TL9 Spaceships

[thrash]

Originally Posted by teviet

I haven't read up as much on the M2P2 sail; maybe it can maintain constant acceleration, but it might also need more consumables as it expands.

Acceleration and consumables remain constant; the density of plasma inside the bubble decreases.

The problem I've seen with M2P2 sails is that there is no perpendicular component to the acceleration -- it is all radially outward, or whatever direction the local plasma wind is flowing in the vicinity of planets. Interplanetary trajectories involve long periods of coasting with the drive shut off, waiting for gravity to turn you in the direction you need to accelerate or decelerate.

So, for example, an Earth-Jupiter run starts with a long "burn" onto a very eccentric transfer orbit. You then coast to an aphelion 'way beyond Jupiter. As you turn inbound, you make another long "burn" to decelerate. The voyage ends with a stop against Jupiter's magnetotail.

A practical M2P2 ship at TL9 probably has an auxiliary propulsion system (VASIMR or some such) for maneuvering near planets and expanding the available trajectories. The combination of plasma sail + fusion drive + fuel tanks is still probably more efficient than an all-fusion system at that TL.