwin: Yeah. (Pause)

164:56:54 Scott: Man!

164:56:56 Irwin: Well, I thought we'd whip right over to the rille. I didn't think we'd have this type of terrain!

164:57:01 Scott: Oh, it was a lot easier driving yesterday.

164:57:03 Irwin: Yeah.

164:57:07 Scott: Surprises, surprises!

[Jones - "I gather that you wouldn't have seen these depressions in the SEVA because they were down-Sun of the LM"]

[Scott - "Yeah. And we probably weren't high enough. You start losing them on the horizon."]

[Jones - "And, also, in the early morning light you don't get any definition down-Sun."]

[Scott - "Yeah, but you have to be in the zero-phase (exactly down-Sun) to have it washout."]

[Jones - "Pete and Al landed due east of Head Crater and weren't aware of it for an hour or so."]

[Scott, from a 1996 letter - "During the SEVA, I was not really aware of such features since they had never been discussed (pre-flight) and the Hadley photos did not show such things. Maybe we should call them 'Irwin's Dunes' (as per Jim's comment at 164:56:05). They were really unique! In retrospect, the LRV should have had a 'tiltmeter' to enable a readout (or recording) of the angle of the LRV with the local horizontal. That would have really helped a real-time terrain map."]

164:57:11 Irwin: Look at that rock over at, oh, 1 o'clock. It's right. Well, it was on the horizon; like kind of a pedestal.

164:57:16 Scott: Yeah.

164:57:18 Irwin: You can see a lot of them, right on the horizon. (Pause) Okay. We probably want to, when you can, Dave, swing around to the west; we're going a little too far south here.

164:57:30 Scott: No. We're doing fine. Say again the coordinates, Joe, of the station.

164:57:36 Allen: Dave, you're driving towards 1.8 clicks; 088, bearing.

164:57:45 Scott: Rog. We're doing good. We're (at a bearing of) 092, now; heading slightly south.

[Dave is headed slightly south of due west so that the bearing will decrease from the present 092 to the desired 088. Once he gets to 088, he can then follow the complementary heading of 272 and drive along a radial from the LM until he gets to the desired range.]
164:57:50 Irwin: Yes. Well, what I'm thinking, there's nothing unique about (the exact location of) Station 9, is there? Except maybe Scarp Crater.

164:57:55 Allen: And you're thinking correctly, Jim...

164:57:56 Irwin: Scarp Crater is over this way.

164:57:57 Scott: Okay.

164:57:58 Allen: ...Anywhere along there's beautiful.

164:58:02 Irwin: I was thinking, you know, just a good sample point...

164:58:05 Scott: Yeah.

164:58:06 Irwin: ...along the (rille) rim. And, we can minimize the distance.

[Because they are south of the North Complex, what Jim may be thinking is that, by not driving any farther south, they can cut the amount of driving they would have to do to reach the North Complex and, therefore, increase the chance that Houston will let them make at least a quick visit.]

[Scott, from a 1996 letter - "Yes!"]

164:58:13 Allen: Right on, Jim. (Joking) Just don't drive too far west (and fall into the rille).

164:58:16 Irwin: I was going to say, I thought I could see it. (Responding to Joe, laughing) Okay.

164:58:24 Scott: Yeah, Joe, we'll let you know when the slope gets up to 26.

[The Rover is designed to handle slopes of up to 26 degrees. The rille walls are of that order.]
164:58:28 Irwin: I think I can see the far side of the rille, now.

164:58:32 Scott: I think we're coming up on the rim of it.

164:58:33 Irwin: Yeah.

164:58:35 Scott: Take a little jog over here to where it's a little smoother. (Long Pause) It's a steep slope, isn't it? Yep, I think we (garbled) No, it's another fresh crater.

164:58:59 Irwin: Yeah, fresh crater. And, you do kind of get the impression there's a rim here.

164:59:04 Scott: Yeah.

164:59:06 Irwin: A levee. Off to the left there, the higher part.

164:59:09 Scott: Yeah, sure do. (Garbled) it is.

164:59:12 Irwin: There's rough terrain ahead of us.

164:59:14 Scott: Yeah.

164:59:17 Irwin: We dropped down into another little valley. There's another one of those shallow depressions off at 1 o'clock. Right now our bearing is 89, range 1.4.

164:59:28 Allen: Roger.

