Swann Range, Swann Mountain and Big Rock Mountain

Swann Range, Swann Mountain and Big Rock Mountain

These feature names occur informally in the Apollo 15 transcripts but do not appear on any mission maps or diagrams that have come to my attention.

Swann Range

The lunar Apennines are the mountains that form the southeastern rim of the Imbrium Basin, extending northeast from Crater Eratosthenes to just beyond Mt. Hadley. The Swann Range was named for Apollo 15 Geology Team Leader Gordon Swann and comprises the mountains that form the eastern boundary of the landing site south of Mt. Hadley and north of Silver Spur.

123:51:53 Irwin: And, you know, the terrain, looking from the east (means 'to the east'), is just a general rise to the east. It looks like, oh, 2 or 3 percent. Notice that, Dave?
123:52:06 Scott: Yeah, up to...
123:52:07 Irwin: Right to the base of the Apennines.
123:52:10 Scott: Yeah.
123:52:1 Irwin: And it's a gradual...
123:52:11 Scott: Right up to the Swann Range there.

Notional extent of the Swann Range
drawn on a detail from Lunar Topographic Orthophotomap LTO41B4.

Swann Mountain

144:50:48 Scott: Okay, Joe, I got the 500 pictures. And I took, first, Mount Hadley; two horizontal strips up at the top where there are some outcrops, and probably the only two craters that I can see on the side of any sizable size. And then a vertical strip through one of the outcrops, and a vertical strip through another outcrop, and then two craters that are in, I guess, what we'd call the forward, leading edge of Swann Mountain over there, which are quite prominent craters. And then I swung over to a bright fresh one that we see, oh, to the northwest, way out. And then I turned back around to Hadley Delta and shot upslope at Hadley Delta, and picked up the debris that seems to be exposed up on the top of Hadley Delta. And now the frames say 120.

"Leading edge of Swann Mountain" seen from Station 6.
500-mm frames AS15-84-11316 and 317.

Frames AS15-85-11512 and 513 provide context for the 500-mm shots.

Context for Dave's 500-mm shots of 'Swann Mountain'.
AS15-85-11512 and 513 from Jim's second Station 6 pan.

Dave's comment about the craters being on the 'leading, forward edge' suggests two possibilities: (1) that he meant the 'leading forward edge of the Swann Range'; or (2) that Swann Mountain includes the darker peak on the righthand side of the detail above. Because there is only one reference to 'Swann Mountain' in the transcripts, I am inclined to believe that Dave meant 'Swann Range'. Note that bright, background peak in the center is actually slightly taller than Mt. Hadley and can be seen at the upper right in the map above that shows the notional extent of the Swann Range.

Big Rock Mountain

Big Rock Mountain is named from Rocco Petrone, Apollo Program Director at the time of Apollo 15.

EVA-3 Traverse to LM

The following exchange comes as Dave and Jim leave Station 10 on their way back to the LM at the end of EVA-3.

166:32:32 Irwin: We're looking directly east now as we head back to the LM...Did you put your visor down?
166:32:38 Scott: Haven't yet, but I think I just might.
166:32:40 Irwin: Boy, that Sun is really fierce. (Pause)
[The Sun's azimuth and elevation are about 110 and 39 degrees, respectively. The bearing to the LM is 093, which is almost directly east.]
166:32:49 Irwin: And I can see, as I look to the east, several places up the slope [of] Big Rock Mountain where there're outcrops exposed.
166:33:04 Allen: Roger, Jim. Copy...
166:33:05 Irwin: One about a quarter of the way up directly east from us...That was Big Rock Mountain.
[Jim never finishes his comment about the outcrop 'about a quarter of the way up'.]
166:33:06 Allen: And the name of the mountain again, please.
166:33:12 Irwin: That was Big Rock Mountain.
166:33:14 Scott: You know, Joe. Big Rock-o Candy Mountain.
[Here, Dave is making sure that Rocco Petrone understands that the mountain is being named for him. He is also referring to the song Big Rock Candy Mountain that was first recorded in 1928 by Harry McClintock but was best known from a 1949 Burl Ives recording.]
166:33:18 Allen: Roger; we copy. (Pause) And do we have a big smile here in the MOCR.
166:33:30 Irwin: (Laughs)
[Scott - "I think we decided, at some point, that we would call that 'Big Rock Mountain', after Rocco Petrone. He picked the landing site. He made the decision."]

Because Station 10 is near the rille rim and, therefore, is below the level of the mare surface, Jim's Station 10 pan doesn' t show the base of the mountains to the east. However, Dave's Station 9 pan is a good subsitute, having been taken on the mare surface only about 400m ESE of Station 10 and only about 90 minutes earlier.

Eastern portion of Jim's Station 10 pan.

