Interstellar comet 3I/ATLAS is photographed in unprecedented detail by the Chinese probe Tianwen-1

Space exploration has reached a new milestone with the release of high-resolution images of comet 3I/ATLAS, an object of interstellar origin. The feat was accomplished by the Chinese probe Tianwen-1, which operates in the orbit of Marte, consolidating the ability of the China space program to conduct complex observations in deep space.

The captures took place in October 2025, when the comet passed at a distance of approximately 30 million kilometers from Planeta Vermelho. The Este event represents the first time that a visitor from another star system has been observed in detail by a probe orbiting Marte, opening new fronts of research into the composition and dynamics of extrasolar celestial bodies.

The operation was not isolated, being part of a global collaborative effort. Agências spacecraft from different countries, including NASA and ESA, also directed their instruments at Marte to record the passage of 3I/ATLAS, generating an unprecedented volume of data that will be fundamental for analyzing its unique characteristics.

A visitor from another star system

Comet 3I/ATLAS is only the third interstellar object confirmed to cross our Sistema Solar, following the detections of Oumuamua in 2017 and 2I/Borisov in 2019. Chile, its hyperbolic trajectory, an open orbit that does not close around Sol, was the main evidence of its external provenance. With a rocky core estimated to be 5.6 kilometers wide and traveling at a speed of 58 kilometers per second, 3I/ATLAS offers a rare window into the primordial matter of other planetary systems. Análises preliminary spectra, carried out by ground and space observatories, indicate a composition rich in water ice and carbon dioxide, with traces of carbon monoxide. Essa’s chemical signature suggests that the comet formed in a very cold protoplanetary disk, possibly on the outskirts of its parent star, in a region distant from Via Láctea, before being ejected on its long journey through interstellar space.

The Tianwen-1 observation maneuver

Capturing the images by Tianwen-1 required a complex engineering and planning maneuver. The probe’s high-resolution camera, known as HiRIC, was originally designed to accurately map the topography of the Martian surface. Adaptá to track a small, dimly lit, fast-moving target in the vacuum of space was a significant technical challenge for the Administração Espacial Nacional team at China (CNSA).

To ensure success, engineers carried out extensive simulations on land. Foi necessary to calculate the ideal exposure time, short enough to avoid blur caused by the speed of the comet and the probe itself, but long enough to capture the faint light reflected by the object. The team precisely adjusted the orientation of Tianwen-1 and ensured the thermal stability of the instruments to obtain the necessary clarity at a distance of almost 30 million kilometers.

Details revealed in the images

The photographs processed and released by CNSA clearly reveal the main structures of comet 3I/ATLAS. The core, a solid body made up of rock and ice, appears as a bright spot in the center of the images.

Around the nucleus, an extensive coma is visible, a spherical cloud of gas and dust that forms when ice on the surface sublimates due to solar heat. Durante observation, the coma reached a diameter of thousands of kilometers, indicating intense cometary activity.

Although faint, the comet’s tail was also recorded, extending tens of thousands of kilometers in the opposite direction to Sol. Essa structure is formed by dust particles and ions ejected from the nucleus by solar radiation pressure and solar wind.

International scientific collaboration

The 3I/ATLAS observation campaign from Marte was a notable example of scientific cooperation. The Mars Express probe from Agência Espacial Europeia (ESA) used its instruments to analyze gas emissions in the coma, complementing the visual data from China.

For NASA’s part, the Mars Reconnaissance Orbiter (MRO) used its powerful HiRISE camera to obtain very high-resolution images of the nucleus, searching for details of its surface. On the Martian surface, the Perseverance rover also attempted to perform visual detection from its location in the Jezero crater.

The Hope probe, Emirados Árabes Unidos, and NASA’s MAVEN mission also participated, collecting spectrometric data and monitoring the comet’s interaction with the space environment around Marte. The combination of these multiple observation points allows us to refine models about the orbit, rotation and non-gravitational forces acting on the comet.

Trajectory and objectives of the Chinese mission

Tianwen-1, whose name means “Questions to Céu”, is the first interplanetary mission independent of China. Lançada in July 2020, it is made up of an orbiter, a landing module and a rover, the Zhurong.

The probe successfully entered the Marte orbit in February 2021, a historic milestone for the country’s space program. Enquanto the orbiter mapped potential landing sites, preparing the ground for the rover’s descent.

The legacy of the Zhurong rover on Mars

In May 2021, the Zhurong rover successfully landed on the vast plain of Utopia Planitia. During its period of operation, which lasted one Earth year, the vehicle explored local geology, analyzed soil composition and climate, and provided crucial data on the history of water in the region, before going into hibernation.

Implications for future explorations

The successful observation of comet 3I/ATLAS serves as an important validation of China’s dynamic target tracking capabilities. Essa experience is vital for future missions, such as Tianwen-2, launched in May 2025.

Tianwen-2 has the ambitious objective of collecting samples from an asteroid close to Terra and, later, visiting a comet in the main belt. Improved 3I/ATLAS observation techniques will be directly applied to ensure the success of this complex sample return mission.