China's Tianwen-2 probe has successfully reached asteroid 2016 HO3 after a journey of 400 days covering over 1 billion kilometers (621 million miles), state broadcaster CCTV reported on Monday.

The China National Space Administration announced the probe is now close enough — about 20,000 km from the asteroid — to begin scientific exploration. Tianwen-2 will study the asteroid's morphology, material composition, and internal structure with an eye toward collecting samples at a later stage. It has already transmitted initial images of the rocky body.

The mission, launched on May 29, 2025 aboard a Long March-3B rocket from the Xichang Satellite Launch Center, represents China's first attempt to bring pristine asteroid samples back to Earth. After completing its work at 2016 HO3 — a quasi-satellite of Earth measuring roughly 40–100 meters across — the probe will depart for a comet, making Tianwen-2 a multi-target deep-space explorer.

2016 HO3 was discovered by the Pan-STARRS telescope in Hawaii in April 2016. It orbits the Sun in an elliptical path that keeps it in a stable "horseshoe" orbital resonance with Earth, making it an accessible target for a sample-return mission.

The achievement places China alongside NASA and JAXA as only the third space agency to rendezvous with a near-Earth asteroid for sample collection. Japan's Hayabusa2 returned samples from Ryugu in 2020, and NASA's OSIRIS-REx delivered material from Bennu in 2023.

China's broader planetary exploration program envisions a series of increasingly ambitious missions, with Tianwen-3 targeting a Mars sample return and Tianwen-4 headed for Jupiter in the coming decade.

Sources