Apollo on its way back to Earth?

Question

As you can see in the video (sources) the takeoff speed/velocity of Apollo is look like very small and after certain height it should fall again on the moon’s surface by its gravitational pull which is six times weaker than earth. Also was rocket fired for escape velocity from moon’s gravitational pull. How many total number of rockets were used for changing direction and speed in this mission, when and where? Any idea or source.

http://www.hq.nasa.gov/alsj/a15/a15v_171...
http://www.youtube.com/watch?v=cOdzhQS_M...

Answer 1

The ascent from the lunar surface used the single engine in the ascent stage to accelerate to about 3,500mph, which is fast enough to go into lunar orbit. The ascent stage then met up with the orbiting command/service module, docked, the crew tranferred, the lunar module was discarded, and then the service module engine was used to accelerate the command/service module to lunar escape velocity. After that the spacecraft crossed into Earth's gravitational influence and began falling to Earth. By the time it got there (having made a few minor course corrections if required on the way) it was going at about 25,000mph, a which speed it hit the atmosphere and used the tremendous friction to slow down before deploying parachutes for a nice sodt splashdown.

I might also point out that the take-off speed of any rocket looks small, but that's because acceleration takes time.

Answer 2

The LM's upper stage was only strong enough for it to achive orbit. Once in orbit, it docked with the Command/Service module, and then the large SPS engine on the Service module was fired to bring the ship home.

The Saturn V's first stage had 5 large engines. It's second stage also had 5, but they were smaller. The third stage had a single engine; it completed getting the ship into orbit, then was fired again for the trip to the moon.

The command/service module had 1 big engine, which was fired to slow the spacecraft into a lunar orbit, and again to send the ship home. Attached to the side of the service module was the attitude control system - 4 sets of 4 thrusters each, for a total of 16.

The command module didn't have a main engine, just thrusters to control it's attitude as it re-entered the Earth's atmosphere. (I think it had 18 total, but I could be dead wrong.) There were (I believe) 8 around the top of the cone, and 10 around the bottom.

The Lunar module had 2 stages. The descent stage with the legs had one main engine. The ascent stage also had 1 main engine, and it, too, had an attitude control system, 4 sets of 4 thrusters, similar to the service module.

On the 3rd stage, there were 3 'separator jets', which fired to move the craft away from the 2nd stage after it burned out; when it was clear enough (I think it was 60 feet or so), the 3rd stages' main engine fired.

There were probably a few more, but those were the major thrust systems.

Answer 3

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