The detection of an interstellar object is a momentous occasion for the scientific community. So when 3I/ATLAS was identified as only the third such visitor, astronomers were determined to study it. Unlike comets born in our own solar system, this one was a messenger from the void between stars, carrying clues about its distant origins.
The comet's calculated trajectory carried it on a path that would take it relatively close to Mars in early October 2025. This presented an extraordinary, if challenging, chance for observation. Stationed in orbit around Mars was the European Space Agency's ExoMars Trace Gas Orbiter, a veteran spacecraft not originally designed for celestial photography.
Engineers faced the complex problem of redirecting the orbiter. They had to slew the entire spacecraft to aim its primary imaging system away from the Martian surface and toward the faint, speeding comet. It was a delicate maneuver, pushing the hardware to its limits to capture an object up to 100,000 times fainter than its usual targets.
The effort resulted in an unprecedented success: clear images of an interstellar comet from the perspective of another planet. These pictures are far more than simple snapshots; they are valuable data points. Scientists can analyze the comet's coma of gas and dust to find clues about the chemical makeup of its home star system.
Observing 3I/ATLAS offers a profound reminder of the dynamic nature of the galaxy. It demonstrates that the spaces between stars are not empty but are highways for such travelers. Capturing its image from Mars represents a significant achievement in our ongoing quest to comprehend the cosmos.