POEM is the spent fourth stage of PSLV-C53, turned into a small orbiting platform for experiments after the rocket delivered its satellites in June 2022.
The PSLV Orbital Experimental Module uses the rocket's spent fourth stage (PS4) as a platform for experiments in orbit. PSLV-C53 was the first time a PS4 stage orbited Earth as a stabilised platform.
POEM carried six payloads, including two from the Indian space start-ups Digantara and Dhruva Space, enabled through IN-SPACe and NSIL.
A dedicated navigation, guidance and control system keeps the stage steady. Solar panels mounted around the PS4 tank and a lithium-ion battery supply power. It works out its orientation with four sun sensors, a magnetometer, gyros and NavIC, steers with control thrusters fed by stored helium gas, and can receive commands from the ground.
PSLV-C53 launched from the second launch pad at Sriharikota on 30 June 2022. It was NSIL's second dedicated commercial mission, carrying three Singapore satellites: DS-EO, NeuSAR and SCOOB-I.