PSLV-C56 spent stage de-orbited to minimise space debris

The Indian Space Research Organisation (Isro) reduced the altitude of the spent stage of PSLV-C56/DS-SAR, launched on July 30, in line with India’s commitment to mitigation of space debris.

The space agency said the orbit of the spent PS4 stage was reduced to a 300-km circular orbit. At the achieved 536-km circular orbit, the PS4 stage would orbit the earth for over 25 years.

Isro said since the number of satellites in Low Earth Orbit is growing and the space around this orbit is of “particular interest”, the orbit of the spent stage was reduced. “In line with India's commitment to supporting worldwide space debris mitigation efforts, the Onboard Guidance Algorithm was modified to achieve this orbit-change manoeuvre. The Orbit Change Thrusters (low thrust engines) were fired twice for the orbit change,” it said.

In line with standard launch practices, the PS4 stage was passivated after the re-orbiting process, as no further active propulsion need was anticipated. “By mitigating the possibility of pressurised compartment failures, the chance of fragmentation of the spent stage in orbit is minimised, thereby further reducing the creation of space debris,” Isro said.

DS-SAR and six co-passenger customer satellites were injected into their intended 536-km circular LEO, with a 5-degree inclination, 20 minutes after the July 30 lift-off.

The vehicle achieved the precise target orbit conditions using the Onboard Navigation, Guidance and Control system and completed its mission.

The PSLV-C56/DS-SAR was launched from the Satish Dhawan Space Centre in Sriharikota, with the primary payload – the 352-kg earth observation satellite DS-SAR – and six co-passenger satellites, all from Singapore.

The primary satellite carries a Synthetic Aperture Radar (SAR) payload and is designed to support the satellite imagery requirements of agencies functioning under the Government of Singapore.