Friday, October 30, 2015
NASA Finds Pluto Steeped in Flowing Glaciers and Kilometre-High Mountains
Suddenly Pluto becomes interesting as a potential source for terra forming Venus. It has the necessary goodies which are typically rare elsewhere. At least this gives us our first serious look at the remote objects located where wevneed to find them.
All good and we will surely be back when we are able to establish a base there.
Again we get surprises.
NASA finds Pluto steeped in flowing glaciers and kilometre-high mountains
Oct 15, 2015 2 comments
Image of Pluto taken by New Horizons
Rich and colourful: Pluto as seen by New Horizons
Pluto is a chilly world where glaciers of frozen nitrogen, methane and carbon dioxide flow around sturdy hills made of water ice. That's the picture painted by scientists working on NASA's New Horizons mission to the dwarf planet, who have revealed that it also has mountains several kilometres high, escarpments that run for 600 km and a "bedrock" made of frozen water.
Discovered in 1930, Pluto was viewed for the next six decades as a planet that did not fit in with the rest of the solar system. While the Earth and the other planets occupy near-circular orbits close to the same plane (the ecliptic), Pluto's orbit is about 17° away from the ecliptic and much more elliptical in shape.
Pluto's status as a planet began to wane in 1992 when astronomers discovered the Kuiper belt – a region stretching from Neptune's orbit out to about 55 astronomical units (AU) that contains lots of protoplanetary objects. In 2006 the International Astronomical Union decided that Pluto and other small planets in the Kuiper Belt do not fulfil all the criteria to be planets, reclassifying Pluto as a dwarf planet, to the chagrin of some astronomers.
"I was astonished to see such spectacular surface colour and geological diversity"
Silvia Protopapa, University of Maryland
Pluto was back in the news earlier this year when NASA's New Horizons craft flew to within 12,500 km of the dwarf planet, sending back spectacular images. Now, scientists working on the mission have analysed those images. Publishing their initial results in the journal Science, they say that Pluto's surface has "a wide variety of landforms and terrain ages, as well as substantial albedo, colour and compositional variation". The researchers have also found evidence that Pluto has a crust rich in frozen water. "I was astonished to see such spectacular surface colour and geological diversity," says Silvia Protopapa of the University of Maryland, who is part of a team studying the composition of Pluto's surface.
The Multispectral Visible Imaging Camera (MVIC) on board New Horizons paints a colourful picture of Pluto's surface, with dark, red regions at the equator and much brighter and bluer regions at higher latitudes. This general pattern is interrupted by a huge heart-shaped region called Tombaugh Regio that varies in colour from east to west.
The western portion of this region is a plain dubbed Sputnik Planum, which is free from craters. Other parts of Pluto are pockmarked with craters so Sputnik Planum's smooth surface suggests that it was created relatively recently by ongoing geological activity, according to the team.
The surface of Sputnik Planum comprises polygonal and oval-shaped cells that are tens of kilometres across and separated by shallow troughs 2–3 km wide. The team believes that the plain comprises frozen nitrogen, methane and carbon dioxide. Patterns in this ice suggests that it flows around water-ice hills at the edge of the plain in much the same way as glaciers on Earth flow around obstacles such as hills. Other surface features spotted by the mission that could be associated with recent geological activity include escarpments and troughs up to 600 km long.
Shadow-length measurements made by New Horizons show that Pluto is home to mountains that rise 2–3 km above the surrounding terrain. According to the mission team, the mountains suggest the presence of a strong, solid "bedrock" that is made mostly of frozen water. Furthermore, the team believes that the frozen nitrogen, methane and carbon dioxide spotted by New Horizons must only form a relatively thin veneer on top of this bedrock.
Meanwhile, data from the Linear Etalon Imaging Spectral Array (LEISA) instrument suggest that the reddish hues signal the presence of organic compounds called tholins. These are formed when ultraviolet light or charged particles irradiate mixtures of methane, nitrogen and carbon monoxide.
One unexpected discovery by New Horizons is that Pluto has an atmosphere that extends further than expected – to about 300 km above its surface. The atmosphere comprises nitrogen, methane and other hydrocarbons as well as a haze of dust particles.
The paper also looks at Pluto's largest moon Charon, which is 606 km in radius compared to Pluto's 1187 km. Like Pluto, the surface of Charon is rich in structures such as mountains, smooth and cratered plains, escarpments and other features associated with geological activity. Two of Pluto's other four moons, Nix and Hydra, have similar surface compositions with Hydra having several crater-like features, and Nix having large crater that is a different colour than the rest of the moon.
About the author
Hamish Johnston is editor of physicsworld.com