The Indian Space Research Organisation (ISRO) informed that the upper stage of the Polar Satellite Launch Vehicle C-37 (PSLV C-37 mission) re-entered the Earth’s atmosphere on October 6.

About PSLV-C37 Mission

• Launched on February 15, 2017 with Cartosat-2D as the main payload along with another 103 satellites,
  • INS-1A, INS- 1B, Al-Farabi 1, BGUSAT, DIDO-2, Nayif 1, PEASS, 88 Flock-3p satellites, and 8 Lemur-2 satellites. 
• 104 satellites: Highest number of satellites launched in a single flight so far

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Orbital Decay and Re-entry

• After injecting satellites into orbit, the PS4 upper stage was left in a 470×494 km orbit.
• Due to atmospheric drag, the orbit decayed, leading to re-entry.
• Re-entry occurred in the North Atlantic Ocean, as predicted by both ISRO and US Space Command (USSPACECOM).

Compliance with International Guidelines

• The re-entry was compliant with the Inter-Agency Space Debris Coordination Committee (IADC) guidelines, which recommend limiting post-mission orbital life of defunct objects in Low-Earth Orbit (LEO) to 25 years.
• ISRO reduced the residual orbital lifetime to 8 years through a passivation sequence.

Future Debris Mitigation Initiatives

• ISRO is working to reduce the post-mission orbital lifetime of PSLV upper stages to less than 5 years using engine restarts.
• Controlled re-entry is planned for future PSLV missions.
• ISRO aims to achieve the “Debris Free Space Mission” (DFSM) by 2030 as part of its commitment to space sustainability.

About Debris-Free Space Missions (DFSM)

• The Debris-Free Space Missions (DFSM) is an initiative by the Indian Space Research Organisation (ISRO) to make all Indian space missions debris-free by 2030. 
• The initiative aims to ensure the sustainability of space by reducing the amount of space debris and preventing future collisions. 
• The DFSM initiative includes: 
  • Avoiding debris generation: This includes avoiding debris during the operational life of satellites and launch vehicles, as well as during post-mission disposal. 
  • Avoiding on-orbit collisions: This includes using failure mode studies, redundant systems, and mission design with high reliability. 
  • Guidelines for space actors: 
    • This includes guidelines for all Indian space actors, both governmental and non-governmental,
    • It is on how to select clean orbits, budget fuel for post-mission disposals, and control trajectories during atmospheric re-entry. 

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Re-entry missions of ISRO

• LVM3-M3
  • The LVM3-M3 rocket body was disposed of through natural orbital decay within two years of orbital injection. 
  • This complied with international guidelines and India’s Debris Free Space Missions (DFSM) initiative. 
• Crew Module Atmospheric Re-entry Experiment (CARE)
  • Launched on December 18, 2014, CARE was an experimental test vehicle for ISRO’s future orbital vehicle, Gaganyaan.