Team Discusses Next Steps For Mission
NASA's Phoenix Mars Lander placed a sample of Martian soil in
the spacecraft's wet chemistry laboratory Wednesday for the first
time. Results from that instrument, part of Phoenix's Microscopy,
Electrochemistry and Conductivity Analyzer, are expected to provide
the first measurement of the acidity or alkalinity of the planet's
soil.
The analysis of the soil sample and others will help researchers
determine whether ice beneath the soil ever has melted, and whether
the soil has other qualities favorable for life.
The Phoenix team is discussing what sample to deliver next to
the lander's other analytical instrument, which bakes and sniffs
soil to identify volatile ingredients. Engineers have identified
possible problems in the mechanical and electrical operation of
that instrument, the Thermal and Evolved-Gas Analyzer, or TEGA.
Scientists are studying information provided by TEGA's analysis
of the first Martian soil sample put in that instrument. The
instrument has eight single-use oven cells; each cell can analyze
one sample. When doors for a second TEGA oven were commanded open
last week, the doors opened only partway. Later, the team
determined that mechanical interference may prevent doors on that
oven and three others from opening fully. The remaining three ovens
are expected to have one door that opens fully and one that opens
partially, as was the case with the first oven used.
"The tests we have done in our test facility during the past few
days show the robotic arm can deliver the simulated Martian soil
through the opening with the doors in this configuration," said
William Boynton of the University of Arizona, Tucson, lead
scientist for TEGA. "We plan to save the cells where doors can open
wider for accepting ice samples."
Scientists believe the first soil sample delivered to TEGA was
so clumpy that soil particles clogged a screen over the opening.
Four days of vibration eventually succeeded at getting the soil
through the screen. However, engineers believe the use of a motor
to create the vibration may also have caused a short circuit in
wiring near that oven. Concern about triggering other short
circuits has prompted the Phoenix team to be cautious about the use
of other TEGA oven cells.
Subsequent soil samples for TEGA will be delivered with a
different method than the first. The new method will sprinkle soil
into the instrument to make it easier for particles to get through
the screens.
The Phoenix mission is led by Peter Smith at the University of
Arizona with project management at NASA's Jet Propulsion Laboratory
in Pasadena, CA and the development partnership at Lockheed Martin
in Denver, CO. International contributions are 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.