Unprecedented images of the interstellar comet 3I/ATLAS are recorded by a Chinese satellite on Mars

Chinese space equipment Tianwen-1 achieved a historic milestone in astronomy by photographing the interstellar comet 3I/ATLAS. During the month of October 2025, while orbiting the Red Planet, the spacecraft managed to focus its lenses on the visiting celestial body, which passed at an estimated distance of 30 million kilometers from the equipment.

This is the first visual record of a celestial body outside our solar system made directly from Martian orbit. This privileged point of view, far from Earth, offers scientists an unprecedented stereoscopic angle, allowing them to map the three-dimensional trajectory of the object with a precision impossible to achieve with ground-based telescopes alone. The joint effort of several nations has accelerated understanding of the formation of this type of space rock.

Officially identified on July 1, 2025 by researchers in Chile, 3I/ATLAS is only the third interstellar visitor confirmed by modern science. It succeeds the famous Oumuamua, detected in 2017, and 2I/Borisov, found in 2019, having a hyperbolic trajectory that mathematically proves its origin in another star system.

Adaptations to photographic equipment to capture the fast target

To make the recording possible, the team needed to reprogram the HiRIC camera, originally built to photograph the Martian soil. The very high-resolution instrument underwent software adjustments to be able to follow a very weak light point that crossed the vacuum at very high speed.

Technicians at the control base in Beijing ran dozens of virtual simulations before the real event, looking for the exact time to open the lenses to prevent the image from coming out blurry. The entire data packet received on Earth passed through a processing filter that transformed the raw captures into half-minute video clips.

Obstacles faced by the team during orbital alignment

Maintaining focus on a target located almost 30 million kilometers away required delicate maneuvers to position the probe. Temperature control of the sensors and millimeter stabilization of the satellite were fundamental steps to ensure that the bright core was not lost in the darkness.

With the photographic material in hand, the scientists put together a visual representation that highlights the movement of the rock against the fixed stars in the background. These visual measurements help calculate the non-gravitational forces pushing the comet, revealing details about the release of gases inside.

What the new images reveal about the visitor’s structure

According to material released by the China National Space Administration, the rocky center of 3I/ATLAS is surrounded by a dense cloud of cosmic dust. This gaseous layer, known as a coma, measured thousands of kilometers in diameter, signaling that the Sun’s heat is rapidly melting its components.

The main rock measures approximately 5.6 kilometers from tip to tip and tears through space at an impressive 58 kilometers every second. During the month of August, its luminous tail expanded until it reached 56 thousand kilometers in length, always pointing in the opposite direction to solar radiation.

Preliminary chemical analyzes point to a large concentration of common ice and carbon dioxide, as well as subtle traces of carbon monoxide. This mix of elements indicates that the celestial body was born in an extremely icy environment, probably on the edges of a planetary system very far from our cosmic neighborhood.

• Central structure: Compact mixture of ice and rock that reflects a reddish hue due to organic compounds.
• External cloud: Envelope of gas created by the immediate melting of the surface upon receiving sunlight.
• Luminous trail: Row of particles pushed by the force of light, visible depending on the position of the observer.
• Change of route: Change in speed caused by gas jets, deviating from the normal laws of gravity.

Advance planning ensured the success of the Chinese mission

Preparations for this historic moment began in September 2025, based on rigorous mathematical models. The researchers cross-referenced the target’s speed data with its low light output to find the perfect minute window to trigger the cameras.

Communication tests were carried out weeks in advance to ensure that no image bytes were lost on the way to Earth. The strategy of using rapid lens clicks proved to be the best choice for capturing light from an object that was more than 28 million kilometers away from the lens.

Using a planetary mapping satellite to hunt for comets served as a stress test for the equipment on board. The maneuver’s absolute success creates a new instruction manual for future ships that need to track small targets in the dark of space.

The entire process yielded practical learning about how machines can make decisions on their own far from home. The onboard computer was able to process the images and adjust the sensors in real time, without having to wait for commands from our planet.

Joint effort by international agencies enriches research

European equipment, including ExoMars TGO and Mars Express, also turned their lenses to 3I/ATLAS around the same time. This crossing of data between European and Chinese satellites creates a much more complete view of the astronomical event.

On the American side, the space agency activated the powerful MRO satellite to take very high definition photos of the nucleus. On October 4, even the Perseverance robot, which runs on the ground of Mars, tried to point its cameras at the sky in search of the comet.

Climate-focused satellites such as MAVEN and the UAE’s Hope probe took the opportunity to measure the object’s radiation. All this volume of information helps astronomers understand how the comet rotates on its own axis and what makes it accelerate.

• European satellite: Mars Express focused on finding out what gases were leaking from the core.
• American satellite: The MRO used its spy lenses to map the rock’s surface.
• Ground robot: Perseverance sought to record the phenomenon looking from below.
• Arab probe: The Hope mission assessed how the passage affected the surrounding Martian atmosphere.

History of achievements of the space program in Martian orbit

The journey of Chinese equipment began in mid-2020, reaching Martian gravity in early 2021 in an unprecedented technological leap for the Asian country. A few months later, the mission managed to land the Zhurong robot in the Utopia Planitia region, where it spent an entire year drilling into the ground, analyzing minerals and searching for signs of past habitable environments. While the robot rested, the main satellite continued its tireless work of photographing polar ice caps and mapping sandstorms, expanding the catalog of data on the neighboring planet’s climate.

China’s next steps in the hunt for distant asteroids

All the experience gained from photographing this interstellar visitor will serve as the basis for the Tianwen-2 mission, which began its journey in May 2025. The new Chinese project has the ambition of touching a nearby asteroid and a traditional comet to bring pieces of them back to Earth, consolidating the country as a powerhouse in the study of space rocks.