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On the 11th, a large antenna for deep space communication was installed at the Yeoju Satellite Center in Gyeonggi Province to communicate with the Korean Lunar Orbiter (KPLO) scheduled for launch in 2022. / Provided by the Ministry of Science and Information and Communication Technology
The ground team related to the lunar probe (orbiter), whose first launch is scheduled for August 2022, appeared for the first time. The Ministry of Science and Technology and Information and Communication held a ground station antenna lift ceremony in charge of deep space communication for the Korean Lunar Orbiter (KPLO) with the Korea Aerospace Research Institute and SK Broadband at the Yeoju Satellite Center in Gyeonggi Province. A reflector weighing 100 t and a diameter of 35 m was lifted with a large 750t class crane and mounted on the antenna. KPLO refers to a “lunar satellite” that orbits the moon as if an artificial satellite orbited the earth. It is also preliminary work to send a lunar lander aboard a human.
The distance between the Earth and the Moon is about 384,400 km. Communication over long distances (deep space) requires the installation of large antennas because of the low signal sensitivity, and places equipped with such equipment are called deep space ground stations. The deep space ground station controls the motion of the lunar orbiter to successfully land in orbit immediately after launch and maintain mission altitude. After that, data communication is exchanged to check the status of the lunar orbiter in real time and carry out space exploration missions.
There are six payloads, including a high-resolution camera, a wide-field polarization camera, a gamma-ray spectrometer, a space Internet payload, and a shadow camera. The high-resolution camera takes on the role of photographing the lunar surface area and looking for a place for the “lunar lander” to settle down in the future. The wide-field polarization camera being developed by the Institute for Astronomical Research is responsible for analyzing the surface particles of the moon, and the gamma-ray spectrometer of the Institute for Geological Resources Research is responsible for measuring the gamma rays from the surface. It is discovering rare resources that do not exist on Earth.
The space Internet payload being developed by the Electronics and Telecommunications Research Institute (ETRI) tests whether the Internet (DTN) will function properly in a deep space environment. Shadowcam is supported by the National Aeronautics and Space Administration (NASA). It is used to film images of permanently shaded areas of the lunar polar region. It is part of NASA’s 2024 Lunar Antarctic Landing Project (Artemis).
There were many twists and turns regarding the path and the orbital entry way. In 2017, the “ phase orbit transfer method (loop transfer) ” was chosen, which revolves around the Earth in an oval shape and then gradually enters the orbit of the moon. Initially, the weight was 550 kg, the radius of the orbit was 100 km long and short, and the duration of the mission was 1 year.
However, it was felt that it would be technically difficult to maintain the original orbit for a year with a 260-liter fuel tank and six payloads at that weight. Finally, the weight was increased to 678 kg last year. In addition, it was switched to operate in an elliptical orbit (long radius 300㎞, short radius 100㎞) for 9 months and a circular orbit (long / short radius 100㎞) for the remaining 3 months. This is because maintaining a circular orbit is more difficult than an elliptical one.
However, the plan changed again this year when the NASA inquiry turned out that this trajectory was inappropriate. The view was expressed that the “BLT transition orbit” method is more appropriate than the phase orbit transition method. The BLT method refers to a method of flying with minimal fuel consumption by maximizing gravity between the Earth, the Moon and the Sun. It travels a much longer distance than the phase-orbit transfer method, but consumes less fuel.
KPLO is scheduled to depart for space in August 2022 aboard SpaceX’s ‘Falcon 9’ rocket at Cape Canaveral Air Force Base, Florida.
The Yeoju Satellite Center, which was held on this day, was launched in 2017 by SK Broadband to receive overseas broadcast programs as satellites and use them as Internet TV (IPTV) services. It has one 11m class satellite antenna and four 6.4m class satellite antennas. In the future, it will also serve as an advanced base for deep space exploration.
Reporter Lee Hae-seong [email protected]
