Comet 3I/ATLAS will pass 30M km from Mars on Oct. 3, 2025. ESA and NASA orbiters will capture this rare interstellar visitor.
ESA gears up to study interstellar comet 3I/Atlas from the best vantage point in the solar system
Photo Credit: NASA
Image of interstellar comet 3I/ATLAS captured by the Hubble Space Telescope. A newly discovered interstellar comet named 3I/ATLAS is set to make a close pass by Mars next month. Astronomers spotted the comet on July 1, 2025, and designated it 3I/ATLAS as the third known interstellar object. On Oct. 3, 2025, 3I/ATLAS will sweep to about 30 million km from Mars — much closer than its distance from Earth (270 million km). ESA is preparing to use its Mars orbiters to observe the event and gather data as the comet streaks by.
According to Space.com, Colin Frank Wilson, Project Scientist for ESA's Mars orbiters, on Oct. 3, 2025, 3I/ATLAS will sweep about 30 million km past Mars, far closer than its distance from Earth at the same time (around 270 million km).
For an interstellar comet normally speeding silently through space, this is a remarkably near miss. Mars's orbiters will have a prime vantage point to study the visitor up close. Observers hope to image the comet's fuzzy coma and even hint at its nucleus shape with the spacecraft's high-resolution cameras.
ESA will use its Mars orbiters to watch 3I/ATLAS. Scientists plan to image the comet using Mars Express's High-Resolution Stereo Camera (HRSC) and TGO's high-res colour imager (CaSSIS) during the flyby.
They will also employ onboard spectrometers (NOMAD, OMEGA) to check for water vapour or organics in the comet's coma. Other spacecraft around Mars — NASA's MAVEN and MRO and China's Tianwen-1 — may also try to catch the comet. Joern Helbert, head of ESA's Solar System Section, told Space.com that The JUICE spacecraft is also planning observations.
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