Earth observation from the Stratospheric Platform (SPF) has several advantages over traditional airborne or spaceborne observations. Primarily, SPF can continuously monitor a specific area with higher spatial resolution over a longer period of time. We have developed the Earth Observation System for SPF-II (EOSS) for examining the feasibility of observation missions from the SPF and for demonstrating some sensor technologies. EOSS consists of three sensors: Wide-Angle Multi-band Sensor - Visible and Near-Infrared (WAMS-VNIR) for observation of vegetation and aerosol; Wide-Angle Multi-band Sensor - Thermal Infrared (WAMS-TIR) for monitoring distribution and time variation of land surface temperature; and High Resolution Sensor (HRS) for traffic observation. Observation mission tests were performed in October and November 2004. This paper describes the development of the sensor instruments and the results of SPF-II's Earth-observation mission.
Wide-Angle Multi-Band Sensor-Visible and Near Infrared (WAMS-VNIR) has been developed as an Earth-observation mission instrument for SPF-II. SPF-II is a step toward the realization of Stratospheric Platform (SPF) using airships; it is capable of station-keeping flight at an altitude of 4km. WAMS-VNIR is a STARING multi-spectral imaging radiometer and polarimeter with five bands in wavelengths of 500 to 1000nm. WAMS-VNIR has optics of a 110° FOV, two rotating filter wheels, and a 1280 × 1024 pixel Si-CCD FPA. The wide field-of-view optics enable observing an 8km area even from an altitude of 4km. Five narrow-band spectral filters are installed on a rotating wheel, and two polarizers are installed on another rotating wheel. The polarizers rotate around the optical axis separately from the rotation of the wheel, providing several advantages in polarization measurement. The sensor system was completed and performance checks are being conducted. This paper introduces the sensor system and its performance.
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.
Air-OPUS is a hyper spectral imaging spectrograph, with 0.34 nm spectral step, 190-455 nm spectral coverage, and 330 spatial channels covering 15 degrees field of view (FOV). It is designed as an airborne instrument for the demonstration of spaceborne-OPUS. After two-demonstration campaign using the Gulfstream-II aircraft, the performances of AIR-OPUS, such as spectral resolution, signal-to-noise ration (SNR) have been evaluated. It is concluded that the performances have agreed with designed value. This paper describes design, the performance, and the first results of Air-OPUS. Concept of next generation Air-OPUS, with wider FOV and visible/near-IR spectral coverage, will be also briefly presented.
Stratospheric Platform (SPF) project is an enterprize to develop
an airship to float at the altitude of 20 km for the use of
earth observations and telecommunications. SPF-II is one of the
steps toward realizing SPF to examine the stabilized flight of
an airship at the altitude of 4 km, and is planned to be aloft
in 2004. The earth observatoin facility on SPF-II will consist of three sensors: a visible-near infrared (VIS-NIR) sensor for the wavelength region 500 -- 1000 nm, a thermal infrared (TIR) sensor, and a trafic-monitoring sensor. In this paper, we present an outline
of VIS-NIR and TIR sensors. The VIS-NIR and TIR sensors are planned as wide field (110 degree) imagers with 2-dimensional FPAs. Polarizetion will be measured with the VIS-NIR sensor. FOV of the VIS-NIR sensor is to be 8 km square at the footprint, and horizontal resolution to be 8 m with a 1280 × 1024 pixel Si-CCD FPA.
The TIR sensor adopts an uncooled 320 × 240 pixel bolometer array, and has a FOV of 8 km × 6 kmsquare at the footprint, with horizontal resolution of 25 m. It covers three wavelength bands of 8.5, 10.8, and 12.0 μm with the filter wheel device.