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Sept.
12, 2008: There's a special room at the Marshall
Space Flight Center. Researchers call it the "Anechoic
Chamber" and they love to test their high-tech instruments
there. Normal
people think it's just plain spooky.
"In
here, no one can hear you scream," says engineer Mark
James as he opens the door on the surreal:
Above:
The electromagnetically quiet Anechoic Chamber at the Marshall
Space Flight Center in Huntsville, Alabama. [larger
image]
The
door creaks shut behind James and suddenly it's like someone
hit the mute button. Dead silence. Pyramids on the wall seem
to be closing in. The urge to scream ... hard to resist.
James
just gets on with the job. He's lead engineer on a research
team using this cavernous facility to test a prototype hurricane
sensor called HIRAD. Short for Hurricane Imaging Radiometer,
HIRAD is designed to scan large areas of ocean for microwave
signals that portend storm strength and dynamics. By collecting
and transmitting these data to forecasters, HIRAD could reduce
property damage and even save lives.
The
Anechoic Chamber is the perfect place to check HIRAD's antenna.
Weird
shapes lining the chamber's walls are made of a radio-frequency
damping material arranged in a pattern akin to soundproof
rooms. The shapes minimize microwave reflections and eliminate
electromagnetic interference.
"The
electromagnetic quiet allows us to test and fully characterize
the HIRAD antenna," explains James. "Lack of sound
is just a weird bonus."
A
microwave source at one end of the chamber sends signals to
the HIRAD antenna at the other end. In this way, engineers
can explore the antenna's beam pattern to check that it meets
the requirements of the mission ahead.
Using
microwaves, "HIRAD will be able to map out wind speeds
on the ocean's surface--in particular the hurricane strength
within the eye wall and elsewhere," says Tim Miller,
HIRAD principal investigator at the National Space Science
and Technology Center in Huntsville, Alabama. "We can
also determine how heavy the rain is and the temperature of
the ocean surface, more indicators of hurricane characteristics."
(Note:
To learn more about how HIRAD works, read the Science@NASA
story "In
the Blink of a Hurricane's Eye.")
 Because
of its design, HIRAD can make observations over a wider swath
of area than instruments currently used by NOAA. And by using
electronic rather than mechanical means to scan and create
a two-dimensional image of the storm's dynamics, HIRAD can
operate on less power than current wind measuring instruments.
It's also smaller, lighter, and relatively inexpensive to
build.
Right:
Engineer David Simmons adjusts the HIRAD antenna in the MSFC
Anechoic Chamber. [larger
image]
"HIRAD's
observations will not only give weather officials more and
better real-time information on storm strength, but it will
also help them determine how the storm will develop and where
it will go," says Miller. "All of this adds up to
more advanced warnings to the public."
How
is HIRAD doing so far in the "bat cave" testing?
"We're
still reviewing our test data, but so far HIRAD is passing
with flying colors," says Robbie Hood of the MSFC, former
principal investigator for the project and still intimately
involved in its development.
The
next step, she says, "is to build the real thing. This
is just a test unit – a laboratory prototype. Ultimately,
HIRAD will be more compact and lighter weight than the unit
we're testing now."
The
team hopes to have HIRAD ready to fly checkout tests onboard
an aircraft by fall 2009, and ready for its first hurricane
experiment in 2010. HIRAD will have to compete with other
candidate instruments for the hurricane experiment.
The
whole team feels confident that their instrument is going
to succeed. "We've got top-notch personnel working long
hours to make it happen," says Miller. "We all know
that HIRAD is a valuable instrument, and we want to place
it in the hands of weather officials so it can do its work
-- saving lives."
The
trick, says James with a smile, "is not getting locked
in the bat cave."
What?
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Author: Dauna Coulter | Editor:
Dr. Tony Phillips | Credit: Science@NASA
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