h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

With journeys to Mars, it's partly a matter of chronic low-level exposure to the general background of sun-sourced particles and extrasolar cosmic rays, but there's also the risk of being hit by a large slug of solar wind particles resulting from a big solar flare or a coronal mass ejection.

I can't remember if Mars has a magentic field at all, but even if it does, it's massively weaker than Earth's, so I suspect any belts of trapped particles surrounding it would be more diffuse and less energetic than those round the Earth.

Yes, I think it has to do with the length of time the astronauts are exposed - for the moon it's about a week. For Mars it would be around 6 months or more. The chances of a major solar flare occurring during this time will be increased.

It has also been postulated that there is (probably) no life on Mars because of Mars' lack of a magnetic belt. Thus, once every decade or so the surface gets hit by a massive coronal mass ejection, which is er, a bit unhealthy.

As for going higher than the orbit of the shuttle, the basic physics is if you want to go a long distance you need a lot of fuel and you need a big fuel tank. Fuel is expensive and the size of the fuel tank makes the craft even heavier, so the cost of going further than low-earth orbit quickly becomes extortionate.

CR

Heavy? In space?

But you're right about a lot of fuel being needed - especially if you're talking about a return journey. Do you take it with you? Have it sent on afterwards? Find some way of using Martian resources to make a new source?

Tick all of the above! I think there is a lot of work going on to develop a new generation of ion engine, that doesn't need half as much fuel as conventional rockets, but it is still in its early stages of development.

As for heavy, yes actually! A large heavy object in space (or anywhere else for that matter) possesses more inertia than a small, light object, so even in space if you want to move it or kick it or blast it half way across the solar system, it will require a lot of effort to do so. The "weight" of an object refers to its tendency to be pulled by a gravitational force. It is "weightless" when it appears not to be impelled by gravity (ie fall down), but that says nothing about its mass. Kicking a lead weight barefoot is just as painful in space as kicking it on the ground!

Sorry Dragonesque, we are really moving off the point now!

CR

Aha, my unscientific brain had figured it something to do with Mass.

And I don't think we've digressed too much, surely after getting the ISS up and running, Mars is the next step.

Another question the doco raised was: how do you stop the crew from going nuts and killing each other? (Them moonbeams is 10 times stronger in outer space!)

Good selection is how you stop the crew going nuts.

Have you read Stranger in A Strange Land as part of the premise is that the crew of the mars mission end up killing each other (after an affairwhich results in Mike, the man from Mars)

The biggest problem with high earth orbits and mass exists while the craft is still on earth... in other words, getting those massive, bulky fuel tanks up to escape velocity in the first place.

Which is why you wouldn't build the thing on Earth. You build it in space piece by piece a la ISS. Which is why you need *it* up and running first. You have a few trained engineers or whatever on board the Space Station to help out with that, constant contact with the designers back home, bob's your uncle!

It would be slower and probably more expensive to do it in this way, but it in the long run it'll be faster and cheaper. "Bwuuh!?" I hear you say?

Getting things from earth to orbit via rocket is inherently problematic and fraught with perils. If rockets blow up (like the Titans did about this time last year), it would probably be better for *replaceable* bits of a Mars vehicle, to be sent up one at a time, rather than have the whole completed vehicle blow up in one shot. Also when the time comes it to head off, as well as bypassing that whole liftoff problem, you don't have to piss about waiting for the weather to clear.

Back on the subject of the mental health of the crew, you're forgetting that these guys are going to be spending several months together in very cramped, spartan living conditions with increasingly delayed contact with home. No selection process, no matter how stringent, is going to prevent a crew from getting on each other's nerves, so you're going to have to have psychologists monitoring them from Earth around the clock, as they currntly do/did with the crew of Mir.

Noise doesn't travel in a vacuum. D'oh.

Which is a main reason that with the international space station the intention is to lauch long range mssions from space, as it will require less initially inertia to get goin from space.

As for kicking a lead weight in space being as painful as on earth theat is ludicrous. For a start there is no friction in a wieghtless environment. Motor speed is also slower an effect of weightlessness. so the net effect would be a lot easier, some people around here lack basic understanding of physic's basic principles.

Now all we need is someone to pay for the damn thing...

"Bill Gates with a one-way ticket" would have been a good answer to this a few weeks ago, but I haven't a clue who is likely to step into the breach now, as Mr Gates has recently seen his fortunes take a slight dip.

As for friction - I don't buy it. What has friction got to do with it? Sure, an absence of friction would mean the lead weight would go further after you kicked it, but the momentary friction between one's toe and the lead weight upon impact is pretty much the same on earth as in space, and Newton's third law still applies, friction or no friction, namely "if you give something a whack, it will give you an equal whack back" (sorry, Isaac ).

Secondly allowing for any reduced motor abilities (which are minor anyway), if you hit something at the same rate and speed in space as something on earth, you will say "Ouch" at equally the same rate and speed. Mind you, if the object is a 10 ton lead meteorite travelling at 50,000 miles / hour, the chances are you won't say "ouch" for very long....

CR

I would have thought giving a lead weight a kick could be pretty painful wherever you did it. The effect of that kick might be different depending on where you are, the lead would certainly move away from you quicker in space.

Lusk

Go on then, I'm intrigued. What about the photographs?

I must admit I wondered how we had a photo of Mr Armstrong climbing down the ladder - who took it????

Buzz Aldrin, of course, the 2nd guy on the moon.

some thoughts,
i'm no physist, but as far as i understand, you wouldn't say ouch (unless you're a mummies boy). what would happen is you would push yourself away from the large peice of lead. unless of course, you were supported by something, but all through this thread i've been visualizing myself floating in front of a floating peice of lead, so there.
next
buzz took the picture, but this was probably due to the fact that the americans had never written a play before. they wanted neil to be the hero american being the first to decsend on to the moon, but they didn't realize they first had to introduce the character of buzz, to take the ledgendary photo. this leads me to my next point:
it couldn't have been staged. reason: the american government is too dumb to pull it off. so is nasa, the nsa, the cia, and the fbi. sorry to any american i've just offened, but it's true, i haven't lived north of you guys for twenty years without realizing a few truths.
as far as no more men (and women) on the moon, it does come down to funding. there is very little public support, this comes particularly from things like the challenger, the mars landers "disappearing" (crash n burn, but if they say disappearing, then people think something took them), and of course, nasa's attemp to publize through movies (appolo 13 didn't work, people just resented nasa for screwing up, but mission to mars seems to have done a bit better, we'll try, screw up, but then save the day and find a god that you can see and therefore beleive in, instead of the ones we've got now.) and hey, is it a coinsidence that gary sinise was in both movies? there's a conspiracy you can beleive.
as far as the russians are concerned; the reason they've let it drop is that they're not like the american government. they lost, oh well. no justifying, no "oh, america stole our idea", they just moved on. it's interesting to note that russia doesn't still brag about being the first people to manage to get something into orbit (even if the poor pup died up there).