INSAT-4CR was a

communications satellite A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a Transponder (satellite communications), transponder; it creates a communication channel between a source transmitter and a Rad ...

operated by

ISRO The Indian Space Research Organisation (ISRO ) is India's national space agency, headquartered in Bengaluru, Karnataka. It serves as the principal research and development arm of the Department of Space (DoS), overseen by the Prime Minister o ...

as part of the

Indian National Satellite System The Indian National Satellite System or INSAT, is a series of multipurpose geostationary satellites launched by the ISRO, Indian Space Research Organisation (ISRO) to satisfy telecommunications, broadcasting, meteorology, and search and rescu ...

. Launched in September 2007, it replaced the

INSAT-4C INSAT-4C was an Indian communications satellite which was lost in a launch failure in 2006. Had it reached orbit, it would have formed part of the Indian National Satellite System. Launched in 2007, it was intended to have operated in geostationary ...

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 orbit, circular geosynchronous or ...

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 a class of expendable launch systems operated by the ISRO, Indian Space Research Organisation (ISRO). GSLV has been used in List of GSLV launches, fifteen launches since 2001. History The Geo ...

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 deve ...

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 less customized than specially-produced satelli ...

. A spacecraft, it is equipped with twelve K_u band transponders operating at a frequency of 36 MHz, with 140 Watt

travelling wave tube A traveling-wave tube (TWT, pronounced "twit") or traveling-wave tube amplifier (TWTA, pronounced "tweeta") is a specialized vacuum tube that is used in electronics to amplify radio frequency (RF) signals in the microwave range. It was invented ...

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 Airtel Digital TV is an Indian subscription based satellite television provider owned by Bharti Telemedia Limited, a wholly-owned subsidiary of Bharti Airtel. It launched DTH satellite television service in India on 9 October 2008. Airtel D ...

and Sun Direct DTH. 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 agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

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 (physics), orbit that lies away from common operational orbits. One significant graveyard orbit is a supersynchronous orbit well beyond geosynchronous orbit. Some satellit ...

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

References

{{Orbital launches in 2007 Spacecraft launched in 2007 Satellite launch anomalies INSAT satellites 2007 in India Spacecraft launched by GSLV rockets