China's Tianwen-1 Mars Orbiter Observes Dust Activity of Interstellar Object 3I/ATLAS
Summary: A research team led by the Chinese Academy of Sciences National Astronomical Observatory, together with teams from Sun Yat-sen University, the University of Macau, the Shanghai Astronomical Observatory, and Diego Portales University in Chile, used the HiRIC camera aboard China's Tianwen-1 Mars orbiter to capture multiple images of the third interstellar object 3I/ATLAS, providing unique observations of interstellar dust activity from Mars orbit. The findings were published in the Astrophysical Journal Letters (ApJL).
About 3I/ATLAS
3I/ATLAS was discovered in July 2025. It is the third known interstellar object, and the first to be observed at close range by China's Tianwen-1 Mars probe from orbital advantage. The object's orbital eccentricity reaches 6.14, and its hyperbolic trajectory indicates it is an interstellar visitor born billions of years ago. In October 2025, 3I/ATLAS made a close approach to Mars at approximately 0.194 astronomical units, providing a rare observation window for Tianwen-1.
Research Findings
The research team used the High-Resolution Imaging Camera (HiRIC) aboard Tianwen-1 to capture multiple images of 3I/ATLAS during its Mars flyby. This represents the first time humanity has observed interstellar object dust activity from the perspective of Mars orbit, providing new data for understanding the physical properties and evolutionary history of interstellar objects.
Tianwen-1 Mission Background
Tianwen-1 is China's first Mars exploration mission, consisting of an orbiter, lander, and rover. Launched in July 2020, it arrived at Mars in February 2021. Tianwen-1 continues to return large amounts of data on Mars's surface and atmosphere. This observation achievement demonstrates its scientific potential as a deep-space observation platform.