Chinese probe Tianwen-1 records historic images of the interstellar comet 3I/ATLAS in orbit around Mars

In a historic feat for space exploration, the Chinese probe Tianwen-1, operating in the orbit of Marte, managed to obtain high-resolution images of comet 3I/ATLAS in October 2025. The event represents the first time that an object of interstellar origin has been imaged from the orbit of another planet, establishing a monumental milestone for planetary science and modern astronomy. The recording was carried out at a distance of approximately 30 million kilometers from the celestial body, requiring extremely precise orbital maneuvers and detailed planning on the part of Administração Espacial Nacional of China (CNSA). The invaluable images provide the global scientific community with crucial data to further study the composition and trajectory of objects that visit our Sistema Solar from other stars.

A visitor from another star system in focus

Comet 3I/ATLAS is the third object detected with a confirmed origin outside our Sistema Solar, following in the footsteps of ‘Oumuamua, observed in 2017, and 2I/Borisov, identified in 2019. With an estimated diameter of 5.6 kilometers and moving 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 passage of 3I/ATLAS near Planeta Vermelho generated an international mobilization, with several space agencies redirecting their instruments to collect as much information as possible, transforming the event into a global collaborative effort.

The technology behind the unprecedented capture

The Câmera of Alta Resolução (HiRIC), one of the main instruments aboard the Tianwen-1 orbiter, played a crucial role in the success of this observation. 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. Essa operational flexibility demonstrates a significant advance in the responsiveness and multifunctionality of modern space equipment, opening up new possibilities for opportunity observations.

To overcome the challenges posed by the comet’s high speed, which could easily result in blurry images without scientific value, 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 powerful image processing system assembled the sequences, revealing the comet with unprecedented clarity and allowing detailed observation of its features from millions of kilometers away.

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 from Sol sublimates the ice present on the comet’s surface, releasing matter into space.

The coma reached a diameter of thousands of kilometers, an indicator of very intense cometary activity. 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.

Preliminary spectral analyses, based on data collected by other instruments, suggest the presence of water ice and carbon dioxide. Também signs of carbon monoxide were identified, whose composition indicates a formation in an extremely cold region of its home star system.

A scientific collaboration on a planetary scale

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

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.

NASA also actively participated, directing Mars Reconnaissance Orbiter (MRO) to capture images with its powerful HiRISE instrument. On the surface, rovers like Perseverance tried, albeit with great technical difficulties, to detect the comet from the Martian soil.

The context of the mission Tianwen-1 in 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. Durante 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, expanding knowledge about the geological history of Marte.

Meticulous planning for a 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 technology 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 main focuses for the next decade.