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August
15, 2008: When you hear the word "NASA,"
do visions of rocket ships dance in your head?
Well
think again. From now on, it's "earthworms."
That's
right. Using space technology, NASA is now studying the realm
of earthworms, millipedes, and springtails -- the soil beneath
your feet -- with a project called OMEGA (Observing Microwave
Emissions for Geophysical Applications).
Right:
A subterranean cross-section of Alabama soil. Credit: USDA.
[more]
Why
would an agency whose cosmic vision knows no bounds care about
the nitty-gritty crawling-grounds of lowly critters? Because
NASA recognizes the vital role this "underworld"
plays in our lives on Earth.
For instance, if forecasters don't know how damp or dry the
soil is, they can't accurately predict the weather.
"OMEGA
soil moisture data will help us build better weather models,"
says NASA scientist Chip Laymon, principal investigator for
the OMEGA project at the National Space Science and Technology
Center in Huntsville, Alabama. "Better models mean better
forecasts."
But
there's more. According to Laymon, this research could help
forecasters predict flash floods, land-slides and drought. OMEGA
could also help farmers plan crop planting, make important decisions
about irrigation, and predict crop yields.
How
will OMEGA scientists gather the soil moisture data? "We
use a microwave radiometer," says Laymon. Ordinary soil
naturally emits a small amount of low-energy microwave radiation;
all warm objects do. "By analyzing those microwaves we
can tell how much moisture is in the soil."
The
name of the instrument is MAPIR, short for Marshall Airborne
Polarimetric Imaging Radiometer, and it's about to fly on
its first mission onboard a NASA P-3 aircraft. "Our instrument
has to be ready to install on the P-3 by Sept. 15," says
Laymon. "We'll then fly missions over the Delmarva Peninsula
between Oct. 1 and Oct. 14."
The
Delmarva Peninsula, a 180 mile x 60 mile area of land on the
east coast of the United States bounded by the Chesapeake
Bay and the Atlantic Ocean, is a good place for MAPIR's maiden
flight. Two-thirds of the peninsula is agricultural and one-third
forested, so there is a variety of terrain to sample. Moreover,
the USDA Agricultural Research Service has already been studying
the area and they have set up their own moisture sampling
stations. These can provide valuable "ground truth"
comparisons for MAPIR's airborne data.
Above:
OMEGA's microwave soil moisture sensor, MAPIR, will take its
maiden flight onboard a NASA P-3 aircraft like this one. Photo
credit: Stephen Ausmus, USDA-ARS
MAPIR's
berth on the P-3 was an unexpected development. "Another
mission slated to fly on the P-3 scrubbed, and a slot suddenly
opened for us," says Laymon. "We've really had to
accelerate our schedule for developing MAPIR. The intensity
of the schedule is enormous -- trying to refocus and prepare
for airworthiness reviews and other milestones. The team has
worked tirelessly and we have many more long days to come."
The
ultimate goal is three tiers of observation: OMEGA instruments
on a truck and a plane, and a similar instrument built by
NASA's Jet Propulsion Laboratory, on a satellite. Each sensor
will tell the story of soil moisture from its own unique perspective.
The truck, with its own huge microwave antenna, is almost
ready. The satellite will most likely be in the form of the
2013 Soil Moisture Active Passive, or SMAP, space mission
led by JPL. After the P-3 test-flight, OMEGA's regular plane
will be a Polish-built Antonov aircraft, a big beefy biplane
housed at a local airfield, affectionately known to the team
members as "the flying tractor."
Right:
The "Flying Tractor" awaits MAPIR in an Alabama
air field.
"With
this aircraft, we'll be able to do a lot of research locally.
I expect 'the flying tractor' to be airborne before the end
of the year," says Laymon.
Meanwhile,
the rush to prepare for the upcoming P-3 flights has strained
OMEGA researchers to the max. What's the hardest part? "Oh,
probably the hallucinations from stress and lack of sleep,"
grins Laymon. No matter how hard he tries, he can't stop thinking
about flying tractors and a universe of earthworms.
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Author: Dauna Coulter | Editor:
Dr. Tony Phillips | Credit: Science@NASA
End
Notes |
1.
OMEGA
is short for Observing Microwave Emissions for Geophysical
Applications, is one of the first projects of its type,
combining active and passive remote sensing by using
both radar and a radiometer. Radar is called active
because it sends a signal (a pulse) and then looks at
the refection to characterize a surface. A radiometer
is called passive because it simply looks at what the
Earth naturally gives off.
2. Soil moisture is a key variable in
controlling the exchange of water and heat energy between
the land surface and the atmosphere through evaporation
and plant transpiration. As a result, soil moisture
plays an important role in the development of weather
patterns and the production of precipitation. Simulations
with numerical weather prediction models have shown
that improved characterization of surface soil moisture,
vegetation, and temperature can lead to significant
forecast improvements: more
information.
3. Soil moisture also strongly affects
the amount of precipitation that runs off into nearby
streams and rivers. Large-scale dry or wet surface regions
have been observed to impart positive feedback on subsequent
precipitation patterns, such as in the extreme conditions
over the central U.S. during the 1988 drought and the
1993 floods. Soil moisture information can be used for
reservoir management, early warning of droughts, irrigation
scheduling, and crop yield forecasting: more
information.
4. Recent advances in microwave remote
sensing technology indicate that surface soil moisture
can be inferred with both ground-based and aircraft-based
remote sensing systems operating in the microwave region
of the electromagnetic spectrum. Experiments conducted
over the past two decades have resulted in a basic operational
approach whereby microwave brightness temperature is
related to soil moisture. See for more
information.
5. See http://smap.jpl.nasa.gov/
for more information on SMAP.
NASA's
Future: US
Space Exploration Policy
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