Author Topic: Fate of LM 10 in solar orbit  (Read 11862 times)

Offline ka9q

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Re: Fate of LM 10 in solar orbit
« Reply #15 on: January 13, 2013, 07:00:30 AM »
As a young person avidly following the Apollo program, I was absolutely convinced that the A10 crew would do exactly that (if all went well up to that point).
I had similar thoughts when I read about Apollo 10, and like most kids (I was 12 during Apollo 11) I was rather impatient. Why fly all the way to the moon but not land?

At the time I didn't understand that the LM was the pacing item for the entire program, and how much of a struggle it was to shave off the grams if it was to make it back into orbit. I also didn't understand the necessity of methodical testing without trying to bite off too much at once, at least when human lives are at stake.

I realized later that they really were going as fast as they possibly could, maybe even faster, and that when lives weren't at stake they didn't hesitate to bite off a lot at once. It was called "all-up testing" and it was applied to the first (unmanned) test flight of the Saturn V, AS-501 (Apollo 4).

Just consider the mission pace in 1969. Apollo 9 was launched in early March, Apollo 10 in mid-May, and Apollo 11 in mid-July. Apollo 12 followed in mid-November. Four Saturn V launches in one year!


Offline Count Zero

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Re: Fate of LM 10 in solar orbit
« Reply #16 on: January 13, 2013, 07:51:40 AM »
Just consider the mission pace in 1969. Apollo 9 was launched in early March, Apollo 10 in mid-May, and Apollo 11 in mid-July. Apollo 12 followed in mid-November. Four Saturn V launches in one year!

Indeed, the launch schedule that was set prior to the first landing called for five missions in 1969.  Apollo 12 was set for September with Apollo 13 in November.  The basic plan was to launch every two months (barring accidents) until the landing was achieved.  Once the goal was met, the schedule relaxed.  The tentative schedule set on July 29, 1969 called for moon-shots every 4-5 months, concluding with Apollo 20 in December 1972.

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Offline Zakalwe

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Re: Fate of LM 10 in solar orbit
« Reply #17 on: January 13, 2013, 04:06:20 PM »
After jettison in orbit, the ascent engine was fired to depletion as a test.

The ascent stage was not fully fueled since LM-4 was overweight and it would not be taking off from the surface anyway. So it may seem somewhat surprising that it still had enough propellant to escape the moon entirely starting from lunar orbit.

Escape velocity from a surface is equal to sqrt(2) = 1.414 times the velocity of a surface-skimming orbit over the same body, so it does take less delta V to escape from low orbit than to achieve that orbit from the surface.

Gene Cernan has often been asked if they were tempted to land Snoopy and become the first men on the moon. He says that while they could technically have done so, they would have died there because of insufficient ascent-stage fuel, and that tended to discourage the thought.

I'm sure that I read somewhere that the Luminary software that was loaded into the LM computer was not the full suite and did not have the final landing routines or full take-off routines. I can't find a reference for this...can anyone verify it?
"The strain of anti-intellectualism has been a constant thread winding its way through our political and cultural life, nurtured by the false notion that democracy means that 'my ignorance is just as good as your knowledge.' " - Isaac Asimov

Offline ka9q

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Re: Fate of LM 10 in solar orbit
« Reply #18 on: January 13, 2013, 07:41:56 PM »
I don't know offhand, but there is a small but dedicated community of Apollo Guidance Computer enthusiasts who have written software emulators and even built hardware recreations that actually run the original flight software. They have been collecting and publishing as many versions of that software as they can find, and I'm sure you can find out from them what version flew on what mission and what its capabilities were.