INSAT-4CR was a

communications satellite A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Earth ...

operated by

ISRO The Indian Space Research Organisation (ISRO; ) is the national space agency of India, headquartered in Bengaluru. It operates under the Department of Space (DOS) which is directly overseen by the Prime Minister of India, while the Chairman o ...

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 was initially stationed in

geostationary orbit A geostationary orbit, also referred to as a geosynchronous equatorial orbit''Geostationary orbit'' and ''Geosynchronous (equatorial) orbit'' are used somewhat interchangeably in sources. (GEO), is a circular geosynchronous orbit in altitu ...

at a longitude of 74 degrees east, with expected operational life of at least ten years, however this may have been reduced by the underperformance of the

Geosynchronous Satellite Launch Vehicle Geosynchronous Satellite Launch Vehicle (GSLV) is an expendable launch system operated by the Indian Space Research Organisation (ISRO). GSLV was used in fourteen launches from 2001 to 2021. Even though GSLV Mark III shares the name, it is ...

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

Spacecraft

INSAT-4CR was constructed by ISRO, and is based around the

I-2K I-2K is a satellite bus developed by Indian Space Research Organisation (ISRO), and marketed by Antrix Corporation. It is a standard bus for 2,000 kg class satellites; the 'I' in I-2K stands for INSAT, a group of communication satellites devel ...

satellite bus A satellite bus (or spacecraft bus) is the main body and structural component of a satellite or spacecraft, in which the payload and all scientific instruments are held. Bus-derived satellites are opposed to specially produced satellites. Bus- ...

. A 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 Effective radiated power (ERP), synonymous with equivalent radiated power, is an IEEE standardized definition of directional radio frequency (RF) power, such as that emitted by a radio transmitter. It is the total power in watts that would hav ...

of 51.5 dBW. An additional K_u band signal is used as a beacon for tracking. INSAT-4CR operated in a geostationary orbit at a longitudes of 74° East and 48° East, providing communications to India. Broadcasting capacity on INSAT-4CR was allocated to

Airtel Digital TV Bharti Telemedia Limited, doing business as Airtel Digital TV, is an Indian direct-broadcast satellite service provider owned and operated by Bharti Airtel. Its satellite service, launched in October 2008, transmits digital satellite televisi ...

and

Sun Direct DTH Sun Direct is an Indian direct broadcast satellite service provider. Sun Direct was launched in December 2007. It transmits digital satellite television and audio to households in India. Sun Direct uses MPEG-4 digital compression, transmittin ...

. At launch, the satellite was carrying of fuel, for raising itself into geostationary orbit, and subsequently operating there for a planned twelve years. 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.

Launch

INSAT-4CR was launched on 2 September 2007 by the fifth flight of the

, GSLV-F04. The launch occurred at 12:51 UTC on 2 September 2007. 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 The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeedin ...

identified it several days later, however, ISRO denied these claims. As a result of these failures, the operational lifetime of the satellite was reportedly decreased by up to five years.

End of life and replacement

Towards the end of its service life INSAT-4CR was relocated from 74°E to 48°E slot on 10 February 2017 where it stayed until being retired and placed into

graveyard orbit A graveyard orbit, also called a junk orbit or disposal orbit, is an orbit that lies away from common operational orbits. One significant graveyard orbit is a supersynchronous orbit well beyond geosynchronous orbit. Some satellites are moved into ...

on 24 November 2020. Services of INSAT-4CR were handed over to GSAT-31.

References

{{Orbital launches in 2007 Spacecraft launched in 2007 Partial satellite launch failures INSAT satellites 2007 in India Spacecraft launched by GSLV rockets