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The Little Rovers That Could
JULY 2005
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In Learn More the National Geographic magazine team shares some of its best sources and other information to expand your knowledge of our featured subjects. Special thanks to the Research Division.

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Did You Know?Did You Know?

NASA Reinvents The Wheel
NASA's "robot geologists," Spirit and Opportunity, pack an unprecedented tool kit of scientific instruments as they search Mars to uncover evidence of the planet's water-drenched past. But if the vehicles can't move efficiently, the spectrometers, grinders, microscopes, and advanced cameras won't be of much use.
That's why engineers went to such lengths to equip the two rovers with wheels that do much more than simply turn. Paddlewheel-like cleats around the outside provide traction on the rocks, dust, and uneven surfaces of Mars. Spokes that spiral inward toward the hub are able to flex, providing shock absorption for the entire rover. Construction is of aluminum, keeping weight of the six-wheeled, 384-pound (174-kilogram) vehicles to a minimum. As a final touch, the 10-inch-diameter (25-centimeter-diameter) wheels even play a role in science experiments. Controllers can immobilize five of the wheels while the sixth spins, its cleats digging a hole several inches deep to allow scientists to remotely study Martian soil strata.
Bet the all-season radials on your car can't do all that.
—Chris Carroll


Related Links

Mars Exploration Rover Homepage
Review the mission and get updates.
Cornell University/Athena Science Package
Find detailed information about the scientific instruments on the Mars rovers.
Mars Express
Visit the home page for the European Space Agency's orbital mission to Mars.
Time on Mars
Follow the mission with a better understanding of the days and seasons on Mars.
Space Missions
Find information about past, present, and future NASA missions.



Beatty, J. Kelly, et al. The New Solar System, 4th ed. Sky Publishing Corporation, 1999.
Dolnick, Edward. Down the Great Unknown. Harper Collins, 2001.
Hartman, William K. A Traveler's Guide to Mars. Workman Publishing, 2003.
Various. Special section on Spirit at Gusev Crater. Science (August 6, 2004), 737-900.
Various. Special Section on Opportunity at Meridiani Planum. Science (December 3, 2003), 1633-1844.
Wilford, John Noble. Mars Beckons. Alfred A. Knopf, 1990.

NGS Resources

Skurzynski, Gloria. Are We Alone? Scientists Search for Life in Space. National Geographic Books, 2004.
Morton, Oliver. "Mars: Planet Ice." National Geographic (January 2004), 2-31.
Beatty, J. Kelly. Exploring the Solar System: Other Worlds. National Geographic Books, 2001.
Sawyer, Kathy. "A Mars Never Dreamed Of." National Geographic (February 2001), 30-51.
Long, Michael E. "Surviving in Space." National Geographic (January 2001), 6-29.
Winkler, Peter. "Bringing Space Tech Down to Earth." National Geographic World (January 2001), 6-7.
Gonzales, Laurence. "Mars: An Adventurer's Guide." National Geographic Adventure (September/October 2000), 120-26, 128, 159-61
Newman, Aline Alexander. "Destination: Mars." National Geographic World (January 2000), 14-18.

Newcott, William R. "Return to Mars." National Geographic (August 1998), 2-29.

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