MSX to Release Subsat

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• Previous message: Tristan Cools: "Molniya flasher"

I think we should nominate MSX (96 24A) as "SeeSat Satellite of the 
Year" or something!  Here are some neat excerpts from the MSX web page:

"MSX will provide unique opportunities to observe man-made debris in Low Earth 
Orbit (LEO) and Geosynchronous Orbit (GEO) by searching known debris streams 
for unknown objects, observing the dispersal of fragments after the catastrophic destruction of a resident space object, and detecting objects that
may be on or close to collision orbits with MSX. Above an altitude of 500 km, 
knowledge of man-made orbital debris is incomplete for debris 10 to 30 cm in 
diameter and largely unknown at less than 10 cm diameter.
MSX will orbit at 900 km, where current models predict the greatest amount 
of man-made debris in LEO. The figure shows the distribution of the objects 
210 cm in diameter currently tracked by the U.S. Space Command.
The existing model assumes that the distribution of smaller objects throughout 
LEO is proportional to the larger ones." 

"Description"

"MSX will track along the orbits of three known resident space objects (RSO) 
that have fragmented: Cosmos 2227 in LEO, a Titan transtage rocket booster in 
GEO, and Cosmos 1278 in a geotransfer (highly eccentric) orbit. A search around 
these known objects while tracking at the rate of the parent RSO should permit
identification of debris pieces generated by the fragmentation. Multi-spectral 
data from the SBV, SPIRIT III, and UVISI instruments can be combined to yield information about the albedo (percent reflectivity) and size of the
object. These results will address the existence of radar-transparent debris 
and provide data to update existing models at these altitudes." 

"When the fragmentation of an object occurs, the SBV and UVISI instruments will 
track the dispersing pieces during the days-to-months after the fragmentation. 
The dynamics of the fragmentation can then be studied, yielding information 
about the cause of the event." 

That's one experiment, now here's another --

"The MSX mission will provide a unique opportunity to extend the thermospheric 
models and improve predictions of satellite and debris orbital decay using 
coordinated orbital and ground-based observations."

"Calibrated on-board mass spectrometers and a pressure gauge will accurately 
measure the neutral and ionic densities at MSX's 900-km altitude. Data acquired 
at all latitudes and over several annual cycles will provide insight into diurnal, seasonal, solar, latitudinal, and other dynamic variabilities, e.g., winds. 
Current models such as MSIS90 and the International Reference Ionosphere are 
uncertain by 25 to 50% at this altitude; the dependencies on geomagnetic 
and solar activities are not well understood. MSX provides the capability to 
expand and improve the accuracy of those models."

"The reflective reference sphere released by MSX will be tracked using the 
Haystack radar on a routine basis, as depicted in Figure 2. From this tracking 
data and the physical characteristics of the sphere, the orbitally
averaged drag can be measured. This drag reflects accommodation of the 
energy of collisions with the variable composition atmosphere. Preflight 
groundbased measurements will provide these accommodation
coefficients for the reference sphere material. By tracking the sphere over 
many seasons, the drag effects of helium, hydrogen, and oxygen will be 
isolated, using the orbital mass spectrometer composition determinations 
coupled with the improved atmospheric models. Drag predictions are currently 
limited by an accurate knowledge of both the variabilities of the atmospheric composition and the accommodation coefficients. MSX data will improve the 
accuracy of prediction of orbit decay as a function of atmospheric
variability and will increase our understanding of the dynamics of the 
processes that dominate the upper atmosphere at altitudes just below the 
radiation belts." 

End quote.

MSX gets "Satellite of the Year" :) honors for having not one but two
experiments that are directly related to two of our interests on SeeSat:
decay prediction and orbital debris.

Has there ever been discussion on SeeSat about Cosmos 2227 fragmenting?
Allen Thomson's TLE set has 6 elements associated with C 2227...

Anyone know the diameter of the MSX subsatellite (and thus its potential for
visibility)?  I just checked OIG -- no elements except 96 24A and 96 24B, 
so perhaps the subsatellite has not been released yet.

To learn more about MSX:

  http://bradbury.nrl.navy.mil/msx

Good Passes,

Jim



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Jim Varney      |  121^ 23' 54" W,  38^ 27' 28" N   |           Sacramento, CA
Civil Engineer  |            Elev. 31 ft.           |jvarney@mail2.quiknet.com
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