On October 3, 2025, the interstellar object 3I/ATLAS arrived within a distance of 30 million kilometers from Mars.
The European Space Agency (ESA) just released imaging data (accessible here) from their two Mars orbiters: ExoMars Trace Gas Orbiter (TGO) and Mars Express. The series of released color images with 5 second exposures from the Colour and Stereo Surface Imaging System (CaSSIS) onboard ExoMars Trace Gas Orbiter (TGO) show 3I/ATLAS as a fuzzy ball of light, qualitatively similar to the image taken on July 21, 2025 by the Hubble Space Telescope (as reported here and analyzed further here) at the much larger distance of 450 million kilometers. The Mars Express exposure time of 0.5 seconds was not sufficient to allow detection of 3I/ATLAS. It is unclear whether the spectrometers on both orbiters detected enough light for a spectral characterization of the chemical composition of 3I/ATLAS.
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