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From: pgf@space.mit.edu (Peter G. Ford)
Newsgroups: sci.space
Subject: Re: Pioneer Venus ?
Message-ID: <1991Jun18.032420.6121@athena.mit.edu>
Date: 18 Jun 91 03:24:20 GMT
References: <1991Jun17.224627.3146@ists.ists.ca>
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In article <1991Jun17.224627.3146@ists.ists.ca> white@nereid (H. Peter White) writes:
>I've heard rumors lately that Pioneer Venus will be sent into the atmosphere to
>collect data for future Magellan work. I guess this would mean that Pioneer 
>Venus will collect data till the very end.
>Anyone else heard anything about this, or did I hear wrong?

You've got it half right--the Pioneer Venus spacecraft will indeed be
captured by the Venus atmosphere, and burn up, sometime next fall, but
it won't be deliberate... the spacecraft ran out of fuel long, long
ago, (1980, I think) and its orbit has been wandering ever since.

Its last few months will be closely monitored by Magellan engineers
(among others), in order to plan for an aero-breaking manoeuver in
which the Magellan spacecraft (which *does* have plenty of reserve
fuel), will dip into the fringes of the Venus atmosphere in order to
turn its current elliptical orbit into a more nearly circular one,
which is desired in order (a) to obtain high quality measurements of
the Venus gravity field, and (b) to increase radar resolution in polar
regions.

Peter Ford
MIT and Magellan Project
(also Pioneer Venus, a long time ago).