GSLV stage (left), Semi-cryo testing (right)

BENGALURU: Isro achieved two milestones in the past month with the flagging off of the GSLV’s second stage for the upcoming Nasa-Isro mission, Nisar, and the successful testing of its semi-cryogenic engine at the Isro Propulsion Complex (IPRC) in Mahendragiri, it said late Friday.
Isro chairman V Narayanan officially flagged off the second stage (GS2) of the GSLV launch vehicle in the last week of March, destined for the launch complex at Sriharikota. This liquid stage will power the GSLV-F16 mission carrying the Nasa-Isro Synthetic Aperture Radar (Nisar) satellite, with launch campaign activities already underway since early April.

In parallel development, Isro conducted a successful short-duration hot test of its semi-cryogenic engine at IPRC Mahendragiri on April 24. This 3.5-second ignition test marks the second achievement following the breakthrough first hot test conducted on March 28.
“During the test, the engine power head test article — comprising all engine systems except the thrust chamber — was ignited and operated at 60% of its rated power, demonstrating stable and controlled performance,” Isro said.
These tests form part of a planned evaluation series designed to validate the design integrity and performance of critical subsystems, including the turbo pumps, pre-burner, and associated control systems. The data collected will help finalise the operational sequencing of the full semi-cryogenic engine.
Additional qualification tests are scheduled to comprehensively validate the engine system before its integration into Isro’s launch vehicles.