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India’s
GSat 1 Stranded Short of Geosyncrhonous Orbit
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India’s recently
launched experimental satellite, GSat 1, has encountered minor
problems, preventing plans of carrying out experiments on board. The
1.54 metric tonne satellite was orbiting with a period of 23 hours
two minutes, instead of the planned 24 geosynchronous orbit. The
satellite was to be used for a variety of experiments such as
digital audio broadcasting and compressed digital TV signal
transmission.
The GSLV (Geosynchronous
Satellite Launch Vehicle) suffered a performance shortfall during
its first flight resulting in the injection of the experimental
satellite into a geosynchronous transfer orbit of 181 x 32,051 km,
inclined at 19.2 degrees, having an apogee about 4,000 km below the
targeted orbit of 185 x 35,975 km. The satellite used its onboard
propulsion system to raise both its apogee and its perigee to
geostationary orbit as well as to decrease the orbital inclination
to zero, however its propellant was depleted prior to successfully
raising its orbit. The satellite used two different propellant
tanks, built in Germany and India, which resulted in an unequal flow
of fuel, causing the spacecraft to tilt. (The two different fuel
tanks were used because they were readily available.) Recovery
required the use of more propellant than planned which resulted in
the satellite having no propellant left to complete its final
circularization maneuver. The Indian Space Research Organization is
now reviewing options on how to use the satellite from this orbit.
While it may be possible to use the satellite for a few
communications experiments, it is unlikely, that the original
purpose of demonstrating digital TV and audio broadcasts, as well as
Internet services, can be fulfilled.
The
Russian 12KRB cryogenic upper stage was planned to perform for 710
seconds, but its burn apparently lasted only 698 seconds. Another
suspect for the shortfall is the launch vehicle navigation system
which was derived from the PSLV which has flown only to low earth
orbits.
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