APOD: Apollo 17: A Stereo View from Lunar... (2015 Jan 03)

Comments and questions about the APOD on the main view screen.
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APOD: Apollo 17: A Stereo View from Lunar... (2015 Jan 03)

Post by APOD Robot » Sat Jan 03, 2015 5:05 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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Re: APOD: Apollo 17: A Stereo View from Lunar... (2015 Jan 0

Post by BillBixby » Sat Jan 03, 2015 5:58 am

Shot with a FILM camera. Was digital a giant step for mankind?

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Re: APOD: Apollo 17: A Stereo View from Lunar... (2015 Jan 0

Post by Nitpicker » Sat Jan 03, 2015 10:03 am

The position of the CSM appears to be from the next image in the original sequence (67): http://www.hq.nasa.gov/office/pao/Histo ... 2467HR.jpg

(And I'd like to better understand why the LM appears to be above the CSM at this point in the landing procedure.)

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Re: APOD: Apollo 17: A Stereo View from Lunar... (2015 Jan 0

Post by terry » Sat Jan 03, 2015 10:43 am

That was my question as well. How does the LM appear in higher orbit than the CM/SM? Are Nitpicker and I just missing something here?

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Re: APOD: Apollo 17: A Stereo View from Lunar... (2015 Jan 0

Post by Boomer12k » Sat Jan 03, 2015 11:30 am

Cool....

Maybe they needed the "VIEW" to prepare for docking...

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Re: APOD: Apollo 17: A Stereo View from Lunar... (2015 Jan 0

Post by geckzilla » Sat Jan 03, 2015 12:58 pm

It seems that the only explanation for the CSM to appear below the LM is for it to actually be a hundred or so meters below. I guess that whatever small force necessary for separation pushed the two away from one another in such a way that the CSM was pushed down and the LM up.
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Re: APOD: Apollo 17: A Stereo View from Lunar... (2015 Jan 0

Post by rstevenson » Sat Jan 03, 2015 2:21 pm

It's possible to get a landing orbit by changing your original slightly elliptical orbit into a more elongated ellipse, which takes you higher as well as lower. You land at the low end of the ellipse, more or less. And you get to take pictures of the craft you separated from while you're higher. (I don't know that they did this exactly, but it is possible.)

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Re: APOD: Apollo 17: A Stereo View from Lunar... (2015 Jan 0

Post by Chris Peterson » Sat Jan 03, 2015 3:59 pm

rstevenson wrote:It's possible to get a landing orbit by changing your original slightly elliptical orbit into a more elongated ellipse, which takes you higher as well as lower. You land at the low end of the ellipse, more or less. And you get to take pictures of the craft you separated from while you're higher. (I don't know that they did this exactly, but it is possible.)
This might be of interest.
M-933-72-17-T6.jpg
If I'm reading this correctly, the initial descent orbit insertion (DOI-1) was performed by the CSM while it was still docked with the LM. This placed the pair in a highly eccentric orbit (59 / 14.5 nmi). Then we have separation, followed by a short CSM burn that placed it in a slightly different orbit (61.5 / 11.5 nmi). In this orbit, it was lower than the LM at times. Then, the CSM performed another burn to circularize its orbit (required for redocking). Here, too, the CSM perilune (54 nmi) is below the LM apolune (59 nmi). Finally, the LM performs DOI-2, increasing its apolune and decreasing its perilune (59.6 / 6.2 nmi). Still, we have orbit segments where it is higher than the CSM.

These various orbits were maintained for more than two hours after undocking, so there were ample opportunities to photograph the CSM between the Moon and the LM. I think these images were taken shortly before the PDI burn that braked the LM out of lunar orbit and began the final descent.
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Re: APOD: Apollo 17: A Stereo View from Lunar... (2015 Jan 0

Post by rstevenson » Sat Jan 03, 2015 4:08 pm

Yeah. That's what I meant. :)

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Re: APOD: Apollo 17: A Stereo View from Lunar... (2015 Jan 0

Post by geckzilla » Sat Jan 03, 2015 4:31 pm

Oh, right, so they are orbiting together and bobbing up and down in their eccentric orbits and this doesn't have to be right after separation. Almost seems like the possibility of collision exists. For the CSM to be that large in the photo there is no way it is very distant. Only a few hundred meters. I guess < 500m
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Re: APOD: Apollo 17: A Stereo View from Lunar... (2015 Jan 0

Post by Chris Peterson » Sat Jan 03, 2015 5:09 pm

geckzilla wrote:Oh, right, so they are orbiting together and bobbing up and down in their eccentric orbits and this doesn't have to be right after separation. Almost seems like the possibility of collision exists. For the CSM to be that large in the photo there is no way it is very distant. Only a few hundred meters. I guess < 500m
Hard to say. It might be farther than you think. In principle, we might figure out from the features and horizon curvature what the image scale is. The CSM is 11 meters long; it could easily be several kilometers away given a normal range telephoto.

