‘Milestone’: Isro rocket’s 4th stage returns to Earth, accomplishes zero space debris mission | India News

NEW DELHI: In “another milestone” for Isro, the fourth stage of the PSLV-C58 rocket, which doubled up as an experimental platform in space after the launch of primary satellite X-ray Polarimeter Satellite (XPoSat) on January 1 this year, has finally returned to Earth after performing its duties, leaving no junk in space. The PSLV-C58 mission left “practically zero debris in orbit,” Isro said.
After launching primary satellite XPoSat, the fourth rocket stage (PS4), also called PSLV Orbital Experimental Module-3 (POEM-3), allowed nine different payloads to carry out technology demonstrations and scientific experiments in zero gravity in space.By late Jan 2024, POEM-3 achieved all its mission goals, and the only objective that remained to be fulfilled was an atmospheric re-entry. On March 21, POEM-3 made a fiery re-entry to the Earth’s atmosphere and is believed to have splashed down into the North Pacific Ocean at 7.34 pm IST, the agency said.
PSLV-C58 is the third such mission in the series where the fourth stage of the rocket was used as an experimental platform (POEM), scripting success each time.
Through the POEM, which serves as a very cost-effective platform for carrying out short-duration space-borne experiments, Isro has opened up new vistas for academia, startups and NGEs to carry out space experiments with their new payloads. This opportunity has been effectively used by numerous startups, universities and NGEs for carrying out experiments in space, which included electric thrusters, satellite dispensers, and star-tracking. Out of the nine payloads, six were delivered by non-governmental entities (NGEs) through space regulator IN-SPACe. The mission objectives of these payloads were met in a month.

The stage was de-orbited from 650 km to 350 km, which facilitated its early re-entry and was passivated to remove residual propellants to minimise any accidental break-up risks.
The orbital altitude of the upper stage continued to decay under the influence of natural forces, primarily atmospheric drag with the module (NORAD ID 58695) expected to have impacted the North Pacific Ocean (Lat 6.4 N & Long 158.7 W) on March 21, 2024, at 14:04 UTC (19:34 Hrs. IST), Isro said. Till near re-entry, POEM-3 was tracked by Isro’s ISTRAC ground stations. The Multi-Object Tracking Radar at Sriharikota also tracked the fourth stage (PS4 stage) return to the Earth.
Isro said it will continue its commitment to providing a cost-effective orbital experiment platform.