LOS ANGELES – 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 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 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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