Snail sliding on Pluto has scientists mystified
A mysterious snail like object that is sliding on the surface of Pluto has scientists mystified and alien enthusiasts jumping up and down with excitement at the prospect of NASA’s interplanetary space probe New Horizons sending photographic proof of life outside our planet – many are buzzing with bizarre explanations.
Initially-baffled NASA scientists, however, have put forward less exciting but more scientifically-based explanations for the snail-like object on the photograph.
According to NASA editor, Bill Keeter, the dark object in the centre of the image is probably a dirty block of ice ‘floating’ on top of solid nitrogen, which is much denser – it has been dragged to the edge of a convection cell.
Social media sites across the world are full of suggestions regarding what this object might be – some plausible and several others bizarre. (Image Source: www.nasa.gov)
Photo captured by Long Range Reconnaissance Imager
The image, from New Horizons’ Long Range Reconnaissance Imager (LORRI), extends the highest-resolution views of Pluto to the very center of Sputnik Planum, which is the informal name for the icy plain that forms the left side of the dwarf planet’s heart feature.
Sputnik Planum is at a lower altitude compared to most of the surrounding area – a couple of miles lower. However, it is not completely flat.
Sputnik Planum’s surface is separated into polygons or cells from 10 to 25 miles (16 to 40 km) across, and when viewed at low sun angles – with visible shadows – the cells are observed to have slightly raised centres and ridged margins, with about 100 metres of overall height variation.
Slow thermal convection of the ices
Planetary scientists think the pattern of cells stems from the slow thermal convection of the ices (mainly nitrogen) that fill Sputnik Planum. There is a reservoir there of solid nitrogen, which in some places is several miles deep. It is warmed at depth by Pluto’s modest internal heat. As it warms it rises up in great blobs, and then cools down and sinks again, and so the cycle continues.
NASA’s New Horizons is an interplanetary space probe that was launched on January 19th, 2006, as part of the New Frontiers programme. Its main mission was to perform a flyby study of the Pluto system. Its secondary mission was to fly by and study at least one Kuiper belt object. (Image: nasa.gov)
William McKinnon, deputy lead of the New Horizons Geology, Geophysics and Imaging team, from Washington University in St. Louis, said:
“This part of Pluto is acting like a lava lamp. If you can imagine a lava lamp as wide as, and even deeper than, the Hudson Bay.”
According to computer models created by the New Horizons team, these blobs of overturning solid nitrogen can slowly merge over a period of millions of years.
“The ridged margins, which mark where cooled nitrogen ice sinks back down, can be pinched off and abandoned. The ‘X’ feature is likely one of these—a former quadruple junction where four convection cells meet. Numerous, active triple junctions can be seen elsewhere in the LORRI mosaic.
Video – Pluto’s Craters, Mountains and Icy Plains
This NASA movie was published in December 2015, before the pictures of the snail-like object were received. It gives us the sharpest views of Pluto during New Horizons’ flyby on July 14th, 2015.