Tumbleweed Rover Goes on a Roll at South Pole
March 3, 2004
A balloon-shaped robot explorer that one day could search
for evidence that water existed on other planets has
survived some of the most trying conditions on planet Earth
during a 70-kilometer (40-mile), wind-driven trek across
Antarctica.
The tumbleweed rover, which is being developed at NASA's Jet
Propulsion Laboratory in Pasadena, Calif., left the National
Science Foundation's Amundsen-Scott South Pole Station on
Jan. 24, and spent the next eight days rolling across
Antarctica's polar plateau.
Along the way, the beach ball shaped device, roughly six
feet in diameter, used the global Iridium satellite network
to send information on its position, the surrounding air
temperature, pressure, humidity, and light intensity to a
ground station at JPL.
The test was designed to confirm the rover's long-term
durability in an extremely cold environment, with an eye
toward eventually using the devices to explore the martian
polar caps and other planets in the solar system.
The final tumbleweed rover is envisioned as a lightweight,
roughly 88-pound device that can serve multiple roles as an
independent robotic explorer. The rover's design can allow
it to act in turn as a parachute while descending through an
atmosphere; an air bag on landing; and, ultimately, as an
unmanned vehicle equipped with a package of scientific
instruments.
The tumbleweed rover is based on concepts going back to the
1970's and has been pursued by several investigators at JPL.
Dr. Alberto Behar, a robotics researcher in the robotic
vehicles group recently deployed this prototype at the South
Pole. "We are testing a new mode of rover transportation
that uses the available environmental resources to give us
an added edge to cover more ground using fewer on-board
resources," said Dr. Behar. "This gives us the ability to
use the precious cargo (on Earth) or payload (in space) mass
for more applicable science instrumentation."
Even though the average external temperature during the
rover's deployment was recorded to be on average -30 degrees
Celsius or -22 degrees Fahrenheit, the rover kept its
internal instrument payload at an average temperature of
roughly 30 degrees Celsius or 86 degrees Fahrenheit. The
rover was able to stay warm by self-heating due to running
electronics and an internal air pump.
The ultra-durable ball reached speeds of 16 kilometers per
hour over the Antarctic ice cap, and
traveled at an average speed of about 6 kilometers per hour. The winds at the South Pole were
unusually low during the test. As a result, there were
several periods during its deployment when the rover did not
move at all. Even taking those lulls into account, the rover
managed an average speed of 1.3 kilometers per hour over the course of the deployment.
Behar said the rover's design is especially well suited for
polar missions to use instrument packages to look for water
beneath a surface desert or an ice sheet, a task that cannot
be done accurately from orbit.
Plans to construct the next generation tumbleweed rover are
already underway at JPL.
Future refinements of the design are likely to focus on
reducing the rover's weight and rolling resistance to reduce
the minimum winds needed to enable it to travel farther and
the adaptation of the payload to include a ground-
penetrating radar to conduct terrain and ice surveys.
Behar says he hopes an updated version of the rover will be
deployed again later this year, and the design may one day
find itself rolling on the polar icecaps of Mars.
The tumbleweed rover project is managed by NASA's Jet
Propulsion Laboratory and was supported jointly by NASA's
Office of Space Science, Washington, D.C. and the National
Science Foundation.
For more information on the tumbleweed rover visit:
http://robotics.jpl.nasa.gov/~behar/southpoletw.htm
For more information on the National Science Foundation
visit:
http://www.nsf.gov
