September 24, 2013
Rocket-Powered ‘Hopper’ May One Day Replace Mars Rover
Lee Rannals for redOrbit.com - Your Universe Online
Most of us are familiar with the name "Hopper" as Dish Network's DVR box, but soon enough we may know it as the newest resident on Mars.
The Mars hopper would be a rocket-propelled vehicle capable of traveling a half-mile or more in a ballistic "hop," according to a proposal published in the Proceedings of the Royal Society. The vehicle would be propelled by a radioisotope thermal rocket using materials acquired from the Martian atmosphere.
"In concept, a radioisotope heat source heats a core or ‘thermal capacitor’, which in turn heats propellant exhausted through a rocket nozzle to provide thrust," the researchers wrote in the journal.
The team performed a study on the thermodynamics, heat transfer and selection of core materials for a Mars hopper. They wanted to find a way to both advance a motor design as well as assess technical risks and feasibility of a mission like this.
Researchers developed various motor models to generate thermodynamic performance limits, find an ideal hop distance, and plot a materials selection chart.
According to the researchers, the rocket engine would work by extracting carbon dioxide from the Martian atmosphere, compressing it and liquifying it. This liquid would then be pumped into a chamber and exposed to intense heat from a radioactive source. After this, controlled explosions of the CO2 through a nozzle would help the hopper thrust itself to another location on the Martian surface.
The basic idea for the vehicle was first proposed in 2010, but this latest study indicates that the concept of the Mars hopper may in fact be technically feasible.
"The advantage of this approach is that you have the ability to traverse more aggressive terrains but also that you have wider mobility - the possibility of traversing much greater distances than we have with even the very successful rovers," Hugo Williams, from Leicester's Space Research Centre, told BBC.
The new study also highlights some areas that may need a little more research. One road block is that the system takes several weeks to produce a usable volume of propellant. The scientists say this amount of time would need to be reduced in order for the concept to be taken to the next level. However, Mike Williams told BBC that, although the team has identified some limitations, they have also demonstrated that such a mission is feasible.
"A radioisotope thermal thruster represents one of the most novel aspects of the Mars hopper concept, and will rightly be regarded as a technical risk during development. That the thermofluid design appears relatively robust is an important conclusion, albeit one that will require much further work as the concept develops," the authors concluded in the journal.