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Microbes Could Power Future Planetary Rovers

Living batteries could be a super efficient way to generate electricity for space probes

2 min read
Microbes Could Power Future Planetary Rovers

The gigantic rover currently on its way to Mars, Curiosity, is powered by a gigantic butt-mounted radioisotope thermoelectric generator. For the next generation of space probes, the Naval Research Laboratory is looking for power sources that are smaller. Much smaller.

Robots on distant planets and moons (think beyond Mars) can't rely on solar panels for power, since the sun just isn't strong enough out there in the boonies of the solar system. Instead, they've been depending on radioisotope thermoelectric generators (RTGs), which are sort of like little nuclear batteries powered by plutonium. They work just fine, and they can last a very long time, since the half life of plutonium 238 is 87 years.

The problem with RTGs is that they tend to be heavy and bulky and not particularly efficient for their size. If you've got a huge 900 kilogram platform like Curiosity that doesn't matter so much, but when we're talking about small mobile planetary rovers RTGs just aren't going to cut it. What may cut it, however, are microbial fuel cells (MFCs), which offer long-term production of little bits of energy in a very efficient package.

MFCs are batteries that are alive. They're full of (you guessed it) microbes, which feed on sugar, a process that produces electrons -- call it a technically sweet fuel cell. The result is a very small amount of electricity, but this electricity is produced very efficiently: Potentially, MFCs can produce energy at above 50 percent efficiency, while RTGs are below 10 percent. While an MFC can't pump out enough juice to drive a rover or anything, they'd be able to keep low power electronics active indefinitely while trickle charging a battery or capacitor, which would be perfect for a small mobile robot that might make occasional jumps to get from place to place. Specifically, the Naval Research Lab is considering implementing an MFC on "a novel tumbling or hopping locomotion system," and they've just been awarded a NASA grant to make it happen.

[ NRL ] via [ Wired UK ]

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Robot with threads near a fallen branch

RoMan, the Army Research Laboratory's robotic manipulator, considers the best way to grasp and move a tree branch at the Adelphi Laboratory Center, in Maryland.

Evan Ackerman
LightGreen

This article is part of our special report on AI, “The Great AI Reckoning.

"I should probably not be standing this close," I think to myself, as the robot slowly approaches a large tree branch on the floor in front of me. It's not the size of the branch that makes me nervous—it's that the robot is operating autonomously, and that while I know what it's supposed to do, I'm not entirely sure what it will do. If everything works the way the roboticists at the U.S. Army Research Laboratory (ARL) in Adelphi, Md., expect, the robot will identify the branch, grasp it, and drag it out of the way. These folks know what they're doing, but I've spent enough time around robots that I take a small step backwards anyway.

The robot, named RoMan, for Robotic Manipulator, is about the size of a large lawn mower, with a tracked base that helps it handle most kinds of terrain. At the front, it has a squat torso equipped with cameras and depth sensors, as well as a pair of arms that were harvested from a prototype disaster-response robot originally developed at NASA's Jet Propulsion Laboratory for a DARPA robotics competition. RoMan's job today is roadway clearing, a multistep task that ARL wants the robot to complete as autonomously as possible. Instead of instructing the robot to grasp specific objects in specific ways and move them to specific places, the operators tell RoMan to "go clear a path." It's then up to the robot to make all the decisions necessary to achieve that objective.

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