Chinese probe Tianwen-1 photographs interstellar comet 3I/ATLAS in Martian orbit

The Tianwen-1 probe, in orbit around Marte, performed a historic feat by capturing detailed images of comet 3I/ATLAS, a rare object originating from outside Sistema Solar. The recording, made in late 2025, marks the first time that an interstellar “visitor” has been photographed from Martian orbit, demonstrating a remarkable advance in the ability to monitor distant and dynamic celestial bodies. The comet was observed at an approximate distance of 30 million kilometers from the Chinese probe, while traveling at an impressive speed of 58 kilometers per second.

Imagens reveals structure of cometary nucleus

Images released by Administração Espacial Nacional of China (CNSA) display the comet’s nucleus and gaseous coma with remarkable clarity, allowing in-depth analysis of its structure. The HiRIC high-resolution camera, originally designed to map the surface of Marte, confirmed its versatility in tracking a high-speed target in deep space. The spectral data collected indicate a dense and well-defined core, probably composed of a mixture of rock and different types of ice. Analysis of the light reflected by its surface points to the presence of reddish organic dust, a common feature in celestial bodies formed in cold regions far from their host star.

Espectrômetros aboard other missions have detected signatures of water ice and carbon dioxide sublimating from the surface, along with traces of carbon monoxide, confirming typical cometary activity. Esses gaseous components and dust fragments ejected by the comet carry the signature of a distant stellar environment, allowing astronomers to indirectly study worlds that are light-years away.

Origens in distant star system

3I/ATLAS is suspected to have originated in a cold protoplanetary disk, a distant region where volatile elements such as water ice, carbon dioxide and carbon monoxide can remain preserved for billions of years. Spectral analysis of these components is essential to determine the temperature and density of the nebula where the comet was born. Compreender these conditions are critical to refining theories about how planetary systems, including our own, evolve over time. Interstellar objects are seen as true cosmic time capsules, as they carry crucial information about the chemical and physical conditions of their stellar systems of origin.

• Terceiro confirmed interstellar comet detected by astronomers.
• Descoberta performed in July 2025 by the ATLAS telescope system.
• Hyperbolic Trajetória confirms extrasolar origin of the object.

Terceiro interstellar visitor confirmed

Comet 3I/ATLAS is the third confirmed interstellar visitor to be detected by astronomers, following the passage of ‘Oumuamua in 2017 and 2I/Borisov in 2019. Confirmation of its extrasolar origin came quickly from the analysis of its trajectory, described as hyperbolic. Essa is a clear mathematical signature that indicates an origin external to our planetary system. Diferentemente from the elliptical orbits of local comets and asteroids, a hyperbolic trajectory means the object has enough speed to escape the gravitational pull of Sol, allowing it to continue its journey through interstellar space after its brief passage through our cosmic neighborhood.

Manobra of unprecedented orbital engineering

The capture of images of comet 3I/ATLAS by Tianwen-1 was an engineering feat that required meticulous and innovative planning. The mission team at Terra needed to develop a completely new observation strategy from scratch, involving complete recalibration of the probe’s targeting systems and performing precise orbital maneuvers to align the equipment with the comet’s predicted trajectory. Foram performed exhaustive simulations to determine the ideal exposure times, which needed to be short enough to avoid blur caused by the relative motion between the probe and the comet, but long enough to capture the faint light reflected by its nucleus and coma. The thermal stability of the instruments was also a critical factor, requiring adjustments to ensure the lenses and sensors operated in their optimal temperature range during the observation window, which lasted just a few minutes.

International Esforço in Martian orbit

The 3I/ATLAS observation was not an isolated initiative by the Chinese space agency. The presence of an international fleet of probes in orbit around Marte enabled a coordinated observation campaign, which significantly expanded the quantity and quality of data collected about the object. Agência Espacial Europeia (ESA) and NASA also directed their orbiters to study the gaseous composition of the comet’s coma and attempt to obtain even higher resolution images of its nucleus. On the surface, the Perseverance and Curiosity rovers were programmed to attempt to locate and observe the comet in the Martian sky, contributing a unique perspective. The success of the comet tracking operation served as a rigorous test of the capabilities of the Tianwen-1 probe in addition to its primary mission of studying Marte, demonstrating the flexibility and robustness of its navigation and attitude control systems.

The experience gained from observing 3I/ATLAS is considered extremely valuable for future Chinese missions, especially Tianwen-2. Lançada in 2025, this new mission has the ambitious objective of collecting samples from an asteroid and studying a comet. The protocols developed to observe the interstellar visitor will be directly applied to these new and complex deep space exploration missions.