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How scientifically accurate is The Martian? | Film | The Guardian
...the ship was so big and elaborate and expensive-looking. Going to Mars is not about realising the vision of a giant science-fiction spaceship, it is about sending a payload from Earth to Mars that is capable of supporting a small group of people, and then sending that or a comparable payload back. There'll be ships like that some day, just like there were ocean liners a few hundred years after Columbus made his voyage. But if Columbus had waited for ocean liners, or even clipper ships, he never would have gone anywhere.

On this one, I am less negative, for two reasons. First, the spaceship in the film seemed to have an ion drive, which makes a much lower fuel mass per payload mass ratio possible, plus almost all of the spaceship can be re-usable (as in the film). So, if the technology is available by the time of a Mars mission, it could be cost-effective. Second, the greatest danger to astronauts on a Mars mission is cosmic rays (the film said little about this BTW), which you can deal with if you have an on-board magnetic field, and methinks you need a larger spaceship for that, too.

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Wed Oct 7th, 2015 at 06:51:35 AM EST
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Too powerful to be an ion drive. Most likely something like this: https://www.nasa.gov/pdf/718391main_Werka_2011_PhI_FFRE.pdf

First you take a dozen nuclear warheads, then you take them apart, and grind the cores into nano-scale dust. Radioactive decay will make this dust very highly electrically charged, which means you can - in low gravities - suspend it in magnetic fields. So you take a magnetic bottle, expose it to vaccum, surround it with a moderator, and pour in bombdust until it goes critical. Since this reactor core is mostly vaccuum, each atom that splits mostly doesn't turn into heat - instead the halves of the former fissile atom try to leave the magnetic bottle going at 4-5 percent of the speed of light. Use more magnets to point this stream of particles out the back, and it's a rocket. An absurdly good rocket. I mean, you can't take off from anything bigger than ceres using it, and you should avoid pointing the exhaust directly at planet earth (as long as you point it even slightly away from any planets, the exhaust will be leaving the solar system shortly. So, no this isn't a polluting engine...) but.. the isp's and the masses it allows you to move are very impressive.
Space exploration fueled by disarmament, what's not to like?

by Thomas on Sun Oct 11th, 2015 at 09:07:43 AM EST
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