Mercury 2000: Stereoscopic Observations of Gamma Ray Flares

Abstract

Stereoscopic observations of gamma ray radiation from solar flares would provide further scientific impetus to recent proposals for a planetary observer mission to Mercury in the late 1990's. The solar monitoring phase of this mission could continue through the period of maximum flare activity in the years 2002-2006 with a dawn-dusk polar orbit which would allow continuous solar visibility and minimize solar tracking requirements. Simultaneous measurements of flare radiation from gamma ray instruments with comparable solar flux sensitivity in orbits around Mercury and Earth would provide stereoscopic information on directivity and altitude location in the solar atmosphere of the flare radiation sources and might significantly advance understanding of energy release and particle acceleration processes in solar flares. The closer proximity of Mercury to the Sun would allow use of a much smaller gamma ray spectrometer system than required at 1 A.U. and would also provide the first opportunity for direct detection of solar neutrons at energies of 1-10 MeV. The Mercury orbiter would also be capable of monitoring 1-500 MeV solar protons to search for decay protons from solar neutron flares and to provide automatic early warning of large proton flares which would be a hazard to manned space operations near Earth and beyond.