Possibility of asteroid impact is slim. No guarantee in 2036.

Asteroids are called’solar system fossils’. Unlike large planets whose internal material was changed by heat and pressure, there is a high probability of retaining the material from the early days of the solar system. Space powers such as the United States and Japan are working on asteroid exploration to uncover the secrets of space. The exploration ship Hayabusa2, launched by Japan in 2014, collected underground material from the asteroid Ryugu, 340 million km away from Earth, and brought it to Earth last year.

Korea is also starting an asteroid exploration. The target of the exploration is Apophis, a stone asteroid with a diameter of 370m, which passed the Earth at a distance of 1680 km on the 6th. In 2029, Apophis will pass the Earth at a distance of 37,000 km, which is much closer than this time. It is about 4000 km closer than geostationary satellites such as’Cheonrian’ and’Mugunghwa’. Apophis-sized asteroids get this close to Earth once every 1000 years. As the distance is close, fuel can be saved, which is advantageous for exploration. The Korea Astronomical Research Institute unveiled a sketch last January that it will pursue exploration in 2029.

There are other reasons why exploration during this period is advantageous. In order to obtain meaningful scientific results from asteroid exploration, it is important to look below the surface. The surface of the asteroid has been constantly weathering since it was created by the solar wind or the high-energy particles of spacecraft. It is different from what it looked like when the solar system was first formed. This is the reason why Japan’s Hayabusa 2 collected internal materials after creating a puddle with metal bullets in Ryugu.

In 2029, it is expected that materials inside the Apophis can be investigated without digging the surface with bullets or the like. This is because a landslide is highly likely to occur due to the influence of the tidal force (the force pulled by the surrounding planets or satellites) caused by the Earth’s gravity.

Kim Myung-jin, senior researcher Cheon Mun-yeon, said, “If you look closely at the topography of Apophis where the landslide occurred, you will be able to see the material inside the asteroid that has never been exposed to sunlight.” If the Apophis exploration becomes a reality, the probe is expected to be equipped with a fluorescent camera that can identify particles and a multi-band camera that can identify colors. Moon-Yeon Cheon is also examining a way to send microscopic robots to the surface.

The exploration of Apophis also has the purpose of Earth defense. Apophis has been classified as one of the most dangerous asteroids since it was first discovered by the U.S. National Optical Observatory in 2004. According to NASA, Apophis is one of the four celestial bodies with the highest probability of impacting Earth in 100 years. The probability of a collision in 2029 is slim, at 1 in 380,000. However, the probability of collision between 2036 and 2068, when this asteroid orbiting in a 6-7 year cycle, passes close to Earth next time, is calculated differently from time to time.

The asteroid’s orbit is affected by sunlight. It is because of the’Yarkowsky effect’ that the orbit changes in the process of absorbing and emitting sunlight. The influence of Earth’s gravity is also expected to be large. In order to accurately measure the orbit of an asteroid that changes due to various factors, it is most important to properly grasp the shape. The detailed form can only be known by getting closer. Cheonmunyeon aims to acquire precise images through’accompaniment flight’ observed while moving at the same speed as an asteroid.

South Korea’s exploration of Apophis has yet to be confirmed. Moon-Yeon Chun is conducting preliminary research to apply for a preliminary feasibility study. I plan to release a report this year.

Reporter Choi Han-jong [email protected]

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