From: Chuck Kuecker <ckuecker@mcs.net>, Thu, 22 Jun 2000
>Relatively speaking, any man made device today is puny compared to the
>volume of solar wind, but it's locally very intense. I remember reading
>about Soviet Topaz reactors trailing a plume of energetic particles that
>could fry microcircuits "down orbit".
Adding to this -
Satellites in orbit shed alot of junk- paint flakes, plastic and metal
erosion and so forth. All of this junk is usually charged, and it
leads to chemical contamination and erosion of satelite comonents
like solar panels, optical windows, etc
When satelites are boosted from geo transfer orbit to geostationary orbit
(GEO = 6.6 earth-radii), many of the solid rocket motor burns release
aluminum oxide spherules, (which become quickly charged) adding even more
stuff to the space environment. This debris in the .01 to 10 micron size
range outnumbers the natural micrometeroids (in this size range).
About 80% of the exhaust particles hit the Earth in a day or less, some
after just a few hours. However about 20% can have stable orbits
of lifetimes of many years- depending on the magnetospheric conditions.
(Strong magnetospheric conditions will cause the charged submicron particles
to lose energy and eventually hit the Earth in a month or so.)
(BTW, a tiny number of these spherules can leave the Earth's environment and
the Solar System, under the right conditions too)
I have a colleague, Hakan Svedhem, at ESTEC in Noordwijk that is flying
a dust detector in GEO, piggy-backing to a Russian satellite. This detector
is twin, a spare unit actually, of the Ulysses and Galileo dust detectors.
Hakan's particle impact data is quite unusual- he is seeing impacts
of particles carrying potentials of thousands of volts. There are several
possible explanations having to do with various charging processes and what
can happen to particles of particular material properties and in particular
plasmas, but it seems sure now that a correlation exists for a large
number (say > 50%)) of those highly charged particles occurring at a
close proximity in time to a geo-transfer orbit (GTO) burn. In fact I
hear that he's able to identify from his data whether the boost
was a NASA rocket boost or an ESA rocket boost.
The Earth's enviroment is really dynamic. The magnetosphere is
constantly changing in close response to the Sun and the energy
of electrons can easily be in the kilo-electron Volt range. Geostationary
orbit conditions are highly variable- the orbit location skims the inner
boundary of the Earth's magnetospheric plasma sheet, and the radiation
belts are located nearby as well.
ESA models these "debris plumes", by the way, and spends a huge amount
of time, effort, and money measuring the effect of rocket debris on
satellites and determining the natural and man-made Earth debris populations
and how those populations evolve in time, and also the charging
and dynamics of the particles in the Earth's magnetosphere (that's
the part I'm involved with).
I realize that most of this discussion was about conditions at low Earth
orbit (and below), but I thought I'd tell you a little bit about what
is happening further up.
Amara
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Amara Graps | Max-Planck-Institut fuer Kernphysik
Interplanetary Dust Group | Saupfercheckweg 1
+49-6221-516-543 | 69117 Heidelberg, GERMANY
Amara.Graps@mpi-hd.mpg.de * http://galileo.mpi-hd.mpg.de/~graps
*****************************************************************
"Never fight an inanimate object." - P. J. O'Rourke
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