This volume on the Solar Radiation and Climate Experiment (SORCE)
mission continues a Solar Physics tradition of special topical issues
dedicated to major solar space missions. As one element of NASA's Earth
Observing System, SORCE is a satellite carrying four instruments to
measure the solar radiation incident at the top of the Earth's
atmosphere. These observations are improving our understanding and
generating new inquiry regarding how and why solar variability occurs
and how it affects our atmosphere and climate. The SORCE mission is a
joint effort between NASA and the Laboratory for Atmospheric and Space
Physics (LASP) at the University of Colorado. The mission is a Principal
Investigator-led mission under the direction of Dr. Gary Rottman from
LASP. LASP developed, calibrated, and tested the four science
instruments before integrating them onto a spacecraft procured from
Orbital Sciences Corporation. The SORCE instruments include the Total
Irradiance Monitor (TIM), the Spec- tral Irradiance Monitor (SIM), two
Solar Stellar Irradiance Comparison Experi- ments (SOLSTICE), and the
XUV Photometer System (XPS). The TIM instrument continues the precise
measurements of total solar irradiance (TSI) that first began in 1978.
SORCE also provides measurements of the solar spectral irradiance (SSI)
from 1 to 2000 nm with its other instruments. The Sun has both direct
and indirect influences on the terrestrial system, and SORCE's
comprehensive total and spec- tral solar measurements are providing the
requisite understanding of this important climate system variable.
