[meteorite-list] Curiosity Mars Rover Begins Study of Ridge Destination

[Ron Baalke]

https://www.jpl.nasa.gov/news/news.php?feature=6894

Curiosity Mars Rover Begins Study of Ridge Destination
Jet Propulsion Laboratory
July 11, 2017

The car-size NASA rover on a Martian mountain, Curiosity, has begun its 
long-anticipated study of an iron-bearing ridge forming a distinctive 
layer on the mountain's slope.

Since before Curiosity's landing five years ago next month, this feature 
has been recognized as one of four unique terrains on lower Mount Sharp 
and therefore a key mission destination. Curiosity's science team informally 
named it "Vera Rubin Ridge" this year, commemorating astronomer Vera Cooper 
Rubin (1928-2016).

"Our Vera Rubin Ridge campaign has begun," said Curiosity Project Scientist 
Ashwin Vasavada of NASA's Jet Propulsion Laboratory, Pasadena, California. 
"Curiosity is driving parallel to the ridge, below it, observing it from 
different angles as we work our way toward a safe route to the top of 
the ridge."

A major appeal of the ridge is an iron-oxide mineral, hematite, which 
can form under wet conditions and reveal information about ancient environments. 
Hematite-bearing rocks elsewhere on Mars were the scientific basis for 
choosing the 2004 landing site of an older and still-active rover, Opportunity. 
Studies of Mount Sharp with the Compact Reconnaissance Imaging Spectrometer 
for Mars, on NASA's Mars Reconnaissance Orbiter, identified hematite in 
the ridge and also mapped water-related clay and sulfate minerals in layers 
just above it.

Vera Rubin Ridge stands about eight stories tall, with a trough behind 
it where clay minerals await. Curiosity is now near the downhill face, 
which forms an impressive wall for much of the ridge's length of about 
4 miles (6.5 kilometers).

"In this first phase of the campaign, we're studying the sedimentary structures 
in the wall," said JPL's Abigail Fraeman, a Curiosity science-team member 
who helped plan these observations.

This summer's investigations also seek information about the boundary 
zone between the material that makes up the ridge and the geological unit 
that Curiosity has been studying since late 2014: the Murray formation 
of lower Mount Sharp, which holds evidence of ancient lakes. The Murray 
formation has variable levels of hematite, but whether the hematite in 
it and in the ridge accumulated under similar environmental conditions 
is unknown. The planned ascent route will provide access to closer inspection 
of the hematite-bearing rocks.

"We want to determine the relationship between the conditions that produced 
the hematite and the conditions under which the rock layers of the ridge 
were deposited," Fraeman said. "Were they deposited by wind, or in a lake, 
or some other setting? Did the hematite form while the sediments accumulated, 
or later, from fluids moving through the rock?"

Deciphering the history of the ridge's hematite may shed light on whether 
the freshwater environments that deposited the layers of the older Murray 
formation were turning more acidic by the time the layers of the ridge 
formed. The mission also will be watching for clues about whether a gradient 
in oxidation levels was present, as that could have provided a potential 
energy source for microbial life.

Terrain near the base of the ridge is rife with boulders and sand, creating 
challenging conditions for navigation, as well as opportunities to add 
to the mission's studies of sand dunes and ripples. The largest sand dunes 
were at lower elevations, including a linear dune informally named "Nathan 
Bridges Dune" in memory of Nathan Bridges (1966-2017), a Curiosity team 
member who helped lead the mission's dune studies.

During the first year after its landing on Aug. 5, 2012, PDT (Aug. 6, 
EDT and Universal Time), the Curiosity mission accomplished a major goal 
by determining that billions of years ago, a Martian lake offered conditions 
that would have been favorable for microbial life. Curiosity has since 
traversed through a diversity of environments where both water and wind 
have left their imprint. The upcoming exploration of Vera Rubin Ridge 
and the higher clay and sulfate layers provides opportunities to learn 
even more about the history and habitability of ancient Mars. For more 
about Curiosity, visit:

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

Status of Curiosity's Drill

The rover team will not have Curiosity's rock sampling drill available 
in the first phase of studying "Vera Rubin Ridge." The drill feed mechanism, 
which moves the bit forward or back, faulted on Dec. 1, 2016, and no rocks 
have been drilled since then. While continuing to test possible ways to 
move the bit with the drill feed mechanism, rover engineers are also now 
studying alternative ways to drill. For the 15 rocks that Curiosity has 
sampled with its drill so far, two stabilizer posts, one to each side 
of the bit, were placed against the rock before the bit was extended with 
the feed mechanism.

"We are investigating methods to drill without using the stabilizers," 
said Curiosity Deputy Project Manager Steve Lee, of JPL. "Instead of using 
the feed mechanism to drive the bit into the rock, we may be able to use 
motion of the arm to drive the bit into the rock." Adaptation in delivering 
the resulting rock powder to laboratory instruments is also under study, 
such as use of the arm's soil scoop.

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

Laurie Cantillo / Dwayne Brown
NASA Headquarters, Washington
202-358-1077 / 202-358-1726
laura.l.cantillo at nasa.gov / dwayne.c.brown at nasa.gov

2017-189