Test Results From the Prelaunch Characterization Campaign of the Engineering Test Unit of the Ocean Color Instrument of NASA’s Plankton, Aerosol, Cloud and Ocean Ecosystem (PACE) Mission

Meister, Gerhard; Knuble, Joseph J.; Chemerys, Leland H.; Choi, Hyeungu; Collins, Nicholas R.; Eplee, Robert E.; Gliese, U.; Gorman, Eric T.; Jepsen, K.S.; Kitchen-McKinley, Samuel; Lee, Shihyan; McIntire, Jeff; Patt, Frederick S.; Tse, Bradley C.; Waluschka, Eugène; Werdell, P. Jeremy

doi:10.3389/frsen.2022.875863

Cited by 17 publications

(13 citation statements)

References 27 publications

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“…*corresponding author: shihyan.lee@nasa.gov The prelaunch radiometric characterization of OCI was completed in 2022 3 . In the stray light measurements of that test campaign, using a collimated-monochromatic light source with a size of 1x1 pixel 4 , a crosstalk feature was detected that is much wider than the source.…”

Section: Introductionmentioning

confidence: 99%

PACE OCI crosstalk characterization based on pre-launch testing

Lee,

Meister,

Kitchen

et al. 2023

Sensors, Systems, and Next-Generation Satellites XXVII

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Scheduled to launch in 2024, the Ocean Color Instrument (OCI) onboard the Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission will collect hyperspectral data from 315 nm to 895 nm via two grating spectrometers (in both the blue and red spectral regions) and 9 multi-spectral bands in the short-wave infrared (940 nm to 2260 nm). The increased spectral resolution and radiometric accuracy is expected to improve upon data collected by heritage sensors such as SeaWiFs, MODIS, and VIIRS, allowing new applications in ocean color, aerosol, and cloud science. During ground testing, higher than expected spatial-spectral crosstalk was measured for the hyperspectral bands in the blue spectrograph. Using a monochromatic-collimated light source, light from a single science pixel (1km x 1km) was found to produce crosstalk signals over 31 pixels in the cross-track direction. This spatial augmentation is caused by the spectral crosstalk’s asynchronous spatial movement during Time Delay Integration (TDI). To fully characterized the magnitude and spectral dependency from this, a crosstalk model was developed by synthesizing data collected from monochromatic-collimated light and monochromatic light that filled the OCI optical aperture. The model was validated by showing good agreement between predicted values and other relevant test data collected using both monochromatic and white light sources.

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Section: Introductionmentioning

confidence: 99%

PACE OCI crosstalk characterization based on pre-launch testing

Lee,

Meister,

Kitchen

et al. 2023

Sensors, Systems, and Next-Generation Satellites XXVII

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“…Unlike its predecessors, OCI will cover a spectral range from 340nm to 2260nm. Below 900nm, OCI will include two spectrometers that continuously span the ultraviolet to 600nm and 600nm to near-infrared spectral regions to provide hyperspectral radiances sampled every 1.25 to 2.5nm, with a bandwidth of 5nm for each channel [2,10]. Wavelengths above 900nm are measured in seven discrete multispectral bands of varying bandwidths, six of which are at similar wavelengths to those on heritage missions to support both atmospheric and ocean color applications [2].…”

Section: Introductionmentioning

confidence: 99%

Measurement techniques for the high-contrast and in-field stray light performance of OCI

