The Geospace Dynamics Observatory (GDO) mission observes the near-Earth region in space called Geospace with
unprecedented resolution, scale and sensitivity. At a distance of 60 Earth Radii (Re) in a near-polar circular orbit and a
~27-day period, GDO images the earth’s full disk with (1) a three-channel far ultraviolet imager, (2) an extreme
ultraviolet imager of the plasmasphere, and (3) a spectrometer in the near to far ultraviolet range that probes any portion
of the disk and simultaneously observes the limb.
The exceptional capabilities of the GDO mission include (1) unprecedented improvement in signal to noise for globalscale
imaging of Earth’s space environment that enable changes in the Earth’s space environment to be resolved with
orders of magnitude higher in temporal and spatial resolution compared to existing data and other approaches, and (2)
unrivaled capability for resolving the temporal evolution, over many days, in local time or latitude with a continuous
view of Earth’s global-scale evolution while simultaneously capturing the changes at scales smaller than are possible
with other methods.
This combination of new capabilities is a proven path to major scientific advances and discoveries. The GDO mission (1)
has the first full disk imagery of the density and composition variability that exist during disturbed “storm” periods and
the circulation systems of the upper atmosphere, (2) is able to image the ionosphere on a global and long time scale
basis, (3) is able to probe the mechanisms that control the evolution of planetary atmospheres, and (4) is able to test our
understanding of how the Earth is connected to the Sun.
This paper explores the optical and technical aspects of the GDO mission and the implementation strategy. Additionally,
the case will be made that GDO addresses a significant portion of the priority mission science articulated in the recent
Solar and Space Physics Decadal Survey.1