Video = Korea Aerospace Research Institute
The Korea Aerospace Research Institute (KARI) and the Ministry of Science and ICT on Dec. 19 said the nation's first lunar orbiter Danuri on Dec. 17 at 2:45 a.m. conducted the first maneuver of lunar orbit insertion (LOI) as planned.
LOI is a maneuver using the orbiter's thruster to reduce speed for entering a circular mission orbit 100 km above the moon. Insufficient speed reduction causes the craft 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 it from passing the moon.
After the first maneuver, KARI analyzed orbit information for about two days and confirmed on Dec. 19 that Danuri reduced its speed from 8,000 km per hour to 7,500 km to get stably captured by the moon's gravity.
KARI researchers said Danuri became a "true lunar orbiter" after being captured by lunar gravity and circling around the moon.
The craft will perform four more maneuvers. Confirmation of whether it finally entered its mission orbit is expected on Dec. 29 after the fifth and final maneuver on Dec. 28, followed by a day-long data analysis.