ISRO’s ‘zero orbital debris’ milestone

• The Indian Space Research Organisation (ISRO) has said its PSLV-C58/XPoSat mission has practically left zero debris in earth orbit.

Key highlights

• The space agency explained that the last stage of the Polar Satellite Launch vehicle (PSLV) used in the mission was transformed into a kind of orbital station — called the PSLV Orbital Experimental Module-3 (POEM-3)
  • Before it was left to re-enter the earth’s atmosphere instead of floating in orbit once its mission was completed.
• After it completed the primary mission of injecting all satellites into their target orbits, the fourth stage of the PSLV was transformed into the POEM-3.
• It was subsequently de-orbited from 650 km to 350 km, rendering it more susceptible to being pulled towards the earth and burning up in the atmosphere.
• It “passivated the stage,” meaning dumped its fuel, to avoid an explosion that could have flung small pieces of debris into orbit.

ISRO’s ‘zero orbital debris’ milestone

• Orbital threat: With the increasing number of satellites launched, space debris has become a major concern.
• ISRO's solution: The Indian Space Research Organisation (ISRO) achieved a “zero orbital debris” feat with its PSLV-C58/XPoSat mission.

PSLV Orbital Experimental Module (POEM-3):

• Purpose: To minimize space debris by re-entering Earth's atmosphere after mission completion.
• Function: Transformed from the spent fourth stage of the PSLV rocket into a temporary space platform.

POEM-3's journey:

• Launched in January 2024.
• Deployed XPoSat satellite and lowered its own orbit to 350 km for faster re-entry.
• Conducted experiments with nine payloads for 25 days.
• Re-entered Earth's atmosphere in March 2024.

Significance of POEM-3:

• Mitigates space debris issue by ensuring the launch vehicle's stage doesn't become permanent orbital clutter.
• Sets an example for responsible space practices.

Why is space debris a problem?

• LEO (Low Earth Orbit) is crucial for various applications like navigation and communication.
• Growing space debris in LEO (from defunct satellites, rocket parts, etc.) poses a collision risk to operational satellites.
• Collisions can create even more debris, triggering a domino effect.

Current situation:

• Thousands of operational satellites and millions of debris pieces orbit Earth.
• International guidelines exist (IADC Space Debris Mitigation Guidelines 2002) but no binding laws for LEO debris management.

The future of space debris:

• The number of debris objects is expected to rise significantly by 2030.
• More space debris can render certain orbits unusable and create a cascading effect of collisions.