Er, no. When you get close enough to the moon it becomes downhill. Ignoring the sun because it is so far away, when you get within about 26000 miles from the moon, you are falling toward it as** Spectre of Pithecanthropus** said.
Ah. I see what you were saying and I misunderstood.
My point with respect to springear’s use of the description “spiral” was that in any frame of reference the path of Apollo missions was essentially a straight line. The spiral, or figure-eight representation was an artifact of the scale used to depict it.
Interestingly, a 1950s era SF film *Rocketship X-M involves a lunar mission, and at one point the planned trajectory is traced as a series of at leas 5 or 6 widening spirals around the earth, only after which escape velocity would be reached. As with Star Trek in the next decade, scientific accuracy was not held at a premium. Still a worthwhile movie if you can find it.
That’s not correct.
The first stage fired for about 2.5 minutes, boosting the spacecraft to an altitude of about 38.5 miles and 6120 mph. Then the second stage burned for about 6.5 minutes boosting the spacecraft to 115 miles. Then the third stage fired briefly to place the spacecraft in an orbit of 118 miles and about 17500 mph.
After checking all systems and confirming that there weren’t any problems, the third stage fired again for a bit over five minutes, boosting the spacecraft to about 24000 mph on a long elliptical orbit that would take it to the Moon. That’s the point where it’s at its top speed.
From then on the spacecraft coasts “uphill”, continuing to slow until it reaches a point where it’s close enough to the Moon for its gravity to be a stronger influence than the Earth’s (that’s at about 200,000 miles from the Earth). That’s the point it’s going the slowest, about 2000 mph iirc. It then begins to accelerate “downhill” to the Moon, until they fire the service module engine to slow it a bit and place it in lunar orbit. Their speed in lunar orbit was around 3600 mph.
The only burns after this were minor ones for course corrections, and the one to place the ship in orbit, as mentioned.
Also, what was being done was really a change in orbit around Earth - as was often done to put a spacecraft into a higher orbit. Thus escape velocity would never be necessary.
Lumpy do you have a cite for L1 rendezvous? I did a lot of research on Apollo for a book, and never came across that one. There was a proposal for the entire space craft to land, with construction and refueling in earth orbit. The advantage was being close in case of a problem - an L1 rendezvous wouldn’t offer that.
BTW, Stephen Baxter’s Voyage has many of the incidents of the Apollo program (including this one) translated into a Mars trip.
Uh, sorta like throwing a football, huh?
I thought Eve was kidding.
I am actually reading a book on the Apollo missions right now, and I can confirm that it went:
- Saturn rocket to high earth orbit
- Assuming all is well, burn to leave orbit and head towards moon
- Minor course corrections as needed
- Burn to achieve the desired moon orbit
Not sure about speed of orbit around moon, but IIRC it took 43 mins to go around the dark side (where radio contact was lost) so you can extrapolate a 1.5 hours (approx) orbit around the entire body.
Someone way smarter than me could probably take the height of an average moon orbit along with the size of the moon and calculate MPH based on that.
Also, I think Eve was kidding as well and found the comment highly humerous.
In MY day, we flew to the moon uphill BOTH WAYS, in the snow… or something
The Illuminati got a better deal on set and prop rental for a week rather than just a day; that, and it was just too much hassle to rent a trailer to carry all the stuff, fake the mission and get it all back by 5 PM.
There’s no 'arm in that.
Quite possible. I’m only 5’ 8" (and getting shorter) and maybe it went over my head.
No no, L1 was never considered for Apollo; it’s one scenerio for the return to the moon proposed by Bush. From what I’ve read on the Astronautix.com website, it would have the advantage that from there you can basically “fall” to any point on the moon’s surface you want, without launch window restrictions. I don’t know how it compares in terms of velocity change (=fuel mass) needed or human safety; ditto direct ascent.
And if you tell that to the young people today, they won’t believe you…
Thanks for the answers people. Now I can sleep soundly at night.
Thanks.
I wish I’d said that. :dubious:
IIRC the first few Apollo missions that got to lunar orbit used the safe return orbit, Apollo 13 used a different orbit without this ‘saftey factor’.
First thing, I am no physicist or mathematician, so the question that I have may be stupid so please don’t ridicule me for asking. But if the Earth is moving around the sun at 67,000mph (1,608,000 miles per day) and the moon is being pulled through space by the earth at a distance of 240,000 miles, shouldn’t we (NASA, humans, whatever) then be able to go to space and just stop and wait 3 1/2 hours for the moon to get to us? Or is it because of the Earth’s gravity that we can’t really just stop in space and wait?
Remember, anything that starts on the earth is also moving at that same speed. In order to “stop” in space, if I’m correctly understanding what you mean, you’d have to cancel out your existing velocity 67,000 mph velocity. That would be the same thing as boosting yourself up to 67,000 mph with respect to the earth.