# Re: starship-design: still some hope

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In a message dated 8/6/97 10:13:37 AM, you wrote:

>
>Let's not give up on this light-deceleration quite yet.
>
>Sure, light pressure can't do it alone, but there's more than just light.
>There's also the solar wind and gravity.  Here's a way we could maybe use
>all three:
>
>The sail doesn't come in straight toward the sun, but rather in a tight
>parabolic orbit around it.  We'd have to figure out how close we could get,
>but the closer the better.  The details of the star probably matter quite
>a bit as well.
>
>So on the way in we slow down from light pressure (although keep in mind
that
>we're getting deeper into the star's graivty well, which will speed us up
>a little bit)  When we're close enough, the solar wind acts as a drag;
>charging up the ship might help matters even more.  As we get close to the
>nearest approach to the star the light pressure is now coming at the wrong
>angle to slow us down much, but the solar wind keeps getting denser and
>denser.  Then we start to move away from the star, still braking in the
>solar wind, although nowthe light pressure is speeding us up again.
>At some optimal point we dump the sail (with as much velocity as we can
>handle, slowing us down even more) and let the star's gravity apply the
final
>braking as we coast away.
>
>I don't have time to look at numbers, and I'm not even sure where I'd
>start.  The first question to answer, though, would be: how close to a
>star can we get without frying the ship?  From that we can compute the
plasma
>density, and I should be able to give some braking numbers.  (I'm supposed
to
>be a plasma physicst, after all...)
>
>Ken

Ah, Ken.  The ships cruse speed is a major fraction of light speed.  Unless
your doing a close approach to a neutron star.  Your "parabolic orbit" would
be indistinguishable from a straight line.

Kelly

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