Chinese probe Tianwen-1 captures unprecedented photos of interstellar comet 3I/ATLAS in orbit around Mars

Space exploration reached a new milestone in October 2025, when the Chinese probe Tianwen-1, operating in the orbit of Marte, captured high-resolution images of comet 3I/ATLAS. The event represents the first time that an object of interstellar origin has been observed and photographed in detail from the orbit of another planet, consolidating a significant advance for planetary science and global astronomy. The feat positions Administração Espacial Nacional of China (CNSA) at the forefront of deep space exploration.

The images were obtained at an approximate distance of 30 million kilometers from the celestial body, a feat that required highly precise maneuvers and meticulous planning. The data provides crucial material for the scientific community, which can now study in greater depth the composition and trajectory of visitors from outside our Sistema Solar, offering a rare window into the composition of other star systems.

The transit 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 proved essential to cross-reference data and obtain a more complete understanding of the nature of this rare cosmic object, joining the efforts of nations that often compete in the space race.

A visitor from another solar 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.

About 5.6 kilometers in diameter and traveling at a speed of 58 kilometers per second, its analysis offers a unique opportunity to study materials formed in the protoplanetary disk of another star. Isso provides valuable clues about the formation of other planetary systems on Via Láctea, allowing scientists to compare the “recipe” of other worlds with ours.

Technical details of the capture

The Câmera of Imagem of Alta Resolução (HiRIC), on board the Tianwen-1, was the central instrument for the success of the observation. Originalmente designed to map the surface of Marte in unprecedented detail, the mission engineering team adapted its use to track a small, faintly glowing, fast-moving target in vast space.

To overcome the challenge of capturing such a fast-moving object without generating blurry images, extensive simulations were carried out on land. The strategy adopted involved the use of extremely short exposure times, optimizing light capture and ensuring the sharpness necessary for the detailed scientific analysis of the comet’s nucleus and coma.

After capture, the raw data was transmitted to the control center at Pequim. Lá, a specialized processing system assembled the image sequences, correcting distortions and highlighting details that would be invisible to the naked eye, transforming the raw data into scientifically valuable photographs.

What the images reveal about 3I/ATLAS

The photographs released by CNSA clearly show the rocky and icy core of 3I/ATLAS. 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, creating a temporary atmosphere around it.

The coma reached a diameter of thousands of kilometers, indicating very intense cometary activity for an object of its size. Isso suggests that the comet is rich in volatile materials that react strongly to solar radiation, even at great distances.

The tail, formed by particles ejected by solar radiation pressure, extended for approximately 56,000 kilometers. Durante observations, it was positioned in the opposite direction to Sol, a characteristic behavior of comets, but whose study in an interstellar object offers new insights.

Preliminary spectral analyses, based on the data collected, suggest the presence of water ice and carbon dioxide. Sinais fainter carbon monoxide was also detected, a composition that points to its formation in a very cold region of its home star system, far from its parent star.

An international scientific collaboration

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 Chinese visual data. Essa collaboration allowed us to obtain a more three-dimensional view of the object’s activity, combining different observation angles to refine models of its composition and structure. Combining imaging and spectrometry data is critical to understanding the complex chemistry that occurs when a comet approaches a star.

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 due to the planet’s thin atmosphere. NASA’s MAVEN and Hope probes collected spectrometric data, enriching the set of information and helping to refine estimates about the orientation of its rotation axis and the forces acting on it.

The journey of mission Tianwen-1 so far

Launched in July 2020, the Tianwen-1 mission represents a milestone for the Chinese space program, being the country’s first mission, Marte, which included an orbiter, a lander and a rover in a single expedition. The probe successfully entered Martian orbit in February 2021, beginning a mapping and reconnaissance phase of the landing site. In May 2021, the Zhurong rover landed on the vast plain of Utopia Planitia, where it operated for approximately one Earth year. Durante its mission on the surface, the rover collected geological data, analyzed the composition of the soil and atmosphere and sent back detailed images of the terrain, contributing to the understanding of the geological history of Marte. Enquanto this, the orbiter continues its work, mapping the planet, studying the Martian poles and acting as a communication relay, now with the additional function of an astronomical observatory for targets of opportunity such as comet 3I/ATLAS.

Next steps for Chinese exploration

The successful 3I/ATLAS observation serves 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 CNSA’s focuses for the next decade, which includes ambitious asteroid sample return missions.

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. The successful tracking of 3I/ATLAS confirms the ability of China to perform complex operations in deep space, paving the way for even more audacious explorations.