Pathfinder and the little rover that could

'A 100 percent success'

(CNN) -- In August of 1997, as the spacecraft Pathfinder ended its primary 30-day mission to Mars, giddy NASA scientists hailed the project as a "100 percent success." "We have successfully completed all of the science, engineering and technology goals of the mission," said a beaming Matthew Golombek, Pathfinder project scientist manager. Pathfinder and its rover Sojourner, NASA said, had returned nearly double the amount of data expected.

By all accounts, the project was a resounding triumph -- for NASA, for the future of space exploration, and for space junkies everywhere. All over the world, Pathfinder's arrival was heralded with more fanfare than any space event since, perhaps, Apollo 11 landed on the moon. NASA's Pathfinder Web sites broke all known records on the Internet.

Pathfinder's rover Sojourner, which had been expected to roam the red planet for only a week before running out of power, ran until September 27, 1997. By that time, the rover had traversed the rock-strewn terrain of Mars' surface 11 times longer than its planned one-week operation.

After hurtling through millions of miles of space since its launch in December 1996, Pathfinder landed on Mars on Friday, July 4, 1997 less than a second from its projected arrival time. Using a drop, bounce and roll technology that had never been tried before, it landed without incident; at 1:07 p.m. EDT, the little spacecraft began sending back signals telling NASA scientists it was OK. A resounding chorus of cheers broke out at NASA's Jet Propulsion Laboratory, followed by hugging, handshakes, and more than a few tears.

Before long, NASA had learned the spacecraft had landed in the rough, rocky flood plain called Ares Vallis, only 31 miles (50 kilometers) from the center of the zone where NASA had been aiming.

The next step: to get the rover Sojourner off of the lander. But here, engineers ran into a problem: one of the air bags that cushioned Pathfinder's landing had not fully retracted, blocking the rover's pioneering roll to Martian soil. Engineers soon managed to clear a route for Sojourner, but as soon as that problem was fixed they discovered another: only the smallest bits of information were getting through from the rover to the lander. This could hamper their ability to move the rover around the surface.

The JPL team labored all day to correct what they believed was a software problem in a communications modem. Then, suddenly, they began to receive data sent from the rover to the lander to Pasadena, indicating that their efforts had been successful. Cheers and high-fives erupted again in Mission Control, as someone exclaimed, "We're alive, we're alive."

Finally, Sojourner was ready to journey onto the Martian surface. The six-wheeled rover rolled down a ramp and into history; early Sunday morning pictures clearly showed the microwave oven-sized rover was on the Martian surface -- humanity's first autonomous vehicle to travel on another planet.

"The images that you see... show a perfectly deployed rover that has driven down a perfectly deployed ramp, making its first track in the soil of this planet, opening a new era of exploration," exclaimed rover project manager Jacob Matijevic.

Immediately, Sojourner began performing scientific analyses of soil and rocks. Within a week, scientists were saying they had already met the major mission objectives. After a few more weeks of probing, sampling, and analyzing, Project scientist manager Golombek declared the rover's work a historic accomplishment that for the first time provided scientists with a true representation of the Martian surface.

"We finally have a feeling of what it would be like to be on the surface of Mars now standing there," he said. "The dust would kick up. We would feel these temperature changes."

Golombek outlined what he considered the three most important discoveries:

• Scientists accurately predicted from orbit what the Mars landing site would be like, even though the closest objects identified prior to landing were the size of football fields. "That gives us tremendous confidence that we can do this again in the future," Golombek said.
  
  
• The rover discovered a rock containing high amounts of silica, a mineral found in various forms on Earth. "That's very, very unusual. That's like something that happens on Earth," he said.
  
  
• Mars' temperatures were found to fluctuate greatly, sometimes as much as 20 degrees in a matter of seconds. "Your toes would be comfy and your head would need a hat," Golombek said.

Other scientists were impressed by evidence that water was once prevalent on Mars and that there may have been enormous floods there. Photographs taken by the Pathfinder lander showed boulders stacked against each other as if piled by flood waters.

"This (flood) was huge," said Michael Malin, one of the Pathfinder scientists. "A comparable flood on Earth would be one that filled the Mediterranean Basin."

The scientists speculated that the flooding occurred between 1 billion and 3 billion years ago and was hundreds of miles wide, moving at a rate of about 35 million cubic feet (one million cubic meters) per second. It is these indications of water, and plenty of it, that have scientists thinking the planet may have supported life in some form.

An artist's rendering of future probes in Mars

For non-scientists, the most spectacular feature of the mission was undoubtedly the pictures Pathfinder beamed back. The first series of black-and-white shots, taken around the edges of the spacecraft, started coming into NASA's Jet Propulsion Laboratory a few hours after the landing. A couple of hours later, NASA released the first spectacular full-color views of the planet.

For the next few weeks, both the lander and the rover continued sending back stunning color photographs showing a red, dusty, barren, water-scarred surface. Scientists say they are amazed by the colors in the pictures, and by the variety of rocks.

"This has been just an absolutely wonderful surprise," said James Bell, a planetary scientist from Cornell University in New York. "We hadn't anticipated the amount of color information that we're seeing."

NASA scientists lengthened Pathfinder's battery life by shutting down on four out of every five nights everything on the lander except a timer . The timer turns the lander systems on when the sun rises. Battery-powered activities are conducted on the fifth night.

Eventually, the batteries would no longer charge. On Tuesday, March 10, 1998, scientists declared the craft officially "dead." At NASA's Jet Propulsion Laboratory, team members said good-bye to the lander and its little rover. The official time of death was 1:21 p.m. PST -- 250 days after its dramatic landing.

Pathfinder's presence, though, will be felt for years to come. The data it gathered will help determine what technology will be needed to design future Mars probes, which scientists hope could even lead to a manned mission by 2012.

"Sending robots to Mars is satisfying the basic human need to explore," said NASA administrator Daniel Goldin. "NASA is doing it in a way which will bring enormous benefits to those on Earth, new inspirations for the youth of the world, and new economic opportunities for all humankind."