Historical record of the Tianwen-1 probe reveals details of the interstellar comet 3I/ATLAS near Mars

Space exploration reached a new level in October 2025, when the Chinese probe Tianwen-1, in orbit around Marte, accomplished an unprecedented feat. The equipment managed to capture high-definition images of comet 3I/ATLAS, a celestial object with a confirmed origin outside our Sistema Solar. Este event marks the first time that an interstellar body has been photographed with such a level of detail from the orbit of another planet.

The maneuver, conducted by Administração Espacial Nacional of China (CNSA), was carried out at a distance of approximately 30 million kilometers from the comet. The success of the operation required meticulous planning and extraordinary navigation precision, demonstrating the Chinese space program’s advanced technological capabilities for complex deep space missions.

The data obtained is considered invaluable to the global scientific community. The images provide crucial information about the composition, structure and trajectory of cosmic visitors, allowing astronomers and planetary scientists to study materials formed around other stars without leaving our own planetary system.

A visitor from another star system

Comet 3I/ATLAS is the third interstellar object formally identified by astronomers, following the detections of the enigmatic ‘Oumuamua in 2017 and comet 2I/Borisov in 2019. Cada one of these visitors offers a rare window into the diversity of other planetary systems in Via Láctea.

The main evidence of its extrasolar origin is its trajectory, described as a sharp hyperbolic orbit. Diferente of the elliptical orbits of comets and asteroids in our system, a hyperbolic trajectory indicates that the object has enough speed to escape the gravitational attraction of Sol, confirming that it is just passing through.

With an estimated diameter of 5.6 kilometers and moving at a speed of 58 kilometers per second, 3I/ATLAS represents a cosmic time capsule. Sua analysis allows the direct study of materials that made up the protoplanetary disk of its parent star, providing clues about planetary formation processes elsewhere in the galaxy.

Detecting and tracking such celestial bodies is crucial to understanding galactic dynamics. Eles act as natural probes, transporting chemical and physical information from their original environments, which allows direct comparisons with the composition of our own Sistema Solar.

Technical details of the capture

The fundamental instrument for the success of this observation was the HiRIC (High Resolution Imaging Camera) high-resolution camera, one of the main equipment on board the Tianwen-1 orbiter. Originalmente designed to map the geology and surface topography of Para To overcome the difficulty of photographing such a fast-moving object without the images becoming blurred or blurry, engineers carried out extensive simulations and developed an innovative observation strategy. The solution involved using extremely short exposure times, combined with precise probe tracking, to maximize light collection and ensure the sharpness needed for detailed scientific analysis. The raw data was then transmitted to the mission control center at Pequim, where a specialized image processing system combined multiple exposures to create the final records, revealing the comet with clarity never before seen from an interplanetary perspective.

What the images reveal about 3I/ATLAS

The photographs released by CNSA clearly show the core of 3I/ATLAS, a body composed of rock and ice. Este nucleus is surrounded by a coma, a temporary atmosphere of gas and dust that forms when heat from Sol sublimates volatile materials on the comet’s surface. The observed coma was vast, with a diameter of thousands of kilometers, indicating intense cometary activity and suggesting a composition rich in ices.

The comet’s tail, formed by dust and gas particles pushed by solar radiation pressure and solar wind, was also clearly recorded. Durante observations, it extended for approximately 56,000 kilometers, pointing in the opposite direction to Sol, as is characteristic of these bodies. Analysis of the structure, brightness and color of the tail provides valuable information about the size of dust particles and the rate of gas release, allowing scientists to estimate how much material the comet loses as it travels through our system.

Comet composition analysis

Spectral data collected by Tianwen-1, complemented by observations from other agencies, point to a composition rich in water ice and carbon dioxide in 3I/ATLAS.

Weaker but significant signals of carbon monoxide were also detected, which suggests that the comet formed in an extremely cold region of its home star system, much further from its star than comets from Nuvem to Oort are from our Sol.

Furthermore, the comet’s nucleus displays a reddish glow, a characteristic attributed to the presence of dust rich in complex organic compounds, which are considered fundamental building blocks for life as we know it.

Scientists are also investigating a slight deviation in its trajectory, known as non-gravitational acceleration. Esse phenomenon is caused by the ejection of gas jets from its surface, which act as small thrusters, and its analysis helps to map the active areas in the comet’s nucleus.

An international scientific collaboration

The 3I/ATLAS observation was not an exclusive effort by China. Agência Espacial Europeia (ESA) directed its Mars Express and ExoMars Trace Gas Orbiter probes to analyze the composition of gases in the comet’s coma, providing a complementary spectral perspective to the Chinese images.

NASA also played an active role, using the powerful HiRISE camera aboard Mars Reconnaissance Orbiter (MRO) to attempt to capture very high-resolution images of the object. On the surface, the Perseverance rover attempted to detect the comet in the Martian sky, a technical challenge that, if successful, would provide unique data on the interaction of the comet’s light with Marte’s thin atmosphere.

The Journey of Mission Tianwen-1

Launched in July 2020, the Tianwen-1 mission is a milestone for the Chinese space program, being the country’s first to simultaneously send an orbiter, a lander and a rover to Marte. The probe successfully entered Martian orbit in February 2021, and the Zhurong rover landed on Utopia Planitia in May of the same year, operating for nearly an Earth year and collecting valuable geological and atmospheric data.

Next steps for Chinese exploration

The successful 3I/ATLAS observation validates crucial technologies that will be employed in future China deep space exploration missions. The experience gained strengthens the asteroid and comet exploration program, one of CNSA’s main focuses for the next decade.

The Tianwen-2 mission, launched in May 2025, aims to collect samples from an asteroid close to Terra and, subsequently, study a comet in the main belt. The 3I/ATLAS tracking confirms China’s ability to conduct complex operations, consolidating its position as a leading power in modern space exploration.