ROCHESTER, N.Y. — The cheaper, faster and — one hopes — better route to Mars was the topic when James Bell, associate professor of astronomy at Cornell University, spoke at a dinner lecture at the 11th IEEE ASIC conference here. Bell intertwined a review of planetary data gleaned from the Pathfinder missions with insights into how NASA's pervasive new culture of economy has influenced engineering decisions in the Mars program.

From the view of the planetary scientist, Bell said, Mars is emerging as an even more cryptic place than the 19th-century image of an inhabited planet struggling against its fate. Evidence from the Pathfinder mission appears to confirm earlier data suggesting that over a significant period of the planet's life, massive amounts of liquid water coursed about on the surface, carving deep gorges and streamlined islands. Yet today the planet is bone dry, with a dust-laden atmosphere too thin to retain water vapor and temperatures too low for the presence of liquid water.

How an entire planet could make the transition from partially immersed in water to entirely dry is becoming one of the great questions of planetary science, Bell said. In particular, he suggested that the mechanism might be of interest to the residents of the only other water-covered planet in the solar system.

If the red planet is proving strange, Bell suggested, so is the engineering program that undertakes to explore it. Driven by what Bell described as "NASA's new mantra" of cheaper, faster and better, the Mars exploration program is moving in directions that would have been unthinkable in the days of Apollo. One example he cited was the design philosophy for the orbiters and landers that will do the real work on Mars. The devices are designed with off-the-shelf imaging components, and without the redundancy so characteristic of earlier NASA work.

This was a welcome concept for the Rochester audience, rich in Eastman Kodak employees. Both the Pathfinder lander and rover carried CCD imaging equipment developed by Kodak.

The lander's imaging camera was of fundamental importance to the mission, not just for making pictures of the Martian surface, but for operation of the rover. The rover, Bell explained, was an autonomous vehicle with very limited intelligence. Because of the time delay and power cost of communications, the rover could not be driven interactively from earth.

So the rover team assembled a set of detailed images of the rover's next objective, using the lander's camera. Back in the labs at the Jet Propulsion Laboratory, these images were used to build a virtual-reality model of a few-meter portion of the planet's surface. Rover controllers practiced steering the rover through the virtual model in the lab, and from that experience built up a list of commands to send up for the next day's exploring.

"We would be sending a whole string of things like 'go forward 1 meter, then turn left 30 degrees, then go back 0.3 meter . . . ' and so on," Bell said. "The rover would execute the commands and send back its images. Then you would analyze what you got back. Some days the rover would be right where you thought it would be. Some days it would have slipped on a pebble or something, and it would be missing. You'd spend all day playing find-the-rover."

The good news, of course, is that the Pathfinder modules, with their off-the-shelf technology and lack of redundancy, worked. "The mission was successful far beyond our expectations," Bell said. He explained that Pathfinder's mission was not so much science as engineering. "Pathfinder was to validate the technologies needed for later phases, not so much to return scientific data," Bell said.

That Pathfinder worked at all was vindication for an engineering team that had pushed the limits. One example cited by Bell was the technique for putting the Pathfinder lander on the surface of Mars in the first place. It was determined that a controlled, lunar-lander-style landing on Mars would be too expensive. So another approach was taken.

As the lander entered Mars' thin atmosphere, it deployed a parachute that slowed its descent. At a low altitude, thrusters fired to stop the descent altogether. At that point, with the whole package hovering well above the surface, the lander was ejected, encased in — essentially — huge air bags.

"So here is the lander, with the rover packed inside it, inside this 10-meter-in-diameter bundle of air bags," Bell said. "The bundle falls, bounces randomly 15 or 20 times across the Martian surface — at about 20 g's per bounce — and comes to rest somewhere. That is the new, inexpensive way to put a payload" on Mars.

Nor will such a direct approach be limited to Pathfinder. It will apparently be used on future landers as well. But it will be eclipsed by an even more violent technique planned for the mission to be launched in January.

"The next lander carries two assemblies called Microprobes," which are "lawn-dart-sized projectiles," Bell said. "Just before the lander's parachute opens, the Microprobes separate from the lander and crash into the planet at 500 g's. They make a bit of a crater and end up at the bottom of it. After impact, a boring device separates from Microprobe, burrows about 2 meters and takes soil samples" to analyze. Though the Microprobes have been "drop-tested all over the earth to prove the idea is sound," Bell said he would "eat my hat if it works on Mars."

Other new technologies developed under the streamlined program are more elegant. Bell described an appendage that would be carried under a future rover. "A company called HoneyBee Robotics in New York has developed an electric drill that runs on a few watts. It can slowly penetrate rocks. The idea is for the rover to crawl over an interesting rock. Then the drill can take a core, analyze it, present it to the rover's imaging camera [and] put it in a sample box. Eventually, we intend to have a mission that will go to Mars, land, retrieve the samples from the box, take off and return the samples to earth."