[They are near BS.5/67.4 or, if we apply the 8-degree correction, near BR.7/67.5. The "rough terrain" ahead of them may be the ejecta blanket surrounding Scarp Crater. In a few minutes, they will stop at a small, 15-m-diameter crater which they will mistakenly call Scarp but which, in fact, is about 75 meters south of the rim of Scarp.]

[Readers interested in the question as to which crater should now be known as Scarp should consult the discussion following 147:02:55. I belong to the camp that believes that craters keep the names given to them pre-flight, because that is my sense of the way the astronauts were thinking at the time. The dialog over the next few minutes illustrates that thought process.]

[Irwin, from the 1971 Technical Debrief - "I did not see any change in the rock distribution as we proceeded to the edge of the rille until we came up to that very fresh one which we incorrectly called Scarp, initially. It was probably Rim Crater."]

[Scott, from the 1971 Technical Debrief - "Probably, because it was too small to be Scarp, and it was fairly fresh."]

[Rim Crater is actually about 300 meters west of their current location. In large measure, the confusion is probably due to the poor quality of the maps they are using. As Jim said at 164:57:50, it is not important exactly where they stop to do Station 9.]

164:59:29 Scott: Look at this one, Jim. It must be...Holy cow! This must be...I'll go around to the left here.

164:59:36 Irwin: Yeah! Or towards the right, [it's] fairly smooth on the right.

164:59:40 Scott: Yeah, it's closer here. (Pause)

164:59:45 Irwin: (To Houston) Okay, we're heading down into another depression. It has oh, one, two, three other recent craters. The one of the southern rim looks to be the most recent. In fact, it's kind of a doublet with a smaller crater in the north rim of it.

[This is probably the feature east southeast of Scarp Crater, the one with the shadow extending from BR.8 to BS.5 at 67.5.]
165:00:03 Scott: Well, look at the two here. Yeah (garbled)

165:00:04 Irwin: Another doublet there on the left.

165:00:05 Scott: Yeah. (Pause) Another one.

165:00:10 Irwin: Okay; we're heading (means 'bearing'), 087. Right now, we're heading, oh, about 250. Range, 1.5.

[They are near BS.3/67.0 or, if we apply the 8-degree correction, near BR.5/67.1.]
165:00:26 Irwin: Boy, look at the fresh blocks ahead of us.

165:00:28 Scott: Yeah.

165:00:29 Allen: Rog. We copy...

165:00:30 Irwin: That might...I wonder if...Are we...

165:00:31 Allen: ...You must be very near Scarp Crater.

165:00:34 Irwin: I was going to say, that's probably Scarp Crater.

165:00:36 Scott: The fresh one.

165:00:37 Irwin: Yeah.

165:00:38 Scott: It's a beauty!

165:00:39 Irwin: It sure kicked up a lot of rocks. What are you going to do, go on the north side of it?

165:00:44 Scott: I want to take a look and see if that's it. Yeah. Boy, it's really fresh with a lot of debris. Nice ejecta blanket. Nice ejecta blanket. Good typical one. That's Scarp. And we're 088 for 1.6. (Pause)

[They are near BS.4/66.6 or, if we apply the 8-degree correction, near BR.5/66.7.]
165:01:04 Scott: I'd say this is probably Scarp Crater, wouldn't you?

165:01:09 Irwin: I would, because we can definitely see the far side of the...

165:01:12 Scott: Yeah. The rille.

165:01:13 Irwin: ...the rille now.

165:01:14 Scott: Yeah.

165:01:15 Irwin: We could drive back to this one. Sample it, right?

165:01:17 Scott: Yeah, but

165:01:18 Irwin: Let's press on to the...

165:01:19 Scott: Take a look.

165:01:20 Irwin: Yeah. Make you...

165:01:21 Allen: Roger. We agree...

165:01:22 Scott: Yeah, but this is so much ... anyway.

165:01:23 Allen: ...and with any luck at all, that is Scarp Crater.

165:01:27 Scott: Yeah, let's do this one anyway, Jim. Driving back means...(Subvocal) Oh, my. Wait a minute, let me get to where I can...

165:01:44 Irwin: And we can definitely see the west side of the rille from here.

165:01:47 Scott: Yeah.

165:01:49 Irwin: Probably see, oh, 10 to 15 percent of the (rille wall on the) far side.

165:01:53 Allen: Copy.

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