alt Hacker NewsAlso, how much fuel do you need to bring along to accelerate a human and life support system and the whole craft including fuel, for a lifetime? Is it larger than a planet?
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Since we're already in the realm of far out engineering, you could get the energy from a laser beam from a source orbiting the sun. Your spaceship would have some kind of array to capture the energy beam.
This gives you energy, but I'm not sure how to turn that into velocity. Presumably you'd want some kind of ion beam emitter on board to propel your craft forward. Halfway through the journey, you'd turn the ion beam around to decelerate as you approach your destination.
In the Arthur C Clarke novel Songs of Distant Earth, spacecraft pushed huge blocks of ice ahead of them to absorb stray interstellar dust.
Less if we just send some eggs and sperm and spin up a human on arrival. We can construct a larger life support system out of things we find at the destination.
Or better yet, send some cancer cells so they can replicate during the journey, then switch from cancer mode to gamete mode for the final generation. That way they're fresh when you need them. You're gonna want DNA repair happening continuously, rather than all at once upon a thaw.
If I recall correctly, it's about the size of a large asteroid (assuming 100% conversion to energy). It's a long time since I worked the problem, though, so I could remember wrong.
Yeah, I added that I think around the time you replied :)
Actually, even something as primitive as a NSWR (https://en.wikipedia.org/wiki/Nuclear_salt-water_rocket) can reach a good percentage of the speed of light after basically processing a comet for fuel. From the Wikipedia article:
"The design and calculations discussed above are using 20%-enriched uranium salts. However, it would be plausible to use another design which could achieve much higher exhaust velocities (4,725 km/s) and use a 30,000-tonne ice comet along with 7,500 tonnes of highly enriched uranium salts to propel a 300-tonne spacecraft up to 7.62% of the speed of light and potentially arrive at Alpha Centauri after a 60-year journey."
Sure, not 99% the speed of light or continuous 1 g acceleration but IMHO good enough for an oversized nuclear squirt gun.