Unprecedented records of comet 3I/ATLAS are made by the Tianwen-1 probe directly from Mars

The Chinese probe Tianwen-1, operating in the orbit of Marte, performed a historic feat by capturing detailed images of the interstellar comet 3I/ATLAS. The records were obtained in October 2025, when the celestial object passed at a distance of approximately 30 million kilometers from Planeta Vermelho, marking the first time that a visitor from outside our Sistema Solar has been observed by equipment in Martian orbit.

This achievement represents a significant advance for astronomy and the China space program, providing crucial data for the international scientific community. Analysis of the images and information collected contributes to a deeper understanding of the composition and behavior of celestial bodies that originate in other stellar systems.

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

A visitor from another solar system

The trajectory of 3I/ATLAS is one of the main focuses of study by scientists. Diferente of the comets and asteroids that belong to our Sistema Solar and follow elliptical orbits around the Sol, interstellar objects travel in open, or hyperbolic, paths. Isso means they make a single pass before continuing their journey through deep space, making each observation opportunity extremely valuable.

Confirmation of its interstellar nature mobilized observatories and space agencies around the world. The relatively close passage of Marte provided a unique window for the various probes orbiting the planet to direct their instruments and collect as much information as possible about this rare cosmic messenger.

The precision of the HiRIC camera

The images were captured by the HiRIC high-resolution camera, one of the scientific instruments on board the Tianwen-1 orbiter. Embora designed primarily to map the topography and geology of the surface of

To overcome this challenge, Administração Espacial Nacional engineers at China (CNSA) developed specific command sequences. Foram carried out complex simulations to calculate the ideal exposure time, short enough to prevent the speed of the comet and the probe from blurring the images, but long enough to capture the faint light reflected by the celestial body.

The raw data was transmitted to the control center at Pequim, where it underwent specialized processing. The result were 30-second sequences that reveal not only the comet’s nucleus, but also its coma, the cloud of gas and dust that surrounds it.

Overcoming cosmic distances

Operating at a distance of almost 30 million kilometers between the probe and the target presented significant logistical challenges. The mission team needed to make highly accurate aiming adjustments to ensure the HiRIC camera was pointed at the exact location at the right time.

The thermal stability of the probe was also a critical factor. Variações temperature in the instruments could affect image quality, requiring careful management of the Tianwen-1 systems during the observation period.

From the photographs obtained, an animation was created that clearly demonstrates the movement of 3I/ATLAS in relation to the background stars. Esses visual records are fundamental for astronomers who calculate the so-called non-gravitational acceleration of the comet.

This phenomenon, which causes a slight deviation from the expected trajectory, is caused by the release of gases from the core as the ice sublimes with heat. Studying this acceleration provides important clues about the comet’s internal composition and activity.

What the images reveal about 3I/ATLAS

Photographs released by CNSA show a rocky, frozen core, estimated to be around 5.6 kilometers in diameter, surrounded by a diffuse coma of gas and dust. At its peak, this coma extended for thousands of kilometers, an indication that the comet was in a period of intense activity due to its approach to Sol. The object was moving at an impressive speed of 58 kilometers per second relative to Sol during observation. The tail, formed by ejected particles, grew to tens of thousands of kilometers, always pointing in the opposite direction to that of Sol due to the pressure of solar radiation.

Preliminary spectrometric analyses, carried out by other observatories, complement the visual data from Tianwen-1. The spectra suggest the presence of water ice and frozen carbon dioxide, with fainter traces of carbon monoxide. Essa chemical composition indicates that 3I/ATLAS likely formed in a very cold region of its home star system, a distant protoplanetary disk, before being ejected into interstellar space by gravitational interactions.

An international collaboration in orbit

The effort to study comet 3I/ATLAS from Marte was a true global collaboration, demonstrating the synergy between different space agencies. Além from Tianwen-1, other missions in Martian orbit have aimed their sensors at the interstellar visitor. Agência Espacial Europeia (ESA) used its Mars Express and ExoMars Trace Gas Orbiter (TGO) probes to carry out analyzes of gas emissions in the coma, seeking to identify the molecules present. NASA also actively participated, with Mars Reconnaissance Orbiter (MRO) using its powerful HiRISE camera to attempt to obtain even higher resolution images of the comet’s nucleus. On the surface, the Perseverance and Curiosity rovers attempted to detect the comet in Marte’s night sky, an extremely difficult task but one that could provide a unique perspective. NASA’s Hope probe and NASA’s MAVEN also collected data on how the passing comet could interact with the tenuous Martian atmosphere. The combination of all this data, obtained from different points of view and with different instruments, allows scientists to build a much more complete and accurate three-dimensional model of the comet, refining estimates about its size, rotation and the non-gravitational forces that act on it.

Next steps for Chinese exploration

The successful 3I/ATLAS observation not only enriches the primary mission of Tianwen-1, but also serves as an important validation of the dynamic target tracking capabilities of China. Essa experience is fundamental for future missions, such as Tianwen-2, whose launch took place in 2025 with the aim of collecting samples from an asteroid close to Terra and, later, studying a comet in the main belt.