South Korean lunar orbiter succeeds in critical trajectory correction maneuver

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SEOUL, South Korea — South Korea’s first robotic lunar orbiter is looping back to the moon from the L1 Lagrange point after successfully conducting a critical trajectory correction maneuver Sept. 2, a milestone in its voyage toward the moon.

The science ministry announced Sept. 4 that the maneuver was so successful that the Korea Aerospace Research Institute (KARI), which controls the spacecraft called Danuri, has decided to skip an additional correction maneuver planned for Sept. 16. 

“The maneuver was a critical step for Danuri to make fuel-efficient travel to the moon and reach the moon’s orbit on time,” the ministry said in the statement. 

The orbiter, launched Aug. 5 on a SpaceX Falcon 9 rocket from Cape Canaveral Space Force Station, Florida, is on a ballistic lunar transfer trajectory — which takes the spacecraft toward the sun before looping back to arrive at the moon’s orbit in December. The route, while much longer than traveling directly toward the moon, allows more fuel efficiency as it leverages the sun’s gravity for travel.

The orbiter — if everything goes as planned — will be captured in lunar orbit on Dec. 16. A series of propulsive maneuvers with the spacecraft’s thrusters will steer it into a circular, low-altitude orbit about 100 kilometers from the lunar surface by Dec. 31. After a brief period of commissioning and tests, the spacecraft’s yearlong mission is expected to begin in January.

Roh Hyung-il, a KARI spokesman, told SpaceNews there would be another major trajectory correction maneuver in November. Once captured in lunar orbit on Dec. 16, he added, the spacecraft will conduct five more maneuvers between Dec. 17 and Dec. 31 to get to its final orbit 100 kilometers from the lunar surface.

Starting in January, Danuri — also known as the Korea Pathfinder Lunar Orbiter — will measure terrains, magnetic strengths, gamma rays and other traits of the lunar surface using six onboard instruments, including a NASA-funded hypersensitive optical camera called ShadowCam, during its yearlong mission. The orbiter will also identify potential landing sites for future lunar missions.