Every year, NASA's Innovative Advanced Concepts program looks for projects that will change the way we explore space. They're after ideas that no one has thought of yet, sound kind of crazy, but just might work, like sending rovers to explore the oceans of Europa and Titan for instance.

Diving into extraterrestrial oceans is no day at the beach, so scientists need to get creative. For missions below sea level, they need rovers that can hold their own and maneuver through deep, dark bodies of liquid while gathering information about their surroundings. And if all goes well with two of this year's proposals, there will be a giant robotic space eel swimming around the oceans of Europa some day, and a submarine diving through Titan's hydrocarbon oceans.First, there's that giant robot eel. A team of researchers at Cornell University are working on what they're calling a "soft robotic rover with electromagnetic power scavenging." Catchy name, right? The rover would be made of soft plastic, allowing it to swim through and explore the oceans hiding beneath the icy surface of Europa, and it's meant to look and move a lot like a lamprey eel. But it's not just the way it would move that makes it unique; the electromagnetic power scavenging part is a whole new concept for a rover.

Most scientific instruments floating around in space, like satellites and telescopes, use solar panels or nuclear energy to power their equipment and send their findings back our way. But solar power near Jupiter and its moons is pretty limited, since they're about 780 million kilometers away from the sun, and nuclear batteries are getting harder to come by, since NASA's stock of plutonium is running low. Instead, the robotic eel would have an electrodynamic tether, a long, conducting wire that would actually use Europa's magnetic field to generate electricity.

In 1997, the Galileo probe's magnetometer, designed to measure the strength and direction of magnetic fields, observed an electrically conductive layer within Europa. It turns out that Jupiter's magnetic field generates those electric currents within Europa, which create a magnetic field around the moon. The magnetic field means that there's plenty of energy for an electrodynamic tether to harness; as the tether moves through the field, it'll induce a current within the wire.

The researchers want to use this electrical energy to power the eel using something called "expanding gas locomotion." That's pretty much what it sounds like: you electrolyze water to get hydrogen and oxygen gas, then light it on fire inside the rover's body and tentacles. As the gases heat up, they expand, propelling the whole wiggly robot into motion. If this project is successful, it'll let us explore Europa and other watery moons like never before.

But NASA is also working on other ways to probe extraterrestrial oceans, just in case the whole eel tentacle thing doesn't work out. Another NIAC project wants to send a submarine down into the Kraken Mare sea on Saturn's moon Titan. Kraken Mare is the largest ocean on Titan, about the size of all the great lakes put together, but it's not made of water. Based on the radar images from the Cassini spacecraft, astronomers found that Titan's oceans are made of liquid hydrocarbons, like methane and ethane. This presents a few challenges for designing a submarine to study Kraken Mare's chemical composition, tides, currents, and floor. Heat from the generator used to power the submarine could actually cause the surrounding liquid to boil, but if it's too chilly, all of the electronic equipment will freeze up. And the submarine has to be designed to move through hydrocarbons. which have different densities than water; otherwise, the whole thing could just sink to the bottom as soon as NASA drops it off!

But that's what NAIC is for: taking awesome ideas and figuring out how to make them possible, so that one day, instead of just having probes like Galileo and Cassini flying around moons and sending back pictures, scientists can study whatever might be lurking underneath.

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