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version of the Powerpoint slides being used during the Press Briefing, click
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for CINDI fact sheet> Click for CNOFS fact
Space Has Never Been Closer: NASA
Instruments Document Contraction of the Boundary between the Earth’s Ionosphere
Observations made by NASA instruments onboard an Air Force
satellite have shown that the boundary between the Earth’s upper atmosphere and
space has moved to extraordinarily low altitudes. These observations were made
by the Coupled Ion Neutral Dynamics Investigation (CINDI) instrument suite,
which was launched aboard the U.S. Air Force’s Communication/Navigation Outage
Forecast System (C/NOFS) satellite on April 16, 2008.
The CINDI suite, which was built under the
direction Principal Investigator Rod Heelis of the University of Texas at
Dallas, includes both ion and neutral sensors and makes measurements of the
variations in neutral and ion densities and drifts.
CINDI and C/NOFS
were designed to study disturbances in Earth’s ionosphere that can result in a
disruption of navigation and communication signals. The ionosphere is a gaseous
envelope of electrically charged particles that surrounds our planet and it is
important because Radar, radio waves, and global positioning system signals can
be disrupted by ionospheric disturbances.
CINDI’s first discovery was,
however, that the ionosphere was not where it had been expected to be. During
the first months of CINDI operations the transition between the ionosphere and
space was found to be at about 260 miles (420 km) altitude during the nighttime,
barely rising above 500 miles (800 km) during the day. These altitudes were
extraordinarily low compared with the more typical values of 400 miles (640 km)
during the nighttime and 600 miles (960 km) during the day.
of the ionosphere/space transition is controlled in part by the amount of
extreme ultraviolet energy emitted by the Sun and a somewhat contracted
ionosphere could have been expected because C/NOFS was launched during a minimum
in the 11-year cycle of solar activity. However, the size of the actual
contraction caught investigators by surprise. In fact, when they looked back
over records of solar activity, they found that C/NOFS had been launched during
the quietest solar minimum since the space age began.
circumstance is providing an unparalleled opportunity to study the connection
between the interior dynamics of the Sun and the response of the Earth’s space
CINDI is a NASA sponsored Mission of Opportunity conducted
by the University of Texas at Dallas. NASA’s Explorer Program at Goddard Space
Flight Center, Greenbelt, Md., managed the CINDI mission. The Explorer Program
provides frequent flight opportunities for world-class scientific investigations
from space within heliophysics and astrophysics.
The CINDI investigation
is carried out as an enhancement to the science objectives of the C/NOFS
satellite undertaken by the Air Force Research Laboratory and the Space and
Missile Command Test and Evaluation Directorate.Related
Links:> NASA’s CINDI Web
site> University of Texas
at Dallas, CINDI Web site>
Air Force Research Laboratory Web site
Rani C. Gran/Laura
Goddard Space Flight Center, Greenbelt, Md.