NASA's Phoenix Mars Lander has taken
its first-ever picture of a single particle of rusty
Martian dust with one of its microscopes.
The speck
of dust was shown at a higher magnification than anything outside of Earth
has been imaged before. The rounded particle measured only about one
micrometer, or one millionth of a meter, across.
"Taking this image required the
highest resolution microscope operated off Earth and a specially designed
substrate to hold the Martian dust," said Tom Pike, a Phoenix science team member from Imperial
College London. "We always knew it was going to be technically very
challenging to image particles this small."
The device that imaged the dust
speck is called an atomic force microscope, which maps the shape of particles
in three dimensions by scanning them with a sharp tip at the end of a spring.
The atomic force microscope can
detail the shapes of particles as small as about 100 nanometers, about one
one-thousandth the width of a human hair. That is about 100 times greater magnification than seen with Phoenix's optical microscope, which made its first
images of Martian dirt about two months ago. Until now, those images held
the record for the most highly magnified images to come from another planet.
And this won't be the last dust
particle that Phoenix
will image. "After this first success, we're now working on building up a
portrait gallery of the dust on Mars," Pike said.
Dust is a ubiquitous substance on
Mars, coating the surface and giving it its rusty red hue. Airborne dust
particles also color the Martian sky pink and feed storms that regularly envelope
the planet.
The ultra-fine dust is the medium
that actively links gases in the Martian atmosphere to processes in Martian
soil, so it is critically important to understanding Mars' environment, the
researchers said.
The $420-million Phoenix
mission is analyzing the dust and subsurface ice layers of Mars' arctic
regions to look for signs of potential past habitability.
The particle seen in the atomic
force microscope image was part of a sample scooped by the robotic arm from the
"Snow White" trench and delivered to Phoenix's microscope station in early July.
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