Mudshark

Are you sure about that Cing?

You never are COMPLETELY out of the gravity well. what the well does is provide tangental velocity through angular acceleration and the craft needs to produce only the radial acceleration to counter the pull of gravity. Like spinning a yo-yo at the end of the string and letting go. Or am I completely off base here?

CingularDuality

Well, how can you benefit if you don't gain any velocity by entering the gravity well? If you start close to the center of the well, how can you possibly gain more velocity than you would have had if there were no gravity well at all?

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Mudshark

Actually, I did a bit of research about the slingshot matter and it appears that neither of us are entirely correct. What would actually be done in the case of a manned flight would be to put the craft into earth orbit, but instead of using some method to escape the orbit they would burn to expand the orbit eliptically so that the perrigee was near earth and the apogee was near mars (or wherever) the craft would then need to burn again to slow into Mars orbit. The "slingshot" term technically refers to the act of stealing some of the orbital velocity of an intermediary body to gain speed. The gravity well doesn't bestow any velocity itself but it acts as a force to allow a ship to drain off a bit of the planets orbital velocity. Funny, I've always heard of the lunar astronauts "slingshotting" to the moon but i guess that was a misnomer.

So i guess you could do the orbital transfer from lunar orbit but you would have to burn once to go to the moon, once again to orbit the moon, yet again to go to Mars, another time to orbit mars and again to slow to orbit earth.

Seems like two extra steps to me but I'm sure there are other logistical and physical factors I am not prepared to comprehend.

verbose

Yep, cool stuff. And because of the mass difference, the net change on the planetary body is basically immeasurable, while the delta on the craft can be huge.

Daxx

How about looking at it from this perspective:

What have been the two great incentives to develop new and cutting edge technologies in the past century? In my observation, the World Wars (and smaller wars), and the Space Race for the moon.

I'd much rather have another space race than a world war

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verbose

"Cutting the space budget really restores my faith in humanity. It eliminates dreams, goals, and ideals and lets us get straight to the business of hate, debauchery, and self-annihilation."
-- Johnny Hart

NothingMore.

Nice quote.

I'd like to see the space program get a major funding. Space is pretty Interesting I think. I'd never go up, but I'd like to hear about it =P.

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Geisha

Another thing the moon has over Mars: It's a lot closer. Pyschologically, that tends to be pretty comforting to humans. When we screw up (and you can't deny that something will go wrong sometime), we can get supplies, corrections, or (worst case) a forensics team to the moon a lot sooner than to Mars.

Wolfie

Lets look at this from an engineering point of view. To lauch a craft from Earth to Mars would require the craft to perform the following:

1) Escape Earth's gravity (escape Velocity).
2) Be able to sustain the crew for an extended period of time (anyone knows how long to get to Mars)
3) Have a craft capable of landing on Mars' surface and return to the main craft after exploriation/experiments have been completed
4) Again sustain the crew for the return trip

From an engineering point of view, it would be much easier and cheaper in the long run to have a base on the Moon that can be a staging area for exploriation and maybe eventually settlement of Mars. Today, fuel is mostly liquid oxygen. A manufacturing facility can be established on the moon to create the fuel. Less fuel needed to leave the Moon's gravity means that the craft can either be lighter or carry more material on the way there. There would also be less stress on the spacecraft in achieving a lunar orbit than an Earth orbit

Also a moon base has advantages over the space station which some were explain before (the technology to build a moon colony would be the starting step towards a mars colony, better environment to test the ideas first, closer to Earth, etc). There is also the fact that the moon already has gravity which, while it is not as strong as Earth's, is probably alot better than trying to create artificial gravity on a space station.

NothingMore.

Dude... Moonsketball...

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Mudshark

Cmon, the margin for error on the moon is imperceptable. As it stands now, if you f up on the moon, you are dead. There ain't no rescue team comming.

Mudshark

Are you suggesting that we build the entire mars craft on the moon? Why would we do that? How is that cheeper? Why can't we produce more fuel here on earth and launch it up to the mars craft after (or before even) it is in orbit. What is so great about gravity? Why would we create artificial gravity in the ISS?

Those are the questions that I have posited that noone has come up with a decent answer for yet. I have ceeded several points to the pro-moon crowd already, I'm just looking for a little in kind. I agree that the Moon may be a workable test bed for technology for a mars mission but I still don't see a compelling reason to colonize. 'Course I don't see a reason to plan the colonization of mars yet either. Sure, It may be nessisary to do so centuries in the future but let's just have a visit first. Would you plan to build a house on property you've never seen?

Mudshark

I really hope you don't have the perception that I am for cutting the space program... I'm just not for putting the money into a moon colony.

Daxx

Why climb Mount Everest?

Because we can.

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kaxman

No one is saying that a one-off mission would be more expensive than establishing a base. At least, I hope not. The key word here is amortization. Is it cheaper to build, test, launch, and send on their merry way ten manned Mars missions from Earth or from an established base on the Moon?

I certainly can't tell you, but I do imagine that the first mission to Mars will leave from Earth, unless both cost analysis and feasibility studies overwhelmingly favor the Moon-based approach. I can't imagine they will, however, since we've never had to subsist in low-gravity vacuum environments for the years it would take. It's simply something we've never done before. I also cannot imagine a base becoming self-sufficient in a short time; indeed, I would be surprised if it took less than a decade.

Allow me to also mention that I believe any Mars mission starting from Earth, prior to us having established a functional, self-sufficient base on our nearest major satellite will not be the start of any serious colonization attempt. Regardless of the margin for error, I can't imagine that humanity would be psychologically ready to tackle the 35 million mile trip (minimum) without having practiced it first. I mean, 35 million sounds like a lot, no? The Moon is only, what, 300,000 miles away?

lol weve seen it

Edit: Oh, and Arthur C. Clarke told me that the "slingshot" method works because all the fuel you burn up accelerating "downhill" doesn't have to be carried with you when you head back "uphill". Meh.