3IATLAS- Foto: Jack_the_sparow/Shutterstock.com
The China National Space Agency (CNSA) announced that the Tianwen-1 probe, in orbit around Mars since 2021, recorded images of the interstellar comet 3I/ATLAS on October 3, 2025. The object passed approximately 30 million kilometers from the spacecraft, allowing high-resolution captures that show the comet’s coma and displacement. These records are integrated with data from the European probes ExoMars TGO and Mars Express, indicating acceleration not explained by gravity alone. The observation occurred during a planned window, enriching the study of materials from other stellar systems.
Scientists processed the images into a 30-second animation, which highlights variations in brightness and particle dynamics. This perspective of Mars offers angles impossible for ground-based telescopes. The comet, discovered in July 2025, represents the third confirmed interstellar visitor to the Solar System.
International collaboration expands understanding of cometary activity in contexts close to the red planet.
Tianwen-1 Capture Planning
CNSA engineers have adjusted the pointing of Tianwen-1’s high-resolution camera since September, based on trajectory calculations.
The focus prioritized short exposures to avoid blurring during orbital movementbeyond the probe. Telemetry tests ensured the secure transmission of images to the control center in Beijing.
Structure revealed in images
The comet’s coma appears well defined in the frames, with brightness gradients that suggest gas emission.
The time sequence allows you to measure the displacement vector in relation to the background stars.
These details, obtained from 30 million kilometers, surpass terrestrial resolutions limited by distance.
Contributions from European probes
The ExoMars TGO and Mars Express missions captured complementary records in the same period, with different lines of sight.
Combined photometry detects subtle variations in brightness, refining analyzes of coma morphology.
European scientists synchronized the data to test hypotheses about ice sublimation and dust jets.
This integration reduces geometric ambiguities in observations close to Mars.
Characteristics of comet 3I/ATLAS
3I/ATLAS, identified on July 1, 2025 by the ATLAS telescope in Chile, is estimated to be between 3 and 11 billion years old, possibly older than the Sun. Observed color changes indicate the chemical composition of regions close to the center of the Milky Way. The non-gravitational acceleration, confirmed in the joint data, suggests material ejection forces, common inactive etas.
Previous observations from probes such as STEREO and SOHO reinforce the need for time series to isolate intrinsic variability from instrumental artifacts.
- Origin: Probable in a distant stellar environment, with traces of elements formed billions of years ago.
- Size: Core estimated at a few kilometers, surrounded by a coma of up to 100 thousand kilometers.
- Trajectory: Perihelic passage on October 29, 2025, leaving the Solar System.
- Importance: Direct sampling of interstellar materials for planetary formation studies.
Initial data analysis
Advanced frame processing includes stacking to increase usable signal and deconvolution for sharpness.
Advancements for future missions
The operation validates navigation techniques for moving targets, essential for Tianwen-2, launched in May 2025 for asteroid sampling.
The exercise improves thermal controls and stability during long exposures, preparing for imaging faint objects.
These protocols calibrate models for operations on main-belt comets.
Prioritization now involves quantifying asymmetries in the coma and photometry of potential jets.
Next study steps
Cross-check with European data will improve estimates of axial orientation and non-gravitational forces.
