Search

Hyperspectral Imager Suite (HISUI) is a hyperspectral sensor for a remote sensing on the International Space Station (ISS). HISUI is composed of one radiometer that obtains spectral images of 185 bands from the visible to shortwave-infrared region with the ground sampling distance (GSD) of 20 meters for the cross track and 31 meters for the along track. The sensor system is the follow-on mission of the Advanced Space-borne Thermal Emission and Reflection Radiometer (ASTER) in the visible to shortwave infrared region. The observation data of the hyperspectral sensor is expected to an important role in the future spatial-spectral data for the resource exploration, disaster monitoring, environmental observation, agriculture, forestry and fisheries, etc. The tests of a flight model of HISUI have been carried out successfully in 2019 and HISUI is operating on the ISS. This paper describes the design and the performances of the flight model of HISUI and also presents radiometric performances in orbit.

Hyperspectral Imager Suite (HISUI) was launched on Dec. 5, 2019 and successfully attached to Japan Experiment Module Exposed Facility, International Space Station. Currently, initial check out activities are ongoing, and the first light images will be released around August, 2020. The distribution of HISUI Level 1 products will be started in the first half of 2021.

The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is a high spatial resolution optical sensor for observing the Earth carried on the National Aeronautics and Space Administration Terra satellite. ASTER consists of three radiometers covering the following regions: visible and near-infrared (VNIR), shortwave infrared (SWIR), and thermal infrared (TIR). The preflight calibration of VNIR and SWIR utilized standard large integrating spheres whose radiance levels were traceable to primary standard fixed-point blackbodies. The onboard calibration devices for the VNIR and SWIR consist of two halogen lamps with photodiode monitors. In orbit, all three bands of the VNIR showed rapid decreases in the output signal while all SWIR bands remained stable. The TIR onboard blackbody was calibrated against a standard blackbody from 100-400 K in a vacuum chamber before launch. The TIR is unable to see the dark space. The temperature of the TIR onboard blackbody remains at 270 K for a short-term calibration to determine any offset and is varied from 270-340 K for a long-term calibration of both the offset and gain. The long-term calibration just after launch was consistent with the prelaunch calibration but then showed a steady decrease of the TIR response over the five years of operation to date.

Hyper-spectral Imager Suite (HISUI) is a next-generation Japanese sensor that will be on board in 2016 or later. HISUI is composed of two radiometers; one is a hyperspectral imager that obtains spectral images of 185 bands with the ground sampling distance 30 meters from visible to shortwave-infrared region, and the other is a multispectral imager that covers the wide swath of 90 km with the ground sampling distance of 5 meters[1]. The sensor system is the follow-on mission of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) in the visible and shortwave-infrared regions [2]. Synergic operation of these instruments acts an important role in the future spectral-spatial data. Simultaneously, the key components of the flight model are being developed. The design of flight model reflected from the test result of evaluation model as well as the development status of flight model is reported in this work.

The ASTER is a high-resolution optical sensor for observing the Earth on the Terra satellite launched in December1999. The ASTER consists of three radiometers. The VNIR has three bands in the visible and near-infrared region, the SWIR has six bands in the shortwave infrared region, and the TIR has five bands in the thermal infrared region. The onboard calibration devices of the VNIR and SWIR were halogen lamps and photodiode monitors. In orbit three bands of the VNIR showed a rapid decrease in the output signal. The band 1, the shortest wavelength, decreased most to 70% in twelve years. The temperature of the onboard blackbody of the TIR is varied from 270 K to 340 K in the long term calibration for the offset and gain calibration. The long term calibration of the TIR showed a decrease in response after launch. The decrease was most remarkable at band 12 decreasing to 60% in eleven years. The degradation spectra of the TIR shows that the possible causes of the degradation might be silicone and hydrazine. ASTER onboard calibration is normally carried out once in 49 days but additional onboard calibrations were added just before and after the inclination adjustment maneuver (IAM) to check the effect on the RCC. This experiment was carried out three times for each IAM in the fiscal year 2011. The result showed that the change in the RCC was small for both VNIR and TIR.

