Abstract
The Airborne LUnar Spectral Irradiance (air-LUSI) mission has the objective to measure lunar spectral irradiance to an unprecedented level of accuracy: <0.3% (k=1) uncertainty. This is to be accomplished by advancing a ground-based instrument system to fly on a NASA ER-2 aircraft above 90% of Earth's atmosphere, providing a new capability to potentially acquire SI-traceable lunar spectral irradiance over different lunar phases and libration angles. Initially, the air-LUSI measurements can be used to enhance the Robotic Lunar Observatory (ROLO) model of exo-atmospheric lunar spectral irradiance. The mission outcome is expected to greatly improve the accuracy of our knowledge of the Moon as a stable reference for calibration and inter-calibration of Earth-observing satellite instruments over long time periods, from the past into the future. This is of particular value for space-based ocean color measurements such as from SeaWiFS, MODIS, VIIRS and eventually PACE, which are highly sensitive to calibration drifts.
Our activities during the first year of the mission are focused on developing the three subsystems of the air-LUSI instrument. First, the IRradiance Instrument Subsystem (IRIS) is a non-imaging telescope with an integrating sphere at the focus, which feeds light via fiber optics to a spectrograph. An on-board validation source also can send light to the spectrograph via fiber optics. Second, the Autonomous Robotic Telescope Mount Instrument Subsystem (ARTEMIS) keeps the IRIS telescope pointed to the Moon to within less than 0.5°, reducing the effects of vignetting. Third, the High-altitude ER-2 Adaptation (HERA) instrument subsystem protects components from the extreme cold and low pressure during flight and high moisture from condensation during descent. The HERA team also is responsible for the integration of the air-LUSI instrument with the ER-2 aircraft. Our activities also include developing a calibration protocol and detailed uncertainty budget, conducting pre-flight system-level instrument calibrations, supporting engineering and demonstration flights, and performing post-flight data analysis. This report will provide details of the air-LUSI mission progress during the first year and our plans for the second year.
air-LUSI: Airborne LUnar Spectral Irradiance Mission
The Airborne LUnar Spectral Irradiance (air-LUSI) mission has the objective to measure lunar spectral irradiance to an unprecedented level of accuracy: <0.3% (k=1) uncertainty. This is to be accomplished by advancing a ground-based instrument system to fly on a NASA ER-2 aircraft above 90% of Earth's atmosphere, providing a new capability to potentially acquire SI-traceable lunar spectral irradiance over different lunar phases and libration angles. Initially, the air-LUSI measurements can be used to enhance the Robotic Lunar Observatory (ROLO) model of exo-atmospheric lunar spectral irradiance. The mission outcome is expected to greatly improve the accuracy of our knowledge of the Moon as a stable reference for calibration and inter-calibration of Earth-observing satellite instruments over long time periods, from the past into the future. This is of particular value for space-based ocean color measurements such as from SeaWiFS, MODIS, VIIRS and eventually PACE, which are highly sensitive to calibration drifts.
Our activities during the first year of the mission are focused on developing the three subsystems of the air-LUSI instrument. First, the IRradiance Instrument Subsystem (IRIS) is a non-imaging telescope with an integrating sphere at the focus, which feeds light via fiber optics to a spectrograph. An on-board validation source also can send light to the spectrograph via fiber optics. Second, the Autonomous Robotic Telescope Mount Instrument Subsystem (ARTEMIS) keeps the IRIS telescope pointed to the Moon to within less than 0.5°, reducing the effects of vignetting. Third, the High-altitude ER-2 Adaptation (HERA) instrument subsystem protects components from the extreme cold and low pressure during flight and high moisture from condensation during descent. The HERA team also is responsible for the integration of the air-LUSI instrument with the ER-2 aircraft. Our activities also include developing a calibration protocol and detailed uncertainty budget, conducting pre-flight system-level instrument calibrations, supporting engineering and demonstration flights, and performing post-flight data analysis. This report will provide details of the air-LUSI mission progress during the first year and our plans for the second year.