Why in news?

ISRO announced the successful re-entry of the Polar Satellite Launch Vehicle-C37 (PSLV-C37) upper stage into Earth's atmosphere on October 6. This achievement aligns with global efforts to reduce space debris, supporting ISRO's goal of achieving debris-free space missions by 2030.

What’s in today’s article?

• Space Debris
• PSLV- C37 upper stage re-enters Earth orbit

Space Debris

• About
  • Space debris refers to defunct, human-made objects in Earth's orbit, such as non-functional satellites, spent rocket stages, and fragments from satellite collisions.
  • These debris pose a growing threat to operational spacecraft, satellites, and the International Space Station (ISS).
• Challenges
  • Collisions: Even tiny debris can cause severe damage to satellites and space stations due to their high velocities.
  • Chain Reaction (Kessler Syndrome): Increasing debris can lead to more collisions, creating even more debris and increasing the risk of cascading damage.
  • Cost of Mitigation: Tracking and removing debris require advanced technology and substantial financial investment.
• Increasing space debris
  • With the rise in the number of satellites in orbit around the earth, space debris has become a pressing issue.
  • According to ISRO’s Space Situational Assessment report 2022, the world placed 2,533 objects in space in 179 launches in 2022.
    • The number of space objects greater than 10 cm in size in LEO is expected to be about 60,000 by 2030.
• Legal provisions
  • Currently, there are no international space laws pertaining to LEO debris.
  • However, most space-exploring nations abide by the Space Debris Mitigation Guidelines 2002 specified by the IADC. This was endorsed by the U.N. in 2007.
    • The guidelines outline methods to limit accidental collisions in orbit, break-ups during operations, intentional destruction, and post-mission break-ups.
• International Institutions
• Inter-Agency Space Debris Coordination Committee (IADC): A global forum that coordinates efforts to mitigate space debris.
• United Nations Committee on the Peaceful Uses of Outer Space (COPUOS): Sets space debris mitigation guidelines.
• International Telecommunication Union (ITU): Regulates satellite orbital slots to prevent overcrowding.
• Steps taken by India
  • Debris Free Space Mission (DFSM): ISRO is committed to achieving a debris-free space environment by 2030 through passivation, active de-orbiting, and controlled re-entry of spent rocket stages.
    • The implementation of this DFSM initiative will start by the beginning of 2025.
    • This includes selecting clean orbits, budgeting fuel for post-mission disposal, and precisely controlling re-entry trajectories.
  • ISRO’s Debris Mitigation Strategy: India’s space agency, ISRO, follows international guidelines, including the IADC's recommendation to limit post-mission orbital life to 25 years.
  • IS4OM (ISRO System for Safe and Sustainable Space Operations Management): Monitors space debris and orbital decay, ensuring compliance with mitigation guidelines.

PSLV- C37 upper stage re-enters Earth orbit

• Re-entry of PSLV- C37 upper stage
  • On October 6, 2024, the upper stage of ISRO's PSLV-C37 mission, launched in February 2017, re-entered Earth's atmosphere.
    • The PSLV-C37 carried 104 satellites, including Cartosat-2D as the primary payload.
  • After the mission, the upper stage (PS4) remained in orbit at approximately 470x494 km.
  • Over time, its orbit decayed due to atmospheric drag and was closely monitored by ISRO and US Space Command (USSPACECOM).
• Re-entry followed international debris mitigation guidelines
  • This re-entry followed international debris mitigation guidelines, specifically the IADC recommendation to limit the post-mission orbital life to 25 years.
  • ISRO's passivation sequence successfully lowered PS4’s orbit, ensuring re-entry within eight years.
  • ISRO is now working to further reduce the orbital lifetime of rocket stages to five years through active de-orbiting, with future missions focusing on controlled re-entry.
    • ISRO also aims to achieve a Debris Free Space Mission (DFSM) by 2030.