The ASTER Instrument is one of the five sensors on the NASA’s Terra satellite on orbit since December 1999. ASTER consists of three radiometers, VNIR, SWIR and TIR whose spatial resolutions are 15 m, 30 m and 90 m, respectively. Unfortunately SWIR stopped taking images since May 2008 due to the offset rise caused by the detector temperature rise, but VNIR and TIR are taking Earth images of good quality. VNIR and TIR experienced responsivity degradation while SWIR showed little change. Band 1 (0.56 μm) decreased most among three VNIR bands and 30 % in twelve years. Band 12 (9.1 μm) decreased 40 % and most among five TIR bands. There are some discussions of the causes of the responsivity degradation of VNIR and TIR. Possible causes are contamination accretion by silicone outgas, thruster plume and plasma interaction. We marked hydrazine which comes out unburned in the thruster plume during the inclination adjust maneuver (IAM). Hydrazine has the absorption spectra corresponding to the TIR responsivity degradation in the infrared region. We studied the IAM effect on the ASTER by allocating the additional onboard calibration activities just before and after the IAM while the normal onboard calibration activity is operated once in 49 days. This experiment was carried out three times in fiscal year 2011.

Hyperspectral Imager Suite (HISUI) is a next-generation Japanese optical sensor that is composed of a hyperspectral imager and a multispectral imager. Combination of hyperspectral and multispectral imagers contributes land remote sensing with high spectral and spatial resolution. Validation of the HISUI evaluation model, including environmental test such as vibration test and thermal-vacuum test has been carried out to meet the science requirements on the sensor under the space-borne conditions. Major performances of the sensors are obtained. Spectral response of each band of the hyperspectral sensor, distortions in a spectrometer in terms of smile and keystone properties, are investigated. The test results of the evaluation model show appropriate performance of the sensors.

Hyperspectral Imager Suite (HISUI) is a next-generation Japanese optical sensor that is composed of a hyperspectral imager and a multispectral imager, which will be launched on Advanced Land Observation Satellite 3 (ALOS-3). Combination of hyperspectral and multispectral imagers contributes land remote sensing with high spectral and spatial resolution. Calibration of the HISUI functionalequivalent model has been carried out to meet the science requirements on the sensor. A center wavelength and spectral response of each band of the hyperspectral sensor is obtained, from which distortions in a spectrometer in terms of smile and keystone properties are investigated. The results of the calibration activity for the functionalequivalent model show appropriate performance of the sensors.

The hyperspectral and the multispectral (hyper-multi spectral) mission is the Japanese next generation space-borne radiometer development project. This project is a heritage from ASTER launched in December 1999. The performance of the hyperspectral radiometer is 30m ground sampling distance, 30km swath width, 10nm and 12.5nm wavelength distance for VNIR and SWIR respectively, over 450@620nm and 300@2,100nm of the signal to noise (S/N) ratio. The performance of the multispectral radiometer is 5m ground sampling distance, 90km swath width, over 200 for all bands of S/N ratio. This project will be launched on ALOS-3 of JAXA in FY2014. The panchromatic sensor with stereo viewing will also be installed on ALOS-3.

The ASTER is a high-resolution optical sensor for observing the Earth on the Terra satellite launched in 1999. The ASTER consists of three radiometers, the VNIR in the visible and near-infrared region, the SWIR in the shortwave infrared region, and the TIR in the thermal infrared region. The on-board calibration devices of the VNIR and the SWIR were two halogen lamps and photodiode monitors. In orbit three bands of the VNIR showed a rapid decrease in the output signal while all SWIR bands remained stable. The TIR has one on-board blackbody and is unable to see the dark space. Therefore the temperature of the on-board blackbody of the TIR remains at 270 K in the short-term calibration for the offset calibration, and is varied from 270 K to 340 K in the long term calibration for the offset and gain calibration. The long term calibration showed a decrease of the TIR response in orbit. The radiometric calibration coefficients of the VNIR and the TIR were fit to smooth functions.