December 17, 2008
NASA: Ionosphere not where it should be
The U.S. space agency says it has discovered the boundary between the Earth's upper atmosphere and space has moved to extraordinarily low altitudes.
The finding was determined by National Aeronautics and Space Administration instruments aboard an Air Force satellite launched in April. The instruments, including ion and neutral sensors, make measurements of the variations in neutral and ion densities and drifts that can result in disruptions of navigation and communication signals.
NASA said the discovery by the satellite -- subsequently determined to have been launched during the quietest solar minimum since the space age began -- is providing a unique opportunity to study the connection between the interior dynamics of the sun and the response of the Earth's space environment.