# RE: starship-design: Interstellar Probes

```On Thu, 13 Aug 1998, L. Parker wrote:

> 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.

I assume you're actually refering to the GRAVITATIONAL field or else
you've got me really lost... :/

Now how high Velocity could our probe have if we want it to do a 180???

Does anyone know the equation?

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

Of course, but then you'll have access to whatever machinery was used to
launch it. That's got to be a big advantage? :)

>
> 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.

Yeah, you'll have to accelerate the propellant too :(

>
> 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
>

I just have a funny feeling that there is something that I/we have
missed... There just might be some way of using all these Magnetic fields,
sheets and pauses to provide SOME sort of brakeing :|

Or what about brakeing via a solar sail?

Or (worst-case and ONLY for a really tough probe) what about hard-landing
it???

These are just some wild guesses but there's GOT to be something we can
work with???

Bjorn

Ever so Hopefull...
```