Indian Space Situational Assessment Report (ISSAR) for 2023 has revealed that more space objects were placed in orbit last year as compared to 2022.
The report, compiled by ISRO System for Safe and Sustainable Space Operations Management (IS4OM), was released in April by ISRO Chairman S. Somanath.
According to the report, the space object population continued to show a growing trend, indicative of better accessibility to space and the increasingly diverse applications of space technology in day-to-day life. During 2023, more space objects were placed in orbit compared to the previous year.
A total of 3,143 objects originating from 212 launches and on-orbit break-up events were added to the space object population in 2023 compared to 2,533 objects from 179 launches in 2022. There were five major on-orbit break-up events in 2023. Some of these fragments decayed within the same year, resulting in a net addition of 69 fragmented objects to the population of space debris by the end of 2023.
On the Indian scenario, a total of 21 satellites had re-entered the atmosphere till the end of 2023. In 2023 alone, eight Indian satellites re-entered the atmosphere, among them Megha-tropiques-1 underwent controlled re-entry through an immensely challenging exercise.
According to the report, 82 rocket bodies from Indian launches were placed in orbit till 2023. The upper stage of PSLV-C3 underwent an accidental break-up in 2001 and generated 371 debris. While most of these fragments have re-entered the atmosphere, 52 PSLV-C3 debris were still in orbit till the end of 2023. Among the intact Indian upper stages, 35 rocket bodies re-entered the Earth’s atmosphere till 2023-end, and five such re-entries took place in 2023.
The report said that ISRO regularly carries out analyses through IS4OM-ISTRAC to predict close approaches by other space objects to Indian space assets. In case of any critical close approach, collision avoidance manoeuvres (CAM) are carried out to safeguard the operational spacecraft.
About 1,37,565 close approach alerts were received from USSPACECOM (US Space Command). These alerts were re-assessed using more accurate orbital data of the Indian operational satellites.
A total of 3,033 alerts for close approaches within a distance of 1 km were detected for ISRO satellites. Around 2,700 close approaches were observed with other operational satellites within 5 km of close approach distance. On certain occasions, coordination was carried out with other international agencies, like SpaceX and EUMETSAT. However, none of the close approaches were critical enough to warrant a CAM.
In total, 23 CAMs were carried out during 2023 to protect Indian space assets compared to 21 in 2022 and 19 in 2021.
An increasing trend in CAMs per year is observed, which can be correlated with the growing congestion in outer space. No concerning close approaches with other space objects were detected for the Chandrayaan-3 mission throughout its mission phases, and also for Aditya-L1 during its Earth-bound phase.
