Jupiter’s moon Europa has been the subject of fascination ever since the Pioneer 10 and 11 and Voyager1 and 2 missions passed through the system back in the 1970s. While the moon has no viable atmosphere and is bombarded by intense radiation from Jupiter’s powerful magnetic field, scientists believe that one of the most likely places to find life beyond Earth exists beneath its icy surface.
Little wonder then why multiple missions are being planned to study this moon up-close. However, if and when those missions reach Europa sometime in the next decade, they will have to contend with some sharp surface features that could make it hard to land. Such is the conclusion of a new study by researchers from Britain, the US and NASA’s Ames Research Center, which indicates that Europa’s surface is covered in bladed terrain.
When it made its historic flyby of Pluto in July of 2015, the New Horizons spacecraft gave scientists and the general public the first clear picture of what this distant dwarf planet looks like. In addition to providing breathtaking images of Pluto’s “heart”, its frozen plains, and mountain chains, one of the more interesting features it detected was Pluto’s mysterious “bladed terrain”.
According to data obtained by New Horizons, these features are made almost entirely out of methane ice and resemble giant blades. At the time of their discovery, what caused these features remained unknown. But according to new research by members of the New Horizons team, it is possible that these features are the result of a specific kind of erosion that is related to Pluto’s complex climate and geological history.
Ever since the New Horizons probe provided a detailed look at Pluto’s geological features, the existence of these jagged ridges has been a source of mystery. They are located at the highest altitudes on Pluto’s surface near it’s equator, and can reach several hundred feet in altitude. In that respect, they are similar to penitentes, a type of structure found in high-altitude snowfields along Earth’s equator.
These structures are formed through sublimation, where atmospheric water vapor freezes to form standing, blade-like ice structures. The process is based on sublimation, where rapid changes in temperature cause water to transition from a vapor to a solid (and back again) without changing into a liquid state in between. With this in mind, the research team considered various mechanisms for the formation of these ridges on Pluto.
What they determined was that Pluto’s bladed terrain was the result of atmospheric methane freezing at extreme altitudes on Pluto, which then led to ice structures similar to the ones found on Earth.The team was led by Jeffrey Moore, a research scientist at NASA’s Ames Research Center who was also a New Horizons’ team member. As he explained in a NASA press statement:
“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. It turns out that Pluto undergoes climate variation and sometimes, when Pluto is a little warmer, the methane ice begins to basically ‘evaporate’ away.”
But unlike on Earth, the erosion of these features are related to changes that take place over the course of eons. This should come as no surprise seeing as how Pluto’s orbital period is 248 years (or 90,560 Earth days), meaning it takes this long to complete a single orbit around the Sun. In addition, the eccentric nature of it orbit means that its distance from the Sun ranges considerably, from 29.658 AU at perihelion to 49.305 AU at aphelion.
When the planet is farthest from the Sun, methane freezes out of the atmosphere at high altitudes. And as it gets closer to the Sun, these ice features melt and turn directly into atmospheric vapor again. As a result of this discovery, we now know that the surface and air of Pluto are apparently far more dynamic than previously thought. Much in the same way that Earth has a water cycle, Pluto may have a methane cycle.
This discovery could also allow scientists to map out locations of Pluto which were not photographed in high-detail. When the New Horizons mission conducted its flyby, it took high-resolution pictures of only one side of Pluto – designated as the “encounter hemisphere”. However, it was only able to observe the other side at lower resolution, which prevented it from being mapped in detail.
But based on this new study, NASA researchers and their collaborators have been able to conclude that these sharp ridges may be a widespread feature on Pluto’s “far side”. The study is also significant in that it advances our understanding of Pluto’s global geography and topography, both past and present. This is due to the fact that it demonstrated a link between atmospheric methane and high-altitude features. As such, researchers can now infer elevations on Pluto by looking for concentrations of methane in its atmosphere.
Not long ago, Pluto was considered one of the least-understood bodies in our Solar System, thanks to its immense distance from the Sun. However, thanks to ongoing studies made possible by the data collected by the New Horizons mission, scientists are becoming increasingly familiar with what its surface looks like, not to mention the types of geological and climatological forces that have shaped it over time.
And be sure to enjoy this video that details the discovery of Pluto’s bladed terrain, courtesy of NASA’s Ames Research Center:
It’s time to whip out your 3-D glasses to enjoy and scrutinize the remarkable detail of spectacular terrain revealed in a new high resolution stereo image of Pluto – King of the Kuiper Belt! – taken by NASA’s New Horizons spacecraft.
