Yoshihiko Okamura

Development of the Compact InfraRed Camera (CIRC) for wildfire detection

The Compact InfraRed Camera (CIRC) is a technology-demonstration payload to be carried on the Small Demonstration Satellite type-2 (SDS-2). The SDS program is a JAXA activity to demonstrate a variety of new technologies and new missions. The CIRC is an infrared camera equipped with an uncooled infrared array detector (microbolometer). The mission of the SDS-2/CIRC project is to demonstrate the potential of the microbolometer, especially for wildfire detection but also for other applications. This paper introduces the detailed design and concept of CIRC. We also discuss preliminary results of the feasibility study on wildfire detection using thermal infrared images.

The radiation tolerance of chalcogenide glasses

Chalcogenide glasses are compounded from chalcogen elements, such as sulphur, selenium, and tellurium. These glasses are applied to commercial applications, e.g., night vision, because they transmit infrared in the spectral range of 0.8-16μm. Chalcogenide glasses have greater advantages over germanium (Ge), i.e., their wide spectral range of high transmissivity and their small temperature dependence of the refractive index. We have developed the Compact Infrared Camera (CIRC) with an uncooled infrared array detector (microbolometer) for space applications. The CIRC has been scheduled to launch in 2013 to demonstrate the usability of a microbolometer as a space application. The optics of the CIRC adopts two different kinds of materials for athermal optics. One is germanium, and the other is GASIR1® which is a chalcogenide glass (Ge22As20Se58) developed by Umicore. However, the radiation tolerance of GASIR® has not been investigated in the past. We carried out irradiation tests to investigate the radiation tolerance of GASIR1®. We irradiated GASIR1® with gamma-rays (Co60, 1.17 MeV and 1.33 MeV) up to 3Mrad. We measured the transmissivity and refractive index in the infrared range before and after irradiation. In this paper, we report the results of the irradiation tests of GASIR1®.

Design challenge on forthcoming SGLI boarded on GCOM-C

The Japan Aerospace Exploration Agency (JAXA) has the plan of the Global Change Observation Mission (GCOM) for monitoring global environmental change. Second generation Global Imager (SGLI) is a mission instrument to be installed on the satellite of GCOM Mission Climate (GCOM-C) satellite. SGLI is the optical radiometer observed to the frequent Global, Ocean, Land, Cloud and Ice sphere to help determine the Earths climate change. SGLI is a suite of two radiometers called VNR and IRS. The VNR is employing a wide swath (1150km) push-bloom scan with line CCD detector. IRS is employing a conventional cross-track mirror scan system (1400km swath) with cooled infrared detector. We report the SGLI preliminary design and special feature. The current SGLI is BBM development phase which is underway to confirm the feasibility of the design.

Development of the WAMS-TIR instrument for SPF-II

Wide-Angle Multi-band Sensor - Thermal Infrared (WAMS-TIR), one of the three sensors aboard the station-keeping test airship (SPF-II) for the stratospheric platform project, is a thermal infrared multi-band radiometer designed to observe land surface temperature. WAMS-TIR consists of very wide field-of-view (over 100 deg) optics and an uncooled microbolometer array detector. It has band-pass filters mounted on a rotating wheel to select spectral bands in the range of 7 to 12 microns. A blackbody calibrator is also mounted on the same rotating wheel to calibrate sensor performance in the operation. Results of pre-flight performance tests suggest that WAMS-TIR has the predicted image quality and high radiometric performance. This paper describes the instrument design and the performance tests results of WAMS-TIR.

Development status of the Second-Generation Global Imager (SGLI) on GCOM-C

The Second-generation Global Imager (SGLI) on the Global Change Observation Mission (GCOM) is a multi-band imaging radiometer in the wavelength range of near-UV to thermal infrared. SGLI will provide high accuracy measurements of Ocean, Atmosphere, Land and Cryosphere. SGLI project successfully completed its Bread Board Model (BBM) evaluation last year and currently under Engineering Model (EM) development phase. This paper describes current development status of the SGLI instrument.

Operation concept of the second-generation global imager (SGLI)

The Second-generation Global Imager (SGLI) on the Global Change Observation Mission (GCOM) is a multi-band optical imaging radiometer in the wavelength range from near-UV to thermal infrared. SGLI will provide high accuracy measurements of Ocean, Atmosphere, Land and Cryosphere. SGLI will provide the global scale multi spectral data with about 2 days frequency. The observation data over the land area is 250m resolution with more than 1000km swath, and the ocean area in 1km resolution. SGLI also has a unique tilting data to realize the directional polarized observation with red and near infrared wavelength. This paper describes the operation concept and current status of the SGLI instrument development.

