Pluto’s ice secrets revealed
16 Jul 2015 by hddbqtthcb.d hddbqtthcb.d
Images from NASA’s New Horizons spacecraft have revealed an abundance of methane ice on Pluto.
Mission scientists studied infrared spectral images of Pluto taken by the Ralph instrument on board the probe reveal the abundance of methane ice but also found striking differences in its distribution across the surface of the dwarf planet.
To produce the first detailed infrared spectral image of Pluto, the Linear Etalon Imaging Spectral Array – part of the Ralph instrument – recorded three wavelengths. The image shows light of wavelengths 1.62 to 1.70?m – a channel covering a medium-strong absorption band of methane ice – in blue. The green colouration (1.97 to 2.05?m) represents a channel where methane ice does not absorb light and red (2.30 to 2.33?m) shows a channel where the light is very heavily absorbed by methane ice.
By analysing the image, the team found the north polar cap shows strong absorption of infrared light – suggested to be caused by dilution of the methane ice.
“We just learned that in the north polar cap, methane ice is diluted in a thick, transparent slab of nitrogen ice resulting in strong absorption of infrared light,” said New Horizons investigator Will Grundy from Lowell Observatory, Arizona.
The scientists also discovered that in one of the visually dark equatorial patches, the methane ice has shallower infrared absorption indicative of a very different texture.
“The spectrum appears as if the ice is less diluted in nitrogen or that it has a different texture in that area,” said Mr Grundy.
New Horizons’ surface composition team has now begun analysing Ralph data to determine the detailed compositions of the distinct regions on Pluto.
