Scientists who risked their lives on a 128kg diet… The story of the lunar orbiter[과학을 읽다]

[아시아경제 김봉수 기자] Korea’s first space exploration project, the launch of a lunar orbiter, is taking a breeze. The Ministry of Science, ICT and ICT announced on the 1st that the development of the payload and the main body was almost completed, and there was no problem with the launch of the lunar exploration orbiter in August 2022. At the same time, we also revealed the specific mission of the lunar orbiter. For the first time in human history, polarized images are taken to analyze the patterns and causes of changes on the lunar surface. In addition, the NASA’s ShadowCam serves as a scout for Artemis, the second lunar landing project in 2024. This is because NASA plans to select the landing site for the Artemis project by photographing the polar regions of the moon, which were impossible to film because of the permanent shadow area through this camera.

Although this project is being progressed steadily as if it was in the midst of the wind, the lunar exploration plan has gone through numerous twists and turns over the past 10 years since its inception in 2007. Political drafts, technical difficulties, cooperation problems with foreign institutions, internal conflicts, and so on, have suffered from all kinds of difficulties.

The hurdle the first lunar exploration project faced was a political draft. Originally, Korea’s independent lunar exploration plan was established in 2007 by the Roh Moo-hyun administration. It was a long-term project with the opinions of experts such as the Korea Aerospace Research Institute at the time and launching a lunar exploration orbiter in 2020 and a lunar lander in 2025. It was a schedule that took into account the level and budget of related technologies and human resources in Korea. However, in 2013, when the Park Geun-hye administration was established, these plans will be advanced by three to five years. It will be modified with the launch of the lunar orbiter in 2017 and the lunar lander in 2020. It was a measure in accordance with President Park Geun-hye’s pledge for the presidential election.

This plan faces tremendous opposition from field researchers and engineers. It was an unreasonable plan that couldn’t fit the timetable. Eventually, due to technical problems, the lunar exploration schedule was delayed the next day, and for the Moon Jae-in administration, the lunar orbiter was extended for the first time within December 2020, and the lunar lander was extended within 2030. The current schedule of launching the lunar lander within 2030 has been confirmed.

The second hurdle is the technical challenge. That’weight’ is the main character. Initially, the lunar exploration orbiter was planned to be launched into space on the’Nuri’, a Korean launcher that began development at the same time. The problem is that the maximum loading weight of the Nuri is only 1.5 tons. So the researchers tried to reduce the weight of the lunar orbiter to less than 550 kg. Efforts were made to reduce the weight by betting a bounty on its own, but it eventually ran into technical limitations and failed. Currently, the lunar orbiter weighs 678 kg, which is 128 kg more than the target.

As the orbiter became heavier, the entire lunar exploration project was coordinated in September 2019. The launch vehicle was also changed to Falcon 9 of SpaceX, a US private space company, not Nuri. As the budget to be paid to SpaceX has increased, the total cost has increased by more than 20 billion won from 1978 billion won.

The increase in the weight of the payload poses another serious problem. This is because the consumption of fuel increases, which causes problems in the life of the tracker. Accordingly, the anti-accidental scientists are revising the original goal of a 100km orbit in the garden for one year. The plan was to operate in an elliptical orbit that passes 100km when it is close to the moon and 300km in the air for 9 months, and in the last 3 months in a 100km sky garden orbit. It was a hurdle to meet the original goal of the one-year operating period.

However, planning changes like this will face another barrier. NASA protested. NASA insisted that a garden orbit is only possible to capture the surface of the polar region, but it is not possible to obtain enough information in a three-month period, and insist that the original garden orbit should be operated for a year.

Eventually, after controversy, Hang Woo-yeon and NASA agreed to change the way the lunar orbiter enters orbit in a way that reduces fuel consumption as much as possible to achieve the goal of a one-year garden orbit operation. Specifically, the Korean researchers chose the phased orbital transition method (Phasing Loop), a method in which the satellite orbits the Earth several times in a long elliptical orbit and then enters the moon orbit. It takes about a month and is a stable method that Japan and India have already succeeded in.

However, NASA insists on changing to the’Weak Stability Boundary (WBS) method’. This method approaches the lunar orbit using the gravitational field of the Earth, the moon, and the sun. It takes a little longer, but fuel consumption can be minimized. However, although the recent US lunar gravitational field exploration mission Grail has been successful, it is a method that is somewhat risky in that it has not been sufficiently verified. In any case, scientists from both countries have agreed to implement the WBS method last year. The premise is that the United States will pass on their know-how of success to Korea as much as possible.

The development of the lunar orbiter has also experienced numerous internal conflicts. A representative case is the case where the government did not give an incentive of 130 million won to researchers from the lunar exploration project between January and May 2019 after the failure of anti-wooyeon to reduce the weight of the orbiter. Researchers anti-wooyeon filed a lawsuit for arrears in wages early last year, claiming that it was a normal research allowance that should be paid, and the trial is in progress.

The government, on the other hand, said that when the lunar exploration project was delayed at the time, the project was inspected through a separate organization, and it was not able to pay the labor cost as there was no research activity during the period. Although Hang Woo-yeon paid his own wages for that period, it was the fire that did not resolve the incentives. The conflict between the Ministry of Science, ICT and ICT, which is the responsible department, and Hang Woo-yeon, who is a working entity, has also continued to conflict. At the end of last year, former President Hang Woo-yeon, Lim Cheol-ho, who finished his term of office for the last three years, received a notice of dismissal from the Ministry of Science and ICT.

Anyway, the launch of Korea’s own lunar orbiter is well prepared, and it is expected to be launched in August next year. The exploration of the moon through twists and turns will enhance Korea’s external status and inspire national pride. In addition, it will lead to direct national interests such as securing resources through full-scale space development to be carried out in the future, exploration of asteroids and Mars, and guaranteeing safety. I hope that the moon exploration orbiter, which has gone through all of the prenatal battles, will continue to cruise in the future.

Reporter Kim Bong-soo [email protected]