NASA’s New Horizons spacecraft is way, way past Pluto now and still nearly a year away from its next encounter with an object in the Kuiper Belt, but that doesn’t mean it hasn’t been busy. In fact, the probe just broke the record for the farthest images from Earth ever taken by a spacecraft, with new images of a field of stars and two other Kuiper Belt objects. The new images break the record formerly held by the Voyager 1 spacecraft in 1990.
Happy New Year! As well as simply the start of a new year, today also marks another significant date – exactly one year from now, the New Horizons spacecraft will encounter its next target deep in the Kuiper Belt, much farther out than Pluto. On Jan. 1, 2019, New Horizons will fly past another Kuiper Belt Object (KBO) called 2014 MU69. This will be the most distant object to ever be visited by a spacecraft in our Solar System so far.
It has been nearly two-and-a-half years now since New Horizons sped past Pluto and its moons in July 2015, and now the spacecraft is starting to close in on its next target – another object in the Kuiper Belt called 2014 MU69. It lies a billion miles farther out from the Sun than Pluto, and little is still known about it, but the closer New Horizons gets, with a scheduled flyby for Jan. 1, 2019, the more scientists are starting to learn about what it looks like. The newest research indicates that, despite being so small, much smaller than Pluto, it may also have a moon.
Pluto is an intriguing little world, full of geological surprises, as New Horizons revealed back in 2015. This cold, remote body was expected to be pretty much inactive, but instead we saw a place with nitrogen ice “seas” and glaciers, tall mountains of water ice, a hazy atmosphere and possible ice volcanoes, as well as a subsurface ocean which is thought to still be at least partially liquid. One of the most interesting features discovered was the “bladed terrain” – massively tall, blade-like ridges composed of ice.
These blades of ice are huge, soaring hundreds of feet above the surface. They resemble penitentes on Earth, but are much larger – “penitentes on steroids,” as it were. These incredible formations were stunning examples of Plutonian geology, but scientists weren’t sure how they formed. Now though, they think they have solved the mystery, after determining what they are made of – methane ice.
“When we realized that bladed terrain consists of tall deposits of methane ice, we asked ourselves why it forms all of these ridges, as opposed to just being big blobs of ice on the ground,” said Jeffrey Moore, a research scientist at NASA’s Ames Research Center in California’s Silicon Valley. “It turns out that Pluto undergoes climate variation and sometimes, when Pluto is a little warmer, the methane ice begins to basically ‘evaporate’ away.”
One clue was that the formations are found at the highest altitudes on Pluto; methane freezes out at those altitudes, similar to frost on Earth. When it gets a bit warmer again, relatively speaking, the ice then sublimates back into the thin atmosphere. This repeated freezing and sublimating, over millions of years, has eroded the ice formations into their current jagged appearance.
On Earth, penitentes have a similar appearance but are much smaller in scale, only a few meters tall. They can be found in high-altitude snowfields along the equator.
These ice blades were discovered in a region where New Horizons had taken high-resolution images during its flyby of Pluto in 2015. There is evidence for them in other areas as well, but those regions were not seen in as high resolution, suggesting that these formations are wide-spread on Pluto.
New Horizons also saw methane snow on top of the water ice mountains. Along with the nitrogen ice “seas” and glaciers, the observations showed that Pluto’s surface is covered in a variety of exotic ices, unlike anything seen on Earth. There is also evidence for ancient rivers and lakes of liquid nitrogen.
New Horizons is now heading towards its next target, a smaller rocky body called 2014 MU69, which it will reach on Jan. 1, 2019.
The new findings have been published in the journal Icarus.
This article was first published on AmericaSpace.
In 2015, the New Horizons spacecraft provided our first up-close look at Pluto and its moons, helping to transform our knowledge about these small, cold worlds in the outer fringes of the Solar System. The only downside, if there were one even, was that it was a flyby mission, meaning New Horizons would zip past Pluto and then continue on deeper into the Kuiper Belt. Since then, there has been growing advocacy for a return mission such as an orbiter, or perhaps even a lander.
This week, a concept mission for a Pluto lander was presented by Global Aerospace Corporation (GAC) at the NASA Innovative Advanced Concepts (NIAC) Symposium in Denver, CO. As currently envisioned, the probe would land on Pluto using drag from the super-thin atmosphere and a few pounds of propellant. Then, it could explore the surface further by “hopping” from one location to another, using Pluto’s low gravity. The probe would be capable of traveling tens or even hundreds of kilometres at a time and features of interest could be studied up close at many different locations. The “entrycraft” as it is called would need to be almost the size of a football field in order to bring the lander to the surface. According to GAC, the mission could be launched as soon as 12 years from now.
“Pluto’s surface pressure is just 10 millionths of Earth’s, but its atmosphere is extremely spread out, extending about 1000 miles above the surface, said Dr. Benjamin Goldman, principal investigator of the Phase I NIAC effort. “This extended and ultra-low-density atmosphere is ideal for dissipating large amounts of kinetic energy by means of aerodynamic drag, but the key is making the drag area very large while keeping system weight at a minimum.”
Some goals of the mission would be to:
- Shed new light on its origins and relationship to other Kuiper Belt objects and other planets.
- Characterize the dynamics between the subsurface and the atmosphere by investigating outgassing processes such as cryovolcanism.
- Expand the understanding of surface geomorphology from multiple locations (on approach, during descent, and at the surface).
- Use in-situ sampling to study the nature of the its crust and search for hypothesized liquid water oceans.
- Validate New Horizons measurements including atmospheric pressure and temperature profiles.
New Horizons was an exciting mission, even if it only offered a brief look at the Pluto system. But that brief glimpse showed that Pluto is an active world, with nitrogen ice seas and glaciers, water ice mountains with methane snow, tall spikes of ice, ancient rivers and lakes of liquid nitrogen, a hazy atmosphere and possible cryovolcanoes (ice volcanoes). There may even be a subsurface ocean of water. Pluto’s largest moon, Charon, also appears to have had a subsurface ocean, but it is completely frozen now. It is a bizarre and intriguing place, begging for a return mission to explore its mysteries further. An orbiter would be a phenomenal follow-up to New Horizons, and a lander even more so. Pluto was once just a tiny point of light only visible to the largest telescopes, but now it is an incredible world just waiting to be explored in-depth.
This article was first published on AmericaSpace.