The controlled re-entry experiment for the decommissioned Megha-Tropiques-1 (MT-1) was carried out successfully on March 7, 2023. The satellite was launched on October 12, 2011, as a collaborative effort between ISRO and the French space agency CNES for carrying out tropical weather and climate studies. Since August 2022, the satellite’s perigee was progressively lowered through a series of 20 manoeuvres spending about 120 kg of fuel. Multiple Manoeuvres including the final de-boost strategy were designed after taking into consideration several constraints, including visibility of the re-entry trace over ground stations, ground impact within the targeted zone, and allowable operating conditions of subsystems, especially the maximum deliverable thrust and the maximum firing duration constraint on thrusters. All manoeuvre plans were screened to ensure that there would be no post manoeuvre close approaches with other space objects, especially with the crewed space stations like International Space Stations and the Chinese Space Station.
The final two de-boost burns were executed at 11:02 UTC and 12:51 UTC respectively on 7th March 2023 by firing four 11 Newton thrusters on-board the satellite for about 20 minutes each. The final perigee was estimated to be less than 80 km indicating that the satellite would enter the denser layers of the Earth’s atmosphere and subsequently undergo structural disintegration. The re-entry aero-thermal flux analysis confirmed that there would be no surviving large debris fragments.
From the latest telemetry, it is confirmed that the satellite has re-entered the Earth’s atmosphere and would have disintegrated over the Pacific Ocean, the final impact region estimated is in the deep Pacific Ocean within the expected latitude & longitude boundaries. The entire sequence of events was carried out from the Mission Operations Complex in ISTRAC.
In recent years, ISRO has taken up proactive measures to improve the compliance level with the internationally accepted guidelines on space debris mitigation. Efforts are underway to build indigenous capabilities for tracking and monitoring space objects to safeguard Indian space assets. ISRO System for Safe and Sustainable Space Operations Management (IS4OM) has been established to spearhead such activities. The controlled re-entry exercise bears yet another testimony to India’s continued efforts towards ensuring the long-term sustainability of outer space activities.