On Friday, ISRO announced that the fourth edition of the PSLV Orbital Platform Experiment Module (POEM-4), which is a repurposed spent upper stage of the Polar Satellite Launch Vehicle used for a space docking experiment mission, had re-entered the Earth’s atmosphere. ISRO stated that the POEM-4 module made its re-entry and impacted the Indian Ocean at 02:33 UTC (08:03 IST) on April 4, 2025. They highlighted that the successful re-entry of POEM-4 represented another milestone in their commitment to managing space debris, reinforcing the agency's role in ensuring the long-term sustainability of the outer space environment as part of their Debris Free Space Mission (DFSM).
On December 30, 2024, they had launched twin SpaDeX satellites aboard PSLV-C60, and after placing the satellites at an altitude of 475 km, POEM-4 was left in a similar orbit. ISRO explained that POEM-4 was subsequently de-orbited through engine restarts, achieving a nearly circular orbit at an altitude of 350 km with an inclination of 55.2 degrees. They noted that the PS4 had been passivated by venting the leftover fuel to mitigate any potential risks of accidental break-up.
During its mission life, POEM-4 hosted a total of 24 payloads—14 from ISRO and 10 from various non-governmental entities—and all payloads performed as expected, yielding valuable scientific data.
While in orbit, it was continuously tracked by ISRO’s radar facilities as well as those of the United States Space Command (USSPACECOM), information that was subsequently utilised in the re-entry prediction process.
ISRO observed that POEM-4’s orbit had decayed to 174 km by 165 km and predicted its re-entry to occur on April 4, 2025. The atmospheric re-entry event was closely monitored by ISRO's System for Safe and Sustainable Space Operations Management (IS4OM), which provided regular updates on the predictions.
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Inputs from PTI