Interstellar comet 3I/ATLAS, discovered on July 1, 2025, has become the third known object to enter our Solar System from the depths of the galaxy. Currently, the comet is obscured from Earth-based observers by the Sun, but humanity is actively monitoring it using spacecraft positioned near other planets. This period is particularly interesting for scientists, as the comet is the most active.

Observations from Mars Orbit

Between October 1 and 7 October, 2025, two orbiters from the European Space Agency (ESA) — Mars Express and ExoMars Trace Gas Orbiter (TGO) — conducted observations of the comet. The closest approach occurred on 3 October, when the distance between the comet and the spacecraft was approximately 30 million kilometres.

The CaSSIS camera on board the ExoMars Trace Gas Orbiter managed to capture the comet as a blurred white spot, representing the coma—a cloud of gas and dust surrounding the nucleus. Obtaining more detailed images proved challenging, as the cameras on these spacecraft are designed to photograph the bright surface of Mars from close range, rather than faint objects located tens of millions of kilometres away. Despite the low quality, the images the data collected by the spectrometers may provide valuable information about the chemical composition of 3I/ATLAS.

NASA's spacecraft, including the Perseverance and Curiosity rovers, as well as the Mars Reconnaissance Orbiter, were also scheduled to observe the comet.

Future Observations

When comet 3I/ATLAS passes Mars, the opportunities to study it will continue. The next spacecraft set to observe this interstellar visitor will be ESA's Juice, which is en route to Jupiter. Its observations are scheduled for November 2025, coinciding with the comet's closest approach to the Sun, when its activity is expected to peak. This will provide scientists with another opportunity to study the composition of this unique object, which, according to some estimates, may even be older than our Solar System.

Want to learn more about space? Explore our articles and stay updated on astronomical events!