“INSAT-4B has been eliminated after the mission (PMD) at the end of its useful life followed by decommissioning on January 24, 2022 to comply with the UN and the INTER Agency Space Debris Coordination Committee (IDC) recommended space debris mitigation guidelines,” Isro said.
INSAT-4B was launched on March 12, 2007 for DTH and other communication services. After completing nearly 14 years of in-orbit operations, INSAT-4B’s Ku-band and C-band payload services were migrated to other GSATs before the start of post-mission phase-out.
“Under IADC space debris mitigation guidelines, at the end of its useful life, a GEO the object must rise to a nearly circular orbit well above the GEO belt to prevent its orbit from returning to the GEO protected region within 100 years of re-orbiting. In this case, the minimum required orbit increase was 273 km and this is achieved through 11 re-orbiting maneuvers executed from January 17-23, 17-23,” Isro said.
The space agency added that the first maneuver was aimed at circularizing the orbit. Subsequent re-orbiting maneuvers were performed at perigees (closer to land) and the (further) apogees alternating the almost circular intermediate orbits.
“All maneuver plans were reviewed to ensure that there were no close approaches or collision threats between other space objects (active satellites and space debris) in the near future. On January 24, the remaining ventilation activities of propellant and electrical passivation to minimize risk of post-mission breakup before finally dismantling the satellite,” Isro said.
This intensive remote control operation, he said, was carried out between 70 and 74 east grade longitude region to avoid radio frequency interference with the other operational GEO satellites.
“INSAT-4B is India’s 21st GEO satellite to undergo PMD. The booster required for such a relocation was included in the initial fuel budget as part of the standard practice followed in planning the Isro GEO mission. Orbit finally reached is about 340 km above GEO Altitude in perfect compliance with IADC guidelines for space debris mitigation of GEO objects,” Isro added.
Successful PMD through meticulous planning and flawless execution marks another effort by Isro to ensure the safety and sustainability of outer space operations.