Distant Pluto Shows Signs of Youth, Even After 4.5 Billion Frigid Years

Pluto is an outlier, an underdog, a scientific anomaly. The dwarf planet may be small—but it definitely has big potential.

“This far exceeds what we came for,” noted Cathy Olkin, New Horizons Deputy Project Scientist, during today’s 3 p.m. press briefing at the Johns Hopkins Applied Physics Lab.

In a small portion of Pluto’s bright “heart” feature, the New Horizons team imaged mountain ranges that, at up to 11,00o feet high, rival the Rockies. “That’s a ‘balloon popping’ event,” said Alan Stern, New Horizons Project Investigator. These mountain regions could be geologically active, and the scientists predict that they aren’t more than 100 million years old. Compared to the 4.56-billion-year-old solar system, that’s infantile. It’s this ripeness and youth—highly unexpected for a celestial body so far away—that has the mission crew bustling with excitement.

New Horizons captured in great detail the heart-shaped feature, which has been named the Tombaugh Regio after Clyde Tombaugh. In planetary geology, a "regio" is a large area of a planet of moon that is strongly differentiated in color or albedo (reflectivity) from surrounding regions.

In fact, it may be one of the youngest surfaces that we’ve ever encountered. What’s more, the mountains are made of water ice and coated with a thin veneer of methane and nitrogen ices. “We can be very sure that water is there in great abundance,” Stern said. Nitrogen ice may be eroding from the surface; that there’s a veneer at all, though, implies that active internal processes are likely driving these volatile gases to the surface. The New Horizons team has a few guesses as to what could be going on: an internal, subsurface ocean could be freezing and gradually releasing energy, or radioactivity could be at play.

Tidal heating—thermal energy generated by gravitational interactions between planetary bodies—is typically a prerequisite for mountain formation. Or at least, that’s what scientists have always assumed. But Pluto begs to differ; it can’t have tidal energy because Charon and Pluto are in tidal equilibrium. The presence of towering mountain ranges, then, suggests that tidal heating is not needed to power recent geological activity. “This is going to send a lot geophysicists back to the drawing board,” said Stern. “We have to get a bit more clever.” Pluto is now the only icy world that doesn’t orbit a giant planet—and a fledgling example of a brand-new geophysical law.

Another sign of youth is the fact that this section of Pluto’s heart has no impact craters. That discovery came as a huge surprise to the team. This initial region contains strange geological features as small as half a mile long. Material that looks like lava flow (though it’s too big to be exactly that) ripples through bumpy terrain. At the same time, a new high-res image of Charon depicts large cliffs, troughs, and canyons—one of which is four to six miles deep. The dark area at its polar cap is also bigger than the team thought it would be. “There’s so much interesting science in this one image alone,” said Olkin as she discussed Charon during this afternoon’s press conference.

In the coming weeks and months, the New Horizons crew will investigate how and why Pluto still exhibits such ample activity. Is it somehow living off of stored energy from its original formation? They will also extrapolate the data to better understand how the Pluto-Charon system can help us better comprehend the relationship between Earth and its own moon, as well as how our planet may have lost some of its atmosphere early on in its life.