As I write this, Science magazine is releasing its special issue on the results from the New Horizons spacecraft mission to Pluto. This will be the first set of peer-reviewed articles on the mission’s discoveries, and so there is quite a bit of excitement to see what has been learned.
It has been only eight months since New Horizons made its historic fly of the Pluto-Charon system on July 14, 2015. At this point, only about half of the data gathered during the flyby has been downlinked from the spacecraft to Earth. Data analysis and studies are only in their early stages, yet the results are stunning.
Pluto’s Geology is Completely Different Than Earth’s
Pluto’s surface is much more diverse and active than any of us ever expected. In fact, Pluto’s surface is geologically active today! A vast, Texas-sized ice glacier called Sputnik Planum covers 4% of its surface. We believe this “heart” is a nitrogen ice glacier flowing on the surface of Pluto, much like glaciers on Earth. But more intriguing – the interior of the glacier appears to be convecting, driven by an unknown internal heat source. But the most amazing thing is that this glacier is less than 10 millions years old – just the blink of an eye in Pluto’s history!
Another surprising feature on Pluto is (what appears to be) an enormous ice volcano. Unlike volcanoes here on Earth, which are driven by liquid rock (magma), Pluto has volcanoes driven by warm underground liquids. We think the liquids may consist of a mixture of water and ammonia. Pluto’s volcanoes may have built up their huge, rough, crusty mountains with material ejected from its interior over billions of years. This is a completely different type of geology than we have on Earth.
Pluto Has its Own Flavor of Meteorology
Pluto’s atmosphere has an extensive, brilliant blue haze that extends hundreds of kilometers into space. Embedded within this haze are over 20 thin brighter layers that, we believe, are formed by temperature waves in the atmosphere. Yet the atmosphere too holds some mysteries. The upper atmosphere is much cooler than we expected, leading to a more compact atmosphere. But that cooling mechanism is still completely unknown.
Pluto Has Vast Reservoirs of Surface Ices and Rich Organic Materials
The New Horizons cameras took high-resolution images showing diverse ice reservoirs spread across Pluto’s surface. By studying the reflected spectra from the surface, we have identified several different types of ices, in particular, nitrogen, methane, and carbon monoxide. The locations and characteristics of these ice reservoirs suggest that there have been long epochs of ice transport across the dwarf planet’s surface, i.e., Pluto’s own version of climate change.
Chtlulhu Regio is a vast region with a much darker surface that, we believe, has accumulated a meters-thick layer of carbon-rich organic compounds (tholins). Solar radiation converts methane to tholins in Pluto’s atmosphere, and these slowly rain down onto Pluto’s surface. Over the course of Pluto’s lifetime, 4.5 billion years, many meters of tholins have been produced. Exposed ices across the planet that sport this similar dark veneer likely made consist of a tholin material. This means that Pluto’s surface is covered by organic material.
Pluto has frozen water stored in the form of ice mountains. These ice mountains reach several miles above the surface, making them the biggest ice cubes in the solar system! But what is supporting their mass? Could it be a subsurface ocean like we’ve seen on several other moons in the solar system, such as Europa and Enceladus?
Charon’s Past was a Violent One
Images taken of Charon have also presented us with some major surprises. For instance, we see dramatic fractures on the surface that stretch almost all the way around the planet. What caused them? We suspect that Charon may have had a subsurface liquid water ocean that froze. When that ocean froze, the moon expanded in size and created the extensional fractures in the crust that are seen in the detailed images.
The Ingredients for Life are Everywhere, Even Out to the Kuiper Belt!
If we step back and consider the bigger picture of what we have learned about Pluto, we see some things that are at once both obvious and perhaps profound. For instance, Pluto is about half water—and probably has a subsurface ocean. Pluto must also have an unknown source of internal energy driving some of the surface geology (associated with Sputnik Planum)—though we don’t yet know what that energy source is. Lastly, Pluto has carbon-rich organic compounds everywhere!
In summary, Pluto has water, carbon-rich materials, and energy – the three requirements for “life as we know it” on Earth. I’m in no way suggesting that there is life on or inside Pluto. That’s not the point here. But the essential ingredients for life are there. These results are important because they tell us that the essential ingredients for life are found throughout the solar system, even to its furthest regions in the Kuiper Belt. Think about that for a moment.
The solar system is “ready” for life, and perhaps humanity.
Our Backyard is Brimming with Resources
The New Horizons mission has brought the Kuiper Belt into humanity’s “backyard” in the much vaster universe—a backyard that we are moving into rapidly. People everywhere talk about Pluto and its surprises, and this symbolism is important.
After a brief surge of interest in the 1960s to get to the moon, which faded for several decades, we now have renewed national and international efforts coming from both government and commercial organizations that aim to make space profitable for humanity. The prospects in this new “final frontier” are staggering. The asteroid belt has resources to supply humanity’s needs for thousands or perhaps millions of years. There is more liquid water in the outer planets’ moons than in all the oceans on Earth, by far.
Perhaps in another half century, a CNN reporter will stand high upon an ice mountain jutting out over the ice plains of Sputnik Planum. She’ll look out to the enormous engineering projects underway, perhaps building human habitats that utilize Pluto’s water and other resources for their construction. She’ll fix her gaze on the camera and say, “Reporting from Pluto….”
Note: The names of all of the Pluto surface features mentioned in this article are informal, unofficial names used by the New Horizons team.