Mars may have a lot of orangey dust flying around, but now that a rover has retrieved a sample by drilling a rock there, scientists believe the Red Planet may have another color beneath the surface.
The two-ton Mars rover Curiosity, which has been exploring Gale Crater since its miraculous landing on August 6, has become the first robot to drill into a rock to collect a sample on Mars, scientists reported Wednesday. Chemical analyses are still to come, but for now the big news is that the material from the drill appears to be gray.
"We're sort of seeing a new coloration for Mars here, and it's an exciting one to us," said Joel Hurowitz, sampling system scientist for Curiosity at NASA's Jet Propulsion Laboratory.
Confirmation came in Wednesday that the sample from the drill made it into Curiosity's scoop, said Scott McCloskey, rover planner and drill systems engineer for Curiosity. Images straight from Mars show the rover's drill was able to acquire about a tablespoon of powder as it was boring down into the rock. The depth of the drill hole is 6.4 centimeters (2.5 inches).
"You can probably bet that when things turn orange, it's because there's a rusting process of some kind going on that oxidizes the iron in the rock," Hurowitz said.
The gray color may mean the rock the rover drilled did not go through this process, Hurowitz said. That may be good news for looking for evidence of past life, because chemistry involving oxidation destroys organic compounds, said John Grotzinger, principal investigator for the rover mission. But, although organics are associated with life, there are also nonlife organics, and organics aren't always preserved over time.
"Right now we're on the pathway to hopefully characterizing this place as a habitable environment," Grotzinger said.
The rocks are sort of a "time capsule" because they are potentially ancient objects that contain a record of the environment in which they were formed, said Hurowitz. Getting underneath these materials, which may have been affected by the planet's surface environment, is "a really fantastic capability that the Curiosity drill gives us."
"We were well centered in a large plate of bedrock where we knew we could place the drill into a stable location on an interesting rock," Hurowitz said.
The drill did not specifically target the veins or nodular features apparent in this kind of bedrock but it's "hard to imagine" that they would have been missed entirely, he said.
Scientists need to see results from a chemical analysis of the sample to understand it better, but one theory is that this rock could have once been underwater, Hurowitz said.
The successful usage of the drill marks the final check-out of Curiosity's elaborate suite of instruments.
Back on Earth, however, scientists have encountered a potential problem in one of two terrestrial copies of the CHIMRA instrument, which NASA's Daniel Limonadi describes as a "martini mixer on the spacecraft."
CHIMRA has a sieve that filters out material that is bigger than 150 micrometers, because the CheMin instrument needs tiny particles for its X-ray diffraction work. One of the Earth-based units, the "edge welds are popping and slowly unziping the sieve from the primary structure in CHIMRA over time," Limonadi said.
The same problem has not been observed on its Martian counterpart, or in the second copy of CHIMRA.
Scientists have several theories about why this is happening, but there's no established root cause, Limonadi said. However, it's important to note that this copy of CHIMRA has been used more than Curiosity's CHIMRA unit will be used during its two-year prime mission.
Rover planners are taking precautions just in case the CHIMRA sieve on Mars is vulnerable. For example, they've reduced the sieving time of material in this instrument to expose it to less wear and tear, Limonadi said.
Sieving is the next step for the gray powder recovered from the drill. It will then be fed to the CheMin and SAM instruments to gain more insights about the geological history and potential habitability of Mars, Hurowitz said.
Previous analyses by Curiosity instruments determined that white veins seen in this kind of rock are made of calcium sulfate. The rover will soon use its chemistry experiments to see the full composition of the gray stuff found by the drill.
"Stay tuned, results are coming shortly," Hurowitz said.