Chinese probe Tianwen-1 records unprecedented images of interstellar comet from the orbit of Mars

The Chinese probe Tianwen-1, operating in the orbit of Marte, performed an unprecedented feat by capturing detailed images of the interstellar comet 3I/ATLAS. The records, obtained at a distance of approximately 29 million kilometers from the Martian surface, were recently released by Escritório Nacional of Ciência Espacial of China and mark the first monitoring of an object coming from outside of Sistema Solar from the red planet.

3I/ATLAS is the third object with confirmed interstellar origin to be detected by astronomers, identified for the first time in July by ground-based observatories. Sua hyperbolic trajectory and high speed of around 58 kilometers per second are clear evidence that it did not originate in our system, making it a target of great scientific interest for space agencies around the world.

The achievement of the Tianwen-1 mission represents a significant advance in deep space observation capabilities and contributes valuable data to the international effort to analyze the composition and behavior of these rare cosmic visitors. The images provide crucial information about the structure of the comet’s nucleus and coma.

Technical adaptation for a fast target

Capturing images of comet 3I/ATLAS required a complex adaptation of the Tianwen-1 probe’s instruments, which were not originally designed to track small, dark, fast-moving targets. The high-resolution HiRIC camera, whose primary function is to map the surface of Marte, has had its software adjusted by engineers on the ground to track the object accurately. Foram used sequences of short exposures, lasting just 30 seconds, to prevent the high orbital speed of the probe and the comet itself from blurring the images, a considerable technical challenge.

The success of the operation also depended on precise orientation maneuvers of the probe and careful management of the thermal stability of the equipment during pointing. The transmission of data to the control center in Pequim was another obstacle overcome, ensuring that the information arrived intact for processing. The images reveal a rocky core with an estimated diameter of 5.6 kilometers, surrounded by an extensive gaseous coma that extends thousands of kilometers into space, a testament to the sublimation of ice under the influence of solar radiation.

What the images reveal about 3I/ATLAS

The photographs taken by the Chinese probe show the comet’s nucleus with a reddish hue, which suggests the presence of dust rich in organic compounds on its surface.

The coma, a diffuse cloud of gas and dust that surrounds the nucleus, appears very active, indicating a strong evaporation of ice as the object approaches Sol.

A trail of dust and gas, known as the tail, extends for more than 56,000 kilometers, being pushed by the pressure of solar radiation.

Preliminary spectral analyses, based on the data collected, have already detected the presence of water ice, carbon dioxide and possible traces of carbon monoxide in the comet’s composition.

A coordinated operation in deep space

The effort to study comet 3I/ATLAS was not limited to China, involving a global collaboration between different space agencies that have equipment operating at Marte. Agência Espacial Europeia (ESA) used its Mars Express and ExoMars Trace Gas Orbiter orbiters to analyze gas emissions from the comet’s coma, providing complementary data that, combined with images from Tianwen-1, allow a three-dimensional view of the phenomenon. NASA also actively participated, with Mars Reconnaissance Orbiter (MRO) capturing very high-resolution images of the comet’s nucleus. On the surface, the Perseverance rover made attempts to visually detect the object from the Martian soil, while the Hope probe, from the Emirados Árabes Unidos, monitored possible interactions between the comet’s tail and the planet’s upper atmosphere. Esse set of coordinated observations is essential to refine models about the trajectory and non-gravitational forces that act on these interstellar visitors.

Planning and execution of the maneuver

Planning for the observation of 3I/ATLAS began months before, shortly after confirming its trajectory.

Engineering teams performed extensive simulations to predict the comet’s exact orbit and low luminosity, preparing the probe for the challenge.

Rigorous telemetry tests were conducted to ensure safe and stable transmission of images over a distance of nearly 30 million kilometers.

Implications for future missions

This successful operation validates fast, low-light target tracking protocols that will be essential for future missions.

The lessons learned from the 3I/ATLAS observation are already being applied in planning the Tianwen-2 mission, scheduled to collect asteroid samples.

Mission history Tianwen-1

The Tianwen-1 mission was launched in July 2020 and entered Marte orbit in February 2021, representing a milestone for the Chinese space program.

In addition to the orbiter, the mission included the Zhurong rover, which explored the Utopia Planitia plain on the Martian surface for about an Earth year.