India and South Korea's lunar orbiters are on the brink of disaster: what happened?

The Indian orbital spacecraft named "Chandrayaan-2" had to perform a maneuver to avoid a collision with the South Korean spacecraft Danuri while orbiting the Moon. This incident occurred back in September, but the Indian Space Research Organisation (ISRO) has only now reported it, according to Space.

According to a new ISRO report, the Indian spacecraft "Chandrayaan-2" altered its orbit on September 19, rising higher above the lunar surface to prevent a collision with the South Korean probe Danuri. It was anticipated that a collision could happen in two weeks if the flight trajectory was not altered. Furthermore, on October 1, "Chandrayaan-2" adjusted its orbit around the Moon to avoid a collision with NASA's Lunar Reconnaissance Orbiter (LRO).

All three spacecraft are in a nearly polar orbit around the Moon, causing them to come close to each other above the lunar poles, where the risk of collision is very high. Over the past year and a half, the Danuri spacecraft has sent 40 alerts to Earth indicating potential collisions with other lunar probes.

Three years ago, "Chandrayaan-2" also changed its orbit due to the risk of colliding with the LRO above the Moon's north pole. Danuri has performed three avoidance maneuvers since entering lunar orbit in December 2022. One maneuver was executed to avoid a collision with the LRO, another to prevent a crash with "Chandrayaan-2," and the third to evade a collision with the Japanese module SLIM shortly before its landing on the Moon's visible side in January of this year.

Space agencies from India, South Korea, and the United States are continuously exchanging data regarding the flight trajectories of their lunar probes, which helps prevent disasters in space.

The space agencies primarily utilize a platform developed by NASA's Jet Propulsion Laboratory called MADCAP, which calculates collision risks and generates alerts. However, there is currently no mutually agreed-upon international protocol for addressing such collision risks.