Since landing on Mars Aug. 6, 2012, NASA's Curiosity Mars rover has been exploring the planet's surface and conducting science experiments on soil and rocks. One of the mission's key milestones was reached this week when the rover's specialized on-board laser was fired for the 100,000th time as it continues to explore the planet's history.
The laser, called ChemCam, is shot each time at a rock, creating a little ball of plasma or debris, Roger Wiens, the principal investigator of the ChemCam team, told eWEEK. "It abrades some material off of the rock's surface, like a little ball of flame," said Wiens, who is a planetary scientist at the Los Alamos National Laboratory, where the laser was developed.
After each shot, special instruments on the rover capture the spectral signatures of the laser firing, which are used to identify the elements that make up the soil on Mars, he said. Photographs are also taken to document the laser firing and to build a history of the experiments.
The ChemCam laser marks the first time that scientists on Earth have been able to do this kind of research on Mars, said Wiens. A previous Phoenix lander sent to Mars had a laser, but it was aimed into the planet's atmosphere and couldn't collect information about the rocks on Mars.
Other Mars lander missions used a robotic arm to scoop up soil for analysis, but that limited data collection to materials that could be grabbed by the arm, said Wiens. "So it took more effort than just point and shoot," like researchers are able to do with the laser. "This mission provides much more data collection."
Another important advantage to using the laser is that it is helping scientists get below the dusty surface of Mars to see what's really there in the rocks, he said. "Remember, that Mars is a dusty place and these rocks tend to be covered by dust. So the passive tests [using previous arm-mounted scoops] show what's on the surface, while the laser shots get below the surface" and reveal more information about the composition of the materials.
"It gives us a window that we wouldn't have otherwise by using this laser," said Wiens. "I think it's fair to say that we are piecing the data together like pieces in a puzzle."
So far, the Curiosity, which celebrated its one-year anniversary on Mars in August, has delivered some incredible finds to scientists back on Earth, including the discovery of solid evidence that ancient Mars could have supported life, according to NASA.
A key discovery has been uncovered at the rover's landing site, called Gale Crater, where a long- since-dried-up lake once stood, said Wiens. "It's the first time that we have seen lake sediments on Mars. It's still really mysterious. The water was here a very long time ago, but there are some pieces that are telling us a lot."
For example, scientists have found real clay minerals in the materials in the area that were probably sediments in the bottom of a lake, like those found on Earth, he said. "The surprising thing is this appears to be a freshwater lake. Previous discoveries of water on Mars appeared to be very briny. So here's what we think was a fairly big lake that had fresh water."