RE: starship-design: Interstellar Probes

["L. Parker" <lparker@cacaphony.net>]

Bjorn,

Umm, yes, no, maybe....

It is possible to use a star's magnetic field to swing a probe around a star
and onto a different trajectory (even a reciprocal). The actual amount of
deflection possible is determined by the velocity of the probe and the
strength of the magnetic field of the star in question. Obviously, the
higher the velocity the less deflection or steering that can be
accomplished.

But you still have to stop it when it gets home.

In our discussions, we have been able to pretty much agree that there are
several viable methods of accelerating a ship up about .3 or maybe even .4
c. Unfortunately, these methods almost always rely on some trick which
cannot be provided at the other end to slow the vehicle down. Simply
doubling onboard reaction mass or fuel is not the answer. If you do the math
you will discover that doubling the mass of the vehicle will decrease the
cruise velocity significantly and drastically increase mission length.

Propulsion wise, what we need as a BARE MINIMUM is a self contained
accelerate/decelerate capability in the 100,000 m/sec range, or put another
way, a 200,000 m/sec total change in delta v. This would enable us to reach
the nearer stars within the lifespan of a single person (but not necessarily
to return within one person's lifetime.)

I am working from memory here, but I think the best we can currently manage
is only 200 m/sec, which is quite a bit shy of the minimum. We may be able
to reach 100,000 m/sec buy combining several different systems i.e. a
powered perihelion maneuver with a maser sail last stage, but this is again,
only one way.

Lee