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Boundary Between Earth's Upper Atmosphere And Space Has Moved To Extraordinarily Low Altitudes, NASA Instruments Document

Date:
December 16, 2008
Source:
NASA/Goddard Space Flight Center
Summary:
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.

The height 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.
Credit: NASA/Goddard Space Flight Center

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.

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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.

The height 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.

This extraordinary 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 environment.

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.


Story Source:

The above story is based on materials provided by NASA/Goddard Space Flight Center. Note: Materials may be edited for content and length.


Cite This Page:

NASA/Goddard Space Flight Center. "Boundary Between Earth's Upper Atmosphere And Space Has Moved To Extraordinarily Low Altitudes, NASA Instruments Document." ScienceDaily. ScienceDaily, 16 December 2008. <www.sciencedaily.com/releases/2008/12/081215121601.htm>.
NASA/Goddard Space Flight Center. (2008, December 16). Boundary Between Earth's Upper Atmosphere And Space Has Moved To Extraordinarily Low Altitudes, NASA Instruments Document. ScienceDaily. Retrieved November 26, 2014 from www.sciencedaily.com/releases/2008/12/081215121601.htm
NASA/Goddard Space Flight Center. "Boundary Between Earth's Upper Atmosphere And Space Has Moved To Extraordinarily Low Altitudes, NASA Instruments Document." ScienceDaily. www.sciencedaily.com/releases/2008/12/081215121601.htm (accessed November 26, 2014).

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