After placing X-Ray Polarimeter Satellite into an orbit of 650km with 6-degree inclination, the Indian Space Research Organisation (ISRO) has lowered the launch vehicle’s fourth spent stage. It will be used as a platform for upcoming onboard experiments.

“The PS4 stage is successfully brought down to a 350 km orbit,” said ISRO in the mission update.

After completing the primary objective of injecting the XPoSat into a 650km, 6 degree orbit, the PS4 stage underwent an orbit change, descending to a 350km, ~9.6-degree orbit through two restarts.

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The remaining propellant in the PS4 was safely disposed of using the Main engines, setting the stage for future atmospheric re-entry experiments.

ISRO’s PSLV Orbital Experimental Module (POEM) allows in-orbit scientific experiments using the spent PS4 stage as an orbital platform. Power requirements are met through Flexible Solar Panels and a 50Ah Li-ion battery in a tied configuration. Avionic systems manage Navigation, Guidance, Control, telecommands, and the Orbital Platform Attitude Control System, ensuring precise control for payload testing on the orbital platform, the space agency said.

The experiments to be performed on POEM

1. Bellatrix Aerospace, based in Bengaluru, will test Rudra 0.3 HPGP, a green monopropellant thruster, and ARKA-200, a heater-less hollow cathode for Hall thrusters.

2. InspeCity Space Labs, located in Mumbai and incubated by IIT Bombay, will test the Green Impulse TrAnsmitter (GITA), a green bipropellant CubeSat propulsion unit.

3. TakeMe2Space from Hyderabad will test its Radiation Shielding Experimental Module (RSEM) designed to evaluate the effectiveness of Tantalum coating, enhancing CubeSat lifespan.

4. Thiruvananthapuram-based LBS Institute of Technology for Women contributed the Women Engineered Satellite (WESAT), measuring solar irradiance and UV Index.

5. KJ Somaiya Institute of Technology in Mumbai features BeliefSat-0, an amateur radio satellite, onboard POEM.

6. ISRO’s Vikram Sarabhai Space Centre (VSSC) has two payloads, the Fuel Cell Power System (FCPS) and Silicon-based High Energy Cell, onboard POEM.

7. The Ahmedabad-based Physical Research Laboratory has sent the Dust Experiment (DEX) on POEM, designed to measure interplanetary dust count.

One of the experiments intended are, involves testing FCPS. Fuel cells function similarly to batteries, but they do not deplete or require recharging. They generate electricity and heat as long as fuel, such as hydrogen, is provided.

ISRO’s decision to test FCPS in the lower orbit aligns with a broader strategy to validate technologies crucial for the proposed Indian Space Station’s success, reported India Today.