Chinese orbital observatory Tianwen-1 photographs comet 3I/ATLAS as it passes by Mars in 2025

The Tianwen-1 probe, from China, captured unprecedented images of the interstellar comet 3I/ATLAS in October 2025, as the celestial body passed close to Marte. Esta is the first time that an object outside Sistema Solar has been monitored from the orbit of the red planet, at a distance of approximately 29 million kilometers from the Martian surface.

The feat, announced by Escritório Nacional of Ciência Espacial of China, represents a significant advance in astronomy and contributes to an international effort to analyze the composition and trajectory of this unusual cosmic visitor. The data collected is crucial to better understand the origin and characteristics of interstellar comets.

Discovered on July 1, 2025 by the ATLAS telescope on Chile, comet 3I/ATLAS was confirmed as the third object of external origin to Sistema Solar, standing out for its hyperbolic trajectory and speed of 58 kilometers per second.

Technology behind rare Martian observation

The Tianwen-1’s HiRIC camera, originally designed to map planetary surfaces with high resolution, has been adapted for tracking faint, fast-moving targets. Essa Technological flexibility allowed the probe to adjust its systems to focus on a fast-moving object in deep space.

To avoid blurring of images caused by the high orbital speed of the probe and the comet itself, short exposures were used. The 30-second sequences were then processed in Pequim, resulting in photos that reveal crucial details of comet 3I/ATLAS’ nucleus and coma.

HiRIC Camera Challenges and Adjustments

Capturing images of such a distant and fast-moving object required a series of complex technical adjustments. Engineering teams needed to recalibrate the Tianwen-1’s orientation and thermal stability to ensure data transmissions were secure and efficient.

The comet’s rocky nucleus, with an estimated diameter of 5.6 kilometers, appears surrounded by a gaseous coma that extends for thousands of kilometers. Esses details provide important support for studies on non-gravitational accelerations that affect the trajectory of the celestial body.

What the images reveal about 3I/ATLAS

The photographs taken by Tianwen-1 show the comet’s central nucleus with a reddish hue, indicating the presence of organic dust on its surface. Este detail is critical to understanding the primitive composition of interstellar objects.

The coma, the diffuse cloud of gas and dust that surrounds the nucleus, shows signs of ice evaporation under intense solar radiation. Essa activity is an indicator that the comet is releasing material as it approaches Sol, creating a temporary atmosphere around it.

An elongated trail, stretching for around 56 thousand kilometers, is visible in the images, driven by the pressure of solar radiation. Análises Initial spectra detected the presence of water ice, carbon dioxide and traces of carbon monoxide, providing a detailed chemical profile of 3I/ATLAS.

The complex preparation for screening

Planning for the observation of comet 3I/ATLAS began in September 2025, involving orbit simulations and analyzes of the object’s low luminosity to optimize image capture. Testes rigorous telemetry tests were conducted to ensure the safe and complete transmission of images and data collected by the probe. Focusing on brief exposures was crucial to maximizing the signal from the object, which was located at a distance of 29 million kilometers from Marte. Essa extension of the original Tianwen-1 mission not only validates protocols for tracking interstellar targets, but also demonstrates the probe’s ability to perform astronomy operations beyond its primary Martian exploration functions. The integration of several subsystems allowed for near real-time data processing during flight, ensuring that information was captured and sent efficiently.

International collaboration in the study of the comet

The observation of comet 3I/ATLAS generated an opportunity for collaboration between several global space agencies. Agência Espacial Europeia, for example, used its Mars Express and ExoMars missions to record gaseous emissions from the comet’s coma.

This European data complements the varied angles provided by Chinese photographs, creating a more comprehensive view of the comet’s behavior. The synergy of different instruments and perspectives is vital for a complete analysis.

Mars Reconnaissance Orbiter of Nasa also contributed, obtaining higher resolution images of the comet’s nucleus, which allowed a more detailed analysis of its structure. On October 4, the Perseverance rover unsuccessfully attempted a visual detection of the Martian surface due to the distance.

The Hope probe Emirados Árabes Unidos monitored possible atmospheric impacts from the comet’s passage, adding another layer of data to the research. The set of these observations refines the estimates of axial orientation and the non-gravitational forces acting on 3I/ATLAS.

Composition and trajectory analysis

Collecting visual and spectral data from comet 3I/ATLAS allows scientists to improve models of its trajectory and structure. The speed of 58 kilometers per second and the hyperbolic trajectory confirm its origin external to our star system.

The joint analysis of information obtained by different space missions contributes to a deeper understanding of the anomalous accelerations that can deviate the comet from its expected path. Essa tracking and study capacity is essential for planetary defense.

The legacy of the Tianwen-1 mission and future explorations

The launch of Tianwen-1 took place in July 2020, with its orbital insertion in February 2021, demonstrating China’s capacity for interplanetary exploration. Seu rover, Zhurong, landed in May on the Utopia plain, collecting samples and data for an Earth year, expanding knowledge about Martian geology.

The Tianwen-1 orbital platform continues to map polar ice caps and the distribution of dust in the Martian atmosphere with the HiRIC camera. Essa’s versatility now extends to interstellar astronomy, significantly expanding the mission’s scientific scope beyond the initial objectives of Marte.

Understanding the origin of interstellar comets

Comet 3I/ATLAS offers valuable insights into cold protoplanetary disks, suggesting that it may have formed in distant regions, possibly near the center of Via Láctea. Sua age, which exceeds that of Sol, reveals ancient planetary formation processes and the diversity of cosmic environments.