Newsgroups: sci.space
Path: utzoo!henry
From: henry@zoo.toronto.edu (Henry Spencer)
Subject: Re: Solar Impact Mission.
Message-ID: <1991Feb7.165356.8312@zoo.toronto.edu>
Organization: U of Toronto Zoology
References: <1991Feb4.111437.9283@helios.physics.utoronto.ca> <1991Feb5.185021.10001@lonex.radc.af.mil> <3302@polari.UUCP>
Date: Thu, 7 Feb 1991 16:53:56 GMT

In article <3302@polari.UUCP> crad@polari.UUCP (Charles Radley) writes:
>Some of the velocity would be lost due to thermal dissipation, +but
>most of it would be redi+rected into a new solar orbit with much higher
>eccenricity.   The trade of+f is increasing the aphelion by reducing
>the perihlion.   This is done by changing the velocity vector even
>though the magnitude does not increase...
>    Well, Henry, how does that sound ?

Correct as far as it goes, but it doesn't go far enough.  If the planet
were stationary, this would be a reasonable analysis.  You keep the same
magnitude of velocity *with respect to the planet*, but since the planet
is moving, that can result in either increased or decreased velocity
with respect to the Sun.  If you bounce a ball off a car moving rapidly
towards you, the ball comes back faster than you threw it.
-- 
"Maybe we should tell the truth?"      | Henry Spencer at U of Toronto Zoology
"Surely we aren't that desperate yet." |  henry@zoo.toronto.edu   utzoo!henry