From: Michael S. Lorrey (mike@lorrey.com)
Date: Sun Jul 25 1999 - 17:02:13 MDT
> >
> > Spike Jones wrote:
> >
> > > >...He suggested star sailing was not only impossible, but absurd,
> > > since solar gravity is stronger than light pressure, assuming a
> > > single atom thick layer of aluminum, and furthermore, solar
> > > gravity stays stronger than light pressure, regardless of the
> > > distance from the sun, since both drop off as the square of the
> > > distance.
> > >
> >
Using a solar sail to thrust perpendicular to the vector of
gravitational attraction is not necessary. Tacking across the solar wind
to increase tangential orbital velocity is the key, and you do not need
the solar wind to exceed gravity to do this.
Besides this, given a solar sail of a couple microns thickness over
square miles of area is fine. The gravitational attraction is only
important if sailmass X gravitationalacceleration > solarwindmass X
windvelocity^2. The lighter the mass of your sail versus the area, the
better.
Mike Lorrey
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