The ionosphere's wild ride in outer space

Plasma of terrestrial origin is produced chiefly by either solar photo‐ionization or electron bombardment ionization of the Earth's upper atmosphere, forming the ionosphere. Under many conditions, components of the higher‐altitude ionosphere acquire sufficient energy to escape the Earth's gravitational attraction and flow out along geomagnetic field lines into various regions of the magnetosphere, and perhaps beyond, into the solar wind. Over the past two decades, intense observational and modeling efforts by numerous researchers have sought to understand the processes driving these ionospheric outflows and the resulting presence and consequences of these ionospheric plasmas populating the major regions of the magnetosphere. The matter of ionospheric outflows directly influences two significant thrusts of current magnetospheric research. First, the exciting concept of imaging magnetospheric plasmas is now believed to be feasible and is planned for future NASA missions. Some of the envisioned imaging approaches are based on detection of solar EUV radiation resonantly‐scattered from ionospheric‐origin He + and O + ions. Second, there is the major unresolved issue of whether the ionospheric outflows supply much of the plasma content of such regions as the ring current and the plasma sheet, and exactly what the geophysical consequences of the significant presence of heavy ionospheric He + and O + ions might be on general wave‐particle processes and substorm triggering and amplification in the tail plasma sheet.