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▲ nonethewiser 4 hours ago

>Interstellar travel is not impossible, no matter what anyone tells you. We know how, it's just wildly impractical.

This was provocative and intriguing so I looked into it and this is my understanding of some of the options (theoretically).

First, "interstellar" means between stars and the closes star is 4.2465 light years away (Proxima Centauri in Alpha Centauri star system) so I used that. c=speed of light

   - Chemical (Voyager), ~0.006% c: ~75,000 years
   - Nuclear pulse (Orion), ~3-10% c: ~40-130 years
   - Fusion (Daedalus), ~12% c, flyby: ~35 years
   - Laser sail (Starshot), ~20% c, flyby: ~21 years (gram-scale probes only)
   - Antimatter, ~20-30% c stopping: ~14-21 years; ~50% c flyby: ~8-9 years
Nuclear pulse surprised me in particular. My understanding is you basically just detonate a bunch of nukes to propel yourself. There are legal hurdles not to mention fallout, but it sounds like the physics of simply getting there in 40+ years (not stopping, mind you) is possible with todays physics. That's pretty amazing and I had no idea.
▲m4rtink 4 hours ago | parent | next [-]

Yeah - and the mass fraction is also very good for Orion. You can basically build your ship from boiler plate (and you kinda have to) in a shipyard, no need for fragile ultra light stuff.

Also past LEO you don't really have issues with fallout.

So the only real hurdle is securing the supply of couple thousand nuclear bombs for the trip.

But if you told people in 1903 that you can build a plane that will get 850 people 14000 km but you need 250 tons of kerosene to fuel it, they would also think you are insane (e.g. an Airbus A380).

But over time, even with Orion, people will just get used to it. :)

▲throwaway12204 an hour ago | parent | prev [-]

The Orion was proposed over 60 years ago I think.

If we consider the low end your time estimates, we could theoretically have received data from Alpha Centauri by now.