JEFFREY KAYE: It's been nearly six years since the Pathfinder rover, named Sojourner rolled onto the surface of Mars to send back pictures, weather reports and geological data. Now, the next generation of rovers is scheduled for another geological field trip. The teams working on the Mars rovers' expeditions are building on experience gained during that 1997 Pathfinder mission. However, this project is much more complex; the rovers more sophisticated. Joy Crisp is the rover project scientist.
JOY CRISP, Mars Rover Project Scientist: We cannot do things the way we did on Pathfinder, which was just jump in and go at it. You know, we really need to give it thought ahead of time, because it's complicated. We have a short amount of time each day to come up with what the rover should do the next day. And we want to make really good choices. We don't want to be doing it just on the fly.
JEFFREY KAYE: NASA's planners got a sobering dose of reality in 1998 with two unsuccessful Mars missions. An orbiter was destroyed because of a miscalculation. A lander failed to transmit radio signals back to Earth. Firouz Naderi heads NASA's Mars exploration programs at JPL, the Jet Propulsion Laboratory.
FIROUZ NADERI: It seems that we pushed too far in '98 in terms of what we were trying to accomplish with how much resources we're trying to accomplish. So that gave us a chance to sit back and reassess the Mars program, and be somewhat more measured about how we would go about doing this.
JEFFREY KAYE: If things go as planned, in January, three weeks apart after a seven-month trip, twin robots will parachute from their respective spacecraft at two separate sites. They'll bounce to a stop encased in airbags. After they're unwrapped and unfolded, they'll drive off their mother landing crafts to explore the Martian terrain. The $800 million missions are being managed for NASA by JPL, which is near Pasadena, Calif. Here, engineers and scientists have been running tests on duplicates of the machines that will land on Mars. The rovers are in pursuit of signs of ancient life.
FIROUZ NADERI: So we're looking for life, and it's difficult, you know, to just stumble on it, so you look for water as a proxy for life. The grand strategy for Mars exploration ... we call it "follow the water."
JEFFREY KAYE: Water is a condition for life as we know it. Many scientists believe that what is now a dry, dusty planet was once very wet. One of the landing sites, the Meridiani Plateau, has minerals commonly associated with water. The other, the giant Gusev Crater, halfway around Mars, may have once held a lake. Scientists think the lake was fed by water flowing through a massive channel.
JOY CRISP: What it looks like is that water ponded in that crater, and should have deposited lake deposits, water lane deposits. And for us on Mars, that's, for Mars scientists, that's a gold mine. If we can find water-lane sediments, that would be an important find.
JEFFREY KAYE: Why?
JOY CRISP: Because that may be an environment that could have harbored life.
JEFFREY KAYE: The rovers themselves are solar-powered, mobile geologists. Each is a 375-pound, six-wheeled lab, loaded with gear designed to photograph, collect, analyze, and grind Martian rocks. Rick Welch, the flight system chief engineer, helped design the rovers. During the missions, navigators on earth will be guided by panoramic images the rovers transmit.
JEFFREY KAYE: So what's it doing now?
RICK WELCH, Flight Rover Chief Engineer: Right now, it's going to do a sun find.
JEFFREY KAYE: Locating the sun helps orient the rover.
JEFFREY KAYE: This is the panoramic camera...
RICK WELCH: That's correct.
JEFFREY KAYE: ...At the top, and it does a lot more than just look for the sun, right?
RICK WELCH: Right. Those cameras can be used for all of our big science panoramas, and there are four cameras that are up there. They're in stereo pairs. Just like a human eye has two, to be able to determine range to objects, there are two science cameras, which have filter wheels in front of them that provide the color imagery for geology. And then the ones nearer to the center of the mast, the navigation cameras, they have a wider field of view and are better for planning our mobility and traverses on Mars.
JEFFREY KAYE: Cameras mounted on the front and back are also used for driving. Crisp, who is geologist, says the robots are designed to operate much as human field researchers do.
JOY CRISP: And there are things like, on the end of the robotic arms, there's a microscopic imager which is like a hand lens, which is like a hand lens that a geologist uses. So when I'm out in the field, I usually will take a rock hammer with me and crack open a rock to get a fresh look at the interior, because you can see the mineral shapes and textures better that way, and then look at it close up. And you can identify, oftentimes, you can identify minerals that way. On the rover, we have a rock abrasion tool on the end of the robotic arm. And that is like a rock hammer, so it gets us inside the rock, about a half a centimeter, grinds away the outer part of the rock, and gets at that interior, and then we can look at it with a microscopic imager. There are also chemical analyzers and mineralogical analyzers on the end of that robotic arm that tell us what minerals are present and in what amounts.
JEFFREY KAYE: The rovers are programmed to move slowly and cautiously, during what engineers hope will be 90-day life spans.
RICK WELCH: When it's doing autonomous navigation, because it has to take images and actually sense the terrain and actually determine whether there's a hazard out there, it will actually take up to a minute to determine whether it's safe to take its next step, and then it moves in small steps just like the Sojourner rover did on Mars. So, actually, in a given day, we probably won't drive more than, say, 20 or 30 meters in a given day. And that makes for the total mission that we may get several hundred meters away from the landing site.
JEFFREY KAYE: Caution is the watchword, not only of the latest mission, but of NASA's Mars exploration program. Despite enthusiasm for the latest Mars expedition, there are some in the space community who say NASA could be doing even better planning. There are calls to make the U.S. space exploration program more focused on the eventual goal of landing human beings on Mars.
LOUIS FRIEDMAN, Planetary Society: We should be headed toward doing robotic outposts at Mars, to building the infrastructure necessary to support human missions.
JEFFREY KAYE: Louis Friedman is executive director of the Planetary Society, an international organization that promotes space exploration and research. Friedman, an engineer who once headed JPL's Mars program, says NASA should be working methodically to send humans to explore Mars.
LOUIS FRIEDMAN: For example, a goal on this very Mars mission, or at least the next one, could be the survey of two, and selection of two or three candidate landing sites for humans on Mars. And that, then we could begin to choose those places, based on scientific and technical considerations.
JEFFREY KAYE: But NASA's mission is more modest. The space agency has no stated goal of landing humans on Mars. One reason for caution, says Naderi, is the mixed record of Mars missions.
FIROUZ NADERI: Two-thirds of the missions that we have sent to Mars, have not been successful, so the batting average is only about a third; good in baseball, but not good in planetary system.
JEFFREY KAYE: Difficult or not, Mars is turning out to be a popular destination. NASA currently has two orbiters mapping the planet, and plans at least four more Mars missions over the next eight years. In addition, a Japanese orbiter should reach Mars in January. And on Monday, the European Space Agency is planning to launch a Mars-bound spacecraft and lander.
JIM LEHRER: After several delays, the first rover launch now is scheduled for June 8.