Interstellar comet 3I/ATLAS is photographed by the Chinese probe Tianwen-1 in an unprecedented feat near Mars

Space exploration reached a new level in October 2025, when the Chinese probe Tianwen-1, operating in the orbit of Marte, obtained high-resolution images of comet 3I/ATLAS. Este 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 astronomy. The historical record was carried out at an approximate distance of 30 million kilometers from the celestial body, a feat that required high precision 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, enriching knowledge about the formation of other planetary systems.

The successful operation not only demonstrates the advanced technological capabilities of the Chinese space program, but also opens up new possibilities for the study of interstellar objects. Observation from a point of view other than Terra offers a unique perspective, free from interference from the Earth’s atmosphere and allowing complementary analyzes that would be impossible to obtain otherwise. The data collected by Tianwen-1 will be analyzed by scientists around the world in the coming years.

A rare 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. Sua designation “3I” indicates exactly that: the third known interstellar object. Descoberto in April 2025 by an observatory at Chile, its 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 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. Esses materials are like time capsules, providing valuable clues about the formation processes of other planetary systems in Via Láctea and the chemical diversity that exists in the universe. Diferente than its predecessors, the proximity to Marte allowed for a much more in-depth and direct study.

The technical details of the unprecedented capture

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 unprecedented detail, the mission engineering team adapted its use to track a small, dimly glowing, fast-moving target in vast space. The challenge was immense, as the camera needed to compensate for both the movement of the probe and the comet to avoid blurry images, something comparable to photographing a bullet with a long-distance camera.

To overcome the challenge of capturing such a fast-moving object, extensive ground-based simulations were carried out to predict the behavior of the comet and the probe. The strategy adopted was to use extremely short exposure times, optimizing light capture and ensuring the necessary sharpness. The raw data was transmitted to the control center at Pequim, where a specialized processing system assembled the image sequences, revealing the interstellar visitor with stunning clarity. Este accomplished validated new observation techniques that could be applied in future deep space exploration missions.

What the images reveal about the comet

The photographs released by CNSA clearly show the rocky and frozen 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.

The coma reached a diameter of thousands of kilometers, indicating very intense cometary activity for an object of this nature. The tail, formed by particles ejected by solar radiation pressure, extended for about 56,000 kilometers.

Preliminary spectral analyses, based on the data collected, 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 indicates additional forces caused by the ejection of gases from its surface.

International scientific collaboration in orbit

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.

The 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. NASA’s Hope, Emirados Árabes Unidos, and MAVEN probes collected spectrometric data, enriching the set of information.

The journey of mission Tianwen-1 to date

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 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.

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 space 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. The successful tracking of 3I/ATLAS confirms the ability of China to conduct complex operations in deep space.