Request for Apollo 10 document location

In article . com,
addams013 wrote:
As god of all NASA PDFs, do you happen to know of any that detail what
kind of simulations were run for Apollo 10? Specifically, were there
any contingencies for what to do if the ascent stage of the LM failed
to achieve lunar orbital velocity?

Actually, this one's easy: the Apollo 10 LM *was* in lunar orbit
throughout its operations, i.e. it never went below lunar orbital
velocity. Apollo 10 simulated the lunar landing only up to the point
where the main braking burn began. (There were suggestions that maybe it
should go farther, to simulate a later abort, but the added risks were
deemed not worthwhile.)
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Henry Spencer wrote:
Actually, this one's easy: the Apollo 10 LM *was* in lunar orbit
throughout its operations, i.e. it never went below lunar orbital
velocity. Apollo 10 simulated the lunar landing only up to the point
where the main braking burn began. (There were suggestions that maybe it
should go farther, to simulate a later abort, but the added risks were
deemed not worthwhile.)

Whoops. I seem to remember that the LM got pretty low, though; there
was a portion of the transcript I remember reading where Cernan and
Stafford were ooh-ing and aah-ing about swinging so darned close to the
surface -- less than nine miles, if memory serves.

I should have double-checked whether they actually slowed enough to
leave orbit or not.

I suppose the question should have been what kind of contingency
planning was in place to retrieve the ascent module if they had been
unable to fire their engine to shape their trajectory for return to the
command module (in other words, if the command module had to do the
work for rendezvous). In looking over "Chariots for Apollo", it
appears that some of this was actually done with the *descent* engine.

addams013 wrote:
looking over "Chariots for Apollo", it
appears that some of this was actually done with the *descent* engine.

I guess it was a trick of the wording. NASA's "Mission Report: Apollo
10", MR-4, makes it clear that this maneuver was to be done with the
ascent engine.

Thanks for your patience with me while I try to sort things out.

In article .com,
addams013 wrote:
...Apollo 10 simulated the lunar landing only up to the point
where the main braking burn began...

Whoops. I seem to remember that the LM got pretty low, though; there
was a portion of the transcript I remember reading where Cernan and
Stafford were ooh-ing and aah-ing about swinging so darned close to the
surface -- less than nine miles, if memory serves.

Perilune of the descent orbit was nominally 50,000 ft, if I recall
correctly. Which is pretty low for orbital velocities, even lunar
orbital velocities.

I suppose the question should have been what kind of contingency
planning was in place to retrieve the ascent module if they had been
unable to fire their engine to shape their trajectory for return to the
command module (in other words, if the command module had to do the
work for rendezvous).

Don't know details offhand, but there were "go down and get them" options
for the CSM. (On the later landing missions, the CSM in fact delivered
the LM to the descent orbit, to save LM fuel and increase landing/takeoff
payload.)
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

addams013 wrote:


I suppose the question should have been what kind of contingency
planning was in place to retrieve the ascent module if they had been
unable to fire their engine to shape their trajectory for return to the
command module (in other words, if the command module had to do the
work for rendezvous).

Yes, there were massive plans for this, for almost any contingency, and
lots of training for the CM pilot. Basically if the LM was in lunar
orbit, any orbit, where the CM had enough fuel to go get it and still
get home, there was a plan. Mike Collins described having (I think) 17
or 18 scenerios all worked out, written on cards, and hanging around
his neck, since he really, really, did not want to spend time looking
for them if they were needed. Most of the planning was done for the
case where the moon landing was complete, but there were problems in
the ascent, but these would also have applied for Apollo 10.

If I recall correctly, due to the lack of computer power, many of these
called for the CM to do just the opposite of what the LM would have
done in the nomimal sequence, but using many of the same tables and
charts.

Lou Scheffer

Henry Spencer wrote:
Don't know details offhand, but there were "go down and get them" options
for the CSM. (On the later landing missions, the CSM in fact delivered
the LM to the descent orbit, to save LM fuel and increase landing/takeoff
payload.)

Well, then, here's one for the trivia buffs: which Apollo mission
brought the CSM to the lowest lunar orbital altitude, and for how long?

addams013 wrote:
Well, then, here's one for the trivia buffs: which Apollo mission
brought the CSM to the lowest lunar orbital altitude, and for how long?

(Side note: I realize that the periapsis of an elliptical orbit only
exists at a single point. What I mean to ask is this: How long did it
spend in the orbit that brought it to the low point before actively
altering that orbit? Alterations from mascons don't count.)

(Henry Spencer) writes:


Don't know details offhand, but there were "go down and get them" options
for the CSM. (On the later landing missions, the CSM in fact delivered
the LM to the descent orbit, to save LM fuel and increase landing/takeoff
payload.)

So the decent stage could somehow use ascent stage consumables?
I'm confused.


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David Lesher ) writes:
(Henry Spencer) writes:

Don't know details offhand, but there were "go down and get them" options
for the CSM. (On the later landing missions, the CSM in fact delivered
the LM to the descent orbit, to save LM fuel and increase landing/takeoff
payload.)

So the decent stage could somehow use ascent stage consumables?

No. By having the CSM place the LM into the 60 by 10 nautical mile
orbit, the LM saved descent fuel, so that the LM didn't need to carry
the fuel for both that burn, and all of the 50,000 feet to landing
burn.

That way, the LM could pack less fuel, and could thus use that mass
saved, in more payload to the lunar surface.

I'm confused.

Its OK.

Andre

Dave Michelson wrote:
Andre Lieven wrote:

That way, the LM could pack less fuel, and could thus use that mass
saved, in more payload to the lunar surface.

Sorry, your second point is not quite correct. See

http://history.nasa.gov/SP-4029/Apol...ant_Status.htm

In general, the later LMs carried much more fuel and oxidizer in the
descent stage than their earlier counterparts.

Well, yes, but if you look at the initial LM mass for those missions:
http://history.nasa.gov/SP-4029/Apol...on_Weights.htm

You'll see that the LMs that carried substantially more fuel/oxidizer
were also heavier by a decent margin -- over a thousand pounds more
than could merely be accounted for by the increase in fuel/oxidizer
alone. It seems that the issue here is closer to asking how much more
fuel and oxidizer *would* have been required to land these heavier LMs
if their CSMs hadn't lowered them to descent orbit.

Unless, of course, *I'm* confused.