“POEM”

• The Indian Space Research Organisation (ISRO) on Thursday also achieved the feat of successfully launching the PSLV. Orbital Experimental Module or ‘POEM’.

• What is POEM?
  • POEM is a platform that will help perform in orbit experiments using the final, and otherwise discarded stage of ISRO’s workhorse rocket, PSLV. 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 will be utilized as a “stabilised platform” to perform experiments. “It is the first time that the PS4 stage would orbit the earth as a stabilised platform,” ISRO said in a statement prior to the launch.
    After the primary mission, the fourth stage will “write some poems in orbit”, ISRO Chairman S. Somanath said in a post launch address from Mission Control.
  • POEM is carrying six payloads, including two from Indian Space star-ups Digantara and Dhruva Space.

• How will POEM be kept stable in orbit?
  • According to ISRO, POEM has dedicated Navigation Guidance and Control (NGC) system for attitude stabilisation, or controlling the orientation of any aerospace vehicle within permitted limits. The NGC will stabilise the platform with specified accuracy.
  • POEM will 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”.
  • “It carries dedicated control thrusters using Helium gas storage. It is enabled with a telecommand feature,” ISRO said.

• Has ISRO repurposed and used PS4 rocket junk earlier?
  • ISRO first demon-started 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.
  • The latest repurposing and upgrade of the fourth stage of the PSLV rocket involves stabilistion of the orbital platform.