Abstract
Detecting and improving the scientific understanding of global trends in complex Earth systems, such as climate, increasingly depend on assimilating datasets from multiple instruments and platforms over multi-decadal timescales. Calibration accuracy, stability, and inter-consistency among different instruments are key to developing reliable composite data records, particularly from space-based sensors, which generally span different times and different spectral regions. Such instruments commonly carry on-board references for calibration at various wavelengths, but these increase mass and mission complexity and are subject to degradation in the space environment. Having similar radiance to Earth scenes, the Moon can be considered a natural solar diffuser that can be utilized as an on-orbit calibration target by most space-borne Earth-observing instruments. Since the intrinsic lunar surface reflectance is effectively time-invariant, using the Moon as a high-accuracy calibration reference enables broad calibration, intercalibration, and validation opportunities even between temporally non-overlapping instruments, and provides an exoatmospheric absolute radiometric standard. This lunar reference can help to enable high-accuracy absolute calibrations and inter-calibrations of past, current, and future Earth-observing sensors, meteorological imagers, and long-term climate monitoring satellite systems, and constellation architectures.
The goal of the ARCSTONE InVEST project, funded by the NASA Earth Science Technology Office (ESTO), is to demonstrate a novel lunar observation approach from space with focus on high-accuracy measurements of lunar spectral reflectance. The ARCSTONE instrument is a compact spectrometer to be accommodated on a 6U CubeSat intended for low Earth orbit, and has been manifested for launch in June 2025. It will measure the lunar spectral reflectance with combined uncertainty of 0.5% (k=1), across the 350 nm to 2300 nm spectral range. The ARCSTONE InVEST team will present the status of the project; the instrument design, fabrication, and assembly; the calibration approach and concept of operations; and the planned path toward system integration and mission implementation.
ARCSTONE InVEST: Calibration of Lunar Spectral Reflectance from Space
Detecting and improving the scientific understanding of global trends in complex Earth systems, such as climate, increasingly depend on assimilating datasets from multiple instruments and platforms over multi-decadal timescales. Calibration accuracy, stability, and inter-consistency among different instruments are key to developing reliable composite data records, particularly from space-based sensors, which generally span different times and different spectral regions. Such instruments commonly carry on-board references for calibration at various wavelengths, but these increase mass and mission complexity and are subject to degradation in the space environment. Having similar radiance to Earth scenes, the Moon can be considered a natural solar diffuser that can be utilized as an on-orbit calibration target by most space-borne Earth-observing instruments. Since the intrinsic lunar surface reflectance is effectively time-invariant, using the Moon as a high-accuracy calibration reference enables broad calibration, intercalibration, and validation opportunities even between temporally non-overlapping instruments, and provides an exoatmospheric absolute radiometric standard. This lunar reference can help to enable high-accuracy absolute calibrations and inter-calibrations of past, current, and future Earth-observing sensors, meteorological imagers, and long-term climate monitoring satellite systems, and constellation architectures.
The goal of the ARCSTONE InVEST project, funded by the NASA Earth Science Technology Office (ESTO), is to demonstrate a novel lunar observation approach from space with focus on high-accuracy measurements of lunar spectral reflectance. The ARCSTONE instrument is a compact spectrometer to be accommodated on a 6U CubeSat intended for low Earth orbit, and has been manifested for launch in June 2025. It will measure the lunar spectral reflectance with combined uncertainty of 0.5% (k=1), across the 350 nm to 2300 nm spectral range. The ARCSTONE InVEST team will present the status of the project; the instrument design, fabrication, and assembly; the calibration approach and concept of operations; and the planned path toward system integration and mission implementation.