Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.3 4.3bsd-beta 6/6/85; site ucbvax.BERKELEY.EDU
Path: utzoo!watmath!clyde!burl!ulysses!ucbvax!mc.lcs.mit.edu!KFL
From: KFL@MC.LCS.MIT.EDU ("Keith F. Lynch")
Newsgroups: net.space
Subject: Re: Fusion for Rockets
Message-ID: <[MC.LCS.MIT.EDU].848824.860312.KFL>
Date: Wed, 12-Mar-86 21:42:57 EST
Article-I.D.: <[MC.LCS.MIT.EDU].848824.860312.KFL>
Posted: Wed Mar 12 21:42:57 1986
Date-Received: Sat, 15-Mar-86 19:45:06 EST
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The ARPA Internet
Lines: 23


    Power can be supplied to all points in the solar
    system by kilometer-size lasers.

  Since it takes hours for a signal to travel to or from the outer
solar system, any such laser would have to know just where the target
will be.  This would make any sort of interplanetary travel except
prearranged computer controlled travel quite difficult.  This is the
trolley-car approach.  Perhaps this is the way to go, but it has a lot
of restrictions.

    Interstellar ships could be beam powered (laser sails) ...

  Perhaps a laser could be used to vaporize the reaction mass, as I
assume you meant in the previous paragraph, but as for laser sails,
how would the starship decelerate as it approaches its destination?

    Fusion limits you to about 10% of the speed of light.

  The starship could pick up fuel, i.e. interstellar hydrogen, en
route.  As such, it can get a close to the speed of light as you like.

								...Keith