News: The MMOD threat gained attention after space debris hit China’s Shenzhou-20 crewed vehicle, causing a minor crack in its return capsule window.
About Micrometeoroids and Orbital Debris (MMOD)
- Micrometeoroids: These are naturally occurring, extremely small particles ranging from a few micrometres to about two millimetres in size.
- Origin: Most originate from asteroid collisions in the asteroid belt, with some coming from comets.
- Velocity: They travel at very high velocities.
- Orbital Debris: These are human-made objects in Earth’s orbit that no longer serve any useful purpose.
- Origin: They mainly come from exploded rocket stages, defunct satellites, accidental collisions, and anti-satellite weapon tests.
- Threats Posed by MMOD
- The extreme velocity of MMOD means that even tiny fragments carry enough kinetic energy to cause critical damage or catastrophic failure to spacecraft systems.
- Kessler Syndrome: Increasing debris density may trigger cascading collisions, known as the Kessler Syndrome, potentially making space travel impossible in certain orbits.
- Mitigation and management strategies
- Space agencies use engineering models, tracking data, and software tools to assess MMOD risk and protect spacecraft using physical shielding such as Whipple shields.
- Large debris is tracked, and collision avoidance manoeuvres are performed when a risk is detected.
- International cooperation
- Inter-Agency Space Debris Coordination Committee (IADC): An international forum for governmental bodies to coordinate efforts in space debris research.
- ESA’s Zero Debris Charter: Aiming for zero new space debris by 2030.
- Indian initiatives
- Project NETRA (ISRO): An early warning system in space to detect debris and other hazards to Indian satellites.
- ISRO System for Safe and Sustainable Space Operations Management (IS4OM): A dedicated facility to monitor and mitigate space debris.
- POEM (PSLV Orbital Experimental Module): ISRO’s initiative to use spent rocket stages as orbital platforms, reducing “dead” junk in orbit.
