It is known that suspended particles accrete on surfaces of a satellite through its assembly, check, and storage phases. Particulate contaminants cause masking and scattering of incident light at optical surfaces and lead to the degradation of radiometric accuracy of optical sensors. Especially in the visual and infrared wavelengths, optical characteristics of the sensor is largely affected with the particulate contamination since the size of suspended particles are as large as the observational wavelengths. However, we have not had enough information about the influence of particulate contamination in the visual and infrared range. In this study, we measured the correlation between the area coverage and the surface cleanliness level as the first step of the contamination control. We adopted JIS powder sample as contaminants and measured the number and the area coverage of contaminants by a scanning laser microscope. The area coverage was measured in the range of the cleanliness level from 200 to 1, 000 and against two kinds of particle size distributions. It was found that cleanliness level 350 corresponded to 0.1% area coverage and 550 to 1%. Moreover, it was found that the area coverage might be changed by about three times owing to the difference of particle size distributions. We also compared the area coverages of particular contamination monitors set in the 2nd satellite assembly building at Tanegashima Space Center with our results from the laboratory experiments and found that both results were almost the same and the particle size of 15, um made the largest contribution to the area coverage.

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We study the method of atmospheric correction of AVHRR images, with a particular emphasis placed on the aerosol effects. First, the correction of molecular effect is examined by comparing the difference between the reflectances obtained using the 6S model profile and the observed atmospheric profile. Since the ozone amount observed in winter is considerably less than that in the winter model, the tropical model with small ozone amount is selected as an optimum model. Therefore, observed atmospheric parameters of temperature, atmospheric pressure, ozone amount, and water vapor content are employed in the analysis of the aerosol effect. The atmospheric correction is first carried out in terms of the ground visibility, and the accuracy of the correction is examined for ocean, urban and forest areas. For the ocean areas, the process yields negative values of the reflectivity, indicating an overcorrection. Then, the relationship among the ground visibility, aerosol optical thickness, and the 6S model profile is examined. It turns out that when the optical thickness is computed from the visibility using the 6S code, the resulting value is twice as much as the observed value. This indicates that in order to carry out the atmospheric correction with a good precision, it is necessary to estimate good aerosol models and optical thickness from the ground level to the top of the atmosphere. Thus, in a second approach, we investigate the possibility of atmospheric correction using the bimodal, lognormal distributions with accumulation and coarse particle modes. Size distributions are estimated from sea area images. After the atmospheric correction, the results are quite reasonable for dark pixels such as the forest areas, while improvements are still needed for highly reflective pixels.

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Scaling relation of craters indicates that the lunar central peak material can be related to the lower crust of the moon. Craters, ranging in diameter from 40 to 180 km, are believed to have exhumed material from 5-30 km beneath the surface to form the peaks. Therefore, the craters which have central peaks are selected as probable candidates for a landing site in the future Japanese lunar mission. Tompkins and Pieters (1999) investigated the central peaks of 109 impact craters across the Moon and classified lithologies of central peaks into eleven kinds of plutonic rocks using Clementine UVVIS five-color spectra.
In order to verify the estimated lithologies, influences of space weathering, photometric condition, and quenched glass phase on the estimation were examined by detailed spectral data analysis. The relation between crater diameter and central peak lithologies was also examined.
As a result, we conclude that the estimated mafic lithologies at the sunny side of central peaks are probable. Aristillus, Bhabha, Birkeland, Bose, Bullialdus, Finsen, Fizeau, Jackson, King, Maunder, Stevinus, Tsiolkovskiy, Tycho, Vitello, White, and Zucchius are suitable sampling sites for finding lower crust rocks among 109 central-peak craters. Additionally, we searched out olivine bearing lithologies at the central peaks. The central peaks of Jackson and Tsiolkovsky were regarded as suitable sampling sites for finding olivine bearing lithologies among 109 craters. Strange crater walls, which have more mafic lithologies than their central peaks, were found in Aristarchus, Burg, and Plinius. They suggest the existence of an unknown factor which changes the spectral properties to be more mafic.

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An influence due to supume particle of relatively large size of non-spherical aerosols containing bubbles on the Top of the Atmosphere (ToA) radiance estimation is clariified by using the method based on ray tracing, geometric approximation.
The size of supume particle of aerosol is assumed to be 10μm while that of bubbles ranges from 0 to 5μm. Th non-spherical ratio of aerosol is assumed to be c/a=0.456, 0.716, 1.0, 1.482 and 2.024 where a and c are the minor and the major axis.
It is found that the influences due to supume aerosol on the ToA radiance ranges from 3.2% to 14.6%. It is also found that the influences due to bubbles on the ToA radiance is about 4.7% in the case of spherical aerosol particles and ranges from about 1.4% to 2.9% in the case of non-spherical aerosol particles which depends on the ratio of c/a.

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This paper proposes a new method for temperature and emissivity separation using the multi-band radiometer (MBR) which has five narrow bands and one broad band in the thermal infrared region. Temperature and emissivity separation has difficult problem because there are N measurements but N+1 unknowns. Various approaches have been used to solve this problem, but all approaches require assumptions. The proposed algorithm, we call MBR TES, uses multiple data-sets acquired for the same target at different temperatures, so it can decrease the number of unknowns than the number of measured radiance. In this algorithm, MBR TES, temperature and spectral emissivity are determined by the optimization of the over-determined simultaneous equations. MBR TES was applied to simulated and actual data to evaluate its accuracy. The simulation results show that MBR TES retrieve the emissivity error within the range of about±0.015 (1σ) and the temperature error within the range of about ±0.5K (1σ). MBR TES was also applicable to the actual data obtained at Hawaii and Stonewall Playa too. Furthermore, we validated ASTER TES algorithm using the established MBR TES emissivity at Railroad Valley and Salton Sea. Consequently, the reliability of ASTER TES was shown.

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An assembly, test, and storage of a satellite are carried out in a clean-room to suppress performance degradation of a satellite by particulate accretion. The advanced earth observing satellite 2 (ADEOS-II) was stored in the clean-room at Tanegashima Space Center for 15 months before its launch and the particulate accretion was monitored using collector mirrors during the storage phase of ADEOS-Il. In this study, the chemical composition analysis was performed for the particulate samples on the collector mirrors by an electron-probe micro-analyser. Organic elements, CNO, were remarkably detected and heavy metals, Ti, Cr, Ni, Cu, and Zn, were also detected on a significant level for the samples collected inside the cleanroom. On the other hand, Na, Mg, Ca, Cl, S, and 0, which were the elements of sea salt and/or soil, were detected for the aerosol samples collected under the outdoor environment. Since the chemical compositions between the samples of inside and outside of the cleanroom were clearly different, the sources of suspended particulates inside the cleanroom were ascribed to those inside the cleanroom. Especially, the 70% of analyzed particles collected inside the cleanroom was possible to be classified as particles generated from human bodies and 11 % was classified as fibers.

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The modified cosine correction of topographical effects, which subtracts an offset component before applying the cosine law of solar incidence angle, seems to work well for satellite images with high sun elevation and with high geometric accuracy. The adequate offset component for the correction, however, tend to be bigger than we expect from the radiative transfer simulation, in particular for infrared bands. In this paper, we improve the modified cosine correction by introducing C factor which corresponds to the amount of diffuse sky irradiance and reflected irradiance from adjacent slopes. Although the C factor is assumed to be a constant in conventional C correction, we calculate the diffuse sky irradiance and reflected irradiance for each pixel using digital elevation model. We apply this method to the actual Landsat image (Band 5) to show its effectiveness.

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