[meteorite-list] Curiosity Rover Inspects Pebbly Rocks at Martian Waypoint

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Mon, 23 Sep 2013 17:21:15 -0700 (PDT)
Message-ID: <201309240021.r8O0LFWh009606_at_zagami.jpl.nasa.gov>

http://www.jpl.nasa.gov/news/news.php?release=2013-288

NASA Rover Inspects Pebbly Rocks at Martian Waypoint
Jet Propulsion Laboratory
September 23, 2013

PASADENA, Calif. -- NASA's Mars rover Curiosity has resumed a trek of
many months toward its mountain-slope destination, Mount Sharp. The
rover used instruments on its arm last week to inspect rocks at its
first waypoint along the route inside Gale Crater.

The location, originally chosen on the basis of images taken from NASA's
Mars Reconnaissance Orbiter, paid off with investigation of targets that
bear evidence of ancient wet environments.

"We examined pebbly sandstone deposited by water flowing over the
surface, and veins or fractures in the rock," said Dawn Sumner of
University of California, Davis, a Curiosity science team member with a
leadership role in planning the stop. "We know the veins are younger
than the sandstone because they cut through it, but they appear to be
filled with grains like the sandstone."

This Waypoint 1 site at an outcrop called "Darwin" is the first of up to
five waypoint stops planned along the route of about 5.3 miles (8.6
kilometers) between the "Glenelg" area, where Curiosity worked for the
first half of 2013, and an entry point to the lower slope of Mount
Sharp, the mission's main destination. It is about one-fifth of the way
along the route. The rover departed Waypoint 1 on Sept. 22 with a
westward drive of about 75 feet (22.8 meters).

Curiosity's science team planned the waypoints to collect information
about the geology between Glenelg and Mount Sharp. Researchers want to
understand relationships between what the mission already discovered at
Glenelg and what it may find in the multiple layers of Mount Sharp.
Analysis of drilled samples from veined "Yellowknife Bay" rocks in the
Glenelg area provided evidence for a past lakebed environment with
conditions favorable for microbial life. That means the mission has
fulfilled its principal science goal.

"We want to understand the history of water in Gale Crater," Sumner
said. "Did the water flow that deposited the pebbly sandstone at
Waypoint 1 occur at about the same time as the water flow at Yellowknife
Bay? If the same fluid flow produced the veins here and the veins at
Yellowknife Bay, you would expect the veins to have the same
composition. We see that the veins are different, so we know the history
is complicated. We use these observations to piece together the
long-term history."

Researchers set the top priority for the Waypoint 1 stop to be
examination of a conglomerate rock outcrop, such as the pebbly
sandstone. The veins were a bonus.

"As often happens, the closer we get, the more is revealed," said
Kenneth Williford of NASA's Jet Propulsion Laboratory, Pasadena, Calif.,
a Curiosity science team member active in planning use of the rover's
arm. The first specific location at Waypoint 1 for parking the rover and
using the instruments on its arm was selected because images taken from
nearly a football-field's length away showed outcrops that looked like
conglomerate. Once Curiosity approached that location, new images showed
the veins, so a second location for use of the arm was added to the plan.

The rover spent one day using its arm at the first location and three
more using its arm from the second location. On all four of these
"contact-science" days, the investigations employed two instruments that
are mounted in the turret at the end of the arm: the Alpha Particle
X-ray Spectrometer, which identifies chemical elements present in a
target, and the Mars Hand Lens Imager, which shows targets' textures,
shapes and colors.

Another device on the turret still holds some powder from a rock that
Curiosity drilled into for sample collection at Yellowknife Bay four
months ago. The laboratory instruments inside the rover have already
analyzed portions from this sample, but researchers have options of many
different instrument settings for doing further analyses. In weeks
ahead, additional portions from the sieved powder being held in the arm
may be delivered for those analyses. The powder is a precious scientific
resource, but it also presents a special challenge for use of the
spectrometer and camera on the turret.

"We don't want to put the turret in a position that gets the sample
material onto the back side of the sieve, because that could clog pores
in the sieve," said JPL's Matt Robinson, lead engineer for Curiosity's
robotic arm operations. "We have to consider the orientation of the
turret during all of the moves for reaching the target, not just its
orientation at the target."

Despite this challenge, the team used the arm instruments intensively at
Waypoint 1. On Sept. 19, the rover examined five targets with the
spectrometer and camera on the arm. The next day, from the same
location, it examined three more. The team did leave some potential
targets unexamined, to hasten back on the drive to Mount Sharp, as planned.

"There's a trade-off," Williford said, "between wanting to reach Mount
Sharp as soon as we can and wanting to chew on rocks all along the way.
Our team of more than 450 scientists has set the priority on getting to
Mount Sharp, with these few brief waypoint stops."

JPL, a division of Caltech in Pasadena, manages the Mars Science
Laboratory Project for NASA's Science Mission Directorate, Washington,
and built the project's Curiosity rover. More information about
Curiosity is online at http://www.jpl.nasa.gov/msl ,
http://www.nasa.gov/msl and http://mars.jpl.nasa.gov/msl/ . You can
follow the mission on Facebook at http://www.facebook.com/marscuriosity
and on Twitter at http://www.twitter.com/marscuriosity .

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

2013-288
Received on Mon 23 Sep 2013 08:21:15 PM PDT