China’s Tianwen-2 spacecraft launched on May 28 on a landmark asteroid sample return mission, aiming first to explore the near-Earth asteroid Kamo’oalewa before returning to Earth orbit and eventually heading back out to investigate Comet 311P.
The mission lifted off at 1:31 AM local time from China’s Xichang Satellite Launch Center. Spanning ten years, it will seek to unlock secrets from two unusual celestial bodies in Earth’s planetary neighborhood.
A First for China’s Space Program
“Watching it tear through the sky, in that moment, my heart truly swelled with emotion,” said Su Yan, chief designer of the mission’s data collection system at the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC) in Beijing, who witnessed the launch from Xichang.
Tianwen-2’s initial target, Kamo’oalewa, is a small asteroid estimated to be between 40 and 100 meters in diameter. With a rapid rotation period of just 28 minutes, collecting material from its surface presents a formidable challenge. This marks China’s first asteroid sample return mission, following its successful retrievals from both the near and far sides of the Moon. Other countries have already completed asteroid sample missions—Japan from asteroids Itokawa and Ryugu, and the United States from Bennu.
Kamo’oalewa: An Unusual Quasi-Satellite
Kamo’oalewa is considered a quasi-satellite of Earth—too distant to be gravitationally bound like the Moon, yet it follows a looping, oscillating orbit around the planet.
Once samples are gathered, researchers will analyze them to determine the asteroid’s origin. Leading hypotheses suggest Kamo’oalewa is either a fragment of the Moon dislodged by an impact or a wandering remnant from the asteroid belt between Mars and Jupiter. To date, no known asteroid has been definitively linked to lunar origins. The samples are also expected to provide insights into asteroid formation and evolutionary processes.
“I am really excited for what is to come and to see what surprises this asteroid will reveal,” says Marco Fenucci, a mathematician who studies the dynamics of small astronomical bodies at the European Space Agency, near Rome.
Sampling Strategies and Scientific Toolkit
Tianwen-2 is expected to arrive at Kamo’oalewa in mid-2026 and remain in proximity for nine months. During its journey, the spacecraft will deploy its solar panels, test its instruments, and make minor course corrections.
The conditions of the asteroid remain uncertain. Whether the object is a solid rock or a loosely bound rubble pile will determine how samples are collected. To prepare for all possibilities, the mission includes three alternative collection strategies: the spacecraft may hover about one meter above the surface while a robotic arm collects material, use a sampling probe to sweep up debris, or land and anchor itself before deploying the robotic arm.
The spacecraft carries eleven scientific instruments, including cameras, spectrometers, a magnetometer, particle detectors, radar, and a laser sensor. These tools will help determine the asteroid’s composition and search for signs of water or organic material. Researchers will use this data to construct a detailed model of Kamo’oalewa.
A Second Journey to a Mysterious Comet
Following the sampling phase, Tianwen-2 will return toward Earth to release its sample capsule before using the planet’s gravity for a slingshot maneuver toward Comet 311P. The spacecraft is expected to reach the comet by 2035—ten years after launch.
“I hope its ten-year journey will go smoothly,” says Xu Yi, a planetary scientist at Macau University of Science and Technology (MUST).
The mission’s second phase holds intrigue of its own. Comet 311P is categorized as an “active asteroid,” a body that resides in the asteroid belt but behaves like a comet, producing a visible dust tail. Scientists hope to study the mechanism behind this dust emission and better understand how such hybrid objects form and evolve. Active asteroids remain a poorly understood class of objects in planetary science.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.