Recently, PSLV-C53, carrying three Singapore satellites, was successfully launched by ISRO (Indian Space Research Organisation) in its 55th flight of PSLV, known as ISRO’s workhorse, and the 15th mission using the PSLV-Core Alone type. Along with it ISRO also successfully launched the PSLV Orbital Experimental Module, or ‘POEM’. POEM is an ISRO experimental mission that conducts scientific experiments in orbit utilising the discarded PS4 stage of the PSLV-CA launch vehicle as an orbital platform. The topic is relevant for the IAS Exam preparation.
This topic is covered under the Science and Technology of GS Paper-3 of the UPSC Syllabus. This article details the PSLV Orbital Experimental Module (POEM) platform and its functioning. Also, find answers to questions about how will ISRO keep POEM ‘alive and stable’ in orbit and when the PS4 rocket junk was repurposed and used earlier.
About PSLV Orbital Experimental Module (POEM)
The PSLV Orbital Experimental Module is a platform for conducting in-orbit experiments with the final, and otherwise discarded, stage of ISRO’s workhorse rocket, the Polar Satellite Launch Vehicle (PSLV). The PSLV is a four-stage rocket, where the first three spent stages fall back into the ocean and the last stage (PS4) ends up as space junk after launching the satellite into orbit.
In the PSLV-C53 mission, the expended final stage will be used as a “stabilised platform” for experiments. It is through the POEM platform that the PS4 stage will circle the Earth as a stabilised platform for the first time.
Background:
ISRO launched the second dedicated commercial mission of its commercial arm NewSpace India Limited (NSIL) – ‘PSLV-C53’ carrying three satellites from Singapore on June 30, 2022. The Indian PSLV rocket carried three satellites – the 365 kg DS-EO and 155 kg NeuSAR, satellites belonging to Singapore and built by Starec Initiative of South Korea. The third satellite Scoob-1 of Nanyang Technological University (NTU), Singapore, weighs 2.8kgs. It is important to note that the PSLV rocket has a minimum payload capacity of 1,000kg and that the entire payload mass of Thursday’s mission is barely half as much, thus making it a half-occupied vehicle.
Characteristics of POEM:
- POEM is carrying six payloads, two of which are from Indian Space Start-ups M/s Digantara and M/s Dhruva Space, and are enabled by IN-SPACe and NSIL.
- POEM derives the power from the solar panels mounted around the PS4 tank and a Li-Ion battery.
- It has the telecommand feature activated.
- It has specialised control thrusters that use Helium gas storage.
- It navigates using four sun sensors, a magnetometer, gyros and NavIC.
- Attitude stabilization is achieved using a dedicated NGC system.
Significance of POEM:
- A stabilized orbital platform is a significant upgrade over an orbital platform, as stabilization helps keep the payload in a correct position with respect to the Earth, sun etc. This could offer several scientific advantages for the payloads that are being carried.
- ‘POEM’ is like a pal that not only drops you off at your destination but also lends you the car to use. ‘POEM’ is a technological advancement over what ISRO attempted in 2019, during the launch of the PSLV-C44 mission.
Aspirants should read science and technology-related articles linked below:
| RSTV: Semi-Cryogenic Technology for Gaganyaan | Gaganyaan Mission |
| BHUVAN – Geo-Spatial Data | NISAR |
| Mars Orbiter Mission (MOM) | IN-SPACe |
Has ISRO repurposed and used PS4 rocket junk earlier?
- The PSLV-C44 mission, which inserted Microsat-R and Kalamsat-V2 satellites into their intended orbits, was the first time the Indian space agency showed the feasibility of employing PS4 as an orbital platform. The mission’s fourth stage was preserved as an orbital platform for space-based research.
- The fourth stage (PS4) of the vehicle was transferred to a higher circular orbit of 453 km after two restarts of the stage, to build an orbital platform for carrying out experiments. Kalamsat-V2, the first student payload to employ the PS4 as an orbital platform, was sent into orbit around 1 hour and 40 minutes after liftoff.
- While the fourth stage of that mission used Li-Ion batteries, solar panels have been added this time. The most recent reuse and upgrading of the PSLV rocket’s fourth stage involve orbital platform stability.
Also, read about Reusable Launch Vehicle: Technology Demonstrator (RLV-TD) – Specifications, Cost and Mission, in the linked article.
How will ISRO maintain POEM’s orbit ‘alive and stable’?
- According to ISRO, PSLV Orbital Experimental Module (POEM) features a dedicated Navigation Guidance and Control (NGC) system for attitude stabilisation. This NGC system is responsible for managing any aerospace vehicle’s orientation within permissible limits. The NGC will serve as the platform’s brain, stabilising it with precision.
- POEM will be powered by solar panels installed around the PS4 tank and a lithium-ion battery. It will use four sun sensors, a magnetometer, gyros and NavIC to navigate.
- It has specialised control thrusters that use Helium gas storage and has a telecommand function.
Increase your knowledge about the list of India Satellites from 1975 to 2020 in the linked article.
Some more related links that can be beneficial for Science and Technology preparation for GS 3 are mentioned below:
