An update on the Martian chronicles

When scientists wanted to explore what kind of life might exist on Mars, public television’s “Nova” recorded the building and launch of the rovers sent to the planet.

Now, a year later, the “Nova” team is back with “Welcome to Mars,” featuring data collected by the two robots as they searched for signs that the planet may once have harbored tiny forms of life. The program airs at 8 p.m. Tuesday on KCET.

“I want people to come away from the show with a sense of exploring another planet,” said producer Mark Davis. “What I really try to do is reach other people who don’t have science backgrounds and show them how interesting it can be.”

The scientists who worked on the project faced their share of challenges trying to synchronize their schedules with the rovers, mainly because a day on Mars lasts 40 minutes longer than a day on Earth, Davis said.

“You get this kind of Martian jet lag, and I had to deal with that too, and so it was very confusing, especially for the first couple of weeks. It took a while to grasp what was going on,” Davis said.

The arrival of Spirit, the first of the robots to land Jan. 3, 2004, brought some tense moments for the crew of scientists at NASA’s Jet Propulsion Laboratory in Pasadena.

Spirit got tangled up in its air bag, which is used to cushion the landing, and scientists lost communication with the rover. But during a series of long nights fueled by pizza and ice cream pops, the scientists worked out the kinks and cheered the robot on, prompting it to come out of its mechanical slump and respond to commands.

Spirit’s twin, Opportunity, had an easier time when it arrived Jan. 24. It floated gracefully down at Meridiani Planum, a flat region about the size of Oklahoma, where it took a close-up photo mosaic showing a crater formed by an asteroid strike and an imprint of a dry river bed flowing into it -- two signs that water once existed, said Steve Squyres, an astronomy professor at Cornell University who is in charge of the rover science team.

When the rovers landed, scientists realized that the territory under exploration was once beneath water. One clue was billions and billions of tiny round balls made mostly of the mineral hematite, an iron oxide, which can only form if water is present, Squyres said.

The surface of Mars is very cold and dry. But scientists believe that in the past it was warmer and wetter. The reason the planet changed climates remains a mystery.

Originally, the robots were to stay on the planet for 90 days. But they turned out to be more durable than researchers expected and are still going strong.

The scientists are looking for more clues to microbial life on Mars. Among the questions: Was there a layer of ice over the water? Was the water neutral or acidic? Did the planet alternate between dry and wet phases?

Squyres said scientists hadn’t decided when this mission would end. It depends on wind and dust conditions on the planet and the continuing durability of the rovers, which are powered by the sun and can see their mobility reduced if they get too dirty.

“Mars is a very dirty, dusty place,” he said. “We’re trying to prepare ourselves, to drive them like there’s no tomorrow.”