[meteorite-list] NASA's Phoenix Mars Lander Checking Soil Properties

[Ron Baalke]

http://www.jpl.nasa.gov/news/news.cfm?release=2008-102

NASA's Phoenix Mars Lander Checking Soil Properties
Jet Propulsion Laboratory
June 07, 2008

TUCSON, Ariz. -- The arm of NASA's Phoenix Mars Lander released a
handful of clumpy Martian soil onto a screened opening of a laboratory
instrument on the spacecraft Friday, but the instrument did not confirm
that any of the sample passed through the screen.

Engineers and scientists on the Phoenix team assembled at the University
of Arizona are determining the best approach to get some of that
material into the instrument. Meanwhile, the team has developed commands
for the spacecraft to use cameras and the Robotic Arm on Saturday to
study how strongly the soil from the top layer of the surface clings
together into clumps.

Images taken Friday show soil resting on the screen over an open
sample-delivery door of Phoenix's Thermal and Evolved-Gas Analyzer, or
TEGA, an instrument for identifying some key ingredients. The screen is
designed to let through particles up to one-millimeter (0.04 inch)
across while keeping out larger particles, in order to prevent clogging
a funnel pathway to a tiny oven inside. An infrared beam crossing the
pathway checks whether particles are entering the instrument and
breaking the beam.

The researchers have not yet determined why none of the sample appears
to have gotten past the screen, but they have begun proposing
possibilities.

"I think it's the cloddiness of the soil and not having enough fine
granular material," said Ray Arvidson of Washington University in St.
Louis, the Phoenix team's science lead for Saturday and digging czar for
the mission.

"In the future, we may prepare the soil by pushing down on the surface
with the arm before scooping up the material to break it up, then
sprinkle a smaller amount over the door," he said.

Another strategy under consideration is to use mechanical shakers inside
the TEGA instrument differently than the five minutes of shaking that
was part of the sample-receiving process on Friday. No activities for
the instrument are planned for Saturday, while the team refines plans
for diagnostic tests.

Phoenix's planned activities for Saturday include horizontally extending
a trench where the lander dug two practice scoops earlier this week, and
taking additional images of a small pile of soil that was scooped up and
dropped onto the surface during the second of those practice digs.

"We are hoping to learn more about the soil's physical properties at
this site," Arvidson said. "It may be more cohesive than what we have
seen at earlier Mars landing sites."

The Phoenix mission is led by Peter Smith at the University of Arizona
with project management at JPL and development partnership at Lockheed
Martin, Denver. International contributions come from the Canadian Space
Agency; the University of Neuchatel, Switzerland; the universities of
Copenhagen and Aarhus, Denmark; Max Planck Institute, Germany; and the
Finnish Meteorological Institute. For more about Phoenix, visit:
http://www.nasa.gov/phoenix and http://phoenix.lpl.arizona.edu.

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

Dwayne Brown 202-358-1726
NASA Headquarters, Washington
dwayne.c.brown at nasa.gov

Sara Hammond 520-626-1974
University of Arizona, Tucson
shammond at lpl.arizona.edu

2008-102