Starship Asterisk*

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.>>

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?

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.

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.

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?

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.

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.

ta152h0 wrote:Those were the days
https://www.youtube.com/watch?v=y3KEhWTnWvE