How Chandrayaan-2 avoided colliding with NASA’s orbiter

“Analysis from both ISRO and JPL/NASA, over the period of one week before the conjunction, consistently showed that the radial separation between the two spacecraft would be less than 100 meters and the closest approach distance would be only three km at that time of closest approach. “

Both agencies recognized that the position required collision avoidance maneuvers (CAM) to reduce close approach risk, and it was mutually agreed that CH 2 O would undergo CAM. The maneuver was scheduled for 18 October. It was designed to ensure a sufficiently large radial separation at the next closest conjunction between the two spacecraft, the statement reads.

CAM was nominally executed on 18 October afternoon and, following the orbit determination of CH2O with maneuver tracking data, it was re-confirmed that no further close conjunctions would occur in the near future.

“It may be noted that like CH2O, LRO orbits the Moon in an almost polar orbit and hence, both the spacecraft come close to each other at the lunar poles. It is common for satellites in Earth orbit to undergo CAM to reduce the risk of collisions caused by space objects, including space debris and operational spacecraft.”

ISRO further said that it regularly monitors such critical close approaches and performs CAM for its operational satellites whenever the collision risk assessment is critical.

“However, this is the first time such a seriously close conjunction was experienced for ISRO’s space exploration mission, which required an aggressive maneuver”, the statement said.