Let's make it simple.

1) Space travel is hazardous. Radiation levels are greatly elevated, especially in the case of a solar flare, with virtually no shielding other than the spacecraft itself, and research is going into finding different methods of shielding. Now take the distance to the next neighbouring star (which I doubt has planets), which works out to be about 400,000 times further away, and you have an idea of how far it has to go, and see 2) for how long it'll take.

2) Space travel takes ages. Current plans for travelling to Mars will take at the very least 8 months. Add that to shielding and you have big issues.

3) Habitability of other planets, most likely current candidate: Mars. Carbon dioxide dominated atmosphere, so we still have to get spacesuits, and still need sealed compartments. Also the issue of heating, since the atmosphere of Mars is so thin as to make it susceptible to large temperature fluctuations, which means more problems, and its weak magnetic field (approx 10^-4 of Earth's magnetic field) which means even more radiation shielding is required again.

Or put it this way: The problem with space travel is the humans themselves

This post has been edited by bgeh: Jun 15 2009, 01:42 AM

It's not shielding explosions, it's shielding cosmic rays, shielding gamma rays. All the solutions that exist today weigh a bloody ton, and since space travel requires a small spacecraft mass for efficiency, you have a big big issue there.

No, it's highly unlikely we're going to be able to convert them to any useful form of energy at all, both the cosmic rays and gamma rays, and besides, the energy we can gain from them would be quite negligible compared to the energy required for propulsion. We also need to consider the amount of mass added on to add this exotic converter, which would probably be extremely large.

Yes that's the first step towards any useful spaceship, but the issues with radiation in space have not been solved yet by any means. Propulsion is the next problem, we have nothing that's remotely efficient when it comes to propulsion (ion ones are nice and everything but they're slow...... not much acceleration at all, and you can dream on when it comes to antimatter, we only make less than a nanogram of antimatter each year, and nothing much's going to change on that front either)

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Added on June 15, 2009, 6:49 pmBloody hell. I'm saying that it is highly unlikely methods will be found to convert it due to their penetrating power, and that their main mode of losing energy is from ionisation, which is extremely, extremely hard to actually get any useful energy out of.

We're going to have to get to much more exotic forms of materials before it'll even be possible.

This post has been edited by bgeh: Jun 15 2009, 06:49 PM

No, at the timescales, and extremely slow velocities we're talking about, it'll be in the millions of years before a spaceship even reaches anything close. And here's a question if you think propulsion isn't important: How exactly do you stop your spaceship from zooming past if you find a habitable planet?

Too frequently in fact.

Yes, but that's the realm of science fiction, assume some miraculous solution to fix problem xyz. There's none right now, unless some exotic form of matter is found, and what is the range of this converter? Can it take in 10^20eV rays or will it just let it through? Does it fix the cosmic ray issue?

And at the same time, would it really generate enough useful energy? Doubtful. The shielding's there to prevent us from getting fried, but you'd be surprised at how little energy in total is really needed to irradiate us.


Any crash would kill everyone in the spaceship, and the drop pods have the same problem that they have the same velocity of that mothership and you still need to fix that propulsion problem, because the drop pod's not going to be able to communicate ever again with the mothership.

And if we are to even approach interstellar travel speeds, solar parachutes will not be good enough to slow us down at all.


addendum: Look, I don't mean to rain on your parade. It's a nice idea, but we're really that far behind technologically speaking before we even have a remote chance of getting a useful working spaceship that is self sustaining and can provide enough shielding from the high radiation especially in the timescales we're talking about. There is a place for science fiction, but as of right now, and afaik, for quite a while more (decades perhaps), it simply isn't possible, unless some really big breakthrough occurs.

This post has been edited by bgeh: Jun 15 2009, 07:24 PM

Thinkingfox: Try that, but from a single proton (and yes, they have been observed - cosmic rays of that energy). For comparison's sakes, 1 gram of protons [rest mass] with that energy would have approximately 10^25J. Anything above 1MeV is usually deemed as dangerous to us, so yeah imagine 10^20eV

No the concept wouldn't work for reverse propulsion unfortunately (afaik)

Accelerating to that speed isn't much of a problem because we have plenty of millennia to accelerate. It's a question of how to actually slow down if we see something promising, in say a matter of a century or less? And even that's highly inefficient because plenty of energy is lost and you need to accelerate again, and also a quick deceleration might impose strains on the spaceship's body, so that's again another engineering problem

This post has been edited by bgeh: Jun 15 2009, 07:46 PM

Sorry, included it in the edit above.

Also I confused your above post. Well, I thought you were trying to apply some idea of reverse chain reaction to reverse propulsion, which was a mistake I made. Sorry about that. Well my question would be what would reverse chain reaction do then?

And yes, I do think that this topic isn't really suited to this forum, because it sounds more fictional than real applied science?

Thanatos: Read the above posts on why terraforming Mars will be a much tougher adventure than any of us care to think

My personal POV: Frankly, as a wannabe scientist, I can't be bothered about human exploration in space, I'm more interested in robotic exploration because they're much cheaper, and thus more missions can be sent to gather more information than sending one hugely expensive human mission. I understand it helps to stir the human imagination, and it helps with funding too, but I honestly wish it was spent more on robotic explorations until there is the available technology for humans to explore cheaply.

This post has been edited by bgeh: Jun 15 2009, 08:03 PM

Yes but if you take hundreds to thousands of years to accelerate to anything resembling the speed of light (which will be needed if we're to do any useful interstellar travels, let alone intergalactic ones), you'd need an equally long time assuming the same deceleration rate to do it, i.e. you need to know long in advance, and by that I mean very very long in advance. And what about the fuel issue? There's no more refuelling once you leave the Earth. And even then, we're supposing space is empty. How do you avoid objects in your path, if you travel at say 0.01c, given that we clearly cannot see them until we're relatively close? One collision and there goes the spaceship.

Currently for planet - planet transitions (Earth - Mars, Earth Venus), we rely very strongly on atmospheric braking to land on the planet. This will not be possible at the speeds we're talking about for interstellar travel, and heck landing's probably not even an option, just plain old orbiting

That's very possible now, but the Moon will probably not be able to support an atmosphere containing oxygen at a temperature comfortable to us.

Yes we 'make' antimatter everyday really, in particle accelerators pretty much everywhere. Heck there are 'natural' sources of antimatter emitters (positrons to be exact, or beta+ particles), and I believe they're used in medicine (google positron emission tomography)

That's a different concept. We've been producing antimatter regularly for say, 30+ years now, and they're stored using magnetic 'bottles' to separate them from matter.

Black holes being produced at the LHC are an entirely different matter though.

This post has been edited by bgeh: Jun 15 2009, 11:38 PM