Newly developed high-strength reaction-sintered silicon carbide is an attractive material for lightweight optical mirror with two times higher bending strength than other SiC materials. The polished surface has no pore and is suited to visible region as well as infrared without CVD SiC coating. The fabrication process, with low temperature and small shrinkage, is also suited to develop large scale objects.
Fast and small foot print lossless image compressors aiming at hyper-spectral sensor for the earth observation satellite
have been developed.
Since more than one hundred channels are required for hyper-spectral sensors on optical observation satellites, fast
compression algorithm with small foot print implementation is essential for reducing encoder size and weight resulting in
realizing light-weight and small-size sensor system. The image compression method should have low complexity in
order to reduce size and weight of the sensor signal processing unit, power consumption and fabrication cost. Coding
efficiency and compression speed enables enlargement of the capacity of signal compression channels, which resulted in
reducing signal compression channels onboard by multiplexing sensor signal channels into reduced number of
The employed method is based on FELICS1, which is hierarchical predictive coding method with resolution scaling. To
improve FELICS's performance of image decorrelation and entropy coding, we applied two-dimensional interpolation
prediction and adaptive Golomb-Rice coding, which enables small footprint. It supports progressive decompression
using resolution scaling, whilst still delivering superior performance as measured by speed and complexity.
The small footprint circuitry is embedded into the hyper-spectral sensor data formatter. In consequence, lossless
compression function has been added without additional size and weight.
The hyper-multi spectral mission named HISUI (Hyper-spectral Imager SUIte) is the next Japanese earth observation
project that will be on board ALOS-3 satellite. This project is the follow up mission of the Advanced Spaceborne
Thermal Emission and reflection Radiometer (ASTER). HISUI is composed of hyperspectral radiometer with higher
spectral resolution and multi-spectral radiometer with higher spatial resolution. The functional evaluation model is under
development to confirm the spectral and radiometric performance prior to the flight model manufacture phase. This
model contains the VNIR and SWIR spectrograph, the VNIR and SWIR detector assemblies with a mechanical cooler
for SWIR, signal processing circuit and on-board calibration source.
In order to characterize the pre-launch performance of
Thermal And Near infrared Sensor for carbon Observation
Fourier-Transform Spectrometer (TANSO-FTS) and Cloud and Aerosol Imager (TANSO-CAI) on the Green house
gases Observing SATellite (GOSAT) under the environmental condition on orbit as well as in the laboratory, the Proto
Flight Model (PFM) for TANSO-FTS and CAI have been developed. TANSO-FTS has three narrow bands of 0.76, 1.6
and 2.0 micron (Band 1, 2 and 3) with +/-2.5cm maximum optical path difference, and a wide band of 5.5 - 14.3 micron
(band 4) in thermal near infrared region. TANSO-CAI is a radiometer for detection and correction of clouds and aerosol
effects which might degrade the column concentration retrieval of CO<sub>2</sub> and CH4. It has four spectral band regions;
ultraviolet (UV), visible, near IR and SWIR.
The basic character of TANSO-FTS and CAI, such as the Signal to Noise Ratio (SNR), the polarization sensitivity
(PS), Instantaneous Field Of View (IFOV), spectral response, and also Instrumental Line Shape Function (ILSF)
have been characterized by introducing the light emitted from the black body, halogen lamp and the tunable diode laser.
In addition to these characterizations, micro vibration effect on orbit has been investigated on TANSO-FTS. There prelaunch
test results demonstrated that TANSO will provide data for high accuracy CO<sub>2</sub> and CH<sub>4</sub> retrieval on orbit.
TANSO-FTS (Thermal And Near infrared Sensor for carbon Observation Fourier Transform Spectrometer) and
TANSO-CAI (Cloud and Aerosol Imager) are a space-born optical sensor system mainly oriented for observation of
greenhouse gases (GHGs). TANSO will be installed on the Greenhouse gases Observing SATellite "GOSAT" and
launched in early 2009. The TANSO-FTS is a Fourier transform spectrometer which has 3 SWIR bands (0.76, 1.6 and
2.0 μm) and 1 TIR band (5.5 - 14.3 μm) for observation of scattering light and thermal radiation from the earth, mainly
focused on CO<sub>2</sub> absorption spectra. The TANSO-CAI is an imager for detection and correction of clouds and aerosol
effects to determine GHGs quantities. The instrument characteristics of TANSO-FTS are high SNR (~300), quick
interferogram scan (1.1 ~ 4.0 s) with moderate wave-number resolution (~0.2 cm<sup>-1</sup>), and polarization measurement. Now,
integration and test of proto-flight model of TANSO have been completed. In this paper, the results of performance test
such as SNR, ILS, polarization sensitivity, etc. are described.
Newly developed high-strength reaction-sintered silicon carbide, called New-Technology Silicon Carbide (NT-SiC) is an attractive material for lightweight optical mirror with two times higher bending strength than other SiC materials. The material has advantages in its fabrication process. The sintering temperature is significantly lower than that of pure silicon carbide ceramics and its sintering shrinkage is smaller than one percent. These advantages will provide rapid progress to fabricate large structures. The characteristics of the material are also investigated. The polish of the test piece demonstrated that the polished surface has no pore and is suited to visible region as well as infrared without CVD SiC coating. It is concluded that NT-SiC has potential to provide large lightweight optical mirror.
The Ocean Color and Temperature Scanner (OCTS) is a piece of observation equipment that measures ocean color and temperature from a scientific satellite. The OCTS is equipped with two focal plane assemblies: one observes ocean color in the range of visible to near infrared, and the other measures ocean temperature in the infrared region. We report here results of the so-called break boad model of the latter focal plane assembly. This focal plane assembly contains four infrared detectors that are cooled to 100 K by radiational cooling. We have evaluated this cooled focal plane assembly, and have confirmed that it has satisfied such NEP (noise equivalent power) values, registration accuracy and power consumption as are required in view of the OCTS performance characteristics.
Design of the OCTS, a high-precision remote-sensing instrument for NASDA's Advanced Earth Observing Satellite (ADEOS) for simultaneous measurements of the ocean color and sea-surface temperatures, is presented. The OCTS uses a rotating mirror to scan a swath of the earth 1400 km wide from sun-synchronous orbit at 800 km altitude. It is planned to be placed into orbit in 1995 to provide 3 Mbps image data for visible to thermal infrared spectral range, in 12 bands.