WASHINGTON (States News Service) -- Promising an ambitious course for Mars exploration after recent mission setbacks, NASA will send twin rovers to Mars in 2003 to roam the surface in search of ancient signs of water, the agency announced Thursday.

The identical, golf-cart-sized craft -- described as the "sport utility vehicle of Mars Rovers" -- will be launched within months (the first on May 22, the second on June 4) to radically different landing sites that each may contain signs of water.

Adding a second rover to Mars, an unprecedented goal, will bring "double the science at half the cost of the first mission," said NASA Associate Administrator for Space Science Ed Weiler.

The mission's total cost -- about $600 million -- may have to be deferred from NASA's budget, Weiler said, but would not cause the cancellation of any other mission at NASA. The Mars rovers are an "agency priority," he said. The second rover costs about $200 million, half of the $300 million to $450 million to build and launch the first.

More mobile and scientifically smarter than the 1997 Pathfinder, the rovers are like a "robotic geologist that lands in an airbag," Weiler said. The rovers will be able to roam 110 yards (100 meters) -- the size of a football field -- across the Martian surface each day.

Traversing terrain ravaged by upheaval, and wandering up mesas to examine geological layering, the rovers are intelligent enough to navigate around rocks independently, said Cornell University professor Steven Squyres, the project's principal investigator.

With a combined lifetime of six months, the rovers have "almost human-like characteristics," he said, calling the 4-foot-tall, 250-pound craft "short and fat, with 20-20 vision." The craft has a total of 10 cameras, including a microscopic camera affixed atop a human-length arm, he said. It also has a "rock hammer" to grind its way into a rock and reveal the contents, Squyres said.

Using such tools, the rovers will "measure the dickens" out of geological layers, said Jim Garvin, Mars program scientist at NASA. "We can go to places we have never been before, and we can go with new tools."

Although recent discoveries of signs of water on Mars are encouraging, Weiler said, these craft are to focus on areas where water may have existed millions of years ago.

After the embarrassing loss of Mars Polar Lander to a botched thruster-powered landing last year, NASA is replicating an airbag landing approach to ensure the probe does not break on its 50- to 60-mile-per-hour landing.

Although the exact landing-site locations will be considered later, the agency plans to send one probe to a "safe" site, and the other to a more "aggressive" terrain, Weiler said.

After the spacecraft enters the Martian atmosphere, a parachute will deploy to slow down the craft and airbags will inflate to cushion the landing. The spacecraft will bounce for up to a half-mile (0.8 kilometers) upon hitting the planet's surface before coming to a stop, allowing the rover to emerge.

The rovers, both carrying lollipop-like antennas, will communicate with a Mars orbiter, planned to launch next year, that will "relay" all data from the craft to Earth. In addition, other orbiters may be used as backup, said Scott Hubbard, Mars program director.

The decision to send rovers follows months of heavy thinking, after back-to-back mission failures last year brought a barrage of criticism against NASA for lack of training and personnel.

Given these concerns, NASA will "greatly increase" the size of its management team, Hubbard said, and offer better training and mentoring to staff at the Jet Propulsion Laboratory, which will operate the missions.

Weiler said the agency is following "almost to the letter" the recommendations made in a scathing report released earlier this year that pinpointed lack of communication and poor management skills as the culprits behind last year's failures. This time, Hubbard, the top Mars chief at Headquarters -- a new position -- will oversee all activity.

"It was clear that on the Mars program, we delegated a little too much," in the past, Weiler said.