What was supposed to last only 90 days has turned into a three-year exploration for water on the Martian planet.

Jeff Moersch, assistant professor of earth and planetary sciences, spoke at last week’s University of Tennessee Science Forum about the search for water on Mars through the missions of the Spirit and Opportunity rovers, wheeled robots that have explored the planet’s geology starting more than three years ago.

Prior to the launch of these rovers, scientists studied Mars’ surface attempting to find areas of land that could have once held water. Two spots were picked — Gusev Crater and Meridiani Planum.

The rovers are the updated version of an earlier model, the Sojourner Mars Pathfinder. They have new surface-testing equipment, photography abilities, drills and better communications with NASA.

“Basically, they are very sophisticated robotic geologists,” Moersch said.

Gusev Crater was Spirit’s landing site. At this spot, NASA hoped to find something similar to a dry lake bed. On January 2004, when Spirit landed, the rover discovered there was no similarity between the crater and a dry lake bed, Moersch said.

Spirit still explored the area and took samples of rocks. The first rock examined was the Adirondack rock, named after the New York mountain range.

With any form of new discovery, scientists are allowed to name what they find. This can be the best part of the job, Moersch said.

“The cool thing about being a scientist is you get to name the rocks you look at. I named one after my wife on Valentine’s Day. I got a lot of points that day and now she is famous,” Moersch said.

The crater was a disappointment for NASA. But, inspired by one of geology’s laws that the deeper one digs, the older the rocks are, the team continued to dig. They were still unable to find traces of water.

From there, Spirit traveled to a few more craters and examined many rocks along the way. There were a few complications on its maiden journey. The biggest one was power.

The solar panels that power Spirit and Opportunity were beginning to be covered in dust. NASA did not factor this into part of their mission strategy because the rovers were only meant to last 90 days.

One Martian night, right before settling down, Spirit took a picture of its panels, and they were covered in dust. The next morning, the dust was gone. Moersch said Spirit, that morning, was operating on the same amount of power as it had during its first days. Now free of dust, its solar panels could function as they had originally.

Moersch said NASA believed a dust devil, a small Martian vacuum, came and cleaned all the dust off of Spirit.

“We were just at the right place at the right time,” Moersch said.

While Spirit had explored one side of Mars, the Opportunity rover was the more favored mission for NASA, according to Moersch. Its destination was the Meridiani Planum. A satellite image had previously suggested massive amounts of hematite could be found in the crater, another indicator of past water. Once Opportunity landed, three weeks after Spirit, the NASA team learned that the trace elements of hematite were just small, round hematite rocks.

One of Opportunity’s next destinations was Endurance Crater, “a geologist’s dream,” Moersch said. The crater was a very deep one that would allow for months of examination. But before Opportunity could even go into the crater, it had to find a slope level enough to climb down. Opportunity drove around the crater’s edge taking samples of rocks and trying to find a way in.

Back on Earth, Moersch said scientists were building models of the Martian planet trying to find the maximum and minimum angle that Opportunity could climb.

Opportunity made it into the crater and examined, from the top-down, different layers of rock. Some of the layers suggested water used to exist there.

It was not until Opportunity examined one layer of rock that had unparalleled ripples on it that scientists considered they had found the first evidence that liquid water ever existed on another planet, Moersch said. Water’s uneven effects on sediment could have caused the small, unparalleled lines to mark the crater’s rock.

“We really did find what we were looking for,” Moersch said.

The search was over, but the exploration continued because the rovers were still going strong on Mars. Even throughout the winter, the rovers were able to angle their solar panels just right to collect enough sunlight to surpass their initial 90-day period of exploration.

Audience member Sandra Twardosz, professor of child and family studies, queried about funding.

“Is there ever a time where (the ones supplying the money) ever ask, ‘why is this still important to us?’” Twardosz asked at Friday’s forum.

Moersch said he is hit with budget cuts every year. But, as scientists gain more experience managing the rovers, the missions become more efficient and cheaper, he said.

Opportunity and Spirit have gone way beyond their 90-day mark and will continue to explore the Martian surface until they eventually give out and stop working.

NASA is already on the way to creating a new rover that will be nuclear powered. Moersch said NASA hopes the new rover will add to Opportunity and Spirit’s discoveries.