South Korea's first lunar probe 'Danu-ri' is embarking on a new challenge. It will move out of its familiar orbit at an altitude of 100 km above the Moon, which it has been circling since Dec. 26, 2022, and operate at a lower altitude to capture clearer lunar images. Its mission period, originally set to end by the end of this year, is expected to be extended for more than an additional six months.
According to the Korea Aerospace Administration and Korea Aerospace Industries (KAI) on the 6th, Danu-ri is expected to change its mission altitude soon. An official from the space agency noted, "Danu-ri has sufficiently achieved the objectives it was meant to accomplish at the 100 km mission altitude and has gathered adequate observations," adding, "We decided to adjust the mission altitude while exploring ways to obtain new results."
The Danu-ri probe, South Korea's first lunar exploration vehicle, was launched on Aug. 5, 2022, and arrived at an altitude of 100 km above the Moon on Dec. 26 of the same year. It is equipped with six payloads, including high-resolution cameras and wide-angle polarized cameras that have sent a variety of lunar images back to Earth, capturing vivid details of the Moon's south pole and various craters, as well as images of lunar landers from countries such as the United States, India, and China. Previously, these data could only be obtained with the assistance of other countries like the U.S. or Europe.
Kim Dae-gwan, head of the Future Research and Innovation Center at the Korea Aerospace Research Institute, which led the development of Danu-ri, said, "Not only the scientific achievements but also the fact that South Korea is operating a lunar exploration vehicle brings significant benefits in international cooperation and other areas," explaining, "There are only a few orbiters that can currently capture images of the Moon globally, which increases the importance of Danu-ri."
Both the Korea Aerospace Administration and the Korea Aerospace Research Institute are reviewing plans to lower Danu-ri's mission altitude to about 50 km above the Moon. This change would enable the probe to capture new locations that it has not been able to photograph over the past two years, or to obtain even clearer images.
The mission period for Danu-ri will also be extended. Initially, it was planned to operate until the end of 2023; however, thanks to successful navigation during the Earth-Moon transfer process, 30 kg of fuel was saved. As of Dec. 27, 2022, after entering its mission orbit, the remaining fuel amount was approximately 86 kg, considering the annual fuel consumption of 26 to 30 kg, enabling the possibility for additional missions. As a result, in June 2023, the Ministry of Science and ICT and the Korea Aerospace Research Institute extended the Danu-ri mission period until the end of 2025.
The Korea Aerospace Administration and the Korea Aerospace Research Institute believe that Danu-ri has enough fuel to continue its mission into 2026, and they plan to extend the mission period further. It is expected to conduct additional missions at a lowered altitude for at least six months.
Discussions are underway on how to operate Danu-ri after its mission period ends. Plans include crashing it onto the lunar surface to obtain various data for future lunar landers and moving Danu-ri to a Frozen Orbit around the Moon. A Frozen Orbit is a trajectory that can maintain a constant altitude without fuel-consuming maneuvers. The Lunar Reconnaissance Orbiter, launched by the National Aeronautics and Space Administration (NASA) in 2009, continues to operate in a Frozen Orbit even three years past its initial mission duration.
An official from the space agency stated, "It is common practice for a lunar probe to crash into the lunar surface at a point where control from Earth is possible before it runs out of fuel after completing its mission," adding, "This year, two total lunar eclipses are scheduled during the solar maximum, so we will monitor how this affects Danu-ri's performance and plan to make decisions that will be more beneficial for lunar exploration."