NASA scientists studying the treasure trove of images and data sent back by the New Horizons spacecraft on its close fly-by of Pluto have turned their attention to a region peppered with craters. But like so much of this unexpectedly complex dwarf planet, the images raise almost as many questions as they answer.
The crater-strewn region is to the far western margin of the hemisphere New Horizons spacecraft viewed during its close approach last July. The craters are unusual in the way they have bright walls and rims. The largest of them, at bottom-right of the image above, 50 kilometres across.
The image below has incorporated data from New Horizons' spectral analysis of Pluto and shows the bright regions are composed of ices – both of methane and water. In this false colour image and methane ice is shown in purple and water ice – which appears on the floors and terrain between the craters – in blue.
But scientists are puzzled about why the methane ice should settle on these crater rims and walls, especially as that does not occur elsewhere on Pluto.