In-orbit commissioning activities results of GCOM-C /SGLI

The Japan Aerospace Exploration Agency (JAXA) is pressing forward with Global Change Observation Mission (GCOM) for long-term monitoring of earth environment. GCOM consists of two series of medium-size satellites, GCOM-W (Water) and GCOM-C (Climate). The first satellite, GCOM-W with Advance Microwave Radiometer -2 (AMSR-2), was already launched in 2012 and has been observing continuously. GCOM-C which carries the optical radiometer, Second Generation Global Imager (SGLI), was launched on December 23, 2017. SGLI observation data will produce more than 20 scientific products such as cloud, aerosol, ocean color, vegetation, ice field and so on, and will contribute to improve the understanding of the global mechanism of carbon cycle and radiation budget. SGLI includes two radiometer units of Visible and Near Infrared Radiometer (VNR) and Infrared Scanning Radiometer (IRS), which perform a wide-spectral (380 nm-12 μm) optical observation with relatively high (250 m) spatial resolution. After the launch, the satellite and SGLI instruments were initialized and commissioned for routine operations during a threemonth period called in-orbit checkout. SGLI-VNR performance tests included internal light calibration, solar diffuser calibration, dark signal calibration and electrical calibration. In addition to that, solar angle correction maneuvers were performed within L+2 weeks and lunar calibration maneuvers were performed each synodic period. 90-deg. yaw maneuvers were also performed. In this paper, the in-orbit commissioning activities of SGLI-VNR will be described. Especially we focus on the internal light calibration and solar diffuser calibration results during a commissioning phase.

Pre-launch instrument characterization results and in-orbit verification plan of GCOM-C/SGLI

The Global Change Observation Mission (GCOM) aims to establish and demonstrate a global, long-term satelliteobserving system to measure essential geophysical parameters to facilitate understanding the global water circulation and climate change, and eventually contribute to improving future climate projection through a collaborative framework with climate model institutions. GCOM consists of two polar orbiting satellite observing systems, GCOM-W (Water) and GCOM-C (Climate). The first satellite, GCOM-W with Advance Microwave Radiometer -2 (AMSR-2), was already launched in 2012 and has been observing continuously. The follower satellite, GCOM-C with Second Generation Global Imager (SGLI), will be launched in Japanese fiscal year 2017. SGLI enables a new generation of operational moderate resolution-imaging capabilities following the legacy of the GLI on ADEOS-II (Advanced Earth Observing Satellite-II) satellite. The SGLI empowers surface and atmospheric measurements related to the carbon cycle and radiation budget, with two radiometers of Visible and Near Infrared Radiometer (VNR) and Infrared Scanning Radiometer (IRS) which perform a wide-band (380nm-12μm) optical observation not only with as wide as 1150-1400km FOV (field of view) but also with as high as 250-500m resolution. Also, polarization and along-track slant view observation are quite characteristic of SGLI, providing the sensor data records for more than 28 standard products and 23 research products including clouds, aerosols, ocean color, vegetation, snow and ice, and other applications. Sensor instrument proto-flight tests including optical characterization tests such as radiometric and geometric were completed, and satellite system proto-flight tests have finished including thermal vacuum, vibration and acoustic test. In this paper, the pre-launch phase instrument characterization of SGLI flight model and status of GCOM-C satellite system flight model along with the overview of them will be described. Especially we focus on the pre-launch geometric and radiometric performance test results, in-orbit calibration activities and methodologies: VNRs on-board calibrator, IRSs on-board calibrator and calibration maneuver, and in-orbit verification plan during a commissioning phase lasting approximately 3 months.

Design and breadboarding activities of the second-generation Global imager (SGLI) on GCOM-C

The Global Change Observation Mission (GCOM) is the next generation earth observation project of Japan Aerospace Exploration Agency (JAXA). GCOM concept will take over the Advanced Earth Observing Satellite-II (ADEOS-II) and develop into long-term monitoring of global climate change. The GCOM observing system consists of two series of medium size satellites: GCOM-W (Water) and GCOM-C (Climate). The Second-generation Global Imager (SGLI) on GCOM-C is a multi-band imaging radiometer with 19 spectral bands in the wavelength range of near-UV to thermal infrared. SGLI will provide high-accuracy measurements of Ocean, Atmosphere, Land and Cryosphere. These data will be utilized for studies to understand the global climate change, especially human activity influence on earth environments. SGLI is a suite of two radiometers called Visible and Near Infrared Radiometer (VNR) and Infrared Scanner (IRS). VNR is a pushbroom-type radiometer with 13 spectral bands in 380nm to 865nm range. While having quite wide swath (1150km), instantaneous field of view (IFOV) of most bands is set to 250m comparing to GLI’s 1km requirement. Unique observation function of the VNR is along-track ±45deg tilting and polarization observation for 670nm and 865nm bands mainly to improve aerosol retrieval accuracy. IRS is a wiskbroom-type infrared radiometer that has 6 bands in 1μm to 12μm range. Swath and IFOV are 1400km and 250m to 1km, respectively. This paper describes design and breadboarding activities of the SGLI instrument.

Radiometric performance of Second-generation Global Imager (SGLI) using integrating spheres

Second-generation Global Imager (SGLI) has a multi-channel in the wavelength range from near-UV to thermal infrared. SGLI consists of two sensor units, Visible and Near Infrared Radiometer (VNR) and Infrared Scanning Radiometer (IRS). We use three integrating spheres for each wavelength range in radiometric tests. The materials of inside wall of sphere are polytetrafluoroethylene (PTFE) and barium sulfate for ultraviolet-visible to near infrared channels, and gold for shortwave infrared channels, respectively. This paper describes the Proto Flight Model (PFM) radiometric performance using these integrating spheres.