INSAT-4CR

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 longitude 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. INSAT-4CR is planned to be replaced by GSAT-31, which was launched on February 6, 2019.

INSAT-4CR

Mission type	Communications
Operator	INSAT
COSPAR ID	2007-037A
SATCAT no.	32050
Website	http://www.isro.org/satellites/insat-4cr.aspx
Mission duration	Planned: 12 years Elapsed: 13 years, 4 months, 15 days
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 UTC
Rocket	GSLV Mk.I F04
Launch site	Satish Dhawan SLP
Orbital parameters
Reference system	Geocentric
Regime	Geostationary
Longitude	74° East
Perigee altitude	35,026 kilometres (21,764 mi)[1]
Apogee altitude	36,235 kilometres (22,515 mi)[1]
Inclination	0.15 degrees[1]
Period	1,428.12 minutes[1]
Epoch	14 September 2007[1]
Transponders
Band	12 Ku band
Coverage area	India
TWTA power	140 watts
EIRP	51.5 decibel-watts

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 K_u 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 K_u 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 operating there for a planned twelve years.[4] Increased expenditure 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 maneuvering 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. As of 26 August 2016 the satellite is still functioning.

References

1. McDowell, Jonathan. "SATCAT". Jonathan's Space Pages. Retrieved 3 May 2018.
2. 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. Archived from the original on 18 August 2013. Retrieved 29 November 2011.
5. 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. Archived from the original on 5 June 2011. Retrieved 29 November 2011.