The Solar Radiation and Climate Experiment (SORCE) is a NASA-sponsored satellite mission that provides state-of-the-art measurements of incoming X-ray, ultraviolet, visible, near-infrared, and total solar radiation. The measurements provided by SORCE specifically address long-term climate change, natural variability and enhanced climate prediction, and atmospheric ozone and UV-B radiation. These measurements are critical to studies of the Sun; its effect on our Earth system; and its influence on humankind.
SORCE measures the Sun's output with the use of state-of-the-art radiometers, spectrometers, photodiodes, detectors, and bolometers engineered into instruments mounted on a satellite observatory. The SORCE satellite orbits around the Earth accumulating solar data. Spectral measurements identify the irradiance of the Sun by characterizing the Sun's energy and emissions in the form of color that can then be translated into quantities and elements of matter. Data obtained by the SORCE experiment can be used to model the Sun's output and to explain and predict the effect of the Sun's radiation on the Earth's atmosphere and climate.
The SORCE spacecraft launched on January 25, 2003 on a Pegasus XL launch vehicle to provide NASA's Earth Science Enterprise (ESE) with precise measurements of solar radiation. It launched into a 645-km, 40-degree orbit and is operated by the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado at Boulder, Colorado, USA. It will continue the precise measurements of total solar irradiance that began with the ERB instrument in 1979 and has continued to the present with the ACRIM series of measurements. SORCE will also provide the measurements of the solar spectral irradiance from 1 nm to 2000 nm, accounting for 95% of the spectral contribution to the total solar irradiance. SORCE carries four instruments including the Total Irradiance Monitor (TIM), Solar Stellar Irradiance Comparison Experiment (SOLSTICE), Spectral Irradiance Monitor (SIM), and the XUV Photometer System (XPS).
The Spectral Irradiance Monitor is a spectrometer that provides long-duration solar spectral irradiance measurements in the visible and near infrared (Vis/NIR). The wavelength coverage is primarily from 300 to 2400 nm, with an additional channel to cover the 200-300 nm ultraviolet spectral region to overlap with the SOLSTICE, another instrument on board the SORCE satellite.
Payloads are separated by bullets ( · ), launches by pipes ( | ). Manned flights are indicated in bold text. Uncatalogued launch failures are listed in italics. Payloads deployed from other spacecraft are denoted in brackets.