Aquatic Rover Drives on the Underside of the Ice in Antarctica

Not all rovers are designed to roam around on the surface of other worlds like Mars. One rover, at least, is aquatic; a necessary development if we’re going to explore Enceladus, Europa, and the Solar System’s other watery worlds. This rover is called the Buoyant Rover for Under-Ice Exploration, or BRUIE.

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Water Vapor Was Just Found on Europa, More Evidence There’s Liquid Water Beneath All that Ice

What’s been long-suspected has now been confirmed: Jupiter’s moon Europa has water. As we’ve learned more about the outer Solar System in recent years, Europa has become a high-priority target in the search for life. With this discovery, NASA has just painted a big red bulls-eye on Jupiter’s smallest Galilean moon.

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AI Could Help the Europa Clipper Mission Make New Discoveries!

In 2023, NASA plans to launch the Europa Clipper mission, a robotic explorer that will study Jupiter’s enigmatic moon Europa. The purpose of this mission is to explore Europa’s ice shell and interior to learn more about the moon’s composition, geology, and interactions between the surface and subsurface. Most of all, the purpose of this mission is to shed light on whether or not life could exist within Europa’s interior ocean.

This presents numerous challenges, many of which arise from the fact that the Europa Clipper will be very far from Earth when it conducts its science operations. To address this, a team of researchers from NASA’s Jet Propulsion Laboratory (JPL) and Arizona State University (ASU) designed a series of machine-learning algorithms that will allow the mission to explore Europa with a degree of autonom.

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Saltwater Similar to the Earth’s Oceans has been Seen on Europa. Another Good Reason Why We Really Need to Visit This Place

Jupiter’s moon Europa is an intriguing world. It’s the smoothest body in the Solar System, and the sixth-largest moon in the Solar System, though it’s the smallest of the four Galilean moons. Most intriguing of all is Europa’s subsurface ocean and the potential for habitability.

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A Nuclear-Powered Tunneling Robot that Could Search for Life on Europa

Artist’s rendering of the Europa “tunnelbot.” (Credit: Alexander Pawlusik, LERCIP Internship Program NASA Glenn Research Center)

The search for life has led astronomers to the icy moons in our Solar System. Among those moons, Europa has attracted a lot of attention. Europa is Jupiter’s fourth-largest moon—and the sixth-largest in the Solar System—at 3,100 kilometres (1,900 mi) in diameter. Scientists think that its oceans could contain two or three times as much water as Earth’s oceans. The only problem is, that water is hidden under a sheet of planet-wide ice that could be between 2km and 30km (1.2 miles and 18.6 miles) thick.

A team of scientists is working hard on the problem. Andrew Dombard, associate professor of Earth and Environmental Sciences at the University of Illinois at Chicago, is part of a team that presented a possible solution. At the American Geophysical Union meeting in Washington, D.C., they presented their idea: a nuclear-powered tunneling robot that could tunnel its way through the ice and into the ocean.

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ARCHIMEDES: Digging into the ice on Europa with lasers

Ever since the Pioneer and Voyager probes passed through the Jovian system in the 1970s, NASA and other space agencies have dreamed of one-day sending a mission to Europa. Beyond Earth, it is considered one of the most promising candidates for finding life, which could exist in the subsurface ocean that lies beneath the moon’s icy crust.

One of these concepts is known as the Cool High Impact Method for Exploring Down into Europan Subsurface (ARCHIMEDES), a proposed direct-laser penetrator that will use a laser light carried by an optical fiber tether to penetrate Europa’s icy crust. This mission could provide future missions with access to the ocean that exists beneath Europa’s surface and enable the search for life there.

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Europa is Going to be Tough to Land on, it Could Have Towering Walls of Ice Spikes Across its Surface

Jupiter’s moon Europa has been the subject of fascination ever since the Pioneer 10 and 11 and Voyager 1 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.

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Life on Europa Would be Protected by Just a Few Centimeters of Ice

Ever since the Galileo probe provided compelling evidence for the existence of a global ocean beneath the surface of Europa in the 1990s, scientists have wondered when we might be able to send another mission to this icy moon and search for possible signs of life. Most of these mission concepts call for an orbiter or lander than will study Europa’s surface, searching the icy sheet for signs of biosignatures turned up from the interior.

