Interstellar comet 3I/ATLAS, discovered on July 1, 2025, has become the third known object to arrive in our Solar System from the depths of the galaxy. The comet is currently hidden from Earth observers by the Sun, but humanity is monitoring it using spacecraft located near other planets. This period is particularly interesting for scientists, as the comet is exhibiting maximum activity.

Observations from Mars Orbit

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

The CaSSIS camera on board TGO managed to capture the comet as a blurred white spot — this is the coma, a cloud of gas and dust surrounding the nucleus. Obtaining more detailed images was impossible since the cameras on these spacecraft are designed for photographing the bright surface of Mars from a close distance, not a faint object tens of millions of kilometers away. Despite the low quality, these images and the data collected by spectrometers may provide valuable information about the chemical composition of 3I/ATLAS.

NASA 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 not end. The next to observe the interstellar visitor will be ESA's Juice spacecraft, heading towards Jupiter. Its observations are scheduled for November 2025, when the comet will pass its closest point to the Sun and its activity is expected to peak. This will give scientists another chance to study the composition of this unique object, which, according to some estimates, might even be older than our Solar System.

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