Price Tag For Mars Rover Not Sky High Nasa Engineers Pinch Pennies By Crafting New Explorer Out Of “Off The Shelf Parts”

Space probes used to cost $1 billion a pop. No more. Struggling to slash costs while raising quality, NASA has built an unassuming gadget the size of a child’s riding toy to rove across the dry Martian landscape, doing exploration on the cheap.

Despite its relative simplicity, the vehicle, named Sojourner, is to be the first to roam the surface of another planet.

If it proves adept, the Sojourner will wander for a week, taking close-up pictures of rocks and analyzing their chemical makeup, shedding light on the inner nature of Mars. If it is highly successful, it will do so for a month.

“It’s the culmination of a lifelong dream for me,” said Donna L. Shirley, the vehicle’s designer and head of Mars exploration at NASA’s Jet Propulsion Laboratory in Pasadena, Calif.

“Going vicariously is not quite as good as being there,” the 55-year-old engineer said of robotic exploration. “But it’s a lot easier.”

It’s a lot cheaper, too, especially as mission designers have kept a sharp eye on cutting expenses, mainly by using “off the shelf” parts rather than developing new ones.

Costing a mere $25 million, the six-wheeled rover has small motors and a modest computer brain (with just 6,500 transistors, compared with 5.5 million in the best Pentium models). And it has just enough zip to make scientific headway, no more. Any radio-controlled car from a hobby shop can go faster.

The first hint of its birth came in the 1980s as Shirley dreamed of putting roving vehicles on Mars, seeking a way to follow up on the successful but expensive Viking missions of the 1970s, which cost the equivalent of $3 billion in today’s dollars. She eventually headed a panel that said a return to Mars, if ever to be more than a dream, had to pinch pennies.

NASA balked at that advice. But in 1992, Daniel S. Goldin was appointed administrator of the space agency and started a campaign to revitalize it by making its projects smaller, cheaper, faster and better.

Rather quickly, Dr. Shirley’s plan got a thumbs up.

The rover that developed under Dr. Shirley’s guidance is the heart of the $266 million Mars Pathfinder mission. It weighed only 34.2 pounds at launching and a mere 23 pounds once mobile on the Martian surface, where gravity is relatively weak.

At top speed, the vehicle crawls along at just 16 inches a minute, or 80 feet an hour. It has three cameras - a forward stereo pair and a rear-looking one.

Its solar-power cells have an area of 1.9 square feet, sufficient to energize the rover for several hours a day, even in the worst dust storms. As a backup, the rover also has D-cell batteries. For the sake of simplicity and economy, they are not rechargeable.

The rover carries an alpha proton X-ray spectrometer that will be pressed against soil and rock outcroppings to study their composition. Collecting data for each sample will take up to 10 hours, providing the first chemical analyses of what Mars is made of, as well as insights into its evolution and geologic history.

The previous Viking landers conducted biological tests, which failed to detect any unambiguous signs of life.