The New Horizons mission has revolutionized our understanding of Pluto and its moons, after conducting the first-ever flyby last summer. These mysterious worlds were finally seen up close, and this new view created as many, if not more, new questions as it answered old ones. While the flyby may be long over now, the spacecraft itself is still in excellent health and continues to plunge deeper into the Kuiper Belt at the outer fringes of the Solar System. Scientists have been eager for New Horizons to continue exploring this region farther out past Pluto, and now a proposal has been formally submitted to NASA to do just that. This extended mission will conduct a flyby of at least one more Kuiper Belt Object (KBO) and last until 2021.
As has been discussed extensively now, New Horizons has revealed Pluto to be a place unlike any other in the Solar System, with vast plains and glaciers of nitrogen ice, tall mountains of solid water ice capped with methane snow, layers of haze in its atmosphere, and perhaps an ocean of water below the surface. Now, there is additional evidence that Pluto once had rivers and lakes of liquid nitrogen on its surface, during times when the atmosphere was thicker than it is now. Just when you think Pluto can’t get any more bizarre, it does.
Pluto is a tiny world in the outer fringes of the Solar System; for many decades it was only a mere speck of light in even the best telescopes, with only vague hints of surface features. Then, in July 2015, the New Horizons spacecraft flew past Pluto, the first time ever that humanity would get to see this mysterious place up close – and it did not disappoint. An enormous amount of data has continued to be sent back by New Horizons since the flyby, and now five new papers have been published which provide an in-depth overview of the findings so far about Pluto and its moons. Pluto is an active world, with its own unique geology different from anywhere else in the Solar System.
As the data from New Horizons continues to come in, we are learning more about what an incredible little world Pluto really is, with tall mountains of rock-hard water ice, as well as glaciers and vast icy plains composed of nitrogen ice. In some ways, these features are visually reminiscent of similar ones on Earth, and now this week another cool discovery was revealed: methane snow on some of Pluto’s mountain peaks.
One of the most surprising discoveries in recent years in the outer Solar System is that there are small moons which have oceans inside them. Jupiter’s moon Europa and Saturn’s moon Enceladus are now known to have global oceans of water beneath their icy crusts, and others are thought to as well, including Ganymede, Titan, and possibly others. These moons have a lot of ice and rock as well, and gravitational tugging and heating from the large gas giant planets helps maintain a deep layer of liquid water inside them, where otherwise they would most likely be frozen solid in the deep cold so far from the Sun. Now it seems that another moon also once had an ocean, although in this case it is thought to now be solid ice: Pluto’s largest moon, Charon.
Pluto is a tiny world and incredibly distant from the Sun, so it was a pleasant surprise for scientists last summer when the New Horizons spacecraft found that it is such a geologically active and dynamic place, with vast “seas” of nitrogen ice and glaciers, tall mountains of rock-hard water ice, and possible ice volcanoes. A new update this week focuses on some of the most interesting features discovered: iceberg-like blocks of water ice which “float” in the “seas” of softer nitrogen ice.
New Horizons has shown Pluto to be a diverse world, more so than many scientists had anticipated, with tall mountain ranges, vast glaciers, a blue-colored layered atmosphere, and possible ice volcanoes. One thing, however, which seemed to be relatively lacking, was exposed water ice. Not much had been seen on the surface, not even in the glacial regions, which are composed of other ices instead. But now, new data indicates there actually is more water ice than had originally been thought.