China has successfully launched the Tianwen-2 mission, a historic milestone in the country’s space exploration endeavors. In the early hours of Thursday, May 29, 2025, a Long March-3B rocket lifted off from the Xichang Satellite Launch Center in Sichuan Province at 1:31 a.m. Beijing time.
About 18 minutes after liftoff, the Tianwen-2 probe was sent into a transfer orbit between Earth and its first destination, the near-Earth asteroid 469219 Kamo’oalewa. “The spacecraft unfolded its solar panels smoothly, and the CNSA declared the launch a success,” reported Xinhua.
The launch marked the first time a Long March-3B rocket was used to send a payload beyond Earth’s orbit. While typical orbital missions require reaching orbital velocity (about 7.7 kilometers [4.8 miles] per second), the Tianwen-2 launch surpassed escape velocity (about 11.2 kilometers [7.0 miles] per second) to break free of Earth’s gravity.
Reaching that speed was only part of the challenge — the initial trajectory also had to be precise to intercept a target as distant as Kamoʻoalewa. A deviation of just 1 meter per second during launch could result in a positional error of “up to 100 million kilometers,” Xinhua reported. “Achieving such trajectory precision is akin to shooting a basketball from Shanghai to hit a hoop in Beijing,” stated the China Aerospace Science and Technology Corporation (CASC) in an article from Xinhua.
As Astronomy previously detailed, the mission targets two intriguing bodies: Kamoʻoalewa and the enigmatic main-belt comet 311P/Pan-STARRS. Over a decade-long expedition, Tianwen-2 aims to deepen scientific understanding of these bodies, which are crucial to unlocking secrets of the solar system’s formative years.
A highlight of the mission will be collecting samples of Kamoʻoalewa and returning them to Earth in a sample capsule in 2027. Kamoʻoalewa is just 130 to 330 feet (40 to 100 meters) across, making it the smallest asteroid ever visited.
The asteroid is hypothesized to be a fragment of the Moon because it reflects light similarly to lunar rock. Studying and sampling it could help astronomers determine if it truly originated from the Moon or just has a similar reflectivity. If it’s from the Moon, it might reveal more about lunar impacts and debris.
After returning samples from Kamo’oalewa, Tianwen-2 will continue its trek to 311P/PanSTARRS, a main-belt comet. It is also classified as an active asteroid — a body that orbits like an asteroid but sports a dust tail like a comet. Tianwen-2 is expected to reach 311P/PanSTARRS in early 2035 for a year of observations, offering a glimpse into how these hybrid celestial bodies evolve and potentially shedding light on the origins of water and organic life in the solar system.As Tianwen-2 begins its ambitious journey, scientists worldwide await the discoveries it will bring. “There’s a tremendous amount we don’t know about either object,” planetary scientist Teddy Kareta of Lowell Observatory told CNN. “I’m sure some of our current understanding for either object is completely wrong,” Kareta added, “and I’m excited to see how.”
