[meteorite-list] NASA Mars Curiosity Rover Descends Plateau, Turns Toward Mountain

[Ron Baalke]

http://www.jpl.nasa.gov/news/news.php?feature=6532

NASA Mars Rover Descends Plateau, Turns Toward Mountain
Jet Propulsion Laboratory
June 13, 2016

NASA's Curiosity Mars rover has analyzed its 12th drilled sample of Mars. 
This sample came from mudstone bedrock, which the rover resumed climbing 
in late May after six months studying other features.

Since the previous time Curiosity drilled into this "Murray formation" 
layer of lower Mount Sharp, the mission has examined active sand dunes 
along the rover's route, then crossed a remnant plateau of fractured sandstone 
that once more extensively covered the Murray formation.

While on the "Naukluft Plateau," the rover examined its 10th and 11th 
drill targets to repeat an experiment comparing material within and away 
from pale zones around fractures. From there, Curiosity also took the 
latest in a series of self-portraits.

"Now that we've skirted our way around the dunes and crossed the plateau, 
we've turned south to climb the mountain head-on," said Curiosity Project 
Scientist Ashwin Vasavada, of NASA's Jet Propulsion Laboratory, Pasadena, 
California. "Since landing, we've been aiming for this gap in the terrain 
and this left turn. It's a great moment for the mission."

Curiosity landed near Mount Sharp in 2012. It reached the base of the 
mountain in 2014 after successfully finding evidence on the surrounding 
plains that ancient Martian lakes offered conditions that would have been 
favorable for microbes if Mars has ever hosted life. Rock layers forming 
the base of Mount Sharp accumulated as sediment within ancient lakes billions 
of years ago.

The Murray formation is about one-eighth of a mile (200 meters) thick. 
So far, Curiosity has examined about one-fifth of its vertical extent.

"The story that the Murray formation is revealing about the habitability 
of ancient Mars is one of the mission's surprises," Vasavada said. "It 
wasn't obvious from pre-mission data that it formed in long-lived lakes 
and that its diverse composition would tell us about the chemistry of 
those lakes and later groundwater."

The latest sample-collection target, "Oudam," was drilled on June 4. On 
the Naukluft Plateau, Curiosity drilled "Lubango," within a halo of brighter 
sandstone near a fracture, and "Okoruso," away from a fracture-related 
halo, for comparison. The mission conducted a similar experiment last 
year, with two sample targets drilled at another exposure of the fractured 
sandstone.

This sandstone unit, called the Stimson formation, is interpreted to have 
resulted from wind that draped a band of sand dunes over lower Mount Sharp. 
That would have been after the main stack of the mountain's lower layers 
had formed and partially eroded. Water later moved through fractures in 
the sandstone. Investigation of the fracture-related halos aims to determine 
how fluid moved through the fractures and altered surrounding rock.

"We were about to drive off the Naukluft Plateau and leave the Stimson 
formation forever as we go up Mount Sharp," said Curiosity science-team 
member Albert Yen of JPL. "A few of us were concerned. The fracture-associated 
haloes were becoming more prevalent, and we had only one data point. With 
just one data point, you never know whether it is representative."

As with the similar previous experiment, comparison of Lubango and Okoruso 
found higher silica and sulfate levels in the sample nearer to the fracture. 
Multiple episodes of groundwater flow with different chemistry at different 
times may have both delivered silica and sulfate from elsewhere and leached 
other ingredients away.

"The big-picture story is that this may be one of the youngest fluid events 
we're likely to study with Curiosity," Yen said. "You had to lay down 
the Murray, then cement it, then lay down the Stimson and cement that, 
then fracture the Stimson, then have fluids moving through the fractures."

On Mount Sharp, Curiosity is investigating how and when the habitable 
ancient conditions known from the mission's earlier findings evolved into 
conditions drier and less favorable for life. For more information about 
Curiosity, visit:

http://mars.jpl.nasa.gov/msl

News Media Contact
Guy Webster
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6278
guy.webster at jpl.nasa.gov

2016-149