Scientists
ran into a snag when trying to deliver a sample of Martian arctic soil to one
of the instruments on NASA's Phoenix Mars Lander, mission controllers said on
Saturday.
The
lander's robotic arm released a handful
of clumpy Martian soil onto a screened opening of the Thermal and
Evolved-Gas Analyzer (TEGA) on Friday, but the instrument did not confirm that
any of the sample passed through the screen.
Images
taken on Friday show soil resting on the screen over an open sample-delivery
door of TEGA, which is designed to heat up soil samples and analyze the vapors
they give off to determine the soil's composition.
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
digging czar for the $420 million Phoenix mission.
The Phoenix
lander touched down on the red planet on May 25 to begin a planned
three-month mission to hunt for buried water ice in the northern polar region
of Mars. It is equipped with a scoop-tipped robotic arm, weather station, wet
chemistry lab and eight ovens to study samples of Martian terrain and determine
if the region could have once supported primitive life.
TEGA's
screen is designed to let through particles up to 0.04 inch (1 millimeter)
across while keeping out larger particles, in order to prevent clogging a
funnel pathway to a tiny oven inside.
Mission scientists said they planned to
send new commands to Phoenix to try to shake the sample into the oven as early
as Monday. They'll spend Sunday developing the plan for the following Martian
day.
The small
vibration tool can shake the oven screen across a variety of frequencies,
ranging from a light tapping to moderate shake, mission managers said.
"The soil
that we're looking at is probably sandy and it has a lot of fine grains and
dust, but it is also a little bit cohesive," Arvidson said. "I'm pretty
confident that if we shake this stuff, we'll get some in."
For future
samples, they may use the robotic arm to prepare a site by poking and prodding
the Martian surface to break up clumps and clods. They may also collect smaller
scoops of material to pour directly into the oven.
While this
is the first oven they've tried to pour samples into, it is designated Oven 4
of eight. Despite the overflow of soil across the other oven doors, mission
managers are confident the extra stuff won't hinder the opening of other
instruments.
The TEGA
ovens have an opening just 2 mm wide and are designed to collect about 30
milligrams of material for baking.
Phoenix's
planned activities for Saturday include horizontally extending a trench, dubbed
"Dodo," 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."
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