April 11, 2023
HELSINKI, Finland — China has chosen the near-Earth object 2019 VL5 for a 2025 asteroid deflection and observation test.
According to Chen Qi of China's Deep Space Exploration Laboratory's presentation last week at the 8th IAA Planetary Defence Conference in Vienna, Austria, the mission will use a Long March 3B rocket and will carry both an impactor and an observer spacecraft.
After launch, the two spacecraft will diverge on different paths. Notably, the observer spacecraft will arrive at the asteroid first for preliminary observations and topography evaluation.
The impactor will strike the roughly 30-metre-diameter 2019 VL5 with a relative velocity of 6.4 kilometres per second, aiming to change the asteroid's velocity by about five centimetres per second.
According to a mission profile presented at the conference, the observer spacecraft will then evaluate the asteroid after the impact.
It will be equipped with optical, radar, and laser remote sensing payloads, as well as a dust and particle analyzer, to assess the target. According to the mission profile, the observer spacecraft will use a high-resolution camera to observe the impact ejecta while in a 30 km orbit perpendicular to the path of the impactor.
The small asteroid will also be observed using ground-based telescopes and the Xuntian space telescope, which is scheduled to launch into a similar orbit as the Tiangong space station around the end of 2024.
The mission combines elements from NASA's DART impactor mission and the European Space Agency's Hera, which will later observe the DART target system.
DART will be launched by NASA in November 2021. On September 26, 2022, the DART spacecraft collided with the asteroid Dimorphos, a satellite of the larger Didymos. It was discovered that it had altered Dimorphos' orbit, indicating that the world's first planetary defence asteroid deflection demonstration had been a success.
Later this decade, the ESA's Hera mission will observe Didymos and Dimorphos to better understand the effects of the DART collision.
The Chinese test will impact a much smaller, less massive asteroid while simultaneously launching both the impactor and the observer.
China's test is part of a larger planetary defence strategy being developed to counter the threats posed by near-Earth asteroids, which includes an asteroid detection and early warning system. Planetary defence was identified as a critical area of research in China's most recent space white paper, which was published in early 2022.
Breakthroughs in multiple key technologies, including high-speed impact deflection modelling simulations, have been made, according to Chen. Chen also stated that all countries are welcome to take part in the programme.
According to previous reports, the mission was originally planned to launch in 2026 and target the asteroid 2020 PN1.
2019 VL5, like the previous target, is an Aten-class asteroid, which are objects that cross the orbit of Earth but have an orbital period of less than a year. 2020 PN1 has been designated as a backup target, with other potential targets noted if the mission must launch in 2026 or 2027.
The test targets were chosen based on a set of principles. Avoiding objects considered dangerous before or after an impact with an orbital inclination of less than five degrees, relatively high magnitudes for viewing, multiple observation opportunities, potential science value, and launch windows between 2025 and 2027 are among them.
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