its not possible

[kevb]

Hi what do you think of my theory regarding the LEM taking of from the moon.
The LEM takes off and just goes up to the mother ship and docks? I don’t think so
just think about it!
Because the moon dose not revolve like the earth the mother ship has to orbit at many thousand miles per hour.it CANNOT go into a geostationary orbit this means that the LEM has to take off get up to altitude and at the same time chase and catch up with the mother ship that is traveling at a vast speed
I can’t see how a 16 foot LEM with men equipment rocks engine/thrusters and fuel could carry enough fuel to achieve this.
Are there any number crunchers out there that can calculate my theory?
My other question is have I started another hoax theory
Regards Kevin beer

[scooter]

There are a few factors involved in getting a craft into orbit, be it around Earth, the Moon, or any other body.
The propulsion system (fuel and engine) needs to be able to get the craft off the surface, then accellerate it to orbital velocity. On Earth, this also means getting out of the atmosphere, and accellerating to around 17,500mph. The Moon, being a smaller, less massive body without an atmosphere, makes it easier. They did not have to boost to 100 miles, and orbital velocity is significantly less for the Moon. (someone help me with the figure here...)
The LM was built light, strictly for the vaccuum of space and the 1/6 g on the surface. The ascent module was powered by a sufficient powerplant with sufficient fuel aboard to get the craft into orbit and rendezvous with the Command Module. They took off and could immediately start pitching to start gaining groundspeed, unlike Earth launches that require getting out of the lower atmosphere before gaining significant speed.
It was all technically and physically possible, lots of orbital mechanics, math and physics.
There are many things we may not understand, but it doesn't mean they can't be done...welcome aboard!
Dave

[Halcyon Dayz, FCD]

On this board, those that that make the claims are required
to provide the numbers.
You as much state that you don't know if it is possible,
yet you start by saying it isn't.

I advise you to do some research on the site attached to
this board before making such bold statements.

And to learn some basic astronomy.
"the moon dose not revolve"
Sheesh!

[scooter]

Orbital mechanics...
A lower orbit is faster than a higher orbit (in groundspeed)...the ascent module took off and got into a stable orbit that was lower than the CM...then it coasted, closing on the CM. The only significant engine work was establishing that initial orbit, which took about 4 minutes of power. After that it was use of the reaction control system thrusters to tweak the approach for docking.
The CM, meanwhile, just orbited quietly and waited for them to come in...
edit...the Moon does revolve, once every 28 days...makes for very long days and very long nights on the surface, but that's another topic.

[snakeriverrufus]

halcyondayz said:

And to learn some basic astronomy.
"the moon dose not revolve"
Sheesh!

Good catch. I was too busy laughing to notice that. ;D

[kevb]

the moon revolves around the earth every 28 days but dont revole itself
assuming your other info is right what would
Be the g force on the astronauts getting to a speed of 2916 MPH
In four minuets

[BertL]

kevb said:

assuming your other info is right what would
Be the g force on the astronauts getting to a speed of 2916 MPH
In four minuets

Why not calculate it yourself?

[gwiz]

kevb said:

assuming your other info is right what would
Be the g force on the astronauts getting to a speed of 2916 MPH
In four minuets

About half a g. If you can't work this out for yourself, how can you possibly comment on the technical feasibility of the LM Ascent Stage?

[scooter]

The Moon does revolve around it's axis, once per orbit around Earth...that's why we only ever see one side of it from here...

[echnaton]

I highly recommend great laymens level book about space rendezvous titled How NASA Learned To Fly In Space. It is published by Apogee Books. It is the story of the Gemini Program, where the primary goal was to learn all the factors necessary to make a successful docking of a orbiting vehicle and one launched from the ground.

It turns out that on the first Gemini capsule attempted to do station keeping with its booster was a failure. The pilot was untrained and flying by the seat of his pants because no one anywhere new how to station keep in space. Space flying is not the same as aerodynamic flying. Through the successive missions NASA succeeded in learning every aspect needed for rendezvous.

The Gemini missions are much like the Apollo program in that the missions started with relatively easy goals and sometimes had trouble reaching them. The lessons learned from these difficulties were incorporated back into future mission and by the end of the program most of the bugs had been worked out. The last mission went off nearly flawlessly. These lessons were also incorporated into the Apollo program as it was developed.

NASA had learned to make rendezvous before sending an LM to the moon. If you think the LM was not up to the task, then why don’t you provide your analysis that would give some credibility to your assertion? Say by starting with the mass of the LM at liftoff, the energy needed to take it to orbit, the potential energy in the propellants and the efficiency of the engine. Or at least site a credible source. Got any?

[phunk]

scooter said:

The only significant engine work was establishing that initial orbit, which took about 4 minutes of power.

Completely off the top of my head, but I believe it was about 7 minutes.

[tofu]

kevb said:

the moon revolves around the earth every 28 days but dont revole itself

lol. what grade are you in?

assuming your other info is right what would
Be the g force on the astronauts getting to a speed of 2916 MPH
In four minuets

1 mile = 1.609 kilometer therefore
2916 miles/hour = (2916 * 1.609) = 4692 kilometers/hour
*1000 to convert kilometers to meters. divide by 3600 to convert hours to seconds = 1303 meters per second.

So the question is, how many g's of acceleration to go from 0 to 1303 m/s in 4 minutes (4 minutes = 240 seconds)

The formula is, Acceleration = change in velocity / change in time
so 1303/240 = 5.430 m/ss

How many G's is that? Well 1 G = 9.8 m/ss
5.430/9.8 = 0.55

So there's your answer. 0.55 G's

Half a G. Less than what you feel in an elevator.

[gwiz]

In an attempt to end this discussion, I've done a few back of the envelope calculations.

The Ascent Stage has a rather modest mass ratio of about 2, which given the known performance of its engine (Isp = 311 s) gives it a velocity capability of about 2.2 km/s.

The orbital velocity for a low orbit around the moon is about 1.6 km/s.

The Ascent Stage performance thus appears more than adequate.

[twinstead]

Hey, give the OP a break. I learned some stuff on this thread already.

At least he didn't claim the flag was waiving in the wind or the stars are suspiciously absent from photos taken on the moon or something dull like that. ;D

[kevb]

Yes I agree it was a bit of fun
Oslo it was a good way to get somebody else to do the math’s
I never clamed to be a genius

So Theirs No need to bite