I imagine that the burns that produced separate orbits also resulted in slightly different inclinations as well as different apo- and perilunes. All in all, the possibility of a collision seems extremely small, even assuming that the orbits weren't deliberately designed to avoid one (which I don't know was done, but given how carefully the mission was designed, I'd be surprised if that possibility wasn't factored in).
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Re: APOD: Apollo 17: A Stereo View from Lunar... (2015 Jan 0

Post by puke » Sat Jan 03, 2015 6:58 pm

So this is the best you can come up with?
A 42 year old B/R 3D picture of the moon?
I mean with all the new items being seen everyday , this is all you can come up with?
It isn't even the anniversary of when it was taken.

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Re: APOD: Apollo 17: A Stereo View from Lunar... (2015 Jan 0

Post by Beyond » Sat Jan 03, 2015 7:58 pm

puke wrote:So this is the best you can come up with?
A 42 year old B/R 3D picture of the moon?
I mean with all the new items being seen everyday , this is all you can come up with?
It isn't even the anniversary of when it was taken.
Hello, aptly named person. The moon landing was a current event for me when it happened. It's nice once in a while to catch some of the goings on that weren't broadcast. IF you don't care much for such events, just ask for your money back, or wait for an APOD you do like. In the meantime, it would be nice if you helped maintain the quiet, cordial atmosphere of the Good ship Asterisk*
Thank you.

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Re: APOD: Apollo 17: A Stereo View from Lunar... (2015 Jan 0

Post by Chris Peterson » Sat Jan 03, 2015 8:01 pm

puke wrote:So this is the best you can come up with?
A 42 year old B/R 3D picture of the moon?
I mean with all the new items being seen everyday , this is all you can come up with?
Yeah, I know what you mean. I was recently at The Louvre, and all they had was a bunch of old stuff. Seriously, you have to wonder, with all the new stuff that's out there, why they're wasting space with the Mona Lisa and so much other irrelevant garbage.
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Re: APOD: Apollo 17: A Stereo View from Lunar... (2015 Jan 0

Post by geckzilla » Sat Jan 03, 2015 8:07 pm

Chris Peterson wrote:
geckzilla wrote:Oh, right, so they are orbiting together and bobbing up and down in their eccentric orbits and this doesn't have to be right after separation. Almost seems like the possibility of collision exists. For the CSM to be that large in the photo there is no way it is very distant. Only a few hundred meters. I guess < 500m
Hard to say. It might be farther than you think. In principle, we might figure out from the features and horizon curvature what the image scale is. The CSM is 11 meters long; it could easily be several kilometers away given a normal range telephoto.
It is apparently easy to find out the properties of the camera which took the images.
http://www.lpi.usra.edu/resources/apoll ... -147-22467
60mm focal length?
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Re: APOD: Apollo 17: A Stereo View from Lunar... (2015 Jan 0

Post by Chris Peterson » Sat Jan 03, 2015 8:46 pm

geckzilla wrote:
Chris Peterson wrote:
geckzilla wrote:Oh, right, so they are orbiting together and bobbing up and down in their eccentric orbits and this doesn't have to be right after separation. Almost seems like the possibility of collision exists. For the CSM to be that large in the photo there is no way it is very distant. Only a few hundred meters. I guess < 500m
Hard to say. It might be farther than you think. In principle, we might figure out from the features and horizon curvature what the image scale is. The CSM is 11 meters long; it could easily be several kilometers away given a normal range telephoto.
It is apparently easy to find out the properties of the camera which took the images.
http://www.lpi.usra.edu/resources/apoll ... -147-22467
60mm focal length?
The fiducials are 10 mm apart. So the plate scale on the original scan is 1.26 arcmin/pixel. Assuming the CSM is tipped away at about 60° (the circular end appears about twice as wide as high), that suggests a distance of 515 meters. Doing the same calculation using the diameter of the CSM (rotation angle independent, but only a few pixels) gives a distance of 710 meters.

I think it's reasonable to say the separation was between 500 and 1000 meters in these images.
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Re: APOD: Apollo 17: A Stereo View from Lunar... (2015 Jan 0

Post by Nitpicker » Sat Jan 03, 2015 9:55 pm

Very satisfying answers. Thanks all.

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Re: APOD: Apollo 17: A Stereo View from Lunar... (2015 Jan 0

Post by DavidLeodis » Sun Jan 04, 2015 1:04 pm

Patrick Vantuyne is a link that brought up some information (dated July 2008) about Patrick and had a link to his website. When I click on that that link I however get a message "Forbidden. You don't have permission to access / on this server. Additionally, a 404 Not Found error was encountered while trying to use an Error Document to handle the request.". I wonder if this is a problem with my connection or are others getting the same problem, or is it that the link may be old and is now dead but if so why does the "Forbidden. You don't have permission to access / on this server" come up as that would seem to imply the link is still live. :?

