A conceptual diagram of the accompanying flight of the asteroid ‘Apophis’ probe. Provided by the Korea Astronomy and Space Science Institute
On an ordinary day in New York City, USA, when people were walking on the streets and cars were running through the city, big stones suddenly fell from the sky. The building collapses and a large pit is dug in the ground. The cause of this lightning bolt was not a terrorist attack or an accident, but a meteor shower. After close observation, scientists confirm that a bigger problem is coming. The disappointing discovery was that a large asteroid the size of the state of Texas would collide with Earth in 18 days. A commando team is hastily formed to land on an asteroid and perform a detonation mission, and they are tasked with protecting human civilization. American film released in 1998 <아마겟돈> I mean.
The setting of such a large asteroid approaching Earth is not imaginary. Someday it will become a reality. Therefore, accumulating technical defense capabilities in preparation for such events is an important task for mankind at present. Until now, such research has been mostly led by advanced space countries such as the United States.
Domestic government research institutes join hands in asteroid exploration and defense missions. The Korea Astronomy and Space Science Institute announced on the 24th that it had signed a memorandum of understanding with the Korea Aerospace Research Institute and the National Defense Science Institute last month to promote Korea’s first asteroid exploration mission. The asteroid targeted by the three agencies is ‘Apophis’, which will be closest to Earth on April 14, 2029. The Astronomical Research Institute oversees this project and at the same time manufactures scientific payloads such as polarized cameras. The Aerospace Research Institute is in charge of the development of launch vehicles and probes, and the work of the ground station. The Defense Science Research Institute participates in the development of a four-stage kick motor, a rocket that will directly put the probe into Apophis orbit. The Ministry of Science and ICT applied to the Ministry of Strategy and Finance for a preliminary feasibility study for the ‘Apophis Asteroid Proximity Exploration Project’ this month.
Apophis is an asteroid with a diameter of 370 m, which is larger than the 63 Building in Yeouido, Seoul (250 m in height). On April 14, 2029, it will reach a point of 31600 km from Earth. Considering that geostationary orbiting satellites orbit at an altitude of 36,500 km, this means that they pass by the Earth with ‘a paper difference’. It is rare for an object with a diameter of 300 m to come closer to the Earth than a geostationary orbit satellite, occurring only once every thousands of years to 20,000 years.
The probe weighs 534 kg and has a total flight distance of 1.8 billion km. The rover is equipped with advanced equipment called ‘polarized cameras’. With this device, it will be the first in the world to determine whether a change in the topography of Apophis, such as a landslide, occurs due to gravity acting between the Earth and an asteroid. In addition, it is also working to precisely analyze the characteristics of Apophis, whose rotation axis rotates like a falling top.
The most noteworthy part of the Apophis Expedition is the ‘Earth Defense’ mission. The scientific community believes that there is no possibility that Apophis will collide with the Earth within the next 100 years, but it is not easy to be calm. This is because an unexpected orbital change may occur due to Earth’s gravity as Apophis approaches and departs from the Earth in April 2029. Apophis approaches the Earth closely every few years to decades, and monitoring is necessary.
The scientific community believes that if Apophis one day collides with Earth, it will wipe out a continent. This is the reason why this exploration by domestic government research institutes is important as data for earth defense. The accumulated data can be the basis for alternatives such as orbital change or destruction if an asteroid that will hit the Earth really appears.
The three organizations also see the Apophis exploration as an opportunity to comprehensively enhance Korea’s space technology. When launching the Apophis probe, the current 3-stage Nuri is planned to be used, but the total scale will be upgraded to 4-stage to improve performance. In addition, it is possible to secure ‘accompanying flight’ technology that flies at the same speed as the target celestial body. Hong-gyu Moon, senior researcher at the Astronomical Research Institute, explained, “The companion flight technology can also be used for tasks such as docking, refueling and disposing of space debris.”
The three agencies explained that the probe should be launched in mid-October 2027 for the exploration of Apophis. After launch, it will fly into space and begin full-scale observation from April 14, the closest day to Earth, and will conduct exploration around Apophis for three months thereafter. Choi Young-jun, senior researcher at the Astronomical Research Institute, said, “We plan to expand the field of technological cooperation not only with government research institutes but also with domestic private space companies in the course of the Apophis exploration project.”