Probe suggests Pluto is as ‘complex’ as Mars and Earth

By: Kevin Bunch | Roseville - Eastpointe Eastsider | Published October 30, 2015


SOLAR SYSTEM — As the National Aeronautic and Space Administration probe New Horizons continues to beam back photos and data from its July flyby of Pluto, scientists are discovering that the dwarf planet is far more interesting than first thought.

New Horizons passed by Pluto at a distance of only 7,750 miles July 14, devoting all of its processing power to taking measurements and photographs of Pluto and its moons. Due to the amount of data and the distance involved, the probe will be sending back its findings well into 2016 as it continues to fly deeper into a region of space known as the Kuiper Belt.

Alan Stern, principal investigator for New Horizons, said Pluto has turned out to be more than just a ball of dirt and ice orbiting the sun, but rather a complex world on par with Earth and Mars.

“It’s a much more complex planet than the science team or anyone really expected,” Stern said. “It rivals Mars and the Earth, and that puts it on the very top of the list in the solar system in terms of geological history and complexity.”

Among the unexpected discoveries that New Horizons has made, he said, is that portions of the planet’s surface are very young geologically, with no evidence of craters. Scientists currently are baffled, as our understanding of planetary interiors suggests that a small world like Pluto would not have the energy left for that kind of surface shuffling, where the terrain is changed by volcanic activity or earthquakes.

“We don’t understand how a small planet could do that, because they should run out of energy much faster than big ones, because they cool more rapidly,” Stern said. “It threatens to revolutionize geological physics and our understanding of planetary interiors.”

Pluto’s surface ranges from water ice-rich bedrock to volatile ices on the western end of a heart-shaped region on the planet’s surface. That “heart” is home to a variety of nitrogen, methane and carbon monoxide ices.

Ed Cackett, assistant astrophysics professor at Wayne State University, echoed Stern’s statement and said that the geological formations, from mountains to plains, look relatively recent.

“I think that many astronomers, myself included, thought that Pluto’s surface would turn out to be quite boring, but boy were we wrong,” Cackett wrote in an email. “The New Horizons images have been stunningly beautiful, with totally unexpected findings.”

Stern added that Pluto’s atmosphere seems to have haze layers and “chemical constituents” that researchers were not aware of before the flyby. He said that a variety of geological features on Pluto and its moons — particularly its largest moon, Charon, with a massive canyon running across the visible surface — have raised additional questions on how they formed.

One possibility that researchers have put forth to explain those frozen, crater-free plains on Pluto and Charon is “cryovolcanism,” in which an internal water ocean froze, causing a change in the volume of the world and forcing water-based lava to the surface.

With its Pluto visit complete, New Horizons is on its way to rendezvous with a Kuiper Belt object, or KBO. Stern said the Kuiper Belt is full of comets orbiting the sun, along with a few other small planets like Eris, Makemake and Haumea; information on what makes up these objects and their geology is sparse at this time, much like the information on Pluto prior to the flyby this summer.

“When we look at other small planets (in the Kuiper Belt), some have moons, some have atmospheres — there’s a wide range of colors and composition,” Stern said. “What we know and learn about Pluto is bound to inform our perspective, but currently it’s clear that the different planets in the Kuiper Belt are very different from one another, just like Mars, Earth and Venus are very different from each other.”

New Horizons is not in a position to visit any of those three other Kuiper Belt planets with its remaining fuel. Those worlds will remain mysteries for future generations to investigate, according to NASA Director of Planetary Science Jim Green.

“The New Horizons mission completes our initial reconnaissance of the solar system, giving humanity our first look at this fascinating world and its system of moons,” Green said in a statement. “New Horizons is not only writing the textbook on the Pluto system, it’s serving to inspire current and future generations to keep exploring — to keep searching for what’s beyond the next hill.”

For those interested in trying to see Pluto themselves, Cackett said it requires a “good-sized” telescope — around 10 inches in diameter — along with dark, clear skies.

“Even then, it is a challenge to find,” Cackett wrote in an email. “It’s not much to look at either — it will appear as a faint, point-like object. For most people, it’s best to sit back and enjoy the amazing images that New Horizons has taken.”

Stern added that NASA will be putting forth a press release in November detailing the top 10 new questions raised by the New Horizons visit. That release was not available by press time.