NASA's
Phoenix Mars Lander has stuck a fork in Martian dirt for the first time. The
spacecraft also has begun to use a microscope that can determine the shape of
tiny particles in the dirt.
The
activities, initiated on Tuesday, allowed mission scientists to test the
procedure for using Phoenix's robotic arm to stick
the four spikes of the probe into undisturbed dirt on the planet's surface.
The prongs
of the instrument, called a thermal and electrical conductivity probe, are
about half an inch (1.5 centimeters) long. Scientists can use the instrument to
assess how easily heat and electricity move through the Martian regolith, providing
information about frozen or unfrozen water in the dirt.
The probe
sits on a "knuckle" of the 7.7-foot-long (2.35-meter) robotic arm.
The arm can also hold the probe up in the air to take measurements of water
vapor in the atmosphere. The probe has been used to take these atmospheric measurements
several times since Phoenix's May 25 landing in the Vastitas Borealis plains of
far-northern Mars.
Mission
scientists planned to tell Phoenix to insert the probe into the ground again
and then proceed to take its first measurements on Thursday.
As for the
atomic force microscope, after making its first touch test Tuesday, Phoenix took its first
image from the instrument Wednesday.
The atomic
force microscope builds an image of the shape of the surface of a particle by
running a sharp tip mounted on the end of a spring up and down across the
contours of the surface. It can provide details as small as about 100
nanometers, less than one-hundredth the width of a human hair.
The first
test of the atomic force microscope involved running the tip along one of the
substrates on the microscopy station's sample-presentation wheel to test out
the instrument. The substrates will be used to hold soil particles in place in
future tests.
"The
same day we first touched a target with the thermal and electrical conductivity
probe, we first touched another target with a needle about three orders of
magnitude smaller — one of the tips of our atomic force microscope," said
Michael Hecht of NASA's Jet Propulsion Laboratory in Pasadena, Calif. Hecht is
the lead scientist for the suite of instruments that include both the probe and
the microscopy station.
The imaging
showed a grooved substrate that will be used to calibrate future images.
"It's
just amazing when you think that the entire area in this image fits on an
eyelash," Hecht said. "I'm looking forward to exciting things to
come."
With these
two latest developments, Phoenix has now used all the capabilities of its
Microscopy, Electrochemistry and Conductivity Analyzer (MECA) suite of
instruments. This week Phoenix also began analyzing the second
dirt sample to go into MECA's wet chemistry laboratory, which can detect
soluble minerals in the dirt.
The Phoenix team has also been looking for the best method to gather a sample of ice to
deliver to the lander's Thermal and Evolved-Gas Analyzer (TEGA), which bakes
samples of surface material and analyzes the vapors given off to determine the
composition of the samples. Phoenix has already used its rasp to scrap
off pieces of ice from the hard subsurface ice layer.
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