The twin Mars rovers Spirit and Opportunity have outlasted their planned three-month lifetime and given us our closest look yet at the Martian surface. But the solar-powered rovers have covered only 21 miles of Martian terrain in their combined 11 years of operation, leaving most of the surface unexplored. Future Mars surface missions could cover more ground with a platform that can hop great distances in the planet's thin atmosphere and weak gravity. Since summer 2009, researchers and student fellows at the Center for Space Nuclear Research at Idaho National Laboratory have been fleshing out designs for a nuclear-powered Mars hopper that can examine one Martian site, jump to another, and repeat, hundreds of times. The lean, long-lived hoppers are designed to wring as much science and exploration as possible out of every ounce. They don't have to carry fuel with them; they can suck up the carbon-dioxide-rich Martian atmosphere and use it as a propellant. On cue, stored heat from a radioisotope power source hits the propellant and rockets the hopper in an arcing path toward its next landing site. Smaller thrusts orient the hopper and soften its landing. “A single rocket launch from Earth could deploy several hoppers at once. A few dozen hoppers could map the entire Martian surface in a few years,” said Steven Howe, CSNR director. Hoppers could also serve as a network of weather stations monitoring the Martian climate and could collect a trove of air, rock and soil samples to send back to Earth. A trip to Europa is pretty far in the future. But a functioning nuclear Mars hopper may be much closer. INL researchers have already done extensive work on most of the hopper technologies, including radioisotope batteries, Stirling generators, heat transfer, and sturdy engine materials that can withstand the sudden impacts and high temperatures associated with hopper operations. Parts of the beryllium heat transfer core have been manufactured and are waiting to be tested. Within two years, Howe and his collaborators hope to take a prototype hopper engine out to the INL desert site for a test hop. All they need to do now is change the name of the hopper. Really, the researchers spent all that time designing the new exploring device; you’d think they could have spent more than three minutes on the name.
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