he first generation SOLSTICE instrument, UARS
SOLSTICE, is currently orbiting the Earth on board the
spacecraft and makes daily solar irradiance measurements between 119
and 420 nanometers approximately 15 times per day.
The second-generation SOLSTICE instrument will fly on-board the SORCE spacecraft in late 2002, along with a number of other solar-viewing instruments to provide more complete spectral coverage, as well as state-of-the-art measurement of the Toltal Solar Irradiance (TSI).
The two SOLSTICE experiments are part of NASA's Earth Science Enterprise.
The two SOLSTICE instruments incorporate a unique technique for long-term calibration of changes in instrument sensitivity. This technique is designed to make use of frequent observations of numerous stars as the primary measurement of instrument performance over long periods of time.