Seven years after it took flight, the upper stage of the PSLV-C37 rocket has re-entered the Earth’s atmosphere, reported the Indian Space Research Organisation (ISRO) on Tuesday. It entered the Earth’s atmosphere on October 6, at around 9:19 PM IST, according to the US Space Command estimate, and fell into the North Atlantic Ocean.
The iconic PSLV-C37 mission started its flight on February 15, 2017, with Cartosat-2D as the main payload and an additional 103 satellites, namely INS-1A, INS-1B, Al-Farabi 1, BGUSAT, DIDO-2, Nayif 1, PEASS, 88 Flock-3p satellites, and 8 Lemur-2 satellites.It was the first of its kind mission and created history by launching 104 satellites with a single vehicle.
In the official statement, ISRO stated that the upper stage PS4, after injecting the satellites and passivation, stayed in an orbit of approximately 470 x 494 km size. The task of continuously tracking the rocket was headed by the US Space Command, a unified combatant command of the United States Department of Defense. As per reports, the rocket was tracked as an object with a NORAD ID 42052. Over time, its orbital altitude gradually decreased, primarily due to the effects of atmospheric drag.
ISRO’s System for Safe and Sustainable Space Operations Management (IS4OM), which has been tracking the orbital decay since September 2024, had predicted that the rocket might re-enter Earth’s atmosphere in the first week of October.
As per the guidelines of the Inter-Agency Space Debris Coordination Committee (IADC), the post-mission orbital life of a defunct object in Low-Earth orbit (LEO) should be no more than 25 years. The re-entry of the upper stage PSLV-C37 rocket body within 8 years of its launch complies with the aforementioned guidelines. This was done by properly lowering the orbit of PS4 after it had injected the satellites.
ISRO has been implementing measures to limit the residual orbital lifetime of PSLV upper stages to five years or less. This is achieved by de-orbiting them into lower altitude orbits through engine restarts, like what happens in PSLV-C38, PSLV-C40, PSLV-C43, PSLV-C56, and PSLV-C58 missions. Additionally, future PSLV missions are being planned with controlled re-entry strategies to safely dispose of the upper stages.
Space debris or space pollution is a growing concern, which refers to any human-made object in space that is no longer functional or has been discarded. This includes defunct satellites, spent rocket stages, fragments from collisions, paint flecks, and debris shields. These debris are harmful to other functional satellites in space. The Interagency Space Debris Coordination Committee (IADC) is a dedicated international organization that coordinates efforts to deal with space debris.
