To say that the New Horizons mission has been a success would be a massive understatement; this first-ever spacecraft to visit Pluto has revolutionized our understanding of this distant, small world. Pluto and its moons are complex and active places, more so than thought possible by most scientists. Even though New Horizons flew past Pluto instead of orbiting it in July 2015, it still collected an enormous amount of information, which has taken more than a year to be sent back to Earth. That process is now complete, NASA just announced.
It has been 14 months since the New Horizons spacecraft flew past Pluto and its moons, but data still continues to come in, and new discoveries are still being made. The dwarf planet has surprised scientists by its geological activity, for the most part unexpected for such a small, cold body. Now two new results are adding to the mystery of Pluto: the detection of x-rays emanating from the surface and new evidence that Pluto “spray-paints” the north pole of its largest moon Charon a rusty red colour.
So-called “waterworlds” have been found to be surprisingly common in the Solar System – small icy moons which have ice crusts but oceans of liquid water below the surface. These include Jupiter’s moons Europa and Ganymede and Saturn’s moons Enceladus and Titan, and possibly others. These moons are cold and very far from the Sun, but heated inside by the gravitational pull of their giant host planets and/or radioactivity. Now there’s another Solar System body which, even more surprisingly, some scientists think has a subsurface ocean: Pluto.
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.