[meteorite-list] Next Mars Soil Scoop Slated for Last of Lander's Wet Lab Cells (Phoenix)
From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 10 Sep 2008 10:31:45 -0700 (PDT)
Next Mars Soil Scoop Slated for Last of Lander's Wet Lab Cells
Jet Propulsion Laboraboty
September 09, 2008
TUCSON, Ariz. -- The next soil sample that NASA's Phoenix Mars Lander
will deliver to its deck instruments will go to the fourth of the four
cells of Phoenix's wet chemistry laboratory, according to the Phoenix
team's current plans.
The chosen source for that sample is from the "Snow White" trench on the
eastern end of the work area reachable with Phoenix's robotic arm. In
July that trench yielded a sample in which another analytical
instrument, the Thermal and Evolved Gas Analyzer (or TEGA), confirmed
the presence of water ice. One of the three cells previously used on the
wet chemistry laboratory also analyzed a sample from Snow White.
The wet chemistry laboratory mixes Martian soil with purified water
brought from Earth as part of its process for identifying soluble
nutrients and other chemicals in the soil. Scientists have used it to
determine that the soil beside the lander is alkaline and to identify
magnesium, sodium, potassium, chloride and perchlorate in the soil.
The Phoenix team plans to fill the last four of eight single-use ovens
on the TEGA instrument without waiting for the analysis of each sample
to be completed before delivering the next. The strategy is to get as
many samples as possible delivered while there is still enough energy
available for digging. The northern Martian summer is nearly half over.
The amount of sunshine reaching Phoenix's solar panels, and consequently
the amount of electricity produced by the panels, is declining.
"Now that the sun is not constantly above the horizon at our landing
site we are generating less power every sol," said Phoenix Project
Manager Barry Goldstein of NASA's Jet Propulsion Laboratory, Pasadena,
Calif. "When we landed in late May, and through much of our mission, we
generated about 3,500 watt-hours every sol. We are currently at about
2,500 watt-hours, and sinking daily. With the remaining sols we need to
scurry to squeeze the last bit of science out of the mission."
One hundred watt-hours is equivalent to what is needed to illuminate a
100-watt bulb for one hour.
As TEGA bakes samples, it identifies the temperatures at which volatile
ingredients in the soil are vaporized. It also has a mass spectrometer
to identify the vapors. A valve that controls the flow of a carrier gas
for transporting the vapors to the mass spectrometer is no longer
reliable, but researchers anticipate that the remaining samples will
yield enough vaporized water and carbon dioxide to carry any scarcer
vapors to the spectrometer. The team is also examining possible
operational workarounds for unanticipated opening of a valve controlling
flow of calibration gas.
The Snow White trench is the chosen source for the next sample to go
into a TEGA oven, as well as the next sample for the wet chemistry
laboratory. For the TEGA sample, the team plans to use a rasp on the
robotic arm to churn up ice-rich material from the hard floor of the
trench. Ice-rich samples stuck inside the scoop during two attempts in
July to deliver them to a TEGA oven. However, a test run on Aug. 30
verified that an ice-rich sample can be delivered using methods that
minimize the time the sample is in the scoop and the exposure of the
scoop to direct sunlight.
The Phoenix mission is led by Smith at the University of Arizona with
project management at NASA's Jet Propulsion Laboratory in Pasadena,
Calif., and development partnership at Lockheed Martin in Denver.
International contributions come from the Canadian Space Agency; the
University of Neuchatel, Switzerland; the universities of Copenhagen and
Aarhus in Denmark; the Max Planck Institute in Germany; and the Finnish
For more about Phoenix, visit: http://www.nasa.gov/phoenix or
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
Received on Wed 10 Sep 2008 01:31:45 PM PDT