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Comment by lmilcin | Hacker News Reader

No, it is not. At least as long as you don't want to get there too fast (which we can't do anyway currently).

Dust is taken care by an ice shield in front of the craft.

Radiation is taken care by a water jacket. Radiation is only a real problem in the vicinity of the star. The atmosphere we have on Earth is only necessary to block radiation that comes from Sun either directly or through solar winds. The radiation from sources outside solar system might be high energy particles an photons but has very low flux.

The funny thing is, everybody focuses on technical issues where the biggest issue is most likely non technical and it is mostly about human health, physical response to lack of gravity and psychological to isolation.

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Indeed regarding psychological issues, my current understanding it 10% the speed of light is feasible, so 40 years to the nearest system with no guarantees there's anywhere to call home.

The water jacket is intriguing, but doesn't it require a tonnage that's never been lifted into space yet? Had me thinking about a space elevator taking water up into space and also alleviating sea levels (to the point where much more water would be exported to something other than the shield).

It surely may be possible but involves risks and costs that no one is willing to take. Perhaps that balance of risk will change in the future.

It is assumed that any kind of ship like that would be assembled in space and if we can't do that we are most likely not ready yet.

Water would be a good candidate for both shield and jacket for the simple reason it is readily available in space in huge amounts and doesn't have to be lifted from Earth. What is necessary is a single remotely controlled ship that will go far enough from Sun to be able to capture and steer one of the watery asteroids. The further you go the slower the orbits the less energy you need to dramatically alter course of any astronomical body.

We don't even need to bring all that water to Earth. Instead, it might be cheaper to fly half-finished craft out, finish assembly by robotic means and then turn it into center of solar system. The craft could then gain velocity, use as many gravitational assists as possible on the way in and then back and pick up the crew before it leaves solar system for its journey.

I don't think you can just divide distance by velocity like that, even ignoring relativity as there are the long acceleration and deceleration phases.

This calculator says it would take 80 years when I approximate a solution where max velocity is .1c: https://www.omnicalculator.com/physics/space-travel?advanced...

.1c isn't fast enough to cause significant time dilation for the travelers so they end up spending nearly the same 80 years on the ship as well.

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