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Laboratory for Atmospheric and Space Physics


The SOLar STellar Irradiance Comparison Experiment (SOLSTICE) was one of ten instruments aboard the Upper Atmosphere Research Satellite (UARS) spacecraft. SOLSTICE provided the scientific community with long-term, accurate measurements of the Solar ultraviolet (UV) and far ultraviolet (FUV) spectral irradiance.

SOLSTICE was operated by the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado in Boulder and was active from October 1991 until September 2001, with Gary Rottman as the principal investigator.

SOLSTICE’s mission

SOLSTICE’s purpose was to aid scientists in researching global atmospheric change.

Solar radiation below 300nm is completely absorbed by the Earth’s atmosphere and becomes the dominant direct energy input. This energy establishes the composition, temperature and dynamics. Even small changes have an important impact on atmospheric processes and trends. Therefore SOLSTICE’s goals were to:

  • Make daily measurements of the solar ultraviolet irradiance (120nm–420nm with λ / Δλ ≈ 1000)
  • The measurement should have an absolute accuracy better than ±5%
  • The measurement should have a relative accuracy better than 1%
  • Measure solar variations on all time scales:
    • 27-day solar rotation variability
    • 11-year solar cycle variations
    • long-term solar variations related to climate