rocket thunders away from Earth, targeting a distant red dot in space. Inside the Pathfinder spacecraft, a 25-pound robotic rover named Sojourner awaits its chance to begin exploring Mars upon arrival seven months later: July 4, 1997.
Humans haven't sent machine surrogates to Mars since 1976, when two of NASA's Viking landers probed the surface during an unsuccessful search for evidence of life. NASA's next Mars mission failed in 1993 when ground controllers lost contact with the US$980 million Mars Observer before it entered Mars orbit.
Now, under a project called the Mars Exploration Program, NASA plans to launch two small $100 million robotic missions to Mars every 26 months until 2005, and perhaps beyond.
Exploration will begin when Pathfinder's lander enters the Martian atmosphere and drops into an area called Ares Vallis. Scientists on Earth will see in 3-D through color stereo cameras as they steer Sojourner across the surface of Mars at a blistering speed of one centimeter per second.
Sojourner's mission is to demonstrate that rovers the size of microwave ovens can perform a useful function in planetary exploration. In humanity's first traverse across the Martian terrain, Sojourner will perform simple tasks such as measuring ground friction and carrying an alpha proton X-ray spectrometer to determine the elemental makeup of the red planet's rocks.
Donna Shirley, manager of the Mars Exploration Program at NASA's Jet Propulsion Laboratory, says Sojourner navigates using "a combination of Earth operators telling the rover where to go and onboard control and sensor systems that enable it to reach its destination without getting into trouble."
Following up the Pathfinder mission, the Mars Surveyor '98 Lander is scheduled to install a weather station near the Martian south pole. This machine will dig trenches in the frozen soil using a six-foot-long robotic arm with cameras on its tip. Measuring the thickness of layers of dirt and ice left by Martian dust storms and winters will help scientists understand more about the planet's climatic evolution. "The action will be pretty autonomous," Shirley says. "We'll tell the robot arm to put dirt in the hopper and it will, whereas with the Viking landers, we'd have to say, Move an inch, move another inch. It took a very long time." Especially since commands and data take at least 10 minutes to travel between Earth and Mars.
Only the first four robotic missions have been inked onto NASA's schedule. Ultimately, semi-autonomous machines could produce fuel, gather water, and build structures in preparation for human arrival. And then, humans will be the Martians.
Dave Cravotta
SCANS
Robots Invade Mars!
