Between 1 and 7 October, ESA’s ExoMars Trace Gas Orbiter (TGO) and Mars Express spacecraft turned their eyes towards interstellar comet 3I/ATLAS, as it passed close to Mars.
The two Mars orbiters had the closest view of the comet of all ESA spacecraft. During its closest approach to the Red Planet on 3 October, the interstellar interloper was 30 million km away from them.
Each spacecraft used its dedicated camera to watch the comet pass. Both cameras are designed to photograph the bright surface of Mars just a few hundred to a few thousand km below. Scientists were unsure what to expect from observations of a relatively dim target so far away.
ExoMars TGO captured the series of images shown in the GIF below with its Colour and Stereo Surface Imaging System (CaSSIS). Comet 3I/ATLAS is the slightly fuzzy white dot moving downwards near the centre of the image. This dot is the centre of the comet, comprising its icy-rocky nucleus and its surrounding coma.
