Curiosity rover drills into Martian sandstone
BY STEPHEN CLARK
Posted: May 7, 2014
NASA's Curiosity Mars rover, stationed at a site selected for closer scientific scrutiny, has drilled into a sandstone outcrop to collect its first sample of rock powder in a year for delivery into the mobile robot's internal instruments to conduct a thorough analysis.
Scientists selected a rock dubbed "Windjana" for the drill, which bored a hole 1.6 centimeters, or 0.63 inch, in diameter and 6.5 centimeters, or 2.6 inches, deep late Monday, Pacific time.
The rock is a sandstone, a different type of material than the mudstones Curiosity drilled into on the mission's first two samplings in 2013.
Curiosity drilled an exploratory hole at the Windjana site last week. The test turned up a darker powder than at the rover's earlier drill sites.
"The drill tailings from this rock are darker-toned and less red than we saw at the two previous drill sites," said Jim Bell of Arizona State University in Tempe, deputy principal investigator for Curiosity's Mast Camera. "This suggests that the detailed chemical and mineral analysis that will be coming from Curiosity's other instruments could reveal different materials than we've seen before. We can't wait to find out!"
Mudstones are deposited in a watery environment, and research based on the drill samples gathered last year led scientists to conclude the rover was exploring an ancient lakebed that once contained the key ingredients for microbial life. Curiosity departed that research site, named Yellowknife Bay, last year to begin a year-long trek to Mount Sharp, a three-mile-high mountain scientists think harbors more evidence of a once-habitable Mars.
Curiosity is now exploring a site known as "the Kimberley," a waypoint on the rover's journey across Gale Crater, a 96-mile-wide impact basin just south of the Martian equator. Four different types of rock intersect at the Kimberley, which is named for a region of western Australia known for its geological riches.
Ashwin Vasavada, Curiosity's deputy project scientist, said Tuesday that the choice of the Windjana sandstone for the rover's next drilling addresses a different force in Martian geology: wind.
"As we've come to understand this area better, our goals for sampling have focused around understanding the role of fluids in transporting, depositing, and eventually cementing the sandstones that we see around the Kimberley," Vasavada told Spaceflight Now. "We think the answers here are applicable to understanding how the landscapes we've encountered in our drive across the plains formed, and have evolved over time through wind and erosion."
The powder extracted by Curiosity's robot arm-mounted drill Monday flowed through an auger into a holding chamber. The material will be dumped out of the drill into the one-ton rover's scoop, then through a sieve to separate larger and small clumps.
The samples will be vibrated over the sieve to only let through particles smaller than 150 microns, or about six one-thousandths of an inch, into the rover's Chemistry and Mineralogy, or CheMin, and Sample Analysis at Mars instruments.
CheMin will examine the rock's chemical and mineral composition, and the SAM payload is tuned to detect organic compounds, the building blocks of life. The rover may resume driving toward Mount Sharp while the instruments do their work, according to mission managers at NASA's Jet Propulsion Laboratory in Pasadena, Calif.
The $2.5 billion mission's first two drill samples contained no trace of organics detectable by SAM, which heats samples to 1,800 degrees Fahrenheit and sniffs the gases released from the dirt to determine its make-up.
Radiation measurements on Mars indicate cosmic rays could destroy organic molecules, but the material might be preserved within one meter, or about 3.3 feet, of the surface, where soil and bedrock could shield organics from the constant life-destroying radiation bombardment.
Curiosity does not carry an instrument to penetrate that deep into the Martian subsurface, but geologists are on the lookout for potential drill sites where wind erosion has exposed underground layers in the red planet's relatively recent past.
While the jury is still out on what Curiosity will find in its latest drilled sample, Vasavada said there is little indication the site hosts organic material.
"Whether we'll find any organic materials is highly uncertain," Vasavada said. "We don't have the evidence for lake-deposited sediments as at Yellowknife Bay. But the fine-grained nature of the rock could help protect any organic materials that were incorporated during its deposition."
Follow Stephen Clark on Twitter: @StephenClark1.
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