Korea Pathfinder Lunar Orbiter (KPLO) DanuriA test lunar orbiter (KPLO, Korea Pathfinder Lunar Orbiter), the first Korean lunar probe, is an unmanned lunar probe expected to carry out the mission of lunar observation while flying at an altitude of 100km over the Moon.
The test lunar orbiter (KPLO) consists of the main body with a width, length, and height of 1.82m, 2.14m, and 2.29m, respectively, and six payloads. The major project details of the test lunar orbiter involve the development of the main body and payloads of the test lunar orbiter, construction of a deep-space ground station, phase 2 preceding research, and international collaboration with NASA.
The project is carried out with the cooperative system in which KARI oversees the system, main body, and ground station with the participation of six major Korean research institutes and NASA of the U.S. It will be equipped with NASA payloads and carry out missions such as orbiter tracking, communication support, deep-space navigation service support, etc.
Technologies required for Lunar Orbit Exploration
The test lunar orbiter (KPLO) is scheduled for launch on board the U.S. SpaceX’s Falcon 9 launch vehicle in August 2022. After its launch, the test lunar orbiter (KPLO) will shoot toward the Moon using the lunar orbit transfer method (BLT/WSB), which approaches lunar orbit by using the nearby astrophysical gravity of the Sun and Earth.
The test lunar orbiter (KPLO) is expected to commence lunar surface filming after going through its initial testing upon entry into lunar orbit.
Six payloads developed by Korean research institutes & NASA
The test lunar orbiter (KPLO) will carry a total of six payloads. The orbiter will contain five payloads developed by Korean universities and research institutes including KARI and one payload from NASA.
Korean universities and research institutes are developing a high-resolution camera for exploring the proposed landing site for lunar landing module, a polarized camera to analyze the lunar surface particles and spacecraft’s effect, and a lunar magnetic field-measuring instrument to measure the magnetic field intensity around the Moon for studying the cause and process of Moon formation.
The Korea Institute of Geoscience & Mineral Resources, which will measure the gamma-ray spectrum for resource exploration of the lunar surface, has been developing a gamma-ray spectrometer for identifying the elements constituting the lunar surface and its distribution pattern, while KARI is developing a 5m-grade high-resolution camera filming the proposed landing site for the Korean lunar probe.
The polarized camera being developed by the Korea Astronomy & Space Science Institute will be used to film the image of the entire lunar surface and capture polarized images of areas except for the polar region. In addition, it will designate the proposed landing site for the lunar probe by using the filmed images and examine the types of materials and particle sizes on the surface of the Moon.
Kyunghee University is developing the lunar magnetic field measuring instrument, a magnetometer for measuring the magnetic force 100km above the surface of the Moon. The gamma ray spectrometer can identify the ingredients and distribution patterns of elements constituting the lunar surface. It is being developed by the Korea Institute of Geoscience & Mineral Resources. The Electronics & Telecommunications Research Institute (ETRI) has been developing the space Internet test equipment for testing the delay-tolerant network. NASA’s ShadowCam will perform the reflectivity mapping of permanently shadowed regions on the surface of the Moon to find the evidence of water.
Going to the Moon with BLT/WSB method
The orbit for going to the Moon broadly consists of Direct Transfer, 3.5 Phasing Loop Transfer, BLT (Ballastic Lunar Transfer), etc.
The Direct Transfer method previously used by the Apollo program requires time within about five days. It directly arrives on the Moon after its launch from Earth. The 3.5 Phasing Loop Transfer used by India’s Chandrayaan program is a method of entering lunar orbit after revolving several times around the Earth in a long elliptical orbit. BLT/WSB method entails flying to the L1 Lagrangian point between the Earth and Sun, which was designed to minimize the space probe’s fuel consumption.
After launch, KPLO will be separated from the launch vehicle after entering the Transfer Orbit, an elliptical orbit. Subsequently, after making the solar panels face the Sun, the solar panels will be fully deployed by automation. Then, the process of raising its orbit by liquid apogee engine (LAE) firing occurs in order to enter the drift orbit from transfer orbit.
Once the satellite gets into position, the engine fires a total of five times and ascends into a circular orbit (drift orbit) from an elliptical one. And then, by using orbit information and the satellite-installed star sensor, it acquires its position facing the Earth, and finally reaches satellite mission altitude.