The results of the successful entry maneuver of Danuri (KPLO), which entered lunar orbit 135 days after launch, will be announced on the 19th. This maneuver is a high-level task to stably enter Danuri, which is faster than a bullet, into lunar orbit. In order to settle down on the lunar mission orbit (100 km above the moon), which is the target point, Danuri must go through a total of five mission orbit entry maneuvers by the 28th, including this first maneuver.
According to the Korea Aerospace Research Institute (KARI) on the 18th, Korea’s first lunar orbiter Danuri started its first lunar mission orbit entry maneuver at around 2:45 am on the 17th after sailing a cumulative 5.94 million km in space.
Maneuvering to enter the lunar mission orbit is a task to reduce the speed by using a thruster to settle the Danuri in a circular orbit 100 km above the moon.
The anti-coincidence research team operated the thruster for about 13 minutes that day to reduce the Danuri’s speed from about 8,000 km/h to 7,500 km/h. In order to reduce the speed, the propellant, hydrazine, was sprayed in the opposite direction to the Danuri’s forward direction and propulsion was reversed. This maneuver was carried out in a way that commands sent in advance to Danuri were automatically executed at a fixed time, and all the moments of the maneuver were monitored in real time from the ground.
Hang Woo-yeon explained that this maneuver was a difficult process, like ‘getting on a bullet’. The speed of the moon orbiting the earth is 3600 km/h, which is the speed of a bullet. Danuri’s sailing speed is 7500-8000 km per hour, more than twice as fast as this. It is a high-level task to put Danuri, which is faster than a bullet, into the orbit of the moon moving at the same speed as a bullet.
Hangwooyeon plans to announce on the 19th after analyzing the results of the first entry maneuver.
Danuri will go through four more mission orbit entry maneuvers. The second entry maneuver is on the 21st, the third on the 23rd, the fourth on the 26th, and the fifth on the 28th around 2pm. Whether or not the lunar orbit has been successful will be finally confirmed on the afternoon of the 29th.
When Danuri successfully lands in the lunar mission orbit, the Korea Aerospace Research Institute plans to conduct a calibration maneuver twice on the 30th and 31st to fine-tune the mission orbit.