Unpublished images from the Chinese probe Tianwen-1 reveal details of the interstellar comet 3I/ATLAS

Space exploration reached an unprecedented milestone in October 2025, when the Chinese probe Tianwen-1, in full operation in the orbit of Marte, managed to obtain high-resolution images of comet 3I/ATLAS. The remarkable feat represents the first time an object of interstellar origin has been imaged from the orbit of another planet, marking a monumental advance for planetary science and modern astronomy.

The historical record was carried out at a considerable distance of approximately 30 million kilometers from the celestial body. The operation required highly precise orbital maneuvers and detailed planning by Administração Espacial Nacional of China (CNSA), demonstrating the advanced technical capabilities of the country’s space program.

The images captured are invaluable to the global scientific community, which now has crucial data to further study the composition and trajectory of objects that visit our Sistema Solar from other stars. The passage of comet 3I/ATLAS through the vicinity of Planeta Vermelho mobilized an international collaborative effort to collect as much information as possible.

A visitor from another star system

Comet 3I/ATLAS is the third object detected with a confirmed origin outside our Sistema Solar, following in the wake of ‘Oumuamua, observed in 2017, and 2I/Borisov, identified in 2019. With an estimated diameter of 5.6 kilometers and traveling at an impressive speed of 58 kilometers per second, its analysis offers a unique opportunity to examine materials that formed in the protoplanetary disk of another star. Esses objects function as true cosmic time capsules, carrying primordial information about their systems of origin and providing valuable clues about the formation and evolution of other planetary systems in Via Láctea. The scientific interest is immense, as they can reveal the chemical and physical diversity of other corners of the galaxy, allowing scientists to compare the “recipes” of other systems with our own.

The technology behind the unprecedented capture

The Câmera of Imagem of Originalmente designed to map the surface of Marte with an exceptional level of detail, the Chinese mission engineering team demonstrated great versatility in adapting its use. The camera was reconfigured to track a small, extremely faint, fast-moving target against the dark background of deep space, a task it was not initially designed for.

To overcome the challenges posed by the comet’s high speed, which could easily result in blurry images without scientific utility, the CNSA team carried out exhaustive computer simulations. The final strategy involved the use of extremely short exposure times combined with precise target tracking. Essa technique optimized light capture without sacrificing sharpness. The raw data was then transmitted to the control center at Pequim, where a robust image processing system assembled the sequences, revealing the comet with never-before-seen clarity.

What the images revealed about 3I/ATLAS

The photographs released by the Chinese space agency show with great clarity the rocky and frozen core of 3I/ATLAS, the heart of the comet.

This nucleus is surrounded by a coma, a diffuse cloud of gas and dust that forms when the heat generated by Sol sublimates the ice present on the comet’s surface.

The coma reached a diameter of thousands of kilometers, indicating very intense cometary activity during its approach.

The tail, formed by dust particles and ions pushed by the pressure of solar radiation, extended for approximately 56 thousand kilometers, aligning itself in the opposite direction to Sol.

A scientific collaboration on a planetary scale

The 3I/ATLAS observation was not an exclusive effort by China. Agência Espacial Europeia (ESA) also played an important role, using its Mars Express and ExoMars Trace Gas Orbiter probes to contribute to the analyses.

This equipment was used to analyze gas emissions from the comet’s coma, providing a complementary perspective to the visual data obtained by Tianwen-1 and enriching the set of information available to researchers.

NASA also actively participated, directing Mars Reconnaissance Orbiter (MRO) to perform captures with its powerful HiRISE instrument, while on the surface, rovers like Perseverance attempted to detect the comet from the Martian soil.

Context of the mission Tianwen-1 on Marte

Launched in July 2020, the Tianwen-1 mission is a milestone for the Chinese space program, consolidating the country as a power in interplanetary exploration. The probe successfully entered the orbit of Marte in February 2021 and was comprised of an orbiter, a lander, and the Zhurong rover.

In May 2021, the Zhurong rover landed on the vast plain of Utopia Planitia. During its mission of approximately one Earth year on the surface, the vehicle collected geological data, analyzed the composition of the soil and atmosphere, and sent back detailed images of the terrain.

Detailed planning for the historical record

The Tianwen-1 mission team began planning for observing the comet in September 2025, as soon as orbital predictions became accurate enough to ensure the success of the venture. The complex calculations took into account the high relative speed between the probe and the comet, as well as the object’s low brightness.

The entire process was designed to ensure that the probe was in the correct orbital position and with its instruments properly calibrated at the exact moment of passage. The complexity of the maneuver reinforces the China’s ability to carry out highly technically difficult space operations autonomously.

Next steps for the Chinese space program

The successful 3I/ATLAS observation represents an important validation of the technologies and methods that will be employed in future deep space exploration missions by China. The experience gained strengthens the Sistema Solar exploration program for smaller bodies, such as asteroids and other comets, which will be one of the CNSA’s focuses for the next decade.