The Chinese space probe Tianwen-2 met with Earth’s quasi-moon

China National The Space Administration’s Tianwen-2 asteroid probe has successfully reached the asteroid Kamo’oalewa, which orbits the Sun on a path almost identical to Earth’s.

After undergoing multiple orbital adjustments in deep space, the probe discovered Kamualoa for the first time on June 6, 2026. On July 2, it succeeded in taking the first-ever images of Kamualoa from a distance of about 20 kilometers. This achievement comes at the end of a journey that took 400 days and covered a distance estimated at about one billion kilometres.

Kamualoa is Earth’s most stable known moon, and because it orbits the Sun in near-synchronous motion with Earth, it is considered a relatively accessible celestial body.

But landing on the asteroid – let alone collecting samples – will be a challenge. Kamo’oalewa averages only about 41 meters in diameter and rotates at high speed. This means that the spacecraft must achieve stable communication and collect samples within a limited time frame. If it can collect samples, it will release them in a capsule during a flyby of Earth in November 2027.

Tianwen-2 is equipped with multiple cameras with different focal lengths. In addition to switching between a narrow field of view camera and a wide field of view camera depending on the situation, it also has a detachable camera that will be used during sample collection. Since the probe’s orientation must be precisely adjusted when taking images, seizing these limited opportunities is an extremely difficult task. Tianwen-2 plans to conduct more detailed scientific observations of Kamoalewa’s shape, material composition and internal structure.

If successful, this mission will represent another breakthrough in asteroid sample return, following Japan’s Hayabusa and Hayabusa2 missions — the first to return asteroid samples to Earth — and NASA’s OSIRIS-REx mission. Material from small celestial bodies orbiting near Earth can provide one of the few clues to understanding the formation of the solar system, including Kamuwalewa.

“It very likely contains primitive information from the early days of the formation of the solar system, and it also holds great scientific value for studying early material composition, formation processes and evolutionary history,” explains Han Siyuan, deputy director of the Lunar and Space Exploration Engineering Center and spokesman for the Tianwen-2 mission.

Researchers have previously hypothesized that Kamo’oalewa is a portion of the moon that exploded due to an asteroid impact millions of years ago, and it was widely accepted until recently. This is because the spectrum of reflected light is very similar to the spectrum of silicate minerals found on the moon’s surface. Simulations also supported this theory.

But in May, an international research team — including the Chinese Academy of Sciences — published research that casts doubt on this groundbreaking hypothesis. A reanalysis of the available data found that the central wavelength of the absorption band — the point at which light is attenuated at a specific wavelength — matches the characteristics of an LL chondrite (a type of meteorite with a low iron and mineral content).

The research team conducted an experiment in which they irradiated LL chondrite meteorite powder with a laser to simulate space weathering caused by solar wind and micrometeorites. The results closely matched Kamo’oalewa’s observational data. Researchers hypothesize that Kamuwalewa likely migrated to Earth’s oceans from the Flora family, a group of celestial bodies in the asteroid belt.

If Tianwen-2 successfully completes its sampling mission and returns to Earth, it will likely help answer questions about Kamo’oalewa’s origins. But first, you must reach the surface of the asteroid.

This story originally appeared on Wired Japan It was translated from Japanese.