*********** 081293B.SAT *********** Contributory Categories: BIO, CHM, ENV, MET, PHY Country: Japan From: ADEOS Proposal Letter JNASDA KEYWORDS: Japan, Opportunity Notice, Remote Sensing +++++ Part II/III Appendix-C 1. ADEOS Development Objectives The objectives of ADEOS mission are to acquire data on worldwide environmental changes such as the global warming, ozone layer depletion, tropical rainforest deforestation, and abnormal climatic conditions, in order to contribute to international global environmental monitoring and to develop platform bus technology, interorbital data relay technology, etc. which are necessary for the development of future earth observation systems. To make continuous observations of the entire Earth surface and its atmosphere, the spacecraft carries two core sensors developed by NASDA: the Ocean Color and Temperature Scanner (OCTS) and the Advanced Visible and Near Infrared Radiometer (AVNIR). In addition, the spacecraft carries 6 Announcement of Opportunity (AO) sensors: the Improved Limb Atmospheric Spectrometer (ILAS) and Retro- reflector in Space (RIS) provided by EA, the Interferometric Monitor for Greenhouse Gases (IMG) provided by MITI, the NASA Scatterometer (NSCAT) and Total Ozone Mapping Spectrometer (TOMS) provided by NASA, and Polarization and Directionality of the Earth's Reflectances (POLDER) provided by CNES. ADEOS is a large satellite with a mass of approx. 3500 kg and a power generation capability of more than 4500 W. It is made up of thermally, electrically and mechanically independent units, which facilitate their integration and testing, including the Communications and Data Handling Subsystem (C&DH), the Electrical Power Subsystem (ESP) and the Attitude and Orbital Control Subsystem (AOCS). The satellite features an automatic, autonomous operation function capable of operating a large number of mission instruments, and interorbital communication equipment to transmit observation data via data relay satellite. In early 1996, ADEOS will be launched into a sun synchronous sub-recurrent orbit of an altitude of approx. 797 km by a H-II launch vehicle from the Tanegashima Space Center. The ADEOS mission is planned for 3 years. 2. Sensor description (1) Ocean Color and Temperature Scanner (OCTS) OCTS is an optical radiometer devoted to the frequent global measurement of ocean color and sea surface temperature. OCTS will show the amount of chlorophyll and dissolved substances in the water, and temperature distribution. OCTS's data will be used for determination of ocean primary production and carbon cycle, and be used for obtaining the information of ocean conditions for fishery and environment monitoring etc. OCTS has 8 bands in visible and near- infrared region and 4 bands in thermal region, and achieves highly sensitive spectral measurement with these bands. The observation bands are determined on the characteristics of spectral reflectance of the object substances, atmospheric windows and atmospheric correction. The spatial resolution is about 700 m. This is applicable to the observation of coastal zone and land, the feature of these area varies quickly compared to the open ocean. As the swath width is about 1400 km on the ground, OCTS can observe the same area every 3 days and can monitor rapidly changing phenomena. OCTS has optical calibration functions using solar light and halogen lamp as the calibration source. OCTS has two data transmission modes. All raw pixel data are transmitted through X band with fine data transmission mode. One pixel data is sampled from every 6*6 km area as typical data of the area and is transmitted at UHF band in coarse data transmission mode. OCTS consists of scanning radiometer unit, which contains optical system and detector module, and electrical unit. OCTS adopts catoptric optical system with objective plane rotating mirror. This is because OCTS covers a wide range of wavelength and wide scanning angles. OCTS can tilt its line of sight along the track to prevent the sun glitters on the sea surface. Because OCTS requires high S/N ratio, each observing band has 10 pixels aligned to the track. The infrared detectors are cooled at 100K by a large radiant cooler facing the deep space. *OCTS Characteristics Band Radiance S/N or NEdT or Target Temp. (micron) (W/m^2/sr/micron or K) 0.402-0.422 145 450 0.433-0.453 150 500 0.480-0.500 130 500 0.510-0.530 120 500 0.555-0.575 90 500 0.660-0.680 60 500 0.745-0.785 40 500 0.845-0.885 20 450 3.55-3.88 0.15K 8.25-8.80 Target Temp. 0.15K 10.3-11.4 = 300 K 0.15K 11.4-12.5 0.20K -Instantaneous Field of 0.85mrad. (Approx. 700m on the ground) View (IFOV) -Scanning Angle -40 to +40 deg. (Approx. 