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Comet 31/ATLAS has become one of the most closely watched interstellar objects in history—and the ESA (European Space Agency) is now playing a pivotal role in tracking its path.

In the first week of October, ESA’s ExoMars Trace Gas Orbiter delivered an extraordinary leap in trajectory accuracy, offering scientists a rare opportunity to study a cosmic traveler that will never return.

ESA Tracking Comet 31/ATLAS

Astronomers first spotted the faint object on July 1, 2025, designating it 3I/ATLAS, the third confirmed interstellar visitor ever detected in our Solar System. As ESA explains in its update, the comet is “on a one-way journey… swinging around the Sun once, then heading back out into deep space.”
🔗 Learn more from the European Space Agency: ESA Official Site

Interstellar objects like Comet 31/ATLAS move with extreme velocity—up to 155,000 mph (250,000 km/h). At that speed, the comet could travel from Earth to the Moon in only a few hours, meaning astronomers must be precise in their tracking to capture meaningful data.

ESAs ExoMars Orbiter Changes the Game

Until October, scientists relied solely on Earth-based telescopes to monitor the comet’s direction, brightness, and speed. However, that changed dramatically between October 1 and 7, when ESA aimed the ExoMars Trace Gas Orbiter, which is usually used to study the Martian atmosphere, toward the fast-moving object.

During its flyby, Comet 31/ATLAS passed within 18 million miles (29 million km) of Mars—close enough for the orbiter to capture unique images and data. This vantage point allowed astronomers to triangulate its path with far greater accuracy.

According to ESA, scientists expected only a small improvement in trajectory prediction, but instead saw a “tenfold leap in accuracy.”
🔗 ESA’s NEOCC (Near-Earth Object Coordination Centre): NEOCC

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Using Mars Instruments in a Bold New Way

This mission was far from routine. The CaSSIS camera aboard ExoMars is normally pointed downward to map Mars in high resolution. For this operation, engineers aimed it into deep space to watch the tiny comet sweep across the stars.

“It required a combined effort from flight dynamics, instrument teams, and scientists,” ESA noted. The maneuver demanded careful consideration of the orbiter’s rapidly shifting position in Mars’ orbit—something generally unnecessary for Earth-based observations.

Plotting the Future Path of Comet 31/ATLAS

With new data from Mars orbit, ESA astronomers refined the comet’s ephemeris, giving researchers a clearer idea of where to point telescopes for further study. This precision is essential because Comet 31/ATLAS will soon leave the Solar System forever, offering scientists only a narrow window for observation.