Hello Halo
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Atmospheric specialists were enticed by the clouds pictured in one of
FIDO's first panoramas because clouds provide scientists with wisdom
about the climate.
Researching water clouds on Earth during the FIDO test now equates to
researching dust on Mars during the Mars Exploration Rover mission
later.
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Mark Lemmon |
Mark Lemmon, an atmospheric scientist from Texas A&M explains, "One of
the main goals of the Mars Exploration Rover mission is to figure out
what's in the atmosphere of Mars in order to give us better insight as
to what the global climate was like in the past and what it could be
like in the future."
Understanding the dust on Mars today is vital to understanding how to
prepare for the safety of future astronauts on Mars. "We think the dust
on Mars is composed mainly of iron and magnetic material," explains
Mark. "If humans travel to Mars in the future, they will have to fight
the dust to survive."
"The astronauts on the moon came back to Earth coated from head to toe
in dust, and if the dust on Mars sticks to the astronauts there, its
magnetic properties could short out all of their electronic equipment,
which could technologically cripple the astronauts." No computers, no
radios…not an easy existence.
Mark went to Hawaii and discovered the difficulty of dealing with dust
first-hand. "We hiked around Kauai in the volcanic areas where the dust
is similar to martian dust, and by the time we got back to our rental
car, the entire car, inside and out was coated with red dust. I got
home from my trip and my socks are still red after washing them at least
20 times!"
Mark and his colleagues are using the FIDO test to practice the rigors
of researching the atmosphere in a quick and efficient way. On Earth,
clouds move particles around the globe and can reveal secrets about the
present and past climate all over the world. Scientists noted in this
FIDO Navcam panorama that the large cumulus clouds to the right of the
picture looked like liquid water clouds, while the wispy cirrus clouds
to the left appeared to be water ice clouds. They tested their
prediction of the water-based composition of the clouds by asking the
rover to take pictures of the sun.
One way scientists identify what the clouds are composed of is to
observe whether or not a halo of light forms around the sun. Halos of
light around the sun are caused by the reflection of sunlight off of ice
crystals present in the atmosphere. Therefore, if scientists see a halo
surrounding the sun, it is a definitive sign of ice in the atmosphere.
There can be two types of ice, water ice or carbon dioxide ice, which
can be distinguished by measuring the size of the halo.
The Navcam captured a halo around the sun and scientists measured it,
discovering it indeed was water-based and not carbon-dioxide based. A
second confirmation came from the Infrared Point Spectrometer (IPS)
instrument (which on Mars would be the Mini-TES instrument) to show the
"signature" of water in the light reflected from the halo.
The atmospheric scientists will apply similar tests to the martian
atmosphere when the rover lands in 2004. "The most active process
occurring on Mars is the movement of dust in the atmosphere, so we will
focus on dust obscuring the sun during our real mission." After Mark's
experience with red dust, he may want to recommend the rover take some
bleach...