Energetic neutral atoms are created when energetic magnetospheric ions undergo charge exchange with cold neutral atoms in the Earth's tenuous extended atmosphere (the geocorona). Since they are unaffected by the Earth's magnetic field, these energetic neutrals travel away in straight line trajectories from the points of charge exchange. The remote detection of these particles provides a powerful means through which the global distribution and properties of the geocorona and ring current can be inferred. Due to its 2 × 9 RE polar orbit, the Polar spacecraft provides an excellent platform from which to observe ENAs because it spends much of its time in the polar caps which are usually free from the contaminating energetic charged particles that make observations of ENAs more difficult. In this brief report, we present the first ENA imaging results from Polar. Storm-time ENA images are presented for a northern polar cap apogee pass on August 29, 1996 and for a southern polar cap perigee pass on October 23, 1996. As well, we show with a third event (July 31, 1996) that ENA emissions can also be detected in association with individual substorms
Geophysical Research Letters
American Geophysical Union
Digital Object Identifier (DOI)
Henderson, M. G.; Reeves, G. D.; Spence, Harlan E.; Sheldon, R. B.; Jorgensen, A. M.; Blake, J. B.; and Fennell, J. F., "First energetic neutral atom images from Polar" (1997). Geophysical Research Letters. 297.
Copyright 1997 by the American Geophysical Union.