NASA/Johns Hopkins University/Southwest Research Institute.
By Dan Smith
New high-resolution images downloaded from NASA's New Horizons probe over 5 billion kilometres away have stunned scientists, revealing Pluto's pitted and cratered surface in even more detail than before.
The latest images now show a range of highly complex surface features, including mountains, deep networks of valleys, nitrogen ice flows and possible wind-blown dunes.
"This is what we came for — these images, spectra and other data types that are going to help us understand the origin and the evolution of the Pluto system for the first time," said New Horizons principal investigator Alan Stern, of the Southwest Research Institute (SwRI) in Colorado.
"And what's coming is not just the remaining 95 per cent of the data that's still aboard the spacecraft — it's the best datasets, the highest-resolution images and spectra, the most important atmospheric datasets, and more. It's a treasure trove.
"Pluto is showing us a diversity of landforms and complexity of processes that rival anything we've seen in the solar system.
"If an artist had painted this Pluto before our flyby, I probably would have called it over the top — but that's what is actually there."
The revelation of possible dunes on the dwarf planet's surface has also piqued scientists' interest, as they indicate the atmosphere would have had to be thicker for wind to create the formations.
"Seeing dunes on Pluto — if that is what they are — would be completely wild, because Pluto's atmosphere today is so thin," said William B McKinnon, a GGI deputy lead from Washington University.
"Either Pluto had a thicker atmosphere in the past, or some process we haven't figured out is at work. It's a head-scratcher."
The images have more than doubled the amount of Pluto's surface, seen at resolutions as good as 400 metres per pixel.
They have also revealed Pluto's global atmospheric haze has more layers than scientists realized, creating a twilight effect that softly illuminates nightside terrain near sunset, making it visible to the cameras aboard New Horizons.
"This bonus twilight view is a wonderful gift that Pluto has handed to us," said John Spencer, a GGI deputy lead from SwRI.
"Now we can study geology in terrain that we never expected to see."
The discoveries made from the new imagery will not be limited to the dwarf planet itself — better images of Pluto's moons Charon, Nix and Hydra are also set to be released.