This photo taken by the Danuri lunar orbiter shows the earth and the moon on Nov. 28. The Ministry of Science and ICT said Thursday that the Danuri took the photo when the earth and the moon looked similar in size when viewed from the lunar orbiter. Courtesy of Ministry of Science and ICT

By Baek Byung-yeul

The Danuri lunar orbiter began entering the moon's orbit on Saturday, 135 days after Korea's domestically developed space vehicle was launched on Aug. 5, according to the Korea Aerospace Research Institute (KARI), Saturday.

The KARI said that the Danuri performed its first of five lunar orbit insertion (LOI) maneuvers at 2:45 a.m. on Saturday. The maneuver involved the process of reducing its speed so that the Danuri could be stably captured by the moon's gravity.

During the process of slowing down, the Danuri operated thrusters for around 13 minutes to decelerate its speed from about 8,000 kilometers per hour to 7,500 kilometers per hour to reach its target position.

The KARI said the LOI process is a challenging task because the Danuri, which moves faster than a bullet, must enter the lunar orbit, which itself moves at about 3,600 kilometers per hour.

Whether the first maneuver was successfully performed or not will be announced by the KARI and the Ministry of Science and ICT on Monday. The Danuri is scheduled to slow down its speed four more times until Dec. 28. The second slowdown will be conducted on Dec. 21.

"The LOI process was carried out by automatically executing the commands sent to the Danuri in advance at a set time. But every situation before and after the LOI was monitored in real-time on the ground," the KARI said.

Carried by SpaceX's Falcon 9 rocket, the unmanned space vehicle, the Danuri, was launched from Cape Canaveral Space Force Station in Florida on Aug. 5.

After going through a total of five lunar orbit entry maneuvers, until Dec. 28, the Danuri is scheduled to settle into the moon's orbit, which is 100 kilometers above the moon.

If it is confirmed to have successfully entered the moon's orbit, the Danuri will carry out scientific missions for a year from January. Its missions include finding a spacecraft moon landing site, measuring the magnetic field and gamma rays and testing space-based internet communication.

The Danuri is seen as Korea's first step toward space. The country recently announced its ambitious space development projects including a moon landing by 2032 and Mars by 2045.

During its four-month voyage, Danuri has achieved meaningful results for Korea's space program. It took photos of the earth and the moon with a high-resolution camera on Aug. 26 and 29, sending the first photo taken outside the earth's gravitational zone by domestically developed Korean technology. On August 25 and October 28, the Danuri succeeded in communicating by sending data such as images, photos and text messages from space back to Earth.