Rolling robots like spiky tumbleweeds could be used to explore the moons of Mars, says a team of NASA, Stanford and MIT engineers.
They're proposing a mother spacecraft deploying several spiked, roughly spherical rovers to the Martian moon Phobos. Each half-meter-wide rover, containing three rotating discs pointing in different directions, would hop and tumble across the moon, gathering data on its way.
The team's already developed a prototype for its Phobos Surveyor, a coffee-table-sized vehicle flanked by two umbrella-shaped solar panels, that would orbit Phobos throughout the mission.
One hedgehog would be released at a time, and directed by the Surveyor, with the hedgehogs relaying scientific measurements back. There's be no need for human control.
An entire mission would last up to three years - two years just to get to Phobos in the first place. An initial reconnaissance phase, during which the Surveyor would map the terrain, would last a few months. Then, five or six hedgehogs would be released several days apart.
It's still unknown whether Phobos is an asteroid captured by Mars' gravity, or a piece of the planet flung out during an asteroid impact. Deploying the hedgehogs near Stickney Crater, where the moon's inner layers are exposed, could help the team find out.
Such a mission, says Stanford assistant professor Marco Pavone, would act as an important precursor to a manned mission to Mars.
"It's a piece of technology that's needed before any more expensive type of exploration is considered. Before sampling we need to know where to land. We need to deploy rovers to acquire info about the surface," he says.
The team has already built and tested two generations of rover prototypes and is working on a third to be tested next summer, using a large overhead crane at the Durand Building at Stanford to help mimic low-gravity conditions.
A test of the Phobos Surveyor will likely take place in two to four years, and Pavone hopes that a mission could take place within the next 10 to 20 years.