APOD: Apollo 17: A Stereo View from Lunar... (2018 Feb 23)

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Expand view Topic review: APOD: Apollo 17: A Stereo View from Lunar... (2018 Feb 23)

Re: APOD: Apollo 17: A Stereo View from Lunar... (2018 Feb 23)

by neufer » Tue Feb 27, 2018 3:46 pm

Chris Peterson wrote:
moontrail wrote:
Chris Peterson wrote:
I don't think the LM was ever at a greater altitude than the CM. After they separated, a braking maneuver changed the eccentricity of the LM, with its apapsis at the ~70 mile height of the CM parking orbit, and its periapsis at about 50,000 feet, the height where the descent phase was initiated. I think the CM only appears to be lower here, an illusion caused by the very low altitude of both objects compared with the size of the Moon and its surface features.
It seems to me almost undoubtable that if the LM, taking the picture was bellow [sic] the CM, then the CM should be in the picture above the horizont line. Shouldn't it?
Maybe. Not sure that the 3D nature of the surface wouldn't make an illusion possible at low altitudes. But in any case, it sounds like the CM was lower. If you look at the mission plan, that shouldn't happen. But the injection of the LM into an eccentric orbit may not have exactly matched the plan, and it wouldn't take much of an error to push the apapsis a few hundred meters higher.
  • James Joyce's Finnegans Wake: nor avoice from afire bellowsed mishe mishe to tauftauf thuartpeatrick
https://www.hq.nasa.gov/office/pao/History/alsj/a17/a17.prepdi.html wrote:
<<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 [in the CM] had not yet made his circularization burn and was ahead and slightly below them [in the LM].

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.>>

Re: APOD: Apollo 17: A Stereo View from Lunar... (2018 Feb 23)

by Chris Peterson » Tue Feb 27, 2018 2:25 pm

moontrail wrote:
Chris Peterson wrote:
Soroban wrote:The interesting thing I noticed is that the Command Module is at a lower altitude than the Lander. I had always assumed the landing approach would be a descent only. Did the descent profile include an altitude gain, or alternatively, did the Command Module move to a lower altitude for some reason?
I don't think the LM was ever at a greater altitude than the CM. After they separated, a braking maneuver changed the eccentricity of the LM, with its apapsis at the ~70 mile height of the CM parking orbit, and its periapsis at about 50,000 feet, the height where the descent phase was initiated.

I think the CM only appears to be lower here, an illusion caused by the very low altitude of both objects compared with the size of the Moon and its surface features.
It seems to me almost undoubtable that if the LM, taking the picture was bellow the CM, then the CM should be in the picture above the horizont line. Shouldn't it?
Maybe. Not sure that the 3D nature of the surface wouldn't make an illusion possible at low altitudes. But in any case, it sounds like the CM was lower. If you look at the mission plan, that shouldn't happen. But the injection of the LM into an eccentric orbit may not have exactly matched the plan, and it wouldn't take much of an error to push the apapsis a few hundred meters higher.

Re: APOD: Apollo 17: A Stereo View from Lunar... (2018 Feb 23)

by moontrail » Tue Feb 27, 2018 12:56 pm

Chris Peterson wrote:
Soroban wrote:The interesting thing I noticed is that the Command Module is at a lower altitude than the Lander. I had always assumed the landing approach would be a descent only. Did the descent profile include an altitude gain, or alternatively, did the Command Module move to a lower altitude for some reason?
I don't think the LM was ever at a greater altitude than the CM. After they separated, a braking maneuver changed the eccentricity of the LM, with its apapsis at the ~70 mile height of the CM parking orbit, and its periapsis at about 50,000 feet, the height where the descent phase was initiated.

I think the CM only appears to be lower here, an illusion caused by the very low altitude of both objects compared with the size of the Moon and its surface features.
It seems to me almost undoubtable that if the LM, taking the picture was bellow the CM, then the CM should be in the picture above the horizont line. Shouldn't it?

Re: APOD: Apollo 17: A Stereo View from Lunar... (2018 Feb 23)

by Chris Peterson » Sat Feb 24, 2018 5:00 am

Nitpicker wrote:See last couple of posts from a previous discussion on this repeated APOD:
viewtopic.php?f=9&t=34293&hilit=Apollo&start=25

The CSM was indeed lower than the LEM at times.
I do vaguely recall that discussion...

Re: APOD: Apollo 17: A Stereo View from Lunar... (2018 Feb 23)

by Boomer12k » Sat Feb 24, 2018 1:31 am

Nice one...

:---[===] *

Re: APOD: Apollo 17: A Stereo View from Lunar... (2018 Feb 23)

by Nitpicker » Sat Feb 24, 2018 1:16 am

See last couple of posts from a previous discussion on this repeated APOD:
viewtopic.php?f=9&t=34293&hilit=Apollo&start=25

The CSM was indeed lower than the LEM at times.

Re: APOD: Apollo 17: A Stereo View from Lunar... (2018 Feb 23)

by Chris Peterson » Sat Feb 24, 2018 12:52 am

Soroban wrote:The interesting thing I noticed is that the Command Module is at a lower altitude than the Lander. I had always assumed the landing approach would be a descent only. Did the descent profile include an altitude gain, or alternatively, did the Command Module move to a lower altitude for some reason?
I don't think the LM was ever at a greater altitude than the CM. After they separated, a braking maneuver changed the eccentricity of the LM, with its apapsis at the ~70 mile height of the CM parking orbit, and its periapsis at about 50,000 feet, the height where the descent phase was initiated.

I think the CM only appears to be lower here, an illusion caused by the very low altitude of both objects compared with the size of the Moon and its surface features.

