NASA's Mars Reconnaissance Orbiter also took images of 3I/ATLAS, but details were limited because of a government shutdown in the U.S.

The comet's coma, several thousand kilometers across, was formed by sunlight warming the object, releasing gas and dust, but the tail remained unseen in the images.

The comet is extremely faint, with brightness levels 10,000 to 100,000 times lower than typical targets, making observation challenging; TGO's longer exposures increased detection chances.

Researchers are analyzing data from both orbiters, including spectral studies using instruments like OMEGA, SPICAM, and NOMAD, to understand the comet's composition and how it changes as it approaches the Sun.

These observations aim to improve understanding of interstellar objects, which are considered building blocks from other stellar systems, and compare them to objects from within our solar neighborhood.

3I/ATLAS is only the third known interstellar object passing through our solar system, first observed in July 2025, and may be the oldest comet observed, possibly three billion years older than our Solar System.

ESA is preparing the Comet Interceptor mission, scheduled for launch in 2029, designed to intercept pristine comets from the Oort Cloud or interstellar objects like 3I/ATLAS to expand our understanding of these mysterious visitors.

Following the comet's closest approach to the Sun at the end of October, ESA's Jupiter Icy Moons Explorer (JUICE) will observe 3I/ATLAS in November 2025, with data expected in February 2026, when the comet is more active.

Between October 1 and 7, 2025, ESA's ExoMars Trace Gas Orbiter (TGO) and Mars Express observed the interstellar comet 3I/ATLAS as it passed near Mars, with the closest approach on October 3 at about 30 million kilometers away.

The comet made its closest approach to Mars on October 6, providing a rare opportunity for scientists to study this interstellar visitor.

ESA's orbiters captured images of the comet, revealing its nucleus and a surrounding coma, although the tail was not visible due to its faintness and the comet's distance.

After its journey, the comet will pass Jupiter in March 2026 before leaving our solar system.