The ARCSTONE Project to Calibrate Lunar Reflectance

Swanson, Rand; Kehoe, Michael; Stebbins, Michael; Courrier, Hans; Lukashin, Constantine; Jackson, Trevor; Cooney, Michael; Davis, W. T.; Kopp, Greg; Smith, Paul H.; Buleri, Christine; Stone, Tom

doi:10.1109/aero47225.2020.9172629

Cited by 10 publications

(12 citation statements)

References 3 publications

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“…This novel approach eliminates on-board calibration hardware, saving mass, complexity, and instrument development time. Our calibration accuracy goals will be achieved by using a high-accuracy lunar radiometric reference that is currently under development through efforts of NASA's ARCSTONE project [38], NIST's Ground-and air-LUnar Spectral Irradiance (LUSI) [39], and USGS' RObotic Lunar Observatory (ROLO) lunar model [40][41][42], which is expected to be available before a space deployment of Trutinor. Using the Moon for absolute radiometric calibration makes Trutinor unique among Earth-observing sensors.…”

Section: The Trutinor Concept and Discussionmentioning

confidence: 99%

Trutinor: A Conceptual Study for a Next-Generation Earth Radiant Energy Instrument

et al. 2020

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Uninterrupted and overlapping satellite instrument measurements of Earth’s radiation budget from space are required to sufficiently monitor the planet’s changing climate, detect trends in key climate variables, constrain climate models, and quantify climate feedbacks. The Clouds and Earth’s Radiant Energy System (CERES) instruments are currently making these vital measurements for the scientific community and society, but with modern technologies, there are more efficient and cost-effective alternatives to the CERES implementation. We present a compact radiometer concept, Trutinor (meaning “balance” in Latin), with two broadband channels, shortwave (0.2–3 μm) and longwave (5–50 μm), capable of continuing the CERES record by flying in formation with an existing imager on another satellite platform. The instrument uses a three-mirror off-axis anastigmat telescope as the front optics to image these broadband radiances onto a microbolometer array coated with gold black, providing the required performance across the full spectral range. Each pixel of the sensor has a field of view of 0.6°, which was chosen so the shortwave band can be efficiently calibrated using the Moon as an on-orbit light source with the same angular extent, thereby reducing mass and improving measurement accuracy, towards the goal of a gap-tolerant observing system. The longwave band will utilize compact blackbodies with phase-change cells for an absolute calibration reference, establishing a clear path for SI-traceability. Trutinor’s instrument breadboard has been designed and is currently being built and tested.

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Section: The Trutinor Concept and Discussionmentioning

confidence: 99%

Trutinor: A Conceptual Study for a Next-Generation Earth Radiant Energy Instrument

et al. 2020

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“…(2017) and Swanson et al. (2020). Finally the 0.1 SID neutral density attenuation brings the reduction down to the needed factor 10 −6 .…”

Section: On‐orbit Merbe‐sat Calibration Operationmentioning

confidence: 96%

“…The SID optic has spread the solar radiance over ≈1 Steradian, rather than its usual 0.00001 Steradians (Δθ), giving an approximate factor of 10 5 attenuation. That means the attenuation is achieved by changing solid angle rather than time and space, as normally done by Kopp et al (2017) and Swanson et al (2020). Finally the 0.1 SID neutral density attenuation brings the reduction down to the needed factor 10 −6 .…”

Section: Nfov Scans Of the Sun With Sidmentioning

confidence: 99%

Solar Intensity Dispersing (SID) Concept for CubeSat Spectral CLARREO‐Like Radiance Measurements

Matthews¹

2023

Earth and Space Science

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NRC Decadal Surveys stated that the most critical goal for orbital climate measurements was improving accuracy. This is so comparisons can be better made with models, tuning theory to match the truth. That gives confidence in model predictions of future global cloud albedo warming signals, estimated to be only 0.8%/decade or less. This work considers goals of a future mission CLARREO, currently in the development phase. CLARREO's Earth viewing optics intend to scan lunar radiance for tracking calibration changes, within both a high wavelength and high spatial resolution spectrometer. The current NASA CLARREO design will attempt absolute calibration from the space station by attenuating known solar flux, using pinholes and time under‐sampling. This study presents a cheaper and potentially more effective alternative, instead using the Sun as a near direct absolute calibration target. It does this spreading sunlight over a large solid angle, before integrating signals taken from a spinning orbiting CubeSat. Additionally, after reviewing actual orbital data comparisons, the realistic accuracy of cross‐orbit satellite to satellite calibration is shown several percent at best, even for a perfect CLARREO device (far short of the desired ±0.3% quoted by NASA). That is compared to the accuracy achievable from an absolute lunar spectral characterization from this CubeSat called “MERBE‐Sat,” acting as a transfer for a climate observation system, perhaps better than ±0.3% error. Although discussed individual components of MERBE‐Sat are mostly of high TRL Level, this work suggests experimentation to raise the net TRL level of the new entire concept.

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“…The practical considerations for lunar radiometry from an orbiting platform are particularly relevant for observations acquired for the purpose of characterizing the Moon and its brightness variations. A study conducted to support acquisitions planning for the NASA ARCSTONE project 1 [6] examined the issues of target consistency and temporal variations in the lunar irradiance observed from a Sun-synchronous orbit. The results are applicable to Moon observations acquired from any Earth orbit.…”

Section: Simulation Of Moon Sampling From Leomentioning

confidence: 99%

“…Efforts toward redeveloping the lunar radiometric reference to improve its accuracy have shown the need for collecting a new set of measurements to use as a basis for modeling, with some measurements acquired from high altitude or space to avoid the uncertainty limitations imposed by atmospheric corrections. This measurement need is being addressed by current programs that are actively making lunar radiometric acquisitions and developing new space-based measurement capabilities [1], [6].…”

Section: Introductionmentioning

confidence: 99%

Acquisition of Moon Measurements by Earth Orbiting Sensors for Lunar Calibration

Stone

2022

IEEE Trans. Geosci. Remote Sensing

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The reflected light from the Moon can be utilized as a reference for radiometric calibration by employing a model to generate reference values corresponding to Moon observations made by instruments. Using a calibration target that is outside the atmosphere provides a distinct advantage for space-based instruments; however, the lunar irradiance sensed by satellite instruments naturally changes as the host spacecraft traverses its orbit. This paper presents a study of the potential impact on lunar radiometric measurements due to their acquisition from an orbiting platform. A simulation of a Sun-synchronous orbit was coupled to the USGS lunar model to generate predicted irradiances for points along orbit passes through several lunations. These irradiance values exhibit variations tied to the spacecraft motion, arising primarily from changes in the Moonsensor distance and the phase angle. The two effects are similar in overall magnitude, but their respective contributions depend on the time of month and the orbit. Relative changes in irradiance mostly fall within an envelope of ±0.006% per second, except at the smallest phase angles. These studies enable planning space-based Moon observations to minimize the change in the target irradiance, an important consideration for measurements acquired for radiometric characterization of the Moon.

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The ARCSTONE Project to Calibrate Lunar Reflectance

Cited by 10 publications

References 3 publications

Trutinor: A Conceptual Study for a Next-Generation Earth Radiant Energy Instrument

Trutinor: A Conceptual Study for a Next-Generation Earth Radiant Energy Instrument

Solar Intensity Dispersing (SID) Concept for CubeSat Spectral CLARREO‐Like Radiance Measurements

Acquisition of Moon Measurements by Earth Orbiting Sensors for Lunar Calibration

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