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Insat-4cr

 

Insat-4cr

INSAT-4CR
Mission type Communications
Operator ISRO
COSPAR ID 2007-037A
SATCAT № 32050
Website http://www.isro.org/satellites/insat-4cr.aspx
Mission duration 12 years (planned)
Spacecraft properties
Bus I-2K
Manufacturer ISRO
Launch mass 2,168 kilograms (4,780 lb)
Power 3000 W
Start of mission
Launch date 2 September 2007, 12:51 (2007-09-02T12:51Z) UTC
Rocket GSLV Mk.I F04
Launch site Satish Dhawan SLP
Orbital parameters
Reference system Geocentric
Regime Geostationary
Longitude 74° East
Perigee 35,779 kilometres (22,232 mi)[1]
Apogee 35,809 kilometres (22,251 mi)[1]
Inclination 0 degrees[1]
Period 1,436.1 minutes[1] minutes[1]
Transponders
Band 12 Ku band
Coverage area India
TWTA power 140 watts
EIRP 51.5 decibel-watts

INSAT-4CR is a communications satellite operated by ISRO as part of the Indian National Satellite System. Launched in September 2007, it replaced the INSAT-4C satellite which had been lost in a launch failure the previous year. The satellite is stationed in geostationary orbit at a lognitude of 74 degrees east, and is expected to operate for ten years, however this may have been reduced by the underperformance of the Geosynchronous Satellite Launch Vehicle which placed it into orbit.

Spacecraft

INSAT-4CR was constructed by ISRO, and is based around the I-2K satellite bus.[2] A 2,168-kilogram (4,780 lb) spacecraft, it is equipped with twelve Ku band transponders operating at a frequency of 36 MHz, with 140 Watt travelling wave tube amplifiers. The satellite has an effective isotropic radiated power of 51.5 dBW. An additional Ku band signal is used as a beacon for tracking.

INSAT-4CR operates in a geostationary orbit at a longitude of 74 degrees east, providing communications to India.[3] Broadcasting capacity on INSAT-4CR is allocated to Airtel Digital TV and Sun Direct DTH. At launch, the satellite was carrying 1,218 kilograms (2,685 lb) of fuel,[2] for raising itself into geostationary orbit, and subsequently operateing there for a planned twelve years.[4] Increased expendature of fuel reaching geostationary orbit, due to launch underperformance, may have resulted in a loss of up to five years of operational life.[5]

Launch

INSAT-4CR was launched on 2 September 2007 by the fifth flight of the Geosynchronous Satellite Launch Vehicle, GSLV-F04. The launch occurred at 12:51 UTC on 2 September 2007.[6] The third stage of the carrier rocket underperformed, resulting in the satellite being placed into a lower than planned orbit.

As a result of the underperformance during its launch, INSAT-4CR had to expend manoeuvring and station keeping propellant to raise its orbit by more than had originally been planned. It was subsequently reported by Indian news agencies that ISRO had lost track of the satellite's orbit, and could not locate the spacecraft until NASA identified it several days later, however ISRO denied these claims.[5][7] As a result of these failures, the operational lifetime of the satellite was reportedly decreased by up to five years.[5]

References

  1. ^ a b c d e "INSAT 4CR". N2YO. Retrieved 29 November 2011. 
  2. ^ a b Krebs, Gunter. "Insat 4C, 4CR". Gunter's Space Page. Retrieved 29 November 2011. 
  3. ^ "INSAT 4CR". The Satellite Encyclopedia. Retrieved 29 November 2011. 
  4. ^ "INSAT-4CR". ISRO. Retrieved 29 November 2011. 
  5. ^ a b c Ram, Arun (15 December 2007). "Isro satellite ‘disappears’, loses five years of life". DNA. Retrieved 29 November 2011. 
  6. ^ McDowell, Jonathan. "Launch Log". Jonathan's Space Page. Retrieved 29 November 2011. 
  7. ^ "ISRO refutes INSAT-4CR `disappearance' story". Hindustan Times. Retrieved 29 November 2011. 
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