In the early hours of Thursday, China launched its ambitious Tianwen-2 mission, marking a significant stride in the nation’s deep-space exploration endeavors. The mission aims to shed light on the formation and evolution of asteroids and the early solar system over a decade-long expedition.
At 1:31 a.m. Beijing Time, a Long March-3B carrier rocket lifted off from the Xichang Satellite Launch Center in southwest China’s Sichuan Province. Approximately 18 minutes later, the Tianwen-2 probe was successfully sent into a transfer orbit from Earth to the near-Earth asteroid 2016 HO3, according to the China National Space Administration (CNSA).
This launch marks the first time that this series of carrier rockets has undertaken an Earth escape orbit mission. The spacecraft unfolded its solar panels smoothly, and the CNSA declared the mission a success.
An official from the CNSA highlighted the mission’s importance, stating that Tianwen-2 represents a major step in China’s interplanetary exploration journey. Despite the mission’s long duration and inherent risks, there is hope for groundbreaking discoveries that will expand humanity’s understanding of the cosmos.
Asteroid 2016 HO3, a quasi-satellite of Earth, orbits the sun while appearing to circle around our planet, remaining a constant companion. With only seven such quasi-satellites discovered so far, this asteroid presents a unique opportunity for exploration.
“Asteroid 2016 HO3 is approximately 18 million to 46 million kilometers from Earth,” said Liu Jianjun, a researcher with the National Astronomical Observatories of the Chinese Academy of Sciences. “It’s relatively closer to Earth compared to other asteroids. We know there are millions of small celestial bodies, but choosing this one means it’s truly one-of-a-kind.”
Scientists believe that studying this asteroid will offer critical insights into not only its own formation and evolution but also the broader history of the sun and Earth. “This is the first time internationally that this type of small celestial body will be explored,” Liu added.
Collecting samples from 2016 HO3 means venturing beyond the Earth-Moon system and, for the first time, bringing back samples from interplanetary space. “This represents a huge leap forward in our country’s planetary exploration,” Liu said.
The mission’s second target is 311P, a celestial anomaly discovered in the main asteroid belt between Mars and Jupiter. Known to occasionally emit material and resemble a comet with tails, its discovery challenges conventional understanding, as the region is considered too close to the sun for a comet to retain volatile materials like water ice.
Han Siyuan, deputy director of the CNSA’s Lunar Exploration and Space Engineering Center and spokesperson for the Tianwen-2 mission, stated that the mission is expected to advance understanding of the origins, evolution, and characteristics of these two types of small celestial bodies. The probe will measure physical parameters, investigate topography, composition, internal structures, and possibly study materials ejected by the main-belt comet.
After journeying for about a year to reach 2016 HO3, the probe will perform deep-space maneuvers and mid-course corrections until it is about 30,000 kilometers away from the asteroid. It will then gradually approach the target, carrying out close exploration by circling and hovering to determine the sampling area, using a strategy of simultaneous flying and probing.
Upon completing the sampling, the spacecraft will fly back towards Earth, where a return capsule is expected to separate from the main probe and deliver the samples by the end of 2027. “We aim to make the first leg of the mission successful,” said an official from the China Aerospace Science and Technology Corporation.
The main probe will then continue its voyage to rendezvous with the more distant target, the main-belt comet 311P, to carry out further exploration. The probe is equipped with a range of scientific instruments, including cameras, spectrometers, radar, a magnetometer, and analyzers for charged and neutral particles, as well as for ejected materials.
The mission aims to overcome key technological challenges, such as sampling on a low-gravity celestial surface, high-precision autonomous navigation and control, and trajectory design, according to the CNSA.
