science help for story

[electromagneticpulse]

Okay guys and gals I need some help.

I've started a Novella (Codenamed: 'Ix' for the time being, will change), which needs some science help from the gang here. I don't need any help for vehicles or plot lines or anything just the hard science.

Firstly and mainly I need to know how many tons of Hydrogen (guestimated of course) fuel would be needed to accelerate/decelerate a craft weighing up to 5 billion tons with multiple VASIMR drives. So far there is approx 62,500,000 m^3 of hydrogen storage which means 4,375,000 metric tons.

The trajectory is between Pluto's L3 and Pluto itself, the pass is intended to be very elliptical passing roughly into Mars' orbit (not the planets orbit) and back on to Pluto. No fuel is necessary to compensate for gravity's effects as they'll counter themselves the fuel is necessary for getting it going as fast as possible and bringing it to a 'stop' at Pluto.

Thanks for the help :D

[A Thousand Pardons]

The trajectory is between Pluto's L3 and Pluto itself, the pass is intended to be very elliptical passing roughly into Mars' orbit (not the planets orbit) and back on to Pluto. No fuel is necessary to compensate for gravity's effects as they'll counter themselves the fuel is necessary for getting it going as fast as possible and bringing it to a 'stop' at Pluto.
I may not understand this correctly, but I don't think it'll work.

You're planning to accelerate early (near the sun-opposite point to Pluto, about 30AU), fly close (Mars orbit about 1.5 AU) to the sun, then "coast" up to Pluto orbit, without additional deceleration?

[Kemal]

How quickly do you want your spaceship to get there?

[electromagneticpulse]

The trajectory is between Pluto's L3 and Pluto itself, the pass is intended to be very elliptical passing roughly into Mars' orbit (not the planets orbit) and back on to Pluto. No fuel is necessary to compensate for gravity's effects as they'll counter themselves the fuel is necessary for getting it going as fast as possible and bringing it to a 'stop' at Pluto.
I may not understand this correctly, but I don't think it'll work.

You're planning to accelerate early (near the sun-opposite point to Pluto, about 30AU), fly close (Mars orbit about 1.5 AU) to the sun, then "coast" up to Pluto orbit, without additional deceleration?

No I think you've misunderstood slightly. The plan is to accelerate to full speed as soon as possible and then when passing the sun rotate the ship 180 and decelerate as late as possible. Without additional deceleration the ship would go ballistic, which isn't going to make any money.

Also getting there wants to be as fast as possible, but my guess is about 5 years at full speed (300,000 m/s) but that's fast compared to Pluto's own orbit of near 250 years IIRC.