Re: cassini flyby -Reply

[Dick King <king@reasoning.com>]

 >Date: Thu, 19 Aug 1999 08:00:52 -0600
 >From: Michael S Ford <MFORD@pantex.com>
 >To: radsafe@romulus.ehs.uiuc.edu
 >Subject: cassini flyby -Reply
 >Message-ID: <s7bbb9ce.008@pantex.com>
 >
 >The issue here is that the "fly-by" speed of the Cassini probe (42,300
 >mph) is well above the assumed reentry velocity that the Pu heat
 >source was designed to (25,000 mph).  'Appears to be a valid issue.
 >
 >Perhaps Tad could comment as to whether NASA increased the
 >fly-by distance because of this?
 >

The flyby distance increased because the launch was delayed for a week [due to
a technical problem, unless we're _really_ being lied to].  This was closer to
the optimal time, and the mission became energetically easier.

This makes sense.  The launch window stretches from the first day the mission
can fly with adequate reserves to the last day the mission can fly with
adequate reserves; the _center_ of the window, not the beginning [or end]
should be the optimal time to launch.  Note also that they saved substantial
fuel in the deterministic maneuver [between the two Venus flybys] because of
the launch delay.

See http://www.jpl.nasa.gov/cassini/msnstatus/missionadj.html .

-dk
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