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

me and some friends were discussing after a rather heavy night at the pub the many different ways of space travel! my freind said that just the standard space rocket would do but in my infinite wisdom (or stupidity) decided a giant bubble would survive a longer journey what do you think would be best?

A giant bubble of what?

well at first i thought alcohol but then i realised that wouldnt work! i decicded if you were toi take a rocket into space then shoot some water from it and once it was out and in a big ball type thing pump air to the centre of it

If you want to accelerate your spaceship, you need to be able to apply force to it at some point. This won't work if it is made of water or soap. It is going to need a hard shell.

All you need the rocket stage for is to accelerate you into space. Once the craft reaches the desired escape velocity or orbital speed you don't need any more fuel at all, and they can be any shape you want them to be then. All those satellites in space have just enough power to steer the craft and manage the onboard electronics systems. They don't need big rocket thrusters at all. Gravity does everything else.

If the question is, could you come up with something other than a rocket to *get* you into space? Well, the answer is that it would be tough. You might be able to get a balloon that would take you up into the high atmosphere, but then you would need to employ some serious acceleration if you wanted to get into orbit or further. Light sails and Ion drives would be too weak that close to Earth I would think.

After that you get into theoretically valid, but practically near-impossible ideas such as space elevators and tethers.

I've never understood why all the big fuss over space elevators. They're clearly impractical and impossible. You'd have thought people would realise that you don't get something for nothing.

B

People who don't know anything about space travel that is? Like NASA I suppose who have said sapce elevators are feasible just. They do predict maybe another 1000 years before we see them. There is no theoretical reason why not it is just a question of being able to make strongenough materials.

Having a ready-accelerated bubble leaves the question of how you're going to stop when you get there.

Perhaps you could give it an electric charge and use magnetic fields to accelerate/decelerate it? Possibly the repulsive force might make it fall apart though. I suppose its going to have to be a fairly tough bubble anyway if its going to do any signficant acceleration without the stuff inside falling out.

Two points you haven't defined...
1) How far are you planning to go?
2) How fast are you planning to go?

I'd have thought that at current technology levels the best sort of spaceship you could build would be a 'Project Orion' type - shaped like an enormous pointy Big Mac...

That isn't as strange as it sounds by the way...

The bottom section is a thick, very solid shield for the orion drive, the middle is where the crew lives and the top is a shield to stop the minute particles you'll run across punching holes in your spaceship at high speeds...

The advantage of making it round is that you could then, with a minimum of energy, start it spinning and thus introduce a form of artifical gravity.

sigsfried, NASA says all kinds of crazy c**p the never ends up working. You take the good with the bad, especially when you're trying to push the envelope. But you don't bank on all of it working...

"space elevators. They're clearly impractical and impossible. You'd have thought people would realise that you don't get something for nothing."

Where, precisely, in the idea of a space elevator is anyone getting something for nothing?

Space elevators are clearly USING CURRENT TECHNOLOGY impractical.

They are definitely NOT impossible.

In order for them to be "clearly [...] impossible" they'd have to violate some fundamental law of the universe as we currently understand it. For instance, a rocket capable of moving faster than light IS clearly impossible, for sound reasons having to do with relativity.

A space elevator violates no physical laws. It requires some specialist materials with known properties of tensile strength to weight ratio. While we can't currently make anything that light or strong, there is nothing in physics or chemistry that says that making something that strong is impossible.

Once the cable is in place, ascending it requires little more energy than could be generated by descending it. The potential energy you lose can be stored and reused.

The main problems with space elevators are political ones - yes, it would make spaceflight incredibly cheap, but it would cost a FORTUNE to build, and who would pay? And who would own it? And where would you put it? And how would you protect it from the kind of scum who blow up Tube trains and fly planes into buildings?

It's not inconceivable that we could be in a position *technologically* to construct a space elevator within this century. It very doubtful, to me at least, whether the politics will keep up.

SoRB

Actually carbon nanotubes do have the required strength to weight ratio bt they have not been been in adequate lengths. Though composites might work. I think the main barrier is political as it would have to be a country on the equator leaving: Brazil, Congo, Uganda Somalia Indonesia and a few others I can't remember names of and can't remember exactly where the equator passes thorugh S. America

Ah, Speed of light is the limit... I can't & won't argue but it's always worried me. If it actually proves to be the case over the course of time then, as I see it, we're as good as dead already. One of our major traits is exploration of the (to us) new. Deeper & deeper exploration of what's already discovered isn't enough - that's a 'background' activity.

Anyway, I'm all for Arthur C Clarke & 2001 & the 'Star Child' - or something not altogether different.
Any other takers?

" it would have to be a country on the equator "

Um... not necessarily. It would have to be ON the equator. But there's a heck of a lot of ocean on the equator. Your base station could be a floating platform...

SoRB

I love the idea of a space elevator to build the craft in orbit and then use your newly built spaceship to get to the stars. But how would the newly built spaceship work well it just so happens I've got a little entry in PR at the moment explaining how! A8792427

"Um... not necessarily. It would have to be ON the equator. But there's a heck of a lot of ocean on the equator. Your base station could be a floating platform..."

But ideally you want a height headstart. Brazil would be ideal if it wasn't for the political scene there not being exactly stable. Of course if you get a few up there you can connect then branch out from the equator.

Actually I think you'll find that it being on the equator is a bit of a myth, IIRC you can have an elevator anywhere you could have a geostationary satellite - which, again IIRC, can be, practically, anywhere up to 30 degrees away from the equator...

BTW, please forgive me if I am wrong...

::scurries away to check::

I can't find anything which says 30degrees, but, at least wikipedia, says that there is a "special case" of a Geosynchonous Geostationary orbit - which has to be at the equator, and implies that geosync orbits can be at other than 0 degree latitude (?)...

I am unconvinced by that. At 30 degrees above the equator it is hard to see how the sataliite can maintain its orbit

We need a geostaionary orbit as we can't have our sataliite not being directly overhead.