Tianwen-2

Tianwen-2, China’s second planetary exploration mission under the CNSA’s Planetary Exploration of China program, lifted off on 28 May 2025 from the Xichang Satellite Launch Center atop a Long March 3B rocket. It is the only mission in the program dedicated to small Solar System bodies, tasked with collecting asteroid samples and later exploring a comet. The probe reached the near-Earth asteroid 469219 Kamoʻoalewa on 4 July 2026. This object is a quasi-satellite of Earth. CNSA intends for Tianwen-2 to return samples from the asteroid during an Earth flyby in 2027, releasing a capsule for atmospheric entry. After that flyby, the spacecraft is scheduled to rendezvous with main-belt comet 311P/PanSTARRS in January 2035, using its 11 onboard instruments for study.

The launch vehicle placed Tianwen-2 directly onto an escape trajectory from Earth, a first for the Long March 3B. The probe relies on solar electric propulsion to maneuver between targets. After arriving at Kamoʻoalewa in July 2026, it began remote sensing observations from orbit while searching for a sampling site. The spacecraft will descend through progressively lower altitudes—20 kilometers, 3 km, 600 meters, and finally 300 meters—before touching down or hovering to collect regolith. Explosives will be used to expose subsurface volatiles for detection. For sample collection, Tianwen-2 will employ both an anchor-and-attach method and a touch-and-go method. The anchor-and-attach technique would be a first for an asteroid mission, as previous missions like OSIRIS-REx and Hayabusa2 used only touch-and-go.

In 2027, Tianwen-2 will return to Earth, dropping off a return capsule containing the sample and using a gravity assist to redirect itself toward 311P/PanSTARRS. At that comet, it will conduct remote sensing and in-situ measurements for at least one year. The spacecraft carries a suite of instruments: a visible/infrared imaging spectrometer, thermal radiation spectrometer, multispectral camera, medium field color camera, detection radar, magnetometer, charged and neutral particle analyzers, ejecta analyzer, narrow field-of-view navigation sensor, and a laser integrated navigation sensor. International contributions to these payloads have been encouraged.

The mission was originally proposed in 2018 by Chinese Academy of Sciences researchers as part of a deep space roadmap for 2020–2030, with an initial launch target of 2022 or 2024. It was first called ZhengHe, after the Ming Dynasty explorer. In spring 2019, after a design study by the Chinese Academy of Space Technology, CNSA began soliciting international instrument proposals. Earlier plans included a nano-orbiter and nano-lander for remote sensing and sampling, and the secondary target was originally 133P/Elst–Pizarro, with a possible flyby of an additional unnamed asteroid. On 7 June 2026, the spacecraft performed an engine burn to rendezvous with the quasi-moon, and its close encounter with Kamoʻoalewa began on 4 July, when it approached within 20 kilometers of the asteroid.