Pluto’s Surface Has Changed Over Time

So, Pluto has a second set of mountains along one edge of Tombaugh Regio (the heart-shaped region). The planet continues to stun all of us with amazing views sent back by New Horizons, and the mountains are just the latest in a long string of discoveries to come. I can’t say I’m totally surprised to see them; I remember a geology teacher once saying where there’s one mountain range on a world, shaped by some kind of internal process, there’s bound to be another.

These mountains aren’t quite as high as the Norgay Montes, first seen on July 15th, but they’re still pretty spectacular-looking. They rise up to perhaps only a kilometer or so, but they look quite sharp, standing out in relief against the bright landscape. It looks like they may be younger than the surrounding landscape, but that’s just my guess. If so, then this surface is changing, indeed!

The thing that caught my eye after I checked out the mountains was that very interesting interface between the dark region and the brighter material that makes up Sputnik Planum (which is part of Tombaugh Regio). At first glance, I could tell that there’s been some filling in of craters by the white material. That’s another clue that the lighter-colored landscape is much younger than the darker regions. In fact, the team suspects the dark region is billions of years old, while the lighter landscape is less than a hundred million years old. That’s pretty young in planetary science terms, when you think about it. The solar system formed some 4.56 BILLION years ago, so this surface has only been around for a short time compared the age of the Sun and other worlds.

What Could Be Causing the Mountains on Pluto?

As I mentioned in my article of a few days back, called  Pluto is Geologically Active, mountain-building processes here on Earth are driven by plate tectonics, which is itself driven by heat and motions beneath the planet’s crust. We don’t know yet what’s driving it on Pluto. The planet is just about 70 percent rock, so it might be that there’s activity in the interior related to decay of radioactive materials or some other process.

If that activity generates or is driven by heat, that would affect the icy surface, possibly causing mountains to form in some way, and ices to flow to create smoothed-over landscapes. Remember, the ices on Pluto are largely nitrogen and methane, and those can melt and/or sublimate at pretty low temperatures, so you wouldn’t need a lot of heat. I look forward to hearing a more nuanced and scientifically informed interpretation of the images from the New Horizons team.

There will be a science press conference on the 24th (you can watch at NASA.TV), and I suspect we’ll hear more about those mountains and the dichotomy between the dark and light regions of the planet. So, as I like to say, stay tuned!

Note: the spacecraft has gathered 50 gigabits of data, which it will be sending back over the ever-increasing distance between it and the Earth over the next 16 months. At times, the spacecraft will be returning various types of data, not all of it imaging. However, the team will be releasing images as often as they can, generally once a week or so. The best way to keep up with the news from New Horizons is to check out www.nasa.gov/newhorizons and/or pluto.jhuapl.edu — where you’ll find images, videos, and discussions of the latest Pluto scientific discoveries.