Global Change in the Thermosphere: Compelling Evidence of a Secular Decrease in Density
Abstract
The Naval Research Laboratory has pioneered a fast and accurate method of processing standard data on spacecraft orbits ("two-line element sets" or TLEs) to determine the total mass density of the highest layer of the Earth's atmosphere, known as the thermosphere. Although the atmosphere is extremely thin in this region (the air at the Earth's surface is a trillion times thicker), it is enough to exert a drag force on satellites, causing their orbits to decay slowly and ultimately resulting in a fiery disintegration at lower altitudes. The Naval Space Surveillance System (NAVSPASUR) radar fence, operated from the Naval Surface Warfare Center in Dahlgren, Virginia, provides key observation sets from which the trajectories of Earth-orbiting objects are reduced to TLEs. The resulting Space Object Catalog presently allows the U.S. Space Command to track and predict the locations of more than 12,000 objects, most of which are in low-Earth orbit (LEO). Th is archive extends back 40 years and represents an unexploited source of global information on the thermosphere. The thermosphere exerts drag on LEO objects, reducing their useful lifetimes, orbital predictability, and safety.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2005
- Accession Number
- ADA523458
Entities
People
- J. L. Lean
- J. Michael Picone
- J. T. Emmert
Organizations
- United States Naval Research Laboratory