The ARCSTONE Project to Calibrate Lunar Reflectance
Rand Swanson, Michael Kehoe, Michael Stebbins, Hans Courrier, Constantine Lukashin, Trevor Jackson, Michael Cooney, Warren Davis, Greg Kopp, Paul Smith, Christine Buleri, Thomas C. Stone
Abstract
The purpose of the ARCSTONE project is to more accurately measure the spectral lunar reflectance so the Moon can be used as a high-accuracy SI-traceable exo-atmospheric calibration standard for Earth-viewing instruments in low-Earth orbits. The spectral range is 350 nm to 2300 nm with less than 4 nm sampling. Radiometric modeling indicates the mission goal of better than 1 % (k=1) absolute accuracy is achievable. To reach this goal, the instrument will measure solar and lunar irradiances with a single set of optics, thereby minimizing the impact of long-term optical degradation via a temporally-close ratio method. SI-traceable results will be obtained by scaling the solar irradiance measurements to the calibrated, on-orbit Total and Spectral Irradiance Sensor (TSIS) observations. To date, a first-generation ARCSTONE prototype has been developed and is undergoing system-level characterizations. A more compact second-generation engineering design unit that will fit in a 6U CubeSat is under development.