The Global-scale Observations of the Limb and Disk (GOLD) mission
is a heliophysics Mission of Opportunity for NASA’s Explorers program. GOLD is
intended to perform a two-year mission imaging Earth's thermosphere and ionosphere
from geostationary orbit. GOLD is a two-channel far-ultraviolet (FUV) imaging
spectrograph built by the Laboratory for Atmospheric and Space Physics at the
University of Colorado Boulder and flown as a hosted payload on the commercial
communications satellite SES-14.

  The scientific objectives of the GOLD mission are to determine how geomagnetic 
  storms alter the temperature and composition of Earth’s atmosphere, to analyze 
  the global-scale response of the thermosphere to solar extreme-ultraviolet variability, 
  to investigate the significance of atmospheric waves and tides propagating from 
  below the temperature structure of the thermosphere and to resolve how the structure 
  of the equatorial ionosphere influences the formation and evolution of equatorial 
  plasma density irregularities. The viewpoint provided by GOLD’s geostationary 
  orbit – from which the same hemisphere is always observable – is a new perspective 
  on the Earth’s upper atmosphere. This viewpoint allows local time, universal time 
  and longitudinal variations of the thermosphere and ionosphere's response to the 
  various forcing mechanisms to be uniquely determined.