Maybe it goes here!
The actual Lunar Excursion Module (LEM) required around 11.5 minutes to
descend from the Lunar Module (mothership), to the surface of the moon.
From an orbit of 60 nauticle miles, they throttled the rockets to move closer in.
Next is the braking phase. It is gradual, and saves on fuel.
They then approached the surface like an airport. That is called a
Then, they correct for landing, pilot visibilty, and manual control, if needed.
That is the "lowgate" phase.
The rockets had around 10,000 pounds of thrust, but I do not know what the various missions carried, with Lunar Rovers, but that figure might cover it.
The control was computerized, but could be flown manually.
The actual LEMs had what is called "hypergolic" propellant. DiNitrogen Tetroxide and AeroZine 50 (50% Hydrazine, 50% Unsymmetrical Dimethyl Hydrazine) were kept in helium pressurized tanks.
If you combine them, stand back! They feed into a chamber, and generate
a thrust exhaust. No ignition mechanism to fail.
LEMs had to ascend, go into orbital insertion, and dock with the main ship,
back up at 60 n. miles.
Gyroscopes and hydraulic servos kept the LEM's gimbaled rockets
correcting despite attitude. If the vehicle pitched, the engines kept
The test vehicles had H2O2 thrust rockets.
Something like 5 test vehicles, 3 crashes. Back up rockets for emergency included.
Research vehicle could go into VTOL mode (verticle), attain 200 ft.
while moving forward 400 ft. in eight seconds.
Training the astronauts in these vehicles reminds me of the saying
"flying by the seat of your pants".
Edited by shun, 17 March 2004 - 11:21 PM.