The amazing new stereo Plutonian image focuses on an area dominated by a mysterious feature that geologists call ‘bladed’ terrain – seen above – and its unlike anything seen elsewhere in our solar system.
Its located in a broad region of rough highlands informally known as Tartarus Dorsa – situated to the east of the Pluto’s huge heart shaped feature called Tombaugh Regio. The best resolution is approximately 1,000 feet (310 meters).
The stereo view combines a pair of images captured by New Horizons Ralph/Multispectral Visible Imaging Camera (MVIC) science instruments. They were taken about 14 minutes apart on during history making first ever flyby of the Pluto planetary system on July 14, 2015.
The first was taken when New Horizons was 16,000 miles (25,000 kilometers) away from Pluto, the second when the spacecraft was 10,000 miles (about 17,000 kilometers) away.
The blades align from north to south, typically reach up to about 550 yards (500 meters) high and are spaced about 2-4 miles (3-5 kilometers). Thus they are among the planets steepest features. They are “perched on a much broader set of rounded ridges that are separated by flat valley floors,” according to descriptions from the New Horizons science team.
Mission scientists have also noted that the bladed terrain has the texture of “snakeskin” owing to their “scaly raised relief.”
In the companion global image from NASA (below), the bladed terrain is outlined in red and shown to extend quite far to the east of Tombaugh Regio.
The composite image was taken on July 13, 2015, the day before the closest approach flyby, when the probe was farther away thus shows lower resolution. It combines a pair of images from two of the science instruments – a Ralph/Multispectral Visible Imaging Camera (MVIC) color scan and an image from the Long Range Reconnaissance Imager (LORRI).
The MVIC scan was taken from a range of 1 million miles (1.6 million kilometers), at a resolution of 20 miles (32 kilometers) per pixel. The corresponding LORRI image was obtained from roughly the same range, but has a higher spatial resolution of 5 miles (8 kilometers) per pixel, say officials.
Scientists have developed several possible theories about the origins of the bladed terrain, including erosion from evaporating ices or deposition of methane ices.
Measurements from the Linear Etalon Imaging Spectral Array (LEISA) instrument reveal that that this region “is composed of methane (CH4) ice with a smattering of water,” reports New Horizons researcher Orkan Umurhan.
He speculates that “the material making up the bladed terrain is a methane clathrate. A clathrate is a structure in which a primary molecular species (say water, or H2O) forms a crystalline ‘cage’ to contain a guest molecule (methane or CH4, for example).”
But the question of whether that methane ice is strong enough to maintain the steep walled snakeskin features, will take much more research to determine a conclusive answer.
Umurhan suggests that more research could help determine if the “methane clathrates in the icy moons of the outer solar system and also in the Kuiper Belt were formed way back before the solar system formed – i.e., within the protosolar nebula – potentially making them probably some of the oldest materials in our solar system.”
Pluto continues to amaze and surprise us as the data streams back to eagerly waiting scientists on Earth over many more months to come – followed by years and decades of painstaking analysis.
During New Horizons flyby on July 14, 2015, it discovered that Pluto is the biggest object in the outer solar system and thus the ‘King of the Kuiper Belt.”
The Kuiper Belt comprises the third and outermost region of worlds in our solar system.
Pluto is the last planet in our solar system to be visited in the initial reconnaissance of planets by spacecraft from Earth since the dawn of the Space Age.
New Horizons remains on target to fly by a second Kuiper Belt Object (KBO) on Jan. 1, 2019 – tentatively named PT1, for Potential Target 1. It is much smaller than Pluto and was recently selected based on images taken by NASA’s Hubble Space Telescope.
Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.
Learn more about NASA Mars rovers, Orion, SLS, ISS, Orbital ATK, ULA, SpaceX, Boeing, Space Taxis, NASA missions and more at Ken’s upcoming outreach events:
Apr 9/10: “NASA and the Road to Mars Human Spaceflight programs” and “Curiosity explores Mars” at NEAF (NorthEast Astronomy and Space Forum), 9 AM to 5 PM, Suffern, NY, Rockland Community College and Rockland Astronomy Club – http://rocklandastronomy.com/neaf.html
Apr 12: Hosting Dr. Jim Green, NASA, Director Planetary Science, for a Planetary sciences talk about “Ceres, Pluto and Planet X” at Princeton University; 7:30 PM, Amateur Astronomers Assoc of Princeton, Peyton Hall, Princeton, NJ – http://www.princetonastronomy.org/
Apr 17: “NASA and the Road to Mars Human Spaceflight programs”- 1:30 PM at Washington Crossing State Park, Nature Center, Titusville, NJ – http://www.state.nj.us/dep/parksandforests/parks/washcros.html