Ernest Gotthold Hildner

STEREO: a solar terrestrial event observer mission concept

A STEREO mission concept requiring only a single new spacecraft has been proposed. The mission would place the new spacecraft in a heliocentric orbit and well off the Sun- Earth line, where it can simultaneously view both the solar source of heliospheric disturbances and their propagation through the heliosphere all the way to the earth. Joint observations, utilizing the new spacecraft and existing solar spacecraft in earth orbit or L1 orbit would provide a stereographic data set. The new and unique aspect of this mission lies in the vantage point of the new spacecraft, which is far enough from Sun-Earth line to allow an entirely new way of studying the structure of the solar corona, the heliosphere and solar-terrestrial interactions. The mission science objectives have been selected to take maximum advantage of this new vantage point. They fall into two classes: those possible with the new spacecraft alone and those possible with joint measurements using the new and existing spacecraft. The instrument complement on the new spacecraft supporting the mission science objectives includes a soft x-ray imager, a coronagraph and a sun-earth imager. Telemetry rate appears to be the main performance determinant. The spacecraft could be launched with the new Med-Lite system.