A
spaceship descends with a thunderous roar and deposits a futuristic probe before
taking off again. The Extraterrestrial Vegetation Evaluator (EVE) soon
activates and begins flying around, scanning the barren surface for signs of
life.
Scientists
today can only dream of having a robotic explorer like EVE from the Disney/Pixar
film "WALL•E." But some researchers are working on autonomous spacecraft,
airships and rovers that can cooperate intelligently while exploring distant
worlds.
"The
orbiter gives you global perspective, the aerial platform a more regional
perspective, and that helps determine where to deploy ground assets in a
targeted fashion," said Wolfgang Fink, a physicist at Caltech in Pasadena,
California.
Fink's
vision of "tier-scalable reconnaissance" starts with an orbiting spacecraft to
make a global survey for interesting scientific targets, before deciding on its
own where to deploy
an airship such as a dirigible. The airship could look even closer at a
region to find the best landing site, and finally drop a rover or some other
surface explorer. That surface explorer could then move quickly to the target
area.
A
demonstration of how such a surface explorer might deploy will take place in
the Mars Science Laboratory mission, slated for a 2009 launch. NASA's Sky Crane
carrier will hover above the surface of Mars on retrorockets while lowering an
SUV-sized rover using a winch and tether.
Some
Mars missions have already demonstrated the advantage of coordinating orbiters
with surface explorers. Scientists used data from three Mars orbiters to
determine the landing site for NASA's Phoenix Mars Lander, and also turned
orbiter cameras on the lander as it descended
to the surface. Of the three orbiters, the Mars Reconnaissance Orbiter has
even helped NASA's separate Spirit and Opportunity Rovers navigate
around obstacles on the Martian surface.
However,
Fink and his collaborators want to take humans out of the loop and develop
robots which can decide independently when and where to go. That becomes
crucial for future missions to distant places such as the moons of Saturn or
Jupiter, where a command signal from Earth can take over an hour to reach
robotic explorers.
The
key rests with software algorithms that help robots make command decisions on
their own. Fink's group has begun testing such algorithms by using three small
rovers and a camera that looks down on a simulated indoor landscape. The camera
identifies both targets and obstacles, which allows the rovers to deploy and
drive around obstacles to reach their targets — all without human intervention.
"Integration
is the biggest challenge," Fink noted. "At Caltech, we are now at the point
where we're implementing a test-bed outdoors to develop the software to
demonstrate this in action."
The
outdoors test would involve a miniature airship taking the place of the camera.
Researchers from around the world would be able to give commands to the airship
via Internet and watch it move and deploy the rovers on its own.
The
field tests may pave the way for using similar command software on the proposed
NASA and European mission to Titan
or Europa. Fink and other researchers involved with the planning have begun
discussing how such a mission might shape up by the 2017 launch date.
"A
Titan mission would have the orbiter deploying a balloon, and we're already
thinking about having a lander," Fink explained. "There you have a three-tier
mission."
The
tiered approach may eventually take the form of a robot that "does its own
reconnaissance, goes out and looks for anomalies, finds something interesting
and makes contact with the sender," Fink said, pointing to the Imperial probe
from "The Empire Strikes Back" which lands on the ice planet Hoth.
Perhaps
best of all, intelligent robots could react quickly to surprises and
investigate anomalies — such as a geyser on Saturn's
moon Enceladus, or a landslide on Mars.
"Curiosity
in itself is not present in any of our machine systems," Fink said, remarking
upon WALL•E's childlike tendencies which appear to distract EVE but eventually
help her mission. "That curiosity drives action."
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