TUCSON,
ARIZONA -- Getting a leg up on Mars
requires muscle power. But if you are a robot,
using muscle wire will put spring into your step.
The University of Arizona
is home to a mechanized menagerie of sorts. Need a pick-me-up burst of
power on Mars to hop over a rock? How do you refill your fuel tank when
the nearest gas pump is millions of miles back on Earth?
These are a few of the challenges
being tackled here by Professor Kumar Ramohalli and his students at the
school's aerospace
and engineering department.
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First, there is LORPEX, for
Locally Refueled Planetary Explorer. Then there's the cute and cuddly BiRoD
-- a short way to say Biomorphic Robot with Distributed power. It seems
that in space any good acronym is left to its own devices.
Ramohalli also directs the
Space Engineering Research Center at the university. This group studies
how to use on-the-spot resources on the moon, Mars, or the asteroids.
Pit stop on Mars
Having a space robot make
its own gasoline and oxidizer so it can keep on going…and going…and going
is the thought behind a planetary explorer that refuels itself.
"That is particularly nice
for a planet like Mars where there are no gas stations," Ramohalli told
SPACE.com.
The refillable robot also
has the ability to generate power bursts. The need for quick and snappy
surges of power is a direct message from earlier robots sent to the Red
Planet, Ramohalli said.
"We have learned that you
need power surges on Mars. That is critical if you are going to crush a
rock to see what's inside, or if you have to drill deep below the surface.
Maybe you need to jump over an obstacle. Any one of those things means
you need a power surge. To this day, not even robots in the Star Wars movies
have been able to do that," Ramohalli said.
Outburst of power
The key to power-on-demand
is cranking out fuel from local resources. "Living off the land," is critical
for future space explorers, be they robots or humans, Ramohalli said.
For example, the LORPEX carries
a lightweight unit to suck in oxygen and carbon monoxide from the martian
atmosphere. Panels of photovoltaic cells mounted on the robot convert solar
energy into electrical power to energize this fuel-making hardware.
Placed on Mars, this equipment
would extract oxidizer and fuel slowly over a period of a month. With gauges
on full, a burst of energy can be released, offering a millionfold increase
in power. A power train relays this outburst of energy to whatever device
is required, be that a drill, auger, crusher, wheels, scooper or other
tool.
"Energy has not been a factor.
We can always have energy. But when you need that certain power surge,
the robots to date cannot do that. That's a very big limitation and why
we built LORPEX," Ramohalli said.
Look under the hood
A robot of a different stripe
is the cute and cuddly BiRoD. Meant to mimic biological systems, this little
critter is far simpler than past robots, explains Roberto Furfaro, an aerospace
engineering student at the university.
Cute looking BiRoD, ready
for active duty.
As a micro-beast of burden,
BiRoD features the latest innovations, such as muscle wires, chemical energy
storage, mechanical conversion concepts and sensors. Everything is packed
within a 12-inch (30-centimeter) long box, set atop a combination wheel/leg
system.
Furfaro said that the robot
reproduces the movement of the animal world. That is why it's tagged a
"biomorphic" robot.
Muscle wires are used in
the robot, made of a melding of nickel and titanium, to produce a memory
alloy. "They have a nice property. When you heat it up, it changes its
structure. When muscle wire contracts it produces a force, and you can
use this action for moving the robot," Furfaro said.
Ramohalli beams when talking
about BiRoD, the biomorphic robot.
"The big deal is that there's
nothing under the hood. No gears, no levers, no transmission, no motors
-- that's what makes it light and reliable," Ramohalli said.
~
Limping along
BiRoD is designed to ride
on larger spacecraft. In fact, 25 of this breed of robot can occupy the
same space and has the same payload weight as the single Sojourner robot
that was part of the Mars Pathfinder, which landed on the Red Planet in
July 1997.
Scattering an army of these
tiny robots across Mars would be ideal. If one breaks down, others in the
fleet can keep going.
Pete Lozano (left) and
Kumar Ramohalli pose with BiRoD.
"If a limb of BiRoD breaks,
that's okay. The other limb will still work because there is no central
power location. We have distributed power. It can limp along on the other
legs," Ramohalli said.
BiRoD also has the ability
to produce bursts of power, making it all the more valuable for a wide
range of planetary exploration duties, Ramohalli said.
Furfaro said that space robots
and robots used in a terrestrial setting are much the same.
"Actually, some of the robots
built for Earth are more complex than those designed for space," Furfaro
said, particularly those devices designed to work on the ocean floor.
The philosophy of "faster,
better, cheaper" is being adopted for building space robots -- and "cheaper"
means using something commercial.
"There's an inversion going
on. I see commercial robots as doing something good for space, and not
vice versa," Furfaro said.
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