6
$\begingroup$

We all know that the LEM descended from the CSM to the moon's surface and then rose back again to dock with it. But there are some videos that show the CSM floating in the foreground with the moon's surface in the background. This was obviously shot from the LEM, which must have been at a higher altitude than the CSM. Hence my question - Did the LEM ever rise above the orbit of the CSM at any time?

enter image description here (picture source)

| improve this question | | | | |
$\endgroup$
  • $\begingroup$ It would be great if you showed us that video or image. $\endgroup$ – Star Man Aug 7 '19 at 18:46
  • $\begingroup$ At close range, a few meters in altitude difference would be enough to show up in photos. But I suspect altitude data wasn't kept to that precision. $\endgroup$ – Hobbes Aug 7 '19 at 18:59
  • $\begingroup$ Do an elliptical orbit with apoapsis few centimeters above the CSM count? $\endgroup$ – Manu H Aug 7 '19 at 19:04
  • 2
    $\begingroup$ The fact that this picture exists answers your question. $\endgroup$ – Star Man Aug 7 '19 at 19:59
  • $\begingroup$ If it was decoupled while facing away from the moon, it could feasibly have been above the CSM for a time. $\endgroup$ – Magic Octopus Urn Aug 7 '19 at 20:18
1
$\begingroup$

Yes.

By separating with the LM moving away from the moon, and the CSM towards it, the LM would be at a higher altitude than the CSM. As a consequence orbital mechanics cause the LM to start to fall behind the CSM, so when the descent engine was fired to slow the LM it wouldn't bump into the CSM.

| improve this answer | | | | |
$\endgroup$
  • 5
    $\begingroup$ This sounds reasonable, but do you have a reference for it? $\endgroup$ – Russell Borogove Aug 7 '19 at 20:57
  • $\begingroup$ I'm fairly sure it is documented, however the memory comes from a time of my life I have no desire to revisit. $\endgroup$ – JCRM Aug 8 '19 at 6:26

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.