Unfortunately, Europa’s surface is constantly bombarded by radiation, which could alter or destroy material transported to the surface. Using data from the Galileo and Voyager 1 spacecraft, a team of scientists recently produced a map that shows how radiation varies across Europa’s surface. By following this map, future missions like NASA’s Europa Clipper will be able to find the spots where biosignatures are most likely to still exist.

As many missions have revealed by studying Europa’s surface, the moon experiences periodic exchanges between the interior and the surface. If there is life in its interior ocean, then biological material could theoretically be brought to the surface where it could be studied. Since radiation from Jupiter’s magnetic field would destroy this material, knowing where it is most intense, how deep it goes, and how it could affect the interior are all important questions.

Artist’s impression of water bubbling up from Europa’s interior ocean and breaching the surface ice. Credit: NASA/JPL-Caltech

As Tom Nordheim, a research scientist at NASA’s Jet Propulsion Laboratory, explained in a recent NASA press release:

“If we want to understand what’s going on at the surface of Europa and how that links to the ocean underneath, we need to understand the radiation. When we examine materials that have come up from the subsurface, what are we looking at? Does this tell us what is in the ocean, or is this what happened to the materials after they have been radiated?”

To address these question, Nordheim and his colleagues examined data from Galileo‘s flybys of Europa and electron measurements from NASA’s Voyager 1 spacecraft. After looking closely at the electrons blasting the moon’s surface, Nordheim and his team found that the radiation doses vary by location. The harshest radiation is concentrated in zones around the equator, and the radiation lessens closer to the poles.

The study which describes their findings recently appeared in the scientific journal Nature under the title “Preservation of potential biosignatures in the shallow subsurface of Europa“. The study was led by Nordheim and was co-authored by Kevin Hand (also with the JPL) and Chris Paranicas from the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland.

Artist’s concept of a Europa Clipper mission. Credit: NASA/JPL

“This is the first prediction of radiation levels at each point on Europa’s surface and is important information for future Europa missions,” said Paranicas. Now that scientists know where to find regions least altered by radiation, they will be able to designate areas of study for the Europa Clipper, a JPL-led mission that is expected to launch as early as 2022.

For the sake of their study, Nordheim and his team went beyond a conventional two-dimensional map to build 3D models that examined how far below the surface the radiation penetrates. To test how deep organic material would have to be buried in order to survive, Nordheim and his team tested the effect of radiation on amino acids (the basic building blocks for proteins) to figure out how Europa’s exposure to radiation would affect potential biosignatures.

The results indicate how deep scientists will need to dig or drill during a potential future Europa lander mission in order to find any biosignatures that might be preserved. In the highest-radiation zones around the equator, the depth at which biosignatures could be found ranged from 10 to 20 cm (4 to 8 inches). At the middle- and high-latitudes, closer to the poles, the depths decrease to about 1 cm (0.4 inches). As Hand indicated:

“The radiation that bombards Europa’s surface leaves a fingerprint. If we know what that fingerprint looks like, we can better understand the nature of any organics and possible biosignatures that might be detected with future missions, be they spacecraft that fly by or land on Europa.”

Artist’s impression of a water vapor plume on Europa. Credit: NASA/ESA/K. Retherford/SwRI

When the Europa Clipper mission reaches the Jovian system, the spacecraft will orbit Jupiter and conducting about 45 close flybys of Europa. It’s advanced suite of scientific instruments will include cameras, spectrometers, plasma and radar instruments which will investigate the composition of the moon’s surface, its ocean, and material that has been ejected from the surface.

“Europa Clipper’s mission team is examining possible orbit paths, and proposed routes pass over many regions of Europa that experience lower levels of radiation,” Hand said. “That’s good news for looking at potentially fresh ocean material that has not been heavily modified by the fingerprint of radiation.”

With this new radiation map, the mission team will be able to narrow the range of possible research sites. This, in turn, will increase the likelihood that the orbiter mission will be able to settle the decades-old mystery of whether or not there is life in the Jovian system.

