Explained: What is ISRO’s ‘POEM’ platform?

What is the News?

Indian Space Research Organization(ISRO) PSLV-C53 rocket has successfully placed three Singaporean satellites into orbit.

Besides placing these three Singaporean satellites in orbit, ISRO has also achieved the feat of successfully launching the PSLV Orbital Experimental Module or ‘POEM’.

What is POEM?

The PSLV Orbital Experimental Module is a platform that will help perform in-orbit experiments using the final and otherwise discarded stage of ISRO’s workhorse rocket, the Polar Satellite Launch Vehicle (PSLV).

What is PSLV and how was it used in PSLV-C53?

The PSLV is a four-stage rocket where the first three spent stages fall back into the ocean, and the final stage (PS4) — after launching the satellite into orbit — ends up as space junk.

However, in the PSLV-C53 mission, the spent final stage was utilized as a “stabilized platform” to perform experiments.

Note: This is the first time that the PS4 stage would orbit the earth as a stabilized platform.

How will ISRO keep POEM ‘alive and stable’ in orbit?

POEM has a dedicated Navigation Guidance and Control(NGC) system for attitude stabilization, which stands for controlling the orientation of any aerospace vehicle within permitted limits. The NGC will act as the platform’s brain to stabilize it with specified accuracy.

POEM will also derive its power from solar panels mounted around the PS4 tank and a Li-Ion battery. It will navigate using four sun sensors, a magnetometer, gyros & NavIC.

Has ISRO repurposed and used PS4 rocket junk earlier?

ISRO first demonstrated the capability of using PS4 as an orbital platform in 2019 with the PSLV-C44 mission that injected Microsat-R and Kalamsat-V2 satellites into their designated orbits. The fourth stage in that mission was kept alive as an orbital platform for space-based experiments.

Source: The post is based on the article “Explained: What is ISRO’s ‘POEM’ platform?” published in Indian Express on 1st July 2022