INSAT-4B is the 21st Indian Geostationary Earth Orbit (GEO) satellite to undergo post-mission disposal

Amid the growing concern over junk in outer space, the Indian Space & Research Organisation (ISRO) successfully disposed of one of its satellites after it completed its operational life in orbit. The INSAT-4B underwent Post Mission Disposal (PMD) at the end of its service, followed by decommissioning on January 24, ISRO said.

"INSAT-4B is the 21st Indian Geostationary Earth Orbit (GEO) satellite to undergo post-mission disposal, the required propellant for such re-orbiting was included in the initial fuel budget as a part of standard practice followed in ISRO's GEO mission planning," ISRO said in a statement.

The development is in compliance with the UN and the Inter-Agency Space Debris Coordination Committee (IADC) recommended space debris mitigation guidelines. The IADC guidelines provide guidance for limiting the generation of orbital debris both during and after space operations. The guidelines also define accepted disposal orbits and other conditions, such as the timeline for abandoning commonly used orbits and controlling the risk to people and property on the Earth.

ISRO added that the successful post-mission disposal of INSAT-4B through meticulous planning and flawless execution marks yet another endeavour by the space agency to ensure the safety and sustainability of outer space operations.

The successful post-mission disposal of INSAT-4B

Decommissioning Insat-4B

ISRO said that as per the IADC guidelines at its end-of-life, a GEO object should be raised to a nearly circular orbit well above the GEO belt to prevent its orbit from coming back into the GEO-protected region within 100 years of re-orbiting. The INSAT-4B satellite's orbit was raised by 273 kilometers through 11 re-orbiting manoeuvres executed during 17 23 January 2022.

"The first manoeuvre was aimed to circularize the orbit. The subsequent re-orbiting manoeuvres were executed at the perigees and the apogees alternately making the intermediate orbits near-circular." ISRO said. Once the orbit was raised, the team vented the remaining propellant and electrical passivation activities were carried out to minimise post-mission break-up risk before finally decommissioning the satellite.

What Was The Insat-4B Spacecraft?

The INSAT-4B mission was launched on March 12, 2007 to render DTH and other communication services. After completing nearly 14 years of on-orbit operations, the C band and Ku band payload services of INSAT-4B were seamlessly migrated to other GSATs before the commencement of post-mission disposal.

The spacecraft had outlived its operational life of 12 years in the Geostationary Earth Orbit (GEO). The spacecraft had three earth sensors, two digital sun sensors, eight coarse analogue sun sensors, three solar panel sun sensors, and one sensor processing electronics.

The 3025-kilogram communication satellite was launched into space from French Guiana on an Ariane5 launch vehicle.