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Re: APOD: Apollo 17: A Stereo View from Lunar... (2015 Jan 0

Post by Chris Peterson » Sun Jan 04, 2015 2:50 pm

DavidLeodis wrote:Patrick Vantuyne is a link that brought up some information (dated July 2008) about Patrick and had a link to his website. When I click on that that link I however get a message "Forbidden. You don't have permission to access / on this server. Additionally, a 404 Not Found error was encountered while trying to use an Error Document to handle the request.". I wonder if this is a problem with my connection or are others getting the same problem, or is it that the link may be old and is now dead but if so why does the "Forbidden. You don't have permission to access / on this server" come up as that would seem to imply the link is still live. :?
The domain is still active. But the site is not... it looks like a badly configured Apache server.
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Re: APOD: Apollo 17: A Stereo View from Lunar... (2015 Jan 0

Post by DavidLeodis » Sun Jan 04, 2015 3:15 pm

Thanks Chris :).

Hoping not to sound like I seek out possible errors in APOD explanations (which I do not not) I've now noticed that whereas the explanation states "The stereo anaglyph was assembled from two photographs (AS17-147-22465, AS17-147-22466)" in the information with the anaglyph brought up through the "The scene was recorded" link it states the images used "are AS17-147-22466 and 67". I'm :? but not for the first time :wink:.

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Re: APOD: Apollo 17: A Stereo View from Lunar... (2015 Jan 0

Post by Chris Peterson » Sun Jan 04, 2015 4:11 pm

DavidLeodis wrote:Thanks Chris :).

Hoping not to sound like I seek out possible errors in APOD explanations (which I do not not) I've now noticed that whereas the explanation states "The stereo anaglyph was assembled from two photographs (AS17-147-22465, AS17-147-22466)" in the information with the anaglyph brought up through the "The scene was recorded" link it states the images used "are AS17-147-22466 and 67". I'm :? but not for the first time :wink:.
Interesting. There is some major image fudging going on here. The two images used are 22467 for the cyan channel, and 22466 for the red channel. But 22466 has been altered from the original: the position of the CSM has been changed. It has been erased and cloned into a new position. I'm sure that's because it has moved too far between the two frames for the eyes to accomplish a 3D merge. But it also means that it's anybody's guess just how the actual 3D visual appearance of this scene actually was.

Left is the original, right is the modified.
466both.jpg
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Re: APOD: Apollo 17: A Stereo View from Lunar... (2015 Jan 0

Post by Nitpicker » Sun Jan 04, 2015 11:05 pm

The CSM from 22467 has also been shifted more into the shadow of the South Massif, which at least reveals slightly more detail on the South Massif. And of course, the images have been rotated ~90 degrees clockwise, which I assume spares us from viewing the anaglyph with our heads tilted to the left.

(And certainly, based on the appearance of the central fiducial cross-hairs in the anaglyph, it is composed from original images 22466 and 22467.)

Edit: actually, I'm probably wrong about the shifting of the CSM from 22467. It looks instead like the CSM from 22466 has simply been shifted to a position later than the position shown in 22467. (I haven't pulled out my red-blue glasses yet, nor have I separated the channels as Chris has done. Although I recall viewing this anaglyph in 3-D a few months ago: http://asterisk.apod.com/viewtopic.php? ... 51#p222151.)

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Re: APOD: Apollo 17: A Stereo View from Lunar... (2015 Jan 0

Post by Nitpicker » Mon Jan 05, 2015 3:40 am

Thinking a bit more about this, it seems plausible to me that the shifted position of the CSM from 22466 is intended to represent the position of the CSM from 22467, as it might have appeared from the LM if only the LM was moving relative to the Moon.

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Re: APOD: Apollo 17: A Stereo View from Lunar... (2015 Jan 0

Post by Chris Peterson » Mon Jan 05, 2015 4:09 am

Nitpicker wrote:Thinking a bit more about this, it seems plausible to me that the shifted position of the CSM from 22466 is intended to represent the position of the CSM from 22467, as it might have appeared from the LM if only the LM was moving relative to the Moon.
With the available information, that would be extremely difficult to work out analytically. I think it was just shifted a bit to yield a good visual result.
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Re: APOD: Apollo 17: A Stereo View from Lunar... (2015 Jan 0

Post by Nitpicker » Mon Jan 05, 2015 4:43 am

Chris Peterson wrote:
Nitpicker wrote:Thinking a bit more about this, it seems plausible to me that the shifted position of the CSM from 22466 is intended to represent the position of the CSM from 22467, as it might have appeared from the LM if only the LM was moving relative to the Moon.
With the available information, that would be extremely difficult to work out analytically. I think it was just shifted a bit to yield a good visual result.
In the engineering world -- especially engineering drawing -- that's often the same thing. :ssmile: