Copyright © 2019 Albuquerque Journal
When NASA approved Los Alamos National Laboratory’s SuperCam for the next Mars rover, officials referred to it as a “Swiss Army knife of an instrument.”
The nickname came from all the different tools the device will be able to use to study rocks and soil on the Red Planet, according to Roger Wiens, LANL scientist and principal investigator of SuperCam.
By expanding the scope of what’s been possible with the ChemCam camera currently on Mars aboard the Curiosity rover, Wiens says, scientists will be able to unlock more clues about whether life did or did not once exist out there.
The SuperCam instrument recently completed testing here in New Mexico. SuperCam is expected to undergo several rounds of additional tests at NASA’s Jet Propulsion Laboratory in California over the next several months before the anticipated launch of the Mars 2020 rover next July.
The new rover is expected to get to Mars in February 2021 and remain there for at least two years.
“It’s kind of the whole gamut of geology and geochemistry that we are looking at with this,” Wiens said in a recent interview. “It’s really the eyes and the ears of the rover before it has to drive up and touch something. It’s like a geological observatory of sorts where we get all kinds of different information about the rocks before we even drive up and touch them.”
Wiens’ team at LANL has been working on SuperCam since 2014, with the help of scientists with the French Space Agency and other team members based in Spain, Canada and elsewhere in the U.S.
SuperCam was designed as an evolution of ChemCam, which launched with Curiosity in 2011.
In addition to its high-resolution camera and telescope, the ChemCam also has a laser that has been able to help scientists determine the chemical composition of rocks by zapping them from about 25 feet away. The vaporized rock emits a plasma that scientists can analyze for different elements. The technique is known as Laser Induced Breakdown Spectroscopy, or LIBS.
The new instrument can do all that, and more, Wiens said. The most important add-ons, he said, are spectrometers that will allow scientists to determine mineralogy.
Mineralogy provides another kind of composition, “very complementary to the chemical composition,” he said. “But you can imagine that in some cases chemistry doesn’t tell you nearly everything,” he said.
For example, Wiens compared a diamond and lead from a pencil. Though the two are very different, they have the same chemical makeup.
To measure mineralogy, SuperCam will use Raman spectroscopy, named after the scientist who created it, and infrared spectroscopy. According to Wiens, the Raman also uses a laser beam, but it is altered to emit a different, bright green color than ChemCam sees.
Instead of zapping the rocks, the green beam “tickles” them to excite the molecules on their surfaces. The light that is reflected back to the rover is the same green as the laser beam, unless the “vibration frequency” of the rock’s molecules alters the color.
“So you can tell the sort of bond strength of the molecules by certain colors that are coming back that are not quite the same green color as the laser light that we send out to that rock,” he explained. “The slightly different colors we get in the Raman spectroscopy tell us about the mineral makeup of the rock.”
Infrared spectroscopy, on the other hand, uses sunlight and infrared wavelengths, which Wiens said can detect different types of clay minerals.
Wiens emphasized that with the mineralogy tools, scientists will also be able to detect organic materials. There are organic molecules out in space that do not derive from living organisms, but other organics could be indicative of some kind of living processes that existed on Mars, he said.
“We see the solar system as having two planets that were once habitable,” Wiens said. “Earth is, of course, imminently still habitable, but Mars is not nearly as habitable as it was in the past. So we’re very interested in finding if there would have been life on Mars at one point in time, given it was habitable with lakes, rivers and streams and a warmer climate.”
The new techniques will also be able to help the rover team better study Mars’ climate changes over time and previous existence of water, Wiens said.
Currently, with Curiosity, the rover has examined lake bed sediments on Mars’ Gale Crater and discovered chemical evidence of water. If SuperCam can analyze the existence and the properties of clay minerals in those sediments – which form in areas where standing water once would have been – that can help indicate whether or not water flowed for a long period of time.
SuperCam will also be equipped with a microphone, according to Wiens.
“Which may sound like it’s just for fun,” he said. But when a rock is hit with the laser to extract its chemical breakdown, he said, being able to hear the shock waves and the actual “zap” sound the instrument makes can provide insight into the physical properties of the formations without having to feel or touch them.
“The sound actually tells us something about the rock,” said Wiens. “When we add the microphone, it’s not just listening for Martians. It’s very much working to tell us about the hardness of the rock and also how deeply we penetrate with the laser (when we) make a little pit.”
The LANL team also had a hand in another Mars rover 2020 instrument that will utilize a form of Raman spectroscopy and has a similar goal of searching for signs of previous life. According to Wiens, the “Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals” device, also known as SHERLOC, is being led by the Jet Propulsion Lab, with some parts that were built at and shipped from LANL.
SHERLOC will be on the arm of the rover rather than the mast, Wiens said, and it will have a smaller laser. At closer range, Wiens said SHERLOC can be used for “fine-scale” analyses of the materials.
Talking about the big-picture implications of the Mars 2020 rover, Wiens explained that it is designed to preserve rock samples that can someday be brought back to Earth.
The rover will be able to drill cores in Martian rocks, encase them in titanium tubes and leave them on Mars’ surface. Before astronauts can be sent to explore the planet, Wiens said, the first step would have to be sending a small rocket to Mars that is capable of retrieving and returning with something like these rock samples.
“Of course, it’s going to take some time for those future missions to happen, but we think it’ll happen within the next decade or so,” Wiens said.