Tianwen-2 is set for a rapid mission to asteroid Kamoʻoalewa, with its roundtrip expected to take just two and a half years. In contrast, Japan’s Hayabusa 2 mission spanned six years, while NASA’s OSIRIS-REx required seven years to complete its objectives. Both of those missions targeted near-Earth asteroids that are further away than Kamoʻoalewa, which Tianwen-2 aims to reach by July 2026 to begin its sampling operations.
The spacecraft plans to employ multiple techniques for sample collection. One method involves maneuvering in close proximity to Kamoʻoalewa while synchronizing its rotation with the asteroid. This will allow a robotic arm to extend and gather material. Additionally, Tianwen-2 will perform a “touch-and-go” maneuver, akin to the techniques used by Hayabusa 2 and OSIRIS-REx, allowing it to briefly land on the surface to collect samples.
Another innovative sampling technique being considered is the “anchor-and-attach” approach. This method would see the spacecraft deploy four drill-equipped arms to secure itself to the asteroid’s surface. Although Chinese officials have not disclosed the specific amount of material intended for return, Tianwen-2 is reportedly equipped to collect at least 100 grams of rocks and dust from Kamoʻoalewa.
Mission planners are still gathering information about Kamoʻoalewa’s shape and characteristics. Preliminary measurements indicate that the asteroid has a relatively rapid spin rate of once every 28 minutes. This fast rotation, combined with the asteroid’s weak gravitational pull, will pose challenges to Tianwen-2’s operations in close vicinity.
After collecting samples, Tianwen-2 is scheduled to depart Kamoʻoalewa in early 2027 and make its way back to Earth. It will release a reentry module with the asteroid material for landing at the end of 2027. Scientists will then analyze the specimens to evaluate their physical properties, chemical makeup, mineral compositions, and structural characteristics, as detailed in a study published in the journal Earth and Planetary Physics.
The study’s authors, four Chinese scientists, emphasize that the findings from this mission could extend our understanding of not only asteroids but also larger geological contexts involving Earth and the Moon.
“Verifying Kamo’oalewa’s origin, particularly its proposed link to lunar debris, may provide vital insights into the Moon’s evolutionary narrative,” the authors note. “Such insights could enrich our understanding of the far side of the Moon and the reasons behind the asymmetry observable between the Moon’s two hemispheres.”
