The nation's first lunar orbiter Danuri on Dec. 17 will start entering its mission orbit around the moon. Shown is a picture of Earth (left) and the moon in a photo snapped by Danuri. (Korea Aerospace Research Institute)

By Yun Dahee

The nation's first lunar orbiter Danuri, officially named the Korea Pathfinder Lunar Orbiter, will soon attempt to enter its mission orbit around the moon.

The Ministry of Science and ICT and Korea Aerospace Research Institute on Dec. 15 said Danuri will perform the first stage of the maneuver lunar orbit insertion (LOI) on Dec. 17 at 2:45 a.m. Korean Standard Time for its entry into orbit. 

LOI is a maneuver using the orbiter's thruster to reduce speed and get it to enter a circular orbit 100 km above the moon.

Insufficient speed reduction will cause the orbiter to leave its orbit and fly away into space, while an excessive slowdown could trigger its fall due to lunar gravity. 

The first LOI maneuver is the most crucial as it enables the orbiter to be stably captured by lunar gravity and prevent passing the moon. 

Whether the orbiter is stably captured by lunar gravity after the first stage of LOI will be deduced on Dec. 19 based on data analysis. 

Since its launch into space on Aug. 5, Danuri for about four months has been on a lunar transfer trajectory flight toward the moon and will conduct five LOI maneuvers from Dec. 17-28. 

Confirmation of whether the orbiter finally entered its mission orbit will come on Dec. 29. 

daheeyun@korea.kr