TechKnowledgey 2004
by Jeff Eckert
TechKnowledgey
2004
Events, Advances, and News
From the Electronics World
Advanced
Technologies
Simple, Cheap Rover
Travels with the Wind
Exploded view of the Tumbleweed Rover,
showing layout and electronics package.
Courtesy of NASA Jet Propulsion
Laboratory.
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In any election year, it is not unusual
to see bombastic bags of wind
moving about the countryside.
However, some of them actually
perform a useful function, such as
NASA's Tumbleweed Rover, which is
currently under development at the
Pasadena, CA Jet Propulsion Lab.
Considerably less complex than the
familiar Mars Rover design, this is a
large, wind-blown, inflated ball that
carries an instrument payload in its
interior.
NUTS & VOLTS
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The Tumbleweed is designed to
provide a safe and economical way
of deploying instruments, such as a
ground-penetrating radar and magne-
tometers, in a range of hostile environments. Possible utilization sites include
remote areas of the Earth, as well as
Mars, Venus, and Titan — perhaps
even Saturn's moon Io (via supersonic
volcanic wind) and Neptune's moon
Triton (which shows signs of
significant surface wind erosion).
One version of the rover was
recently deployed in Greenland,
where it completed a more than 130
km autonomous traverse across an
ice sheet. Communicating via the
Iridium satellite network, the rover
relayed live GPS, temperature, and
pressure data to a ground station at
JPL every 30 minutes for nearly 10
days. At the time of this report, two
more rovers were making a traverse
from the South Pole to the coast of
Antarctica, some 2,000 km away.
The Antarctic test is designed to
obtain mapping data — in collaboration
with the Antarctic Digital Database
(ADD) project of the British
Antarctic Survey — to demonstrate
Tumbleweed's effectiveness in harvesting
data in extreme and remote settings.
For more information, visit
http://robotics.jpl.nasa.gov
New Sonar Technique
Screens Out Ocean Floor
Demonstrating that simpler is,
indeed, often better, Dr. David
M. Pierson — a physicist at North
Carolina State University ( www.ncs
u.edu) — and Dr. David E. Aspnes
have developed an improved method
for locating objects buried in the
ocean floor without the use of
complex, unreliable modeling or the
usual arrays of sonar transmitters
and receivers. The method records
the return echo of a sonar transceiver's
"ping," then time-reverses and
transmits that signal. The resulting
echo clearly shows buried objects
and suppresses the response from
the seafloor itself, making the
underwater terrain "transparent."
According to Pierson, using time
reversal to find buried mines requires
only one transceiver — although more
can be used — and the method isn't
limited by the composition of the
ocean floor. "Previous methods had to
incorporate a lot of complex modeling of
the sea floor and the ocean environment
and required sophisticated software
and hardware systems. My time-reversal
technique not only simplifies the
needed equipment, but also can be
implemented using existing sonar
equipment, with minor software
changes. More elaborate analyses of
echoes are also made possible."
In a public statement, an NCSU
representative noted, "The NC State
discovery should please naval
mine-detection experts, who now use
everything from dolphins to divers to
sophisticated software modeling and
elaborate sonar arrays in their grim
work and it should send those who
design such mines back to their
equally grim drawing boards."
Tumbleweed's electronics pallet. Courtesy of NASA Jet Propulsion Laboratory.
18
MAY 2004
