Devising
a robot able to operate in a cave, or more properly, a lava tube is
going to be a real stressor on engineering capabilities here on Earth
where it must be proven first. I suspect
we will have boots on the ground first.
To
work well it will require a six limb system with some effective
grasping ability on each to say nothing of a management program with
independent capabilities. Going there is likely easier and way more
flexible.
On
the other hand it is a good target to aim for.
By Mike Wall
SPACE.com Sun, 25 Nov, 2012
NASA is mapping out a
strategy to return bits of rock and soil from the Martian surface to
Earth, but the most intriguing Red Planet samples lie in underground
caverns, some scientists say.
The space agency's
next steps at Mars are geared toward mounting a sample-return
mission, which is widely viewed as the best way to look for signs
of Red Planet life. Such signs are perhaps more likely to be
found in material pulled from the subsurface, so some researchers
hope NASA's first Martian sample-return effort won't be its last.
"While I'm very
much interested in a surface sample-return to get us over
this hump of doing it, of course I immediately want to go on and
start sampling more cryptic materials in lava-tube caves," said
astrobiologist and cave scientist Penny Boston, of the New Mexico
Institute of Mining and Technology in Socorro. "I would love
that."
The Martian
underground
Subterranean
formations are quite common on Mars, Boston said. Orbiting spacecraft
have spotted many snaking lava tubes, for example, which were created
by long-ago Red Planet volcanism. [Photos: Mars Caves and Lava Tubes]
"I could probably
scrape up a few hundred examples on Mars, and I think that the
numbers are only going to increase as the interest in these
structures increases," Boston told SPACE.com.
Such caverns may
preserve a bounty of information about Martian history and evolution,
including its past and current potential to host life.
"Something like
the lava tubes could be wonderful traps for material from past
climate regimes, particles from previous epochs on Mars," Boston
said, noting that liquid water is known to haveflowed across the
Martian surface long ago.
Lava-tube caves on
Earth commonly trap volatile materials such as water, she added.
"We suspect that
there may be examples of that on Mars," Boston said. "The
ability to tap into frozen volatiles would be fabulous. And maybe bug
bodies — maybe frozen little bodies. You never know."
The frigid, dry and
radiation-bombed Martian surface is unlikely to host life as we know
it today, many researchers say. But organisms might be able to
survive in a Red Planet lava tube or other underground habitat, where
conditions could be far more benign.
"The subsurface
is going to be radically different from the surface," Boston
said. "Every indication we have from caves of all different
kinds all over this planet shows that it doesn't take much
separation vertically for a radically different environment."
No easy task
Exploring the surface
of another world with a rover is a challenging enough proposition,
and investigating the subsurface would be even more difficult. [The
Boldest Mars Missions in History]
For starters, any
potential cave-exploration mission would need to make a pinpoint
landing quite close to the cavern mouth, Boston said. NASA has
improved its Martian touchdown precision greatly over the years —
landing-zone ellipses have shrunk from 62 by 174 miles (100 by 280
kilometers) for the 1976 Viking mission to just 4 by 12 miles (6 by
19 km) for the Curiosity rover, which landed this past August —
but further strides would likely be necessary.
The actual cavern
exploration would require technological advances as well. Cave rovers
would have to be far more autonomous than their surface brethren, for
example, since overlying rock would decrease the ability to
communicate with Earth, said roboticist Red Whittaker, of Carnegie
Mellon University in Pittsburgh.
Cave robots would
need to be nimble navigators, constructing maps of their dark
surroundings and then picking their way through the boulder-strewn
tunnels.
Just getting into a
Martian lava tube — and getting out again, in the case of a
sample-return mission — also presents a daunting challenge. Some
can be accessed via "skylights," holes in the ground where
the tube's roof has collapsed.
A rover might be able
to rappel down the side of such holes, Whittaker said Nov. 14 at the
2012 NASA Innovative Advanced Concepts meeting in Virginia. But this
maneuver could knock rocks loose, potentially endangering the robot
and the mission. So another option is to string a line across the
hole's mouth and have the tightrope-walking robot descend to the
floor on a tether like a spider.
"I like simple,
so that's a good choice," Whittaker said.
Alternatively, the
spelunking robot could leap into the cave, behaving like a
"self-contained cannon," he added. Whittaker is considering
such options as he develops a NIAC-funded prototype mission concept
called "Spelunker," which would explore a lunar skylight
and cave.
Reason for optimism
Scientists and
engineers aren't ready to send cave-exploring robots to Mars yet, but
such a misson is eminently possible, Whittaker said.
"What we're
discussing here is just the grand leap," Whittaker said. "It's
not just new in terms of destination and agenda, but the technologies
that are required to do these missions are both very new to space and
also within reach."
Boston voiced optimism
that a spelunking Mars robot could be ready to launch by the early
2030s or so. Development of the necessary technologies should be
helped along by the fact that they have important applications here
on Earth, she said, citing autonomous search-and-rescue robots as one
example.
"I think we're
really working up to it," Boston said. "I think we're
coming into an era where a lot of things that we've found very, very
difficult in the past are going to become increasingly easy. And so
I'm certainly hoping [a mission could occur] within the next 20
years, where I can hope to still be alive to see it," she added
with a laugh.
Aiding human
exploration
An unmanned mission to
explore the Martian underground could also aid efforts to send
astronauts to the Red Planet, Boston said.
Lava tubes are
probably the most promising spots to establish human settlements
on Mars, she said. But scientists would need to send robotic scouts
to such sites first, to make sure they're safe for habitation and to
check them out for indigenous life-forms (which could theoretically
harm, or be harmed by, astronauts in their midst).
Launching a lunar-cave
mission — something along the lines of Whittaker's Spelunker
concept, perhaps — would be a good way to get the ball rolling
toward a similar effort on Mars, Boston said. And the success of
near-surface Mars sample-return could set the table for a sister
mission to a Red Planet cave.
"I think that
once we get over this technological and psychological barrier of
finally bringing something back from Mars that we can study, that the
next step is going to be easier, because we'll already have looked
over that cliff, and jumped over and gotten to the other side,"
Boston said. "It will embolden us, I hope, at the same time that
the technology is advancing."
Follow SPACE.com
senior writer Mike Wall on Twitter @michaeldwall or
SPACE.com@Spacedotcom.
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2012 SPACE.com, a TechMediaNetwork company. All rights reserved.
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