Eastern portion of Dave's Station 9 pan.
There are two strong candidates for the title of Big Rock Mountain.

Southern Candidate

Readers should note that Dave and Jim could see much more detail on the mountains than can be seen in the photographs.

The first candidate is to the right of the Sun in both pans and has summit outcrops that are prominent even in the photographs.

Details from AS15-82-11081 (top) taken from Station 9
and 11176 (bottom) taken from Station 10.
These are the best photos we have of this peak.

Although this southern candidate has prominent outcrops near the summit, it is not 'directly east' of Station 10, having bearing from that station of about 115 degrees, which is 25 degrees south of east. There are two outcrops lower down the mountain that might qualify as 'one quarter of the way up'; one in the lower left corner of the detail from 11081 and the other on the righthand shoulder. We should note that, during initial part of the drive, Dave drove somewhat south of the direction of the LM and, only 20 seconds after the discussion of Big Rock Mountain, Jim mentioned that they were on a heading of 105.

Northern Candidate

The second candidate is to the left of the Sun in both pans.

Details from AS15-82-11077 (top) taken from Station 9
and 11174 (bottom) taken from Station 10.

Although the outcrops are difficult to pick out in the photographs taken near the rille, Jim would have had no trouble seeing them. Similarly, although the bearing to this peak is 072 and, therefore not 'directly east, either, it is closer to 'directly east' than the other candidate. Importantly, there is a prominent outcrop that really can be described as 'a quarter of the way up'. It is about a quarter of the way from the top of the foreground hill to the summit. It is just to the left of the line to the summit.

When Dave got back to the LM, he took the time at 167:10:16 to take a number of 500mm shots to the east, including a portrait of the northern candidate. Thirty five years after the fact, it is impossible to know with certainty why Dave took these photographs and none of the southern candidate. The one clue we have is the following exchange Dave and Jim had late in the drive back to the LM:

166:38:03 Scott: Boy, look at the few big boulders up there. Yeah, that's pretty neat.
166:38:07 Irwin: Up on the slope of...
166:38:08 Scott: Yeah.
166:38:09 Irwin: It's appropriately named, don't you think?
166:38:11 Scott: Yes, it is. (Pause) It's the only one around here.

A detail may show the boulders discussed here. They are near the summit of the northern candidate. This exchange and Jim's earlier description lead me to believe that the northern candidate is Big Rock Mountain.

Frames AS15-89-12165 to 71 comprise a 500mm portrait of the northern candidate along with the foreground hill discussed above.

In an extended exchange of e-mail in 2005-6, I shared my thinking about this subject with Dave Scott but, throughout the exchange, he insisted that his intent was to apply Petrone's name to Mt. Hadley.

However, based on the clear evidence of Jim's description during the drive back from Station 10, I believe that Jim was applying the name Big Rock Mountain to one of the summits in the Swann Range. Certainly, Jim was not describing Mt. Hadley. In addition, I am not aware of any instances of the Apollo crews giving new names to previously named lunar features. Because of a conflict with the International Astronomical Union over names chosen by the crews for previously-unnamed features that raged throughout the Apollo years, I doubt that the crew would have seriously considered weakening their asserted naming rights by proposing to rename so prominent a feature as Mt. Hadley. Based on the evidence in hand, I believe the northern candidate more closely matches Jim's description than does the southern candidate.

Detail from Lunar Topographic Orthophotomap LTO41B4
with the two candidates labeled.

Stand-up EVA (SEVA)

Dave mentioned Big Rock Mountain during the Stand-up EVA

106:57:23 Irwin: When you finish with the 500, Dave, I have the other camera.
[The third camera has a 60-mm lens and a color magazine.]
106:57:25 Scott: Okay. Try not to hit my foot there. (Long Pause) Looking back into the Sun is almost useless, Joe. Really blots everything out.
[Dave has turned to the east to take a 500-mm mini-pan of the base of Mt. Hadley.]
106:57:57 Allen: Rog, Dave. Any sign of the big mountain back there?
106:58:02 Scott: Yeah. You can see Big Rock Mountain back there!
106:58:07 Allen: Roger. Copy Big Rock Mountain. (Long Pause)
[Note that, at 106:57:57, Joe was not passing on a question from the Backroom but, rather, was reminding Dave to mention Petrone's mountain.]
Although there are no explicit clues as to the identity of Big Rock Mountain in this exchange, the eastern portion of Dave's B & W pan shows the scene.

Eastern portion of Dave's B & W SEVA pan
with Mt. Hadley on the left and Silver Spur on the far right
Dave took the pan at 106:54, which corresponds to 0028 GMT/UTC on 31 July 1971. The solar azimuth and elevation were 96.4 and 13.4 degrees, respectively.

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