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From: dil@mace.cc.purdue.edu (Perry G Ramsey)
Newsgroups: sci.space,sci.astro
Subject: Re: Magellan Update - 11/12/90
Summary: There are useful things to do even after mapping is completed
Message-ID: <6073@mace.cc.purdue.edu>
Date: 14 Nov 90 16:16:07 GMT
References: <1990Nov12.220502.28617@jato.jpl.nasa.gov> <20538.273ffbf3@merrimack.edu>
Followup-To: sci.space
Organization: Department of Earth and Atmospheric Sciences
Lines: 58

In article <20538.273ffbf3@merrimack.edu>, yetmank@merrimack.edu writes:
> In article <1990Nov12.220502.28617@jato.jpl.nasa.gov>, baalke@mars.jpl.nasa.gov (Ron Baalke) writes:
> >                         MAGELLAN STATUS REPORT
> >                           November 12, 1990
> >  
> >      The Magellan spacecraft performance is nominal.   The spacecraft
> > successfully accepted commands on Friday, November 9, resuming mapping on
> > orbit 787 at 4:07 am PST on Saturday, November 10.  One STARCAL (star
> > calibration) occurs every orbit and 1 DESAT (desaturation of the reaction
> > wheels) every 4th orbit.  16 STARCALS and 4 DESATS have been done since
> > mapping resumed.
> >  
> >      A sequence patch to disable solar array control during mapping has
> > prevented the spacecraft vibration from recurring.  Track 1 of tape recorder B
> > was successfully played back on November 9.  It contains the results of
> > STARCALS performed during Superior Conjunction.
> >       ___    _____     ___
> >      /_ /|  /____/ \  /_ /|
> >      | | | |  __ \ /| | | |      Ron Baalke         | baalke@mars.jpl.nasa.gov
> >   ___| | | | |__) |/  | | |___   Jet Propulsion Lab | baalke@jems.jpl.nasa.gov
> >  /___| | | |  ___/    | |/__ /|  M/S 301-355        |
> >  |_____|/  |_|/       |_____|/   Pasadena, CA 91109 |
> What's the JPL/NASA going to do with the Magellan probe when it's done mapping
> Venus?
> 
> Kevin
There are a lot of things Magellan can do after the first mapping pass

1)  Finish mapping.  The conjunction gap leaves a vertical hole in the map.
Another Venus year will be needed to fill that in.

2)  Map it again.  Getting views from two locations gives stereo views, which
is useful in determining topography.

3)  Map the south pole.  It is not currently being mapped.

4)  Work on gravity anomalies.  They can tell a lot about the density
distribution of the planet by tracking the spacecraft while it orbits.
This works best when the spacecraft is close to the planet,
but pointing the high gain antenna at the earth.  The trouble is that
for mapping, you want the antenna pointing toward Venus at closest approach.
If someday it is decided that there is enough mapping data,
(or perhaps the SAR dies but the transmitter continues)
this mode could be selected.

That's just what I know.  Maybe there's more.


Perry G. Ramsey           Department of Earth and Atmospheric Sciences
perryr@vm.cc.purdue.edu   Purdue University, W. Lafayette, IN USA
dil@mace.cc.purdue.edu    Congress thinks that if you have nine women pregnant
			  simultaneously, you can get one baby in one month.

-- 
Perry G. Ramsey           Department of Earth and Atmospheric Sciences
perryr@vm.cc.purdue.edu   Purdue University, W. Lafayette, IN USA
dil@mace.cc.purdue.edu    Congress thinks that if you have nine women pregnant
			  simultaneously, you can get one baby in one month.