On Jun 21, 7:50 pm, neilzero wrote:
Keith Henson;1158169 Wrote: About Skylon and laser propulsion to get the
cost to GEO down.

http://www.theoildrum.com/node/7898

Keith Henson

A very large number of very powerful lasers are needed on Earth's
surface and/or in LEO to send lots of mass to GEO for space solar power.

500 MW. 500 one MW lasers for a flow of 60 t/h starting from a
suborbital Skylon.

These would worry a lot of people that they might be used for war etc.

That's correct. The particular design in that article has the lasers
going up to GEO to redirection/tracking mirrors that track the
accelerating vehicle along 7500 km of the equator. They point to
about a meter of accuracy.

If people still want to do wars, it is going to take new tactics when
there is a FOG (finger of God) overhead. Long as you don't have more
than one set of lasers and mirrors, then they are fixed in GEO and can
only hit targets on the half of the earth visible from a fixed spot at
GEO.

And, of course, anything in orbit.

The energy consumed by the laser stations would not be trivial.

That's true, but all the transport energy is repaid in under two
months.

Perhaps
closer solar synchronous orbits are better as the rectennas or laser
light receiving sites could be much smaller and any where on Earth's
surface instead of only near the equator, and in the temperate zones.

I looked into this. The delta V needed to get to SSO is almost the
same as you need for GEO because of the plane change.

Keith Henson

Neil

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neilzero