China's Tianwen-1 Mars orbiter captures image of interstellar object older than the solar system

Using its high-resolution camera, China's Tianwen-1 orbiter has successfully observed the interstellar object 3I/ATLAS at a distance of about 30 million kilometers, according to the China National Space Administration (CNSA). 

This makes it one of the closest probes to study this celestial body so far. The images clearly show the object's comet-like features, including its nucleus and surrounding coma. Researchers also created an animated visualization of its motion path using a sequence of images taken over 30 seconds to support further study. The successful observation of this faint celestial object has provided valuable experience for the upcoming Tianwen-2 asteroid exploration mission.

Discovered on July 1, 2025, by a sky survey telescope in Chile, the object is believed to have originated near ancient stars close to the galactic center, with an estimated age of between 3 and 11 billion years, possibly predating our solar system. It serves as a rare sample for studying the composition and evolution of exoplanets and the history of early stars, holding significant scientific value.

The observation task was extremely challenging for several reasons, including the vast distance from the object (about 30 million kilometers), the object's high intrinsic speed (around 58 km/s), an even faster relative speed compared to the Tianwen-1 orbiter (approximately 86 km/s), and its small size (with a nucleus diameter of about 5.6 kilometers).

The optical payload on the Tianwen-1 orbiter was originally designed to capture images of the bright Martian surface. This is the first attempt to photograph such a distant and relatively dim target, which is 10,000 to 100,000 times fainter than the Martian surface.

The team started preparing for the observation in early September. Through teamwork, repeated simulations, and theoretical modeling, the Tianwen-1 team ultimately successfully completed the observation.

The Tianwen-1 probe entered Mars orbit in February 2021 and has been operating stably for 4 years and 8 months, remaining in good condition.