Space scientists from the
Applied Physics
Laboratory got a firsthand look at what happened to
Earth's atmosphere when the sun was abruptly "turned off"
during the March 29, 2006, total solar eclipse.
APL scientists are now modeling unique observations of
the eclipse captured by two APL-built instruments and the
only two active space-based ionospheric thermospheric
imagers currently in operation: the Global Ultraviolet
Imager aboard NASA's TIMED spacecraft, built and operated
by APL; and the Special Sensor Ultraviolet Imager aboard an
Air Force Defense Meteorological Satellites Program
spacecraft.
"The TIMED and DMSP spacecraft were in just the right
spot at the right time to image the upper atmosphere as the
sun was eclipsed," said Larry Paxton, project scientist for
the GUVI and SSUSI instruments. "These instruments provided
the first and only look at the altitude and spectral
distribution of the effects of an eclipse on the upper
atmosphere."
From their positions a few hundred miles above Earth's
surface, the "hyperspectral" imagers aboard the two
spacecraft produce images in hundreds of wavelengths by
"sweeping" their fields of view. Before information is sent
back to the science teams on the ground, it is combined
aboard the respective satellites to produce multicolor
imagery of the Earth in the far ultraviolet (100-200
nm).
"These dramatic observations of the eclipse are
providing the atmospheric science community with a unique
opportunity to study how the Earth's upper atmosphere
responds to external changes," Paxton said.
Since its launch in 2001, TIMED has been exploring one
of Earth's last atmospheric frontiers, collecting valuable
data during various phases of the solar cycle. For more
information, go to
www.timed.jhuapl.edu.
For more information about the DMSP satellites, go to
http://heasarc.nasa.gov/docs/heasarc/missions/
dmsp.html.
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