1-billion-km flight brings Tianwen 2 to target asteroid

China's Tianwen 2 asteroid sampling spacecraft has rendezvoused with its target, a near-Earth asteroid called 2016 HO3, and has started to conduct scientific surveys, according to the China National Space Administration.

The administration announced on Monday that the Tianwen 2 robotic probe reached a position about 20 kilometers away from 2016 HO3 last week, and then started flying alongside the asteroid.

It also released an image of 2016 HO3, which was taken by the spacecraft's camera.

Before that point, the spacecraft had traveled around 1 billion km in a 400-day interplanetary journey, the administration noted, adding that in the following steps, the probe will conduct detailed scientific explorations in a phased manner to acquire data on the asteroid's topography, material composition and internal structure to support preparations for the sampling mission.

During its asteroid approach, the Tianwen 2 probe obtained images of the celestial body. The mission team on the ground used optical navigation data, which was collected during the approach process, to refine the asteroid's ephemeris and reduce its position error — previously determined solely by ground-based observations — from hundreds of kilometers down to within a few kilometers, according to the administration.

The Tianwen 2 mission, which is China's first attempt to bring pristine asteroid samples to Earth, was launched on May 29,2025, when a Long March 3B rocket carrying the robotic probe blasted off from the Xichang Satellite Launch Center in Sichuan province.

En route to the asteroid, the probe conducted a series of operations, including deep-space maneuvers and midcourse corrections.

The craft detected and identified the asteroid for the first time on June 6. The following day, it executed capture control to synchronize its motion with that of the asteroid at a distance of 30,000 km, achieving coplanar flight with the celestial body. It reached a position about 2,000 km from the asteroid on June 19.

The asteroid 2016 HO3, which is also known as 469219 Kamo'oalewa, orbits the sun and is a constant companion of Earth. It is too distant to be considered a true satellite of Earth, but is the best and most stable example to date of a quasi-satellite.

Tianwen 2 will study the celestial body up close using a suite of 11 instruments, including cameras, spectrometers and radars, before deploying special devices to collect samples from its surface.