Knuble,

Meister,

Choi

et al. 2023

Sensors, Systems, and Next-Generation Satellites XXVII

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Scheduled for launch in January 2024, the PACE mission represents NASA’s next investment in ocean biology, clouds, and aerosol data records. A key feature of PACE is the inclusion of an advanced satellite radiometer known as the Ocean Color Instrument (OCI), a global mapping radiometer that combines multispectral and hyperspectral remote sensing. A critical requirement for OCI is the high-contrast or spatial crosstalk specification (also referred to as in-field stray-light response). The requirement states that for global top-of-atmosphere radiances based on measured MODIS radiances, the global average residual contamination shall be less than 0.4% for 350 nm, 360 nm, 385 nm, 555 nm, 583 nm, 820 nm and 865 nm and less than 0.20% for all other multispectral bands. Accurate resolution of high contrast in TOA radiance images is important to estimate stray light contamination due to clouds, for studying small scale features like ocean fronts and for working in coastal and estuarine areas where the scales are 1km. This occurs in all wavelengths in the spatial direction. Knowledge of high contrast resolution makes up part of the artifact budget. Accurate measurement of the high-contrast performance of OCI requires laboratory Ground Support Equipment (GSE) that projects a scene of sufficient quality that the unwanted stray light of the GSE itself is not confused with the stray light response of the telescope. This paper concerns the development, analyses and test of the GSE to ensure the quality of the projected image is sufficient to verify the OCI requirements. Optical models were developed for both the instrument as well as the GSE and laboratory environment. Simulation of various non-ideal parameters were critical to accurately predict performance. Measurements using COTS cameras and lenses were also made of the projected GSE image to reasonably verify the optical model predictions. Measured and modelled results from OCI are discussed.

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“…1. The PACE project science team has completed the prelaunch calibration and characterization test campaign 4,5 of OCI in preparation for the January 2024 launch of the mission. This paper discusses the thermal response of OCI, as characterized during the thermal vacuum testing of the instrument.…”

Section: Introductionmentioning

confidence: 99%

“…Additional temperature cycles were performed for other instrument elements during the thermal vacuum testing of the OCI Engineering Test Unit which did not show any temperature dependencies, so were not duplicated during the flight instrument testing. 6 The temperature sensitivities were measured by having OCI observe a constant radiance source while the temperatures of the instrument components were varied. The radiance source was monitored for drift over the test by a reference radiometer.…”

Section: Introductionmentioning

confidence: 99%

Prelaunch radiometric calibration of the thermal response of the PACE Ocean Color Instrument

Eplee,

Meister,

Lee

et al. 2023

Earth Observing Systems XXVIII

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The NASA Plankton, Aerosol, Cloud, and ocean Ecosystem (PACE) mission Ocean Color Instrument Team has completed the prelaunch radiometric characterization of the thermal response of the Ocean Color Instrument (OCI). The radiometric performance of the ultraviolet to visible (UVVIS) and visible to near-infrared (VISNIR) grating spectrographs and the shortwave-infrared (SWIR) filter spectrograph of OCI were characterized during the thermal vacuum testing of the instrument conducted in September and October of 2022. The thermal characterization test program will be outlined, along with the derived radiometric dependencies on temperature. For the UVVIS and VISNIR spectrographs, the change in radiometric response with temperature is consistent with theoretical models of the measured detector performance and is on the order of 0.15 % per • C. For the SWIR spectrograph, the change in radiometric response with temperature in on the order of 0.04 % per • C. For the UVVIS spectrograph, uncertainties in the radiometric measurements as the detector temperatures varied by ∼ 10 • C were less than 0.15 % for wavelengths of 350 − 593 nm. For the VISNIR spectrograph, uncertainties were less than 0.11 % for wavelengths of 625 − 867 nm. For the SWIR spectrograph, the typical uncertainties were less than 0.15 % for all bands. Since the expected temperature range for the instrument on orbit is 0.5 • C, OCI meets the design goals for upper limits on radiometric uncertainties due to thermal effects.

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Test Results From the Prelaunch Characterization Campaign of the Engineering Test Unit of the Ocean Color Instrument of NASA’s Plankton, Aerosol, Cloud and Ocean Ecosystem (PACE) Mission

Cited by 17 publications

References 27 publications

PACE OCI crosstalk characterization based on pre-launch testing

PACE OCI crosstalk characterization based on pre-launch testing

Measurement techniques for the high-contrast and in-field stray light performance of OCI

Prelaunch radiometric calibration of the thermal response of the PACE Ocean Color Instrument

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