Unpublished records of comet 3I/ATLAS are captured by the Chinese probe Tianwen-1 in orbit around Mars

China’s Tianwen-1 probe has achieved a significant milestone in space exploration by capturing unique images of the interstellar comet 3I/ATLAS. The observation took place in October 2025, while the spacecraft orbited Marte, recording the celestial object at a distance of approximately 30 million kilometers.

This feat represents the first time that a visitor from outside our solar system has been observed from the vicinity of Planeta Vermelho. The data collected is considered crucial for the international scientific community that studies the composition and origin of such celestial bodies.

Comet 3I/ATLAS is only the third object with a confirmed interstellar origin, following the discoveries of Oumuamua in 2017 and 2I/Borisov in 2019.

Details of the unprecedented observation

The successful capture was made possible by the high-resolution camera on board Tianwen-1, known as HiRIC, originally designed to map planetary surfaces. The mission’s engineering team adapted its functionality to track a faint, fast-moving target in deep space. Isso required extensive and detailed simulations to determine the ideal short exposure times, a critical step to prevent images from being blurred due to the comet’s high orbital speed. After transmitting the data to the control center at Pequim, it was processed by a specialized system that compiled the individual records into clear 30-second sequences, revealing the comet’s journey against the background of distant stars.

Interstellar Visitor Features

The photographs released by Administração Espacial Nacional of China (CNSA) show the distinct characteristics of 3I/ATLAS. A solid, rocky core is clearly visible, surrounded by a vast coma of gas and dust that has sublimated from its surface.

The comet’s coma expanded to a diameter of several thousand kilometers, a sign of intense activity as it approached the inner solar system. The object itself measures about 5.6 kilometers wide and travels at a speed of 58 kilometers per second.

Initial spectroscopic analyzes suggest the presence of water ice and carbon dioxide, along with faint traces of carbon monoxide. Essa composition points to a formation in a cold protoplanetary disk, probably in a region distant from Via Láctea.

A global observation effort

The 3I/ATLAS observation was not an isolated effort, as several international space agencies directed their Marte-based assets to study the object. Agência Espacial Europeia (ESA) used its Mars Express and ExoMars Trace Gas Orbiter (TGO) probes to collect complementary data.

NASA also played a key role, using its Mars Reconnaissance Orbiter (MRO) to obtain high-resolution images with its HiRISE camera. On October 4, an attempt was made to capture images of the Martian surface using the Perseverance rover.

The Hope probe, Emirados Árabes Unidos, and NASA’s MAVEN orbiter contributed to the collection of spectrometric data. Essa global collaboration provided different geometric perspectives of the comet.

The combined information from these missions is helping scientists refine calculations of its axial orientation and better understand the non-gravitational forces that affect its trajectory, caused by the release of gases from its surface.

Technical challenges of capture

Operating at a distance of 29 million kilometers from the target presented a complex logistical challenge for the Tianwen-1 mission control team. Ajustes Precise aiming was necessary to keep the faint object within the camera’s field of view.

Maintaining the thermal stability of the spacecraft’s instruments was also essential to ensuring image clarity. An animation created from the sequence of photographs clearly illustrates the comet’s movement against the star field, providing valuable data for analysis.

The history of mission Tianwen-1

Launched in July 2020, the mission

The Zhurong rover operated for a full Earth year, performing detailed analyzes of the Martian soil, collecting geological images and studying the local atmosphere. Enquanto this, the orbiter continued its primary mission of mapping the planet, with a current focus on the polar ice caps and global dust distribution, continually expanding our knowledge of Planeta Vermelho.

Implications for future missions

The successful 3I/ATLAS observation serves as a crucial validation of the investigation methods and tracking capabilities that will be employed on the next ambitious China deep space mission. Tianwen-2, launched in May 2025, aims to collect samples from a nearby asteroid Terra and a main-belt comet, further enhancing the country’s proficiency in studying small celestial bodies.