"If large bodies of water were on Mars, they may be buried very deep under the surface, too deep for the rovers to locate such possible water sites.
"NASA had a slogan, 'Follow the water,' meaning we should try to learn whatever we could about water on Mars," Lemmon adds. "If there were ever large amounts of water on Mars, that means there could be life there, and that's always been the big question."
Lemmon says the team did learn that Martian dust is everywhere on the planet. "The dust is so thick it coats everything, including our equipment on the rovers, so thick it clogged up solar panels we used to power some of the machinery on the rovers," he added.
Lemmon says the photographs taken by the rovers were spectacular, both in their clarity and the quality of the images.
"We got some wide panoramic shots that have never been taken before," he notes.
"The rovers also got photos of Martian landscape that were extremely useful to us. We got some shots of small hills that were very sharp."
Some 3-D photos were also taken, which proved to be very informative, Lemmon added.
Lemmon says Spirit and Opportunity are still active on Mars, but they will soon be entering a hibernation stage because of limited sunlight. The rovers rely on solar energy for much of their power, and a sol a Martian day now has less and less sunlight.
"We'll slow things down from now through October," he explains. "After that, we'll have more sunlight to do some other things."