Robots to Go Spelunking in Martian Caves?

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A skylight opens into an underground cavern on the slopes of Mars' Pavonis Mons volcano, as observed by NASA's Mars Reconnaissance Orbiter.
NASA/JPL-Caltech/Univ. of Ariz.

Scientists are beginning to sketch out plans for NASA's new Mars rover Curiosity to climb Mount Sharp, but future robots may have a more direct way to access the planet's history books.

Recent discoveries of "skylights" (pictured here) and lava tubes on the surface of Mars, as well as the moon, are sparking the development of robotic probes that can descend into caves and explore tunnels.

"Geology works in layers, so how many layers can you see? Well, we know there are sinkholes on Mars. Those sinkholes expose potentially hundreds of feet of layers, so if you could lower something down and examine those layers and explore a tunnel underneath, or anything of that sort, the science that can be done with that is just phenomenal," Jason Derleth, senior technology analyst with NASA's Innovative Advanced Concepts Program, told Discovery News.

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Curiosity's landing site inside an ancient impact basin was selected because of the three-mile high mound of layered rock, known as Mount Sharp, rising from the crater's floor. Scientists believe it may be the remains of sediment that once completely filled the basin. By methodically examining the mountain, layer by layer, scientists hope to learn if Mars ever had conditions necessary for life to evolve and for it to be preserved.

An even richer treasure trove may be hidden underground, where potential habitats would be more shielded from the radiation that constantly blasts the planet's surface. Underground abodes also would be better protected from meteorite impacts and would have more stable temperatures throughout the Martian day-night cycles.

"You just couldn't get better samples than what can be retrieved from these depths," robotics researcher William "Red" Whittaker, with Carnegie Mellon University, told Discovery News.

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"There's been these dreams of 'Oh, could you drill 2 meters and get a sample? Could you drill 5 meters and get a sample? Could you drill 7 meters and get a sample? Could you ever, ever, ever, ever drill 10 meters and get a sample?' Well, my gosh, how about you just get out a rope and go down a hole and you can get samples that are from 50 meters down and everything along the way?" he said.

That sort of technological leap requires many small steps.

Whittaker's firm, Astrobotic Technology, for example is looking into how a robot would get itself into a cave in the first place.

Rappelling down, like a mountain climber is one option. It is slow and controlled, but could cause problems if dry, powdery materials on the cave walls shook lose and rained down on the robot.

Another option takes advantage of the planet's reduced gravity by having the robot hop or lob itself down a hole. A third choice is to string a suspension line across a skylight opening, similar to a trapeze wire, and have the robot lower itself down the center, avoiding the cave walls entirely.

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"These are profound mobility challenges compared to the kinds of robots that have gone to space and the kinds of robots that exist in the research world," Whittaker said.

Astrobotic was selected this month for a two-year, $500,000 NASA research grant to develop its cave-exploring robotic technologies and build a prototype that could be tested on Earth.

Whittaker, who is also working on a lunar robot as part of a Google X Prize team, may stage a demonstration mission on the moon within three years.