ISRO’s Chandrayaan-2 Orbiter avoids collision with NASA’s Lunar Orbiter – All you need to know

The Indian Space Research Organization (ISRO) on November 15, 2021, revealed that its Chandrayaan-2 orbiter made a collision avoidance manoeuvre (CAM) in October 2021 with NASA’s Lunar Reconnaissance Orbiter (LRO). The Orbiters of both agencies experienced very close conjunction on October 20, 2021, at 11:15am IST near the Lunar North Pole. ISRO’s Chandrayaan-2 and NASA’s LRO orbit the Moon in a polar orbit and therefore both the Orbiters came close to each other over the lunar poles. Chandrayaan-2 Orbiter has been orbiting the Moon for the last two years.

This was the first time during the space exploration mission of ISRO’s Chandrayaan-2 that such a manoeuvre was undertaken to avoid a collision. Both the Orbiters were predicted to come very close to each other on October 20, 2021, near the Lunar North Pole. Both agencies, ISRO and NASA’s Jet Propulsion Laboratory (JPL) had tracked that the radial distance between the two Orbiters would be less than 100m and the closest approach distance would only be 3-km on October 20, 2021.

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How did ISRO’s Chandrayaan-2 avoid collision with NASA’s Lunar Orbiter?

Both, ISRO and NASA agreed to a collision avoidance manoeuvre (CAM) to avoid the collision of both their Orbiters on October 20, 2021. As per the mutual agreement, ISRO moved its Chandrayaan-2 Orbiter away on October 18, 2021, to ensure a sufficient large radial separation when both the orbiters come at the next closest conjunction on October 20.

Post the collision avoidance manoeuvre (CAM) on October 18, the orbit determination exercise was conducted with post-manoeuvre tracking data. During the post-manoeuvre, it was confirmed that Chandrayaan-2 Orbiter and NASA’s LRO will not have close conjunction in the near future with the modified orbit.

Collision avoidance manoeuvres (CAM)

Collision avoidance manoeuvres (CAM) are a common thing for satellites in Earth orbit to avoid them from colliding because of space objects including other satellites and space debris. In 2020, Russia’s space agency Roscosmos informed that India’s 700-kg cartography satellite Catrosat-2F and Russia’s 450-kg Kanopus-V satellite had a near-miss collision instance. Both satellites came close at a distance of 224-meters from each other.

Also read: Chandrayaan-2 Mission: All you need to know

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