Hiroji Tsu

Overview of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER)

The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is a research facility instrument provided by the Ministry of International Trade and Industry (MITI), Tokyo, Japan to be launched on NASAs Earth Observing System morning (EOS-AM1) platform in 1998. ASTER has three spectral hands in the visible near-infrared (VNIR), six bands in the shortwave infrared (SWIR), and five bands in the thermal infrared (TIR) regions, with 15-, 30-, and 90-m ground resolution, respectively. The VNIR subsystem has one backward-viewing band for stereoscopic observation in the along-track direction. Because the data will have wide spectral coverage and relatively high spatial resolution, it will be possible to discriminate a variety of surface materials and reduce problems in some lower resolution data resulting from mixed pixels. ASTER will, for the first time, provide high-spatial resolution multispectral thermal infrared data from orbit and the highest spatial resolution surface spectral reflectance temperature and emissivity data of all of the EOS-AM1 instruments. The primary science objective of the ASTER mission is to improve understanding of the local- and regional-scale processes occurring on or near the Earths surface and lower atmosphere, including surface-atmosphere interactions. Specific areas of the science investigation include the following: (1) land surface climatology; (2) vegetation and ecosystem dynamics; (3) volcano monitoring; (4) hazard monitoring; (5) aerosols and clouds; (6) carbon cycling in the marine ecosystem; (7) hydrology; (8) geology and soil; and (9) land surface and land cover change. There are three categories of ASTER data: a global map, regional monitoring data sets, and local data sets to be obtained for requests from individual investigators.

ASTER instrument characterization and operation scenario

Abstract The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is a high spatial resolution multi-spectral imaging radiometer, and spectrally covers the visible and near-infrared, short-wave-infrared, and thermal infrared regions with 14 spectral bands, 15 to 90m spatial resolution, and 60 km imaging swath. ASTER has the along-track stereoscopic viewing capability with B H of 0.6 and cross-track pointing function for global coverage. Several new technologies such as long-life active cryocoolers are adopted to realize high observation performances. The radiometric, geometric, and spectral performances of the ASTER instrument were confirmed in the Proto Flight Model (PFM) tests. Since operation of the ASTER will be limited by various constraints such as duty cycle and pointing change controls, it is necessary to optimize the operation scenario for efficient data acquisition. Prioritization of data acquisition requests will be based on factors such as data category, user category, and science discipline.

Scientific basis of ASTER instrument design

The advanced spaceborne thermal emission and reflection radiometer (ASTER), a multi- spectral imaging radiometer with 14 spectral bands, is a research facility instrument that will be launched in 1998 on NASAs EOS-AM1 platform. Characteristics of the ASTER data can be summarized as (1) wide spectral coverage from the visible to thermal infrared regions, (2) multispectral thermal infrared data with high spectral and spatial resolution and (3) stereoscopic capability in the along track direction. ASTER is currently being designed to meet the requirements given by the ASTER science team.

The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) after fifteen years: Review of global products

Abstract The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is a 15-channel imaging instrument operating on NASA’s Terra satellite. A joint project between the U.S. National Aeronautics and Space Administration and Japan’s Ministry of Economy, Trade, and Industry, ASTER has been acquiring data for 15 years, since March 2000. The archive now contains over 2.8 million scenes; for the majority of them, a stereo pair was collected using nadir and backward telescopes imaging in the NIR wavelength. The majority of users require only a few to a few dozen scenes for their work. Studies have ranged over numerous scientific disciplines, and many practical applications have benefited from ASTER’s unique data. A few researchers have been able to mine the entire ASTER archive, that is now global in extent due to the long duration of the mission. Six examples of global products are described in this contribution: the ASTER Global Digital Elevation Model (GDEM), the most complete, highest resolution DEM available to all users; the ASTER Emissivity Database (ASTER GED), a global 5-band emissivity map of the land surface; the ASTER Global Urban Area Map (AGURAM), a 15-m resolution database of over 3500 cities; the ASTER Volcano Archive (AVA), an archive of over 1500 active volcanoes; ASTER Geoscience products of the continent of Australia; and the Global Ice Monitoring from Space (GLIMS) project.

Aster early image evaluation

Abstract The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is a high spatial resolution multi-spectral imaging radiometer, and is onboard the NASAs Terra spacecraft launched on December 18, 1999. It spectrally covers the visible and near-infrared, short-wave-infrared, and thermal infrared regions with 14 spectral bands, and creates high-spatial-resolution (15–90 m) multispectral images of the Earths surface. Referring to the baseline observation performance requirements provided by the ASTER Science Team, the ASTER early images were evaluated from both engineering and scientific points of view, e.g., general image quality, dynamic range, radiometric and geometric performance, etc. It was confirmed that the ASTER instrument generally exceeds the specified observation performance, and the early images exhibit excellent quality even in the preliminary processing level.

ASTER instrument performance, operation status, and application to Earth sciences

Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is a high spatial resolution multi-spectral imaging radiometer on NASAs Terra satellite. Observational performance of the ASTER instrument was examined by using the actual ASTER images, and it was confirmed that the ASTER has excellent radiometric and geometric performance. ASTER obtains data by target observation based upon data acquisition requests. Currently ASTER is acquiring approximately 600 scenes per day as an average, and has already obtained more than 180,000 scenes by the end of March 2001. The ASTER data are being used for a variety of applications in Earth sciences, e.g., intensive monitoring of volcanic eruptions, monitoring of coastal environment, day and night observation of large cities, and surface lithologic mapping.

ASTER data acquisition scenario

The advanced spaceborne thermal emission and reflection radiometer (ASTER) is a multi- spectral imaging radiometer with 14 spectral bands, 60 km imaging swath, and 15 - 90 m spatial resolutions. Since operation of the ASTER instrument will be affected by various constraints such as duty cycle and pointing frequencies, it is necessary to optimize the operation scenario for efficient data acquisition during the 6 year mission period. In addition, many possible combinations of the observation modes of the three ASTER subsystems (VNIR, SWIR, and TIR), which can be operated independently with different gain setting for each spectral band, complicate the data acquisition scenario. There are four data acquisition categories; local observations, regional monitoring, global mapping, and engineering team requests. Local observations will be made