Originally posted by twhitehead
I am curious. What time period would be needed if we chose not to slow down at the far end but let our spacecraft accelerate all the way to Alpha Centauri.
Could we use Alpha Centauri as a slingshot to get us to the next star we wish to visit?
I assume that nuclear power is the only real option for sustained acceleration in interstellar space, so wh ...[text shortened]... of mass of nuclear fuel would need to be expended to keep up that acceleration for the 52 years?
That depends a whole lot of the choice of rockets, or the energy supply.
That 3 Mg accel was thought to take a 200 Mw nuclear supply, presumably fission. You do get a lot of bang for the buck. If I remember right, total conversion of mass to energy Ala E=MC^2 gives 100 MW for thirty years from 1 Kg of mass. Now fission is maybe 1/10% as efficient as total conversion so if we use that as a standard it would mean 1,000 Kg of U238 would power that much so 2000 Kg would do the job for 60 years. A bit over 2 tons. One interesting note about that: The more fuel you use up, the less there is left so the more the thrust, whatever the ratio of fuel to the rest of the mass of the ship ratio is. If the ship weighs in at 20000 Kg, then the fuel would be 10% of the mass, but that is pure conjecture.
I can figure out how fast you are going if you accel all the way to AC:
Well it looks like I goofed, I used 2X the distance when I should have used just the distance, the formula is T=Sqrt (2S/A). To the the right trip time, the way you do it is to accel for half the distance and decel for the other half, and that means you project a trip of half the length, then use the original full distance and double the time. So it turns out to be a two part trip, each leg taking about 37 years for a total trip time of two times that, or 74 years. The numbers I gave would be for a trip where you did not decel, so if you did full-time acceleration you would be going the velocity I mentioned, 30Kmsp or 48,000 Km/s.