1400km on the ground) -MTF 0.35 -Polarization Sensitivity Band 1 less than 5% Band 2-8 less than 2% -Tilting Angle (in orbit) -20, 0, +20 degree (3 Steps) -Calibration Visible, Near IR Solar, Internal Light Source IR Deep Space, Black Body -Quantization 10 bit / pixel -Coarse Data 4 bands with 6*6km resolution Transmission (DTL) (443nm, 565nm, 670nm, 11.0 micron) (2) Advanced Visible and Near-infrared Radiometer (AVNIR) AVNIR is a high spatial resolution optical sensor for observing land and coastal zones in visible and near-infrared regions. AVNIR has 4 spectral bands with 16m spatial resolution and 1 panchromatic band with 8m spatial resolution. The AVNIR data will be useful for environmental awareness and monitoring of such phenomena as desertification, destruction of tropical forests, and pollution of coastal zones as well as resource exploration, land use, etc. AVNIR's Swath Width is about 80 km. AVNIR has features in some aspects as follows; high spatial resolution, a pointing function to change the observation field within +40 and -40 degrees in cross track, a 0.4 micrometer band useful for coastal zones and lakes, an optical calibration function which uses solar light and lamps, etc. AVNIR is composed of two units, the Scanning Radiometer Unit (SRU) and the Electronic Unit (ELU). Optics in SRU adopts a Catadioptric Schmidt optical system to reduce aberration in a wide field of view. Large mirrors used in Optics and Pointing Mechanism Assembly are ultra light mirrors weighting 50 to 70% less than conventional mirrors, made of low expansion glass. CFRP with low thermal and moisture expansion properties is used as the truss structural material in order to make Optics light yet extremely precise in orbit. The large scale linear-array CCDs with 5,000 (Multispectral band) and 10,000 (Panchromatic band) pixels are used as detectors and deliver high spatial resolution. Observation data is compressed in the Image Processing Assembly by about 10% in order to reduce the transmission data rate. *AVNIR Characteristics Multispectral Band (Mu) Panchromatic Band (Pa) -Spectral Band (micrometer) Mu1:0.42-0.50 Pa:0.52-0.69 Mu2:0.52-0.60 Mu3:0.61-0.69 Mu4:0.76-0.89 -Instantaneous Field 20micro rad. 10micro rad. of View (IFOV) (16m nadir) (8m nadir) -Field of View (FOV) 5.7 degree (Swath Width:80 km) -S/N more than 200 more than 90 -MTF more than 0.25 (Mu1-Mu3) more than 0.20 more than 0.20(Mu4) -bits/pixel 8 bit 8 bit -Pointing Function Pointing Direction : Cross Track Direction from -40 to +40 degree, step = 1 degree -Optical Calibration Source : Solar and Inner Lamp Performance Radiometric Absolute Accuracy : plus/minus 10% On-board Calibration Accuracy :5% -Weight Approx. 250 kg -Power Consumption Approx. 300W (3) Improved Limb Atmospheric Spectrometer (ILAS) The ILAS (Improved Limb Atmospheric Spectrometer) sensor is designed to monitor the ozone layer and provide data on the chemistry and dynamics of the upper atmosphere. Since the ILAS measurement is based on the solar occultation technique and the ADEOS (Advanced Earth Observing Satellite) has a sun-synchronous polar orbit, ILAS measurements are made in the stratosphere over high-latitude regions of both hemispheres. The measurements are made at 14 points along a certain latitude per day for each hemisphere. The latitude varies according to the change of solar declination. The latitude band covered by the ILAS measurement in the northern hemisphere varies from about 56 degrees to 70 degrees N and that in the southern hemisphere from 63 degrees to 88 degrees S, depending on the season. The major characteristics of the instrument are shown below. The ILAS consists of two spectrometers for infrared and visible channels. The infrared spectrometer measures lights in the wavelengths from 6.2 micrometers to 11.8 micrometers in which many important chemical species absorb. The targets of the ILAS measurements are ozone (O3), nitrous oxide (N2O), nitric acid (HNO3), nitrogen dioxide (NO2), methane (CH4), and water vapor (H2O), aerosols and, hopefully, CFC11 and N2O5. The visible channel from 753 nm to 784 nm measures absorption by an atmospheric A band of oxygen molecules (O2), from which temperature, pressure, and aerosol concentration are derived. Profiles of these geophysical parameters are taken from the cloud tops to the upper stratosphere. The purpose of this ILAS announcement is to stimulate research (1) to characterize sensor performance, (2) to validate the geophysical data produced by ILAS, (3) to stimulate scientific utilization of the data and (4) to promote developments of algorithms for data reduction. Some of these activities have already been started or will be started soon by the existing ILAS Science Team members and their associates. Principal Investigators (PIs) selected through this research announcement will be expected to contribute to both the ILAS project and the science of the ozone layer. *ILAS Characteristics -Grating Spectrometers with Linear Array Detectors IR detector 44 pixel pyro-electric detector Visible detector 1024 pixel MOS photo-diode array -Spectral Coverage / Resolution IR 850 - 1610 cm-1 (6.21 - 11.77 micrometers) 0.129 micrometer resolution Visible 753 - 784 nm 0.1 nm resolution -IFOV 2 km Vertical x 13 km Horizontal in the IR channel 2 km Vertical x 2 km Horizontal in the visible channel -Weight 125 kg -Power 70 W -Size 800 x 1630 x 550 (XYZ in mm) ************* END Msg B.SAT *************