China Launches Tianwen-2: A Decade-Long Mission to Explore an Asteroid and a Comet
China launched today its 2nd interplanetary space mission with Tianwen-2. The sample return spacecraft will visit an asteroid and comet.t back to earth.
Today, the 28 May 2025 at 17:31 UTC, the China National Space Administration (CNSA) successfully launched its Tianwen-2 spacecraft from the Xichang Space Center. The launch vehicle was a Long March 3B/E rocket, and the payload—the nearly 2,000-kilogram interplanetary spacecraft—is now on its way toward one of the most ambitious deep space missions ever undertaken by China.
Tianwen-2, also known as Zheng He in its early project development, is a multi-phase robotic mission aimed first at visiting a near-Earth asteroid and then, following a sample return to Earth, continuing on to study a comet in the main asteroid belt. It is the second mission in China’s Tianwen planetary exploration program, following the successful Tianwen-1 mission to Mars.
The primary target of Tianwen-2 is the small asteroid 469219 Kamoʻoalewa (2016 HO₃), a quasi-satellite of Earth with an estimated diameter of around 40 to 100 meters. The spacecraft is scheduled to arrive at the asteroid in 2026. Once there, it will perform detailed mapping and analysis before attempting to collect surface and subsurface material. Tianwen-2 is notable for being the first mission to try both sampling technologies: Touch-and-go and anchor-based sampling techniques. Four robotic arms will anchor the spacecraft to the asteroid’s surface during one of the sampling phases, a maneuver never before attempted in the internation planetary exploration.
The spacecraft carries a suite of scientific instruments, including imaging spectrometers, thermal detectors, multispectral and medium-field cameras, subsurface radar, a magnetometer, and particle analyzers. These instruments will be used to study the asteroid’s composition, structure, and physical environment, with particular interest in its possible lunar origin. Some models suggest that Kamoʻoalewa may be a fragment ejected from the Moon following an ancient impact.
After collecting more than 100 grams of asteroid material, the return capsule will separate from the main spacecraft and head back to Earth. The sample is expected to arrive on th 29th November 2027. It will re-enter Earth’s atmosphere at an unusually high velocity—approximately 12.1 kilometers per second—posing technical challenges that exceed those of China’s previous lunar return missions.
The mission does not end with the sample’s return. The main spacecraft, after releasing its return capsule, will conduct an Earth gravity assist to set course for a second target: the active asteroid (or main-belt comet) 311P/PANSTARRS (also known as P/2013 P5). The arrival is expected around 2034 or 2035, with the spacecraft conducting at least one year of observations. This dual-destination design makes Tianwen-2 one of the most complex and far-reaching robotic planetary missions in operation.
Tianwen-2 represents a significant step forward for China’s planetary science program. It aims to return the first-ever samples from a quasi-satellite and to conduct close-up observations of an active asteroid. Its scientific goals include improving our understanding of early solar system processes, testing new space technologies, and contributing data relevant to planetary defense.
The mission is expected to last about ten years in total, concluding around 2035. With its combination of complex engineering, multiple celestial targets, and ambitious science goals, Tianwen-2 has the potential to provide important contributions to asteroid science and to the global understanding of the solar system.
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