ISRO ready for Challenging controlled atmospheric re-entry of MT1 Satellite on Mar 7: ISRO

Chennai: The Indian Space Research Organisation (ISRO) is gearing up for a challenging experiment of controlled re-entry of a decommissioned Low Earth orbiting satellite, Megha-Tropiques-1 (MT1), on March 7 evening.

MT1 was launched on October 12, 2011, as a joint satellite venture of ISRO and the French space agency, CNES for tropical weather and climate studies.

Although the mission life of the satellite originally was to 3 years, the satellite continued to provide valuable data services for more than a decade supporting regional and global climate models till 2021.

An uninhabited area in the Pacific Ocean between 5 deg S to 14 degS latitude and 119 deg W to 100 deg W longitude was identified as the targeted re-entry zone for MT1.

Since Aug 2022, 18 orbit manoeuvres were performed to progressively lower the orbit. In between the de-orbiting, aero-braking studies at different solar panel orientations were also carried out to gain better insights into the physical process of atmospheric drag affecting the orbital decay of the satellite.

ISRo said the final de-boost strategy has been 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 of the thrusters.

The final two de-boost burns followed by the ground impact are expected to take place between 1630 hrs to 1930 hrs on March 7.

Aero-thermal simulations show that no large fragments of the satellites are likely to survive the aerothermal heating during the re-entry.

As a responsible space agency committed to safe and sustainable operations in outer space, the Indian Space Agency proactively takes efforts for better compliance with the UN/IADC space debris mitigation guidelines on the post-mission disposal of LEO objects.

ISRO said the re-entry experiment of MT1 has been undertaken as a part of the ongoing efforts as this satellite with sufficient left-over fuel presented a unique opportunity to test the relevant methodologies and understand the associated operational nuances of post mission disposal by direct re-entry into the Earth’s atmosphere.

UN/IADC space debris mitigation guidelines recommend deorbiting a LEO (Low Earth Orbit) object at its end-of-life, preferably through controlled re-entry to a safe impact zone, or by bringing it to an orbit where the orbital lifetime is less than 25 years.

It is also recommended to carry out “passivation” of on-board energy sources to minimise the risk of any post-mission accidental break-up.

The orbital lifetime of MT1, weighing about 1,000 kg, would have been more than 100 years in its 20 deg inclined operational orbit of 867 km altitude.

About 125 kg on-board fuel remained unutilised at its end-of-mission that could pose risks for accidental break-up. This left-over fuel was estimated to be sufficient to achieve a fully controlled atmospheric re-entry to impact an uninhabited location in the Pacific Ocean, ISRO said.


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