How ISRO Safeguarded Its Satellites From Space Debris Using Collision Avoidance Manoeuvres

In 2023, the space sector witnessed substantial growth, with the Indian Space Research Organisation (ISRO) receiving over 137,565 close approach alerts for its space assets from the US Space Command (USSPACECOM).

Through successful collision avoidance manoeuvres (CAMs), ISRO averted potential collisions with space debris or other objects, safeguarding its satellites as per a report by The New Indian Express.

The annual report, Indian Space Situational Assessment Report (ISSAR) for 2023, released by S Somanath, Secretary of the Department of Space and Chairman of ISRO, and compiled by ISRO System for Safe and Sustainable Space Operations Management (IS4OM), disclosed this data.

According to ISSAR, ISRO detected 3,033 close approach alerts within 1 km distance for its satellites and identified 2,700 close approaches with other operational satellites within 5 km.

ISRO conducted 23 CAMs to protect satellites in Low Earth Orbit (LEO) and Geo-synchronous Earth Orbit (GEO), marking an increase from the previous year's 22 CAMs.

This surge can be attributed to the escalating space debris and frequent global launches, causing congestion in outer space.

Coordination with international agencies like SpaceX and EUMETSAT was undertaken on certain occasions. However, none of the close approaches necessitated a CAM.

Collision Avoidance Analysis (COLA) data for Launch Vehicles revealed crucial delays in launches, such as a four-second delay in Chandrayaan-3's launch to avoid debris collision. Similar delays were observed in DS-SAR's lift-off to prevent close approaches with Starlink satellites.

ISSAR underscored the urgent need for Space Traffic Management (STM) due to the growing population of active satellites. The report cautioned that without a universally accepted STM framework, the resolution of on-orbit close approaches relies on case-by-case inter-operator coordination.

Experts stressed the importance of sustainable space activities, recognising the global implications of actions in space. They emphasised responsible utilisation of near-Earth space to harness its benefits for society.

In 2023, the space object population grew significantly, with 3,143 objects added from 212 launches and on-orbit break-up events, compared to 2,533 objects from 179 launches in 2022.

Additionally, 69 fragmented objects contributed to space debris. India's satellite distribution includes 22 in LEO and 29 in GEO.

The year also saw the successful placement of 5 Indian satellites, 46 foreign satellites, and 8 rocket bodies, including POEM-2, into their designated orbits.