BEIJING, July 6 (Xinhua) -- China's Tianwen-2 probe has successfully arrived at a distance of 20 kilometers from the asteroid 2016HO3, enabling it to begin scientific exploration after an approximately 400-day journey of about 1 billion kilometers, the China National Space Administration (CNSA) announced on Monday.
China launched its first asteroid sample-return mission, Tianwen-2, on May 29, 2025, aiming to achieve multiple goals over a decade-long expedition: collecting samples from the near-Earth asteroid 2016HO3 and exploring the main-belt comet 311P, which is more distant than Mars.
Known as a quasi-satellite of Earth, asteroid 2016HO3 orbits the Sun and appears to circle around Earth as well, remaining a constant companion to our planet.
Dubbed as "cosmic fossils," asteroids preserve critical information about the solar system's infancy, scientists say.
The study of 2016HO3 is akin to opening a window to the early history of the solar system, offering significant scientific value for unraveling the material composition, formation processes and evolutionary trajectory of the solar system in its primordial phase.
During the approach phase, the probe acquired imagery of the asteroid. The mission team leveraged optical navigation data gathered during the close approach to refine the asteroid's ephemeris, reducing the positional uncertainty, previously determined solely through ground-based observations, from hundreds of kilometers down to the kilometer scale, according to the CNSA.
A distinctive feature of the Tianwen-2 mission is its strategy of flying and probing simultaneously, with decisions made throughout the process.
The probe features an innovative sampling system with three operation modes -- touching, hovering and anchoring -- to cope with varying surface conditions of the asteroid.
The probe is equipped with a suite of scientific instruments, including cameras, a visible and infrared imaging spectrometer, a thermal emission spectrometer, radar, a magnetometer and analyzers for charged and neutral particles, as well as for ejected materials, according to the CNSA.
On its voyage to the asteroid, the probe executed deep-space maneuvers and trajectory correction operations. On June 6, 2026, the probe achieved its first detection of the asteroid. On June 7, at a range of 30,000 kilometers, it entered a coplanar trajectory with the asteroid, while on June 19, it approached the asteroid to within 2,000 kilometers.
Next, the probe will progressively conduct more detailed scientific exploration to acquire data on the asteroid's morphology, material composition and internal structure, laying the groundwork for subsequent sample collection operations, the CNSA said. ■
