Artists renderings of the microbots being deployed. Digital illustration by Gus Frederick
Given the chance, Penelope Boston would invade Mars with swarms of hopping microbots. But then again, who wouldn't? Boston, it turns out, actually has funding from the NASA Institute for Advanced Concepts (NIAC) to give it a shot.
"We are envisioning that [microbots] could provide an overarching new way of doing business in planetary landing missions." said Boston, "They could give us an unprecedented ability to get into terrain on Mars that we haven't been able to see before."
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Boston is the director of cave and karst studies at the New Mexico Institute of Mining and Technology. She is collaborating with Steve Dubowsky, director of the MIT Field and Space Laboratory to design and build tennis ball-sized robots that would be able to explore caves on Mars for signs of past or present microbial life. Their project has received support from NIAC, which is focused on fostering inventive research that could "leapfrog" current aerospace technology and thinking even if it might not come to practical application for decades.
"With adequate funding, we think we could do this in six or seven years," said Boston.
Rather than leaping like frogs though, Boston said, "the microbots will hop like jumping beans." The hopper is a small sphere with an artificial muscle that lets it hop. In the gravity of Mars, the microbot could jump 1.5 m vertically or 1 m horizontally.
"The primary advantage of hoppers is that they are relatively simple and can be scaled easily," said David Miller, a professor of aerospace and mechanical engineering at the University of Oklahoma who works on wheeled and legged rovers. He quickly added that hoppers "are much less predictable about where they will go."
Boston and Dubowsky are trading off the ability to precisely predict the motion of each individual microbot in favor of the potential for having many small individuals that can work collectively. They have used work done by Rodney Brooks of MIT applying insect intelligence to robots in designing their swarm of hoppers.
Boston says, "The way communal insects behave with respect to each other produces very elaborate, complex behavior of the total, but the actual rules that any individual uses to relate to its fellows can be very simple," said Boston. "The critical thing is how does the swarm behave? Can we direct the individuals enough that the overall motion of the entire swarm is in the direction we want to proceed?"
Rover specialist Miller thinks the group working on the project is accomplished enough to get the whole scheme to work. "It is definitely a project worth exploring," he said. "When it comes to caves, Boston is one of the leading experts and Dubowsky is a very well-respected engineer. It is a good team to be working on it."
The hoppers' speciality will be the rough terrain on the floors of caves, where they will search for microbial life. "Hoppers fill a niche for exploring surfaces that would be difficult for walkers or rovers to explore," said Bob Casanova of NIAC.
NIAC also funded Boston's work on the feasibility of building in-cave habitats that could allow extended human missions on Mars. "The surface of Mars is bombarded by radiation, so if microorganisms are underground in a cave they would be somewhat protected, and the same thing for humans, it would be a natural habitat," Casanova said. "Before you put astronauts down in a cave, you would like to have something that you could send down to see if it would be suitable. The hoppers may be able to do that."