The British team that described its design in the journal Proceedings of the Royal Society A isn’t the first to suggest a hopper. But unlike previous designs, this hopper wouldn’t rely on solar power for fuel, but would instead by powered by radioactive isotopes and the plentiful carbon dioxide in Mars’s atmosphere.
The ability to hop from place to place would enable the new explorers to cover more of the Martian landscape, and visit rough terrain that earlier rovers couldn’t handle. The 2004 rover Opportunity is just hitting 15 miles of surface driving after almost seven years on Mars.
Dr Richard Ambrosi [who worked on the project], at the Leicester Space Research Centre, commented: “The improved mobility and range of a hopping vehicle will tell us more about the evolution of Mars and of the Solar System and may answer questions as to whether there was life in the past, whether Mars was wetter in the past and if so where that water went.” [Press Release]
The proposed hopper’s propulsion system starts with radioactive isotopes inside a generator–as the radioactive material steadily emits particles, that heat is converted into electricity. This type of light-weight generator, or “nuclear battery,” has been used in numerous space probes, including NASA’s Cassini and New Horizons spacecraft. In the hopper, the electricity would be used to suck in and collect CO2 from the atmosphere and crush it into a liquid. When the hopper needs a boost it can use some stored heat to turn the liquid back into a gas, and use that gas to propel the rover off the ground or soften its landing when it reaches its destination.
“The advantage is that the radioisotope source is long-lived and not dependent on solar energy,” Dr Williams explained to BBC News. “You can operate for a long time, and in areas of Mars where the amount of sunlight is relatively small. Because you’re collecting your propellant from the Martian atmosphere you’re not limited by having to take propellant out from Earth.” [BBC News]
The preliminary plans require about a week of fuel collection at one site to power the hopper to the next site. Visit the paper’s data supplement for a video interview with the researchers.
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