Interstellar comet 3I/ATLAS is recorded in unprecedented images by the Chinese probe Tianwen-1 on Mars

Space exploration reached a new level with the release of extraordinary images captured by the Chinese probe Tianwen-1. Operando in the orbit of Marte, the equipment recorded the interstellar comet 3I/ATLAS, a visitor from outside our Sistema Solar, in an unprecedented feat. The photographs were taken in October 2025, when the celestial object passed at a distance of approximately 30 million kilometers from Planeta Vermelho.

This event represents the first time that an interstellar body has been observed and photographed by a probe orbiting another planet. The achievement not only demonstrates the advanced capabilities of China’s space technology, but also provides crucial data for the global scientific community studying the composition and trajectory of these rare cosmic travelers.

3I/ATLAS is the third object of confirmed interstellar origin to be detected by astronomers, following in the footsteps of ‘Oumuamua in 2017 and 2I/Borisov in 2019. Sol.

A milestone in interplanetary observation

The capture of 3I/ATLAS images by Tianwen-1 is considered a historic milestone. The ability to observe such a distant and dynamic object from the perspective of Marte opens new windows of opportunity for planetary science and astronomy. The Essa approach allows the study of celestial bodies under angles and lighting conditions different from those possible from the Terra or from telescopes orbiting our planet.

The data collected by the Chinese probe is essential to complement observations made by other instruments. The joint analysis of the information allows scientists to build a more accurate three-dimensional model of the comet’s coma and tail, in addition to refining calculations about its trajectory and non-gravitational acceleration, a phenomenon caused by the release of gases from its surface.

This achievement solidifies China’s role as a powerhouse in deep space exploration. By extending the capabilities of its Mars mission to include observation of targets of opportunity like 3I/ATLAS, the nation’s space program demonstrates versatility and a long-term strategic vision for scientific research in the Sistema Solar.

The technical challenges of deep space capture

Photographing a faint, fast-moving object like comet 3I/ATLAS from millions of kilometers away represented a monumental technical challenge for the mission team. Tianwen-1’s high-resolution camera, known as HiRIC, was designed primarily to map the surface of Marte in minute detail. Adaptá her to track a faint point of light against the darkness of space required complex reprogramming and meticulous planning. Engineers had to develop new tracking algorithms and perform extensive simulations to ensure the probe could keep the comet in its field of view.

One of the biggest obstacles was exposure time. A long exposure would be necessary to capture the comet’s faint light, but the rapid relative motion between the probe and the object would cause significant blurring, rendering the image scientifically useless. The solution was to use a series of very short exposures and then combine the data into Terra. The information packets, transmitted from Marte to the control center at Pequim, were processed in a specialized system that aligned and stacked the images to create the final 30-second sequences, revealing the comet’s motion against the background of distant stars.

What the images reveal about 3I/ATLAS

Photographs released by Administração Espacial Nacional of China (CNSA) offer a detailed look at the characteristics of the interstellar comet. In the center, it is possible to distinguish the core, a body composed of rock and ice about 5.6 kilometers wide, which has a reddish glow, possibly due to the presence of dust rich in organic compounds. Este core is surrounded by a coma, a vast cloud of gas and dust thousands of kilometers in diameter, formed by the sublimation of ices as the comet approaches the heat of Sol. The tail, initially tenuous, expanded to a length of 56,000 kilometers and was directed in the opposite direction to Sol, pushed by the pressure of solar radiation. Preliminary spectral analysis of the data indicated the presence of water ice and carbon dioxide, with traces of carbon monoxide, suggesting that 3I/ATLAS formed in a very cold protoplanetary disk, perhaps in a region distant from Via Láctea, before being ejected on its interstellar journey.

International collaboration in the study of the comet

The passage of 3I/ATLAS through Marte mobilized a global observation campaign, with several space agencies pointing their instruments at the cosmic visitor. Essa collaboration was essential to gain a more complete understanding of the object.

Agência Espacial Europeia (ESA) actively participated with its probes Mars Express and ExoMars Trace Gas Orbiter (TGO). Esses equipment performed spectrometric analyzes to study gas emissions in the comet’s coma, complementing the visual data from Tianwen-1.

On NASA’s side, Mars Reconnaissance Orbiter (MRO) used its powerful HiRISE camera to attempt to obtain very high-resolution images of the comet’s nucleus. Além Furthermore, rovers on the surface, like Perseverance, have been programmed to try to visually detect the comet in the Martian sky, an extremely challenging task.

The Hope probe, Emirados Árabes Unidos, and NASA’s MAVEN mission also contributed to collecting data on how the passing comet could interact with the tenuous atmosphere of Marte. The joint effort of multiple nations provided different geometric and instrumentation perspectives, crucial to refining models about the orientation and forces acting on the comet.

The detailed planning of the Tianwen-1 team

The comet observation operation was not a coincidence. The Tianwen-1 mission team began planning in September 2025, shortly after confirming the 3I/ATLAS trajectory. Scientists relied on high-precision orbital predictions to calculate the ideal observation windows, taking into account the comet’s speed, its low luminosity and the probe’s position.

Rigorous telemetry tests were carried out to ensure that the large volume of data generated by the images could be transmitted securely and efficiently from Marte to Terra. The focus on short exposures and subsequent processing was a deliberate strategy to maximize signal quality from the target, which was a considerable distance of 18 million miles at the time of capture.

The trajectory of the Tianwen-1 mission in Marte

Launched in July 2020, Tianwen-1 represents the first interplanetary mission completely independent of China. The probe successfully entered the Marte orbit in February 2021, a milestone for the country’s space program. The success of the mission was consolidated in May of the same year with the landing of the Zhurong rover on the vast plain of Utopia Planitia, a region of great geological interest.

The Zhurong rover operated for approximately one Earth year, exceeding expectations for its primary mission. During this period, he traveled the Martian surface, collected data on the composition of the soil, analyzed the geological structure and monitored the local climate. After Enquanto, the orbiter continued its scientific work, mapping the planet with its HiRIC camera and other instruments, with a current focus on studying polar ice and atmospheric dust dynamics, continually expanding our knowledge of Planeta Vermelho.

Implications for future exploration missions

The success in tracking 3I/ATLAS serves as an important validation of the technologies and methods that will be used in future Chinese missions to explore smaller bodies. The experience gained is directly applicable to the Tianwen-2 mission, launched in May 2025, which has the ambitious objective of collecting samples from an asteroid close to Terra and, later, from a comet in the main belt, deepening the capacity of China to study and interact with these primitive objects from Sistema Solar.