Further Reading: NASA, Nature

NASA Simulation Shows How Europa’s “Fossil Ocean” Rises to the Surface Over Time

In the 1970s, the Jupiter system was explored by a succession of robotic missions, beginning with the Pioneer 10 and 11 missions in 1972/73 and the Voyager 1 and 2 missions in 1979. In addition to other scientific objectives, these missions also captured images of Europa’s icy surface features, which gave rise to the theory that the moon had an interior ocean that could possibly harbor life.

Since then, astronomers have also found indications that there are regular exchanges between this interior ocean and the surface, which includes evidence of plume activity captured by the Hubble Space Telescope. And recently, a team of NASA scientists studied the strange features on Europa’s surface to create models that show how the interior ocean exchanges material with the surface over time.

The study, which recently appeared in the the Geophysical Research Letters under the title “Band Formation and Ocean-Surface Interaction on Europa and Ganymede“, was conducted by Samuel M. Howell and Robert T. Pappalardo – two researchers from the NASA Jet Propulsion Laboratory. For their study, the team examined both Ganymede and Europa to see what the moons surface features indicated about how they changed over time.

Images from NASA’s Galileo spacecraft show the intricate detail of Europa’s icy surface. Image: NASA/JPL-Caltech

Using the same two-dimensional numerical models that scientists have used to solve mysteries about motion in the Earth’s crust, the team focused on the linear features known as “bands” and “groove lanes” on Europa and Ganymede. The features have long been suspected to be tectonic in nature, where fresh deposits of ocean water have risen to the surface and become frozen over previously-deposited layers.

However, the connection between this band-forming processes and exchanges between the ocean and the surface has remained elusive until now. To address this, the team used their 2-D numerical models to simulate ice shell faulting and convection.Their simulations also produced a beautiful animation that tracked the movement of “fossil” ocean material, which rises from the depths, freezes into the base of the icy surface, and deforms it over time.

Whereas the white layer at the top is the surface crust of Europa, the colored band in the middle (orange and yellow) represents the stronger sections of the ice sheet. Over time, gravitational interactions with Jupiter cause the ice shell to deform, pulling the top layer of ice apart and creating faults in the upper ice. At the bottom is the softer ice (teal and blue), which begins to churn as the upper layers pull apart.

This causes water from Europa’s interior ocean, which is in contact with the softer lower layers of the icy shell (represented by white dots), to mix with the ice and slowly be transported to the surface. As they explain in their paper, the process where this “fossil” ocean material becomes trapped in Europa’s ice shell and slowly rises to the surface can take hundreds of thousands of years or more.

Artist’s concept of a Europa Clipper mission. Credit: NASA/JPL

As they state in their study:

“We find that distinct band types form within a spectrum of extensional terrains correlated to lithosphere strength, governed by lithosphere thickness and cohesion. Furthermore, we find that smooth bands formed in weak lithosphere promote exposure of fossil ocean material at the surface.”

In this respect, once this fossil material reaches the surface, it acts as a sort of geological record, showing how the ocean was millions of years ago and not as it is today. This is certainly significant when it comes to future missions to Europa, such as NASA’s Europa Clipper mission. This spacecraft, which is expected to launch sometime in the 2020s, will be the first to study Europa exclusively.

In addition to studying the composition of Europa’s surface (which will tell us more about the composition of the ocean), the spacecraft will be studying surface features for signs of current geological activity. On top of that, the mission intends to look for key compounds in the surface ice that would indicate the possible presence of life in the interior (i.e. biosignatures).

Artist’s impression of a hypothetical ocean cryobot (a robot capable of penetrating water ice) in Europa. Credit: NASA

If what this latest study indicates is true, then the ice and compounds the Europa Clipper will be examining will essentially be “fossils” from hundreds of thousands or even millions of years ago. In short, any biomarkers the spacecraft detects – i.e. signs of potential life – will essentially be dated. However, this need not deter us from sending missions to Europa, for even evidence of past life would be groundbreaking, and a good indication that life still exists there today.

If anything, it makes the case for a lander that can explore Europa’s plumes, or perhaps even a Europa submarine (cryobot), all the more necessary! If there is life beneath Europa’s icy surface, we are determined to find it – provided we don’t contaminate it in the process!

Further Reading: NASA, Geophysical Research Letters