on Friday night said the fourth edition of the PSLV Orbital platform Experiment Module (POEM-4), the repurposed spent upper stage of the Polar Satellite Launch Vehicle used for the space docking experiment mission, has re-entered the Earth’s atmosphere. “Finally, the POEM-4 module re-entered the atmosphere and impacted at 02:33 UTC (08:03 IST), April 04, 2025, in the Indian Ocean,” ISRO said in a post on ‘X’. The safe re-entry of POEM4 is yet another accomplishment of ISRO’s commitment to contain the growth of space debris, reaffirming the prominent role of the space agency in the longterm sustainability of outer space environment and Debris Free Space Mission (DFSM), it said.

 

On December 30, 2024, ISRO’s PSLV-C60 launched twin SPADEX (Space Docking Experiment) satellites and after injecting satellites at 475 km altitude, the specially configured upper stage (PS4) of PSLV-C60 (called PSLV Orbital Experimental Module in short POEM-4) was also almost in the same orbit. Noting that subsequently, POEM-4 was de-orbited by engine restarts to a nearly circular orbit at 350 km altitude with 55.2 inclination, ISRO said, the PS4 was then passivated by venting the leftover fuel to minimise any potential risk for accidental break-up. “During its mission life, POEM-4 hosted altogether 24 payloads (14 payloads from ISRO and 10 from various NGEs) and all payloads worked as expected yielding valuable science data,” it said. While the POEM-4 was in orbit, it was continuously tracked by ISRO’s Radar Facilities and

 

United States Space Command (USSPACECOM) facilities as well. The tracking data was in turn utilised in the re-entry prediction process, ISRO said, adding that it was observed that POEM4’s orbit had decayed to 174 kmx165 km and the platform was predicted to re-enter the Earth’s atmosphere on April 04, 2025. The atmospheric re-entry event of POEM-4 was then closely monitored by ISRO System for Safe and Sustainable Space Operations Management (IS4OM) and regular updates in predictions were made, it added.