China’s Tianwen-2 Arrives at Asteroid Kamoʻoalewa and Reveals First Close-Up Image

In July 2026, China’s Tianwen-2 spacecraft reached the near-Earth asteroid Kamoʻoalewa after traveling roughly one billion kilometers across 400 days, returning the first close-up images of the fast-spinning, roughly 20-meter-wide celestial body and marking a major milestone for deep-space exploration and autonomous navigation.

The mission launched on May 29, 2025, from the Xichang Satellite Launch Center in Sichuan Province aboard a Long March 3B rocket. As reported by SpaceNews, the China National Space Administration (CNSA) maintained silence as the spacecraft approached its target. Ground tracking by AMSAT-DL in Europe revealed that Tianwen-2 was operating in the vicinity of Kamoʻoalewa and executing a series of critical engine burns.

Navigating the Void to a Quasi-Satellite

Kamoʻoalewa, catalogued as 2016 HO3 and whose Hawaiian name translates to “oscillating celestial object,” occupies a stable quasi-satellite orbit shadowing Earth. Discovered in 2016 by the Pan-STARRS telescope system in Hawaii, the body has long puzzled astronomers.

Initial ground-based observations estimated the asteroid’s diameter between 40 and 100 meters. However, the first close-up image released by the China National Space Administration (CNSA) on July 6, 2026, shows a small, elongated rocky body with a diameter of just over 20 meters. According to SpaceNews, this revised measurement closely matches an ArXiv pre-published paper by Sharkey et al. that estimated an 18-meter diameter using observations from the James Webb Space Telescope (JWST).

Mikael Granvik, an astronomer at the University of Helsinki and Luleå University of Technology in Sweden, told SpaceNews that the initial imagery “basically confirms” a high geometric albedo—surface reflectivity—suggested by the Sharkey paper. Granvik noted that this high reflectivity is incompatible with the low-to-moderate albedo of the Moon, strengthening the conclusion that Kamoʻoalewa is of asteroidal origin rather than a chunk of the lunar far side blasted into space by an impactor, a hypothesis previously entertained alongside theories of a main-belt asteroid origin.

Autonomous Approach and Station-Keeping

Reaching a tumbling rock hundreds of thousands of kilometers away required immense precision. Earth-based observations could only pin down the asteroid’s location to a 100-kilometer margin of uncertainty. Tianwen-2 deployed its own optical navigation cameras during the final approach, dramatically compressing positional uncertainty to less than one kilometer.

According to CNSA timeline updates, Tianwen-2 arrived at a distance of 30,000 kilometers from the asteroid on June 7, 2025, and closed to 2,000 kilometers by June 19. By July 2026, the spacecraft reached a 20-kilometer station point, marking the formal start of close-proximity science operations. CNSA stated that the probe will conduct global mapping, surveying, and sample site selection to gather data on the asteroid’s shape, material composition, and internal structure.

Redundancy in Sample Collection

Because surface mechanics and the exact composition of Kamoʻoalewa remain largely unknown, Tianwen-2 carries three distinct sampling mechanisms to ensure mission redundancy. These include hovering sampling, touch-and-go sampling, and anchoring and attachment sampling, with the final method dependent on surface regolith conditions.

Photo: spacenews.com

The spacecraft’s 11 scientific payloads include high-resolution cameras, laser ranging instruments, spectrometers, sounding radar, particle analyzers, and the Italian-built DIANA dust analyzer. Following proximity operations at Kamoʻoalewa, Tianwen-2 is scheduled to depart in April 2027, eventually returning the collected samples via a reentry capsule in late November 2027. The spacecraft also carries payloads for studying its later target, the comet 311P/PANSTARRS.