Re: APOD: Apollo 17: A Stereo View from Lunar... (2018 Feb 23)

by Soroban » Sat Feb 24, 2018 12:27 am

Great photo selection, and both the red/blue and cross-eye pairs worked fine for me. (I do have to reverse the red/blue orientation of my cheap 3-D viewer, however.)

The interesting thing I noticed is that the Command Module is at a lower altitude than the Lander. I had always assumed the landing approach would be a descent only. Did the descent profile include an altitude gain, or alternatively, did the Command Module move to a lower altitude for some reason?

Hard to believe this happened almost half a century ago. The space program fueled my imagination through school and into a great career in the aerospace industry.

Re: APOD: Apollo 17: A Stereo View from Lunar... (2018 Feb 23)

by Chris Peterson » Fri Feb 23, 2018 11:54 pm

heehaw wrote:I am grateful to Chris for providing the "crossed eyes" version, as I never seem to keep the red/green glasses. But it didn't work for me (it usually does). I turned the laptop upside down, and it did sort of work - maybe that was the problem? Some 3D crossed-eye images are terrific. Not these.
It works for me, but I did have some problems with the "is it a crater or a hill" optical illusion kicking in, which sometimes interfered with fusing the images. That might be what's going on with you, too, since turning an image upside down is one way to switch that illusion around.

(Another problem with the anaglyph is that it's not red/blue, but red/cyan. To get the best results, you need red/cyan glasses, but red/blue is also commonly used. So you not only have to find your glasses, you have to have the right kind.)

Re: APOD: Apollo 17: A Stereo View from Lunar... (2018 Feb 23)

by heehaw » Fri Feb 23, 2018 11:44 pm

I am grateful to Chris for providing the "crossed eyes" version, as I never seem to keep the red/green glasses. But it didn't work for me (it usually does). I turned the laptop upside down, and it did sort of work - maybe that was the problem? Some 3D crossed-eye images are terrific. Not these.

Re: APOD: Apollo 17: A Stereo View from Lunar... (2018 Feb 23)

by Chris Peterson » Fri Feb 23, 2018 5:34 pm

Jim Armstrong wrote:Maybe I have a faulty monitor, faulty glasses or just plain old old eyes, but I seldom find that the 3D (stereo) photographs add much to APODs.
I zoomed in on the two black and white images separately and found more useful viewing.
As long as I am complaining, I should mention that it is very difficult to find those images by using the link (AS17,,etc). In fact I never did.
I really like APOD and stop by daily.
FWIW, I constructed the split view from the APOD anaglyph, not by going back to the originals. But they seem easy enough to find. Go to the linked location, select the film magazine (the middle three digits of the image identifer), and then go down the list until you find the image number (the final five digits).

Re: APOD: Apollo 17: A Stereo View from Lunar... (2018 Feb 23)

by Jim Armstrong » Fri Feb 23, 2018 5:14 pm

Maybe I have a faulty monitor, faulty glasses or just plain old old eyes, but I seldom find that the 3D (stereo) photographs add much to APODs.
I zoomed in on the two black and white images separately and found more useful viewing.
As long as I am complaining, I should mention that it is very difficult to find those images by using the link (AS17,,etc). In fact I never did.
I really like APOD and stop by daily.
Potter Valley, CA

Re: APOD: Apollo 17: A Stereo View from Lunar... (2018 Feb 23)

by ta152h0 » Fri Feb 23, 2018 4:02 pm

sshe caught my attention with " Temma Harbor "

Re: APOD: Apollo 17: A Stereo View from Lunar... (2018 Feb 23)

by De58te » Fri Feb 23, 2018 1:08 pm

Actually when that song was playing on the radio regularly in 1969 I thought 'those days' (when the singer was young) wasn't 1969 but the 50s maybe 1960. Because 1969 was the present and known as these days, not those days.

Re: APOD: Apollo 17: A Stereo View from Lunar... (2018 Feb 23)

by heehaw » Fri Feb 23, 2018 10:15 am

ta152h0 wrote:Those were the days
https://www.youtube.com/watch?v=y3KEhWTnWvE
Mary Hopkin ... is now 68 years old ! .... those were the days, my friend! https://en.wikipedia.org/wiki/Mary_Hopkin

Re: APOD: Apollo 17: A Stereo View from Lunar... (2018 Feb 23)

by ta152h0 » Fri Feb 23, 2018 8:31 am

Re: APOD: Apollo 17: A Stereo View from Lunar... (2018 Feb 23)

by Chris Peterson » Fri Feb 23, 2018 6:44 am

Cross-eyed stereo pair version.
22466-22467anaVantuyne_crossed.jpg

APOD: Apollo 17: A Stereo View from Lunar... (2018 Feb 23)

by APOD Robot » Fri Feb 23, 2018 5:08 am

Image Apollo 17: A Stereo View from Lunar Orbit

Explanation: Get out your red/blue glasses and check out this awesome stereo view of another world. The scene was recorded by Apollo 17 mission commander Eugene Cernan on December 11, 1972, one orbit before descending to land on the Moon. The stereo anaglyph was assembled from two photographs (AS17-147-22465, AS17-147-22466) captured from his vantage point on board the Lunar Module Challenger as he and Dr. Harrison Schmitt flew over Apollo 17's landing site in the Taurus-Littrow Valley. The broad, sunlit face of the mountain dubbed South Massif rises near the center of the frame, above the dark floor of Taurus-Littrow to its left. Beyond the mountains, toward the lunar limb, lies the Moon's Mare Serenitatis. Piloted by Ron Evans, the Command Module America is visible in orbit in the foreground against the South Massif's peak.

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