Interstellar comet 3I/ATLAS is photographed for the first time by a Chinese probe on Mars

Space exploration reached a historic milestone in October 2025, when the Chinese probe Tianwen-1, operating in the orbit of Marte, managed to capture high-resolution images of comet 3I/ATLAS. The event represents the first time that an object of interstellar origin is observed and photographed from another planet, consolidating a significant advance for planetary science and global astronomy.

The photographic record was carried out at an approximate distance of 30 million kilometers from the celestial body, a feat that required highly precise maneuvers and meticulous planning on the part of Administração Espacial Nacional of China (CNSA). The images provide crucial data for the global scientific community, which studies the composition and trajectory of visitors from outside our Sistema Solar.

The passage of comet 3I/ATLAS in the vicinity of Planeta Vermelho mobilized several space agencies, which directed their equipment to collect as much information as possible. International collaboration was essential to cross-reference data and obtain a more complete understanding of the nature of this rare cosmic object, which has been traveling the galaxy for millions of years.

A visitor from another star system

Comet 3I/ATLAS is the third object with a confirmed origin outside our Sistema Solar, following the detections of ‘Oumuamua in 2017 and 2I/Borisov in 2019.

The comet’s trajectory, described as a sharp hyperbolic orbit, is the main evidence that it does not belong to our system and is just passing through. About 5.6 kilometers wide and traveling at a speed of 58 kilometers per second, its analysis represents a unique opportunity for scientists.

Studying the materials that make up 3I/ATLAS allows us to investigate the matter formed in the protoplanetary disk of another star. Isso provides valuable clues about how other planetary systems form and evolve in Via Láctea, expanding our knowledge about the diversity of worlds in the galaxy.

The rarity of such events makes each observation extremely valuable. Objetos like 3I/ATLAS are messengers from distant star systems, carrying information that could not be obtained otherwise with current technology, justifying the coordinated effort of multiple nations and space agencies.

Historical Capture Technical Details

The high-resolution camera HiRIC (High Resolution Imaging Camera), on board Tianwen-1, was the central instrument for the successful observation. Originalmente designed to map the surface of Marte in great detail, the mission engineering team adapted its use to track a small, faintly glowing, fast-moving target in vast space. The challenge was immense, as the camera was not designed for astrophotography of distant objects, but rather for planetary observation, which required complex reprogramming of its operating parameters and pointing systems to compensate for the relative movement between the probe and the comet.

To overcome the difficulty of capturing such a fast-moving object without generating blurry images, extensive simulations were carried out on land. The strategy adopted was to use extremely short exposure times, optimizing light capture and ensuring the necessary sharpness for scientific analysis. The raw data was transmitted to the control center at Pequim, where a specialized processing system assembled the image sequences, corrected distortions, and enhanced the details of the comet’s nucleus and coma, transforming weak signals into clear, informative photographs.

What the images reveal about 3I/ATLAS

The photographs released by CNSA clearly show the rocky and frozen core of 3I/ATLAS, which is the heart of the object. The Este nucleus is surrounded by a coma, a cloud of gas and dust that forms when the heat from the Sol sublimates the ice on the comet’s surface. Detailed analysis revealed that the coma reached a diameter of thousands of kilometers, indicating very intense cometary activity, even at great distances from our star. The tail, formed by particles ejected by solar radiation pressure, extended approximately 56,000 kilometers and was positioned in the opposite direction to Sol during observations, a classic behavior of active comets. Análises Preliminary spectral data, based on collected data, suggest the presence of water ice and carbon dioxide. Também weaker signals of carbon monoxide were detected, a composition that points to a formation in a very cold region of its home star system. The reddish glow observed in the core is attributed to the presence of dust rich in organic compounds. Além In addition, scientists analyze a non-gravitational acceleration, a slight deviation in the trajectory that cannot be explained by gravity alone, indicating additional forces caused by the ejection of gases from its surface.

International scientific collaboration on Mars

The passage of 3I/ATLAS through Marte was not observed only through China. Agência Espacial Europeia (ESA) used its Mars Express and ExoMars Trace Gas Orbiter probes to analyze gaseous emissions from the comet’s coma, providing a complementary perspective to the Chinese data.

NASA also actively participated in the effort, directing Mars Reconnaissance Orbiter (MRO) to capture images with its powerful HiRISE instrument. On the surface, rovers like Perseverance have attempted to detect the comet from the Martian soil, a considerable technical challenge.

This collaboration allowed us to obtain a more three-dimensional view of the object’s activity, combining different observation angles to refine models about its composition, structure and dynamic behavior in interplanetary space.

The trajectory of the Tianwen-1 mission

Launched in July 2020, the Tianwen-1 mission represents a milestone for the Chinese space program, being the country’s first mission, Marte. The probe successfully entered Martian orbit in February 2021, carrying an orbiter, a lander and the Zhurong rover.

In May 2021, the Zhurong rover landed on the vast plain of Utopia Planitia, where it operated for approximately an Earth year, collecting geological data and analyzing the composition of the soil and atmosphere, while the orbiter continues its work mapping the planet.

Planning and execution of the maneuver

The Tianwen-1 mission team began planning to observe the comet in September 2025, as soon as orbital predictions became accurate enough. The calculations took into account the object’s high speed and low luminosity to determine the ideal observation windows, ensuring that the probe was in the correct position and the instruments were properly calibrated for recording.

Next steps for Chinese exploration

The successful 3I/ATLAS observations serve as an important validation of the technologies and methods that will be employed in future Chinese missions. The experience gained strengthens the Sistema Solar smaller bodies exploration program, one of the CNSA’s focuses for the next decade.

The Tianwen-2 mission, launched in May 2025, is the next big step. Seu objective is to collect samples from an asteroid close to Terra and, subsequently, study a comet from the main belt, consolidating China’s ability to conduct complex operations in deep space.