Mg super(+) and other metallic emissions observed in the thermosphere

• Published in: Advances in space research Vol. 18; no. 3; pp. 61 - 64
• Main Authors: Viereck, R A, Murad, E, Lai, ST, Knecht, D J, Pike, C P, Gardner, JA, Broadfoot, AL, Anderson, E R, McNeil, W J
• Format: Journal Article
• Language: English
• Published: 01.01.1996
• ISSN: 0273-1177

Limb observations of UV dayglow emissions from 80 to 300 km tangent heights were made in December, 1992, using the GLO instrument on-board STS-53, which was at 330 km altitude and had an orbit inclination of 57 degrees . The orbit placed the shuttle near the terminator for the entire mission, resulting in a unique set of observations. GLO consisted of 12 imagers and 9 spectrographs on an Az/El gimbal system. Data was obtained over 6 days of the mission. Emissions from Mg super(+) and Ca super(+) were observed, as were emissions from the neutral metals Mg and Na. The ultimate source of the metals is meteor ablation; however, the emission spatial distribution is controlled by upper mesospheric and thermospheric winds and, in the case of the ions, by the electromagnetic fields of the ionosphere. Mg super(+) showed the brightest metal emission, and was observed near the poles and around the geomagnetic equator near sunset. The polar emissions were short-lived and intense, while the equatorial emissions were more continuous, with luminous patches observable over the period of several orbits. The instrumentation will be described, as will spatial and temporal variations of the metal emissions with emphasis on the metal ions. A numerical model is being developed to simulate the distribution and brightness of the ions in the near-equatorial region.