Along the equator of Mars, CaSSIS spotted a couple of interesting craters in Ganges Chasma, a mineralogically diverse canyon in the far-eastern portion of Valles Marineris.
This is a false colour image – the blue tones of this image do not represent the real colour of the crater floor. The tonalities are stretched to bring out information about mineral diversity, and include information from the infrared, which is invisible to the human eye.
Thanks to CaSSIS’s colour filters, scientists can highlight mineralogical or geologic differences on Mars’s surface that we would otherwise have difficulty distinguishing.
The shape and texture of the ejecta blanket show that the surface was not completely dry at the time of impact. Water ice in the subsurface mixed with fractured rock and dust formed a ‘fluidised’ mass of material that was ejected outwards from the centre of the impact site. This indicates that there was water ice present in the surface at the time of impact.
The colours in this image help reveal how the blanket of debris surrounding the four-kilometre impact crater is thinning in places. This provides us with information about the original surface beneath, as seen in small patches of blue poking through the greenish-pink blanket.
Next to the large crater sits a 1.2 km diameter crater. Its smooth rims and the fact that it sits on top of its neighbour’s ejecta blanket indicate that this is a younger crater that hit the Red Planet after the larger crater was formed.