aborting a lunar lander

Several times I've heard that aborting a lunar landing would have been
the most complicated maneuver ever done in space. Did they practice a
lunar abort on Apollo 9 or 10? Go through all of the motions and drop
the decent stage, etc?

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"Jud McCranie" wrote in message
...
| Did they practice a lunar abort on Apollo 9 or 10?

Yes, on Apollo 10.

--
|
The universe is not required to conform | Jay Windley
to the expectations of the ignorant. | webmaster @ clavius.org

In article ,
Jud McCranie wrote:
Several times I've heard that aborting a lunar landing would have been
the most complicated maneuver ever done in space. Did they practice a
lunar abort on Apollo 9 or 10? Go through all of the motions and drop
the decent stage, etc?

Kind of, especially on Apollo 10. It lacked some of the complications,
not to mention the time pressure, that would have been found in an abort
at low altitude, mind you.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |

In message , Jay Windley
writes

"Jud McCranie" wrote in message
.. .
| Did they practice a lunar abort on Apollo 9 or 10?

Yes, on Apollo 10.


This topic seems to be appearing frequently in various guises, and I
can't help feeling that the Apollo 10 experience showed that an abort
would probably have killed them.
They got into a spin and nearly crashed. If that had occurred in the
last few seconds of landing they would have crashed. As Henry Spencer
noted in another thread, there comes a point where they would have
simply ignored the "fuel exhausted" light (or whatever) and gone on to
land, as the safest option.

"Jonathan Silverlight" wrote
in message ...
|
| They got into a spin and nearly crashed.

But that was because a guidance system switch had been set improperly, not
because the separation induced the spin.

There is always a danger aborting at low altitudes, and I'm sure the
astronauts, as seasoned test pilots, were well aware of what their options
were.

--
|
The universe is not required to conform | Jay Windley
to the expectations of the ignorant. | webmaster @ clavius.org

"Bad Weather" wrote in message
...
| I'd like to see what would have happened if the lunar rockets
| would have failed during landing when the lander was about a mile
| up in the air

What air? :-)

Seriously, that's a more survivable abort scenario. If the descent engine
had failed for any reason, the landing would be aborted. The descent stage
is discarded and the ascent engine is fired to return them to orbit. And a
mile up you have lots of time in which to do that, and to correct any
problems that the abort manuever creates. The real danger is if the descent
engine fails with only fifty feet or so left to go.

Give any pilot a choice of getting into trouble while low and slow, or while
high and fast, and he'll take the latter.

--
|
The universe is not required to conform | Jay Windley
to the expectations of the ignorant. | webmaster @ clavius.org

On Mon, 23 Aug 2004 11:43:38 -0600, "Jay Windley"
wrote:

Seriously, that's a more survivable abort scenario. If the descent engine
had failed for any reason, the landing would be aborted. The descent stage
is discarded and the ascent engine is fired to return them to orbit.

Were there situations in which they would gain some altitude with the
decent engine before dropping the descent stage?

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there comes a point where they would have
simply ignored the "fuel exhausted" light (or whatever) and gone on to
land, as the safest option.


I wonder how far it could just drop unpowered and survive?
HAVE A GREAT DAY!

In article ,
Jud McCranie wrote:
Seriously, that's a more survivable abort scenario. If the descent engine
had failed for any reason, the landing would be aborted. The descent stage
is discarded and the ascent engine is fired to return them to orbit.

Were there situations in which they would gain some altitude with the
decent engine before dropping the descent stage?

Yes; that was the procedure for a low-altitude abort, due to (e.g.) not
being able to find a suitable landing spot in time. That was the deadline
Armstrong was facing: when there's just enough fuel left to gain enough
altitude to stage safely, in theory you have to abort. (In practice, as
I've noted, if the landing was almost done there would have been great
temptation to use the abort fuel to finish the landing instead.)

If the descent-stage engine just quits, say, fifty meters up, you die.
There simply isn't enough time to get the stages separated and the ascent
stage lit, *and* cancel the downward velocity acquired while doing so,
before impact.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |

I'd like to see what would have happened if the lunar rockets would have
failed during landing when the lander was about a mile up in the air


"Jud McCranie" wrote in message
...
Several times I've heard that aborting a lunar landing would have been
the most complicated maneuver ever done in space. Did they practice a
lunar abort on Apollo 9 or 10? Go through all of the motions and drop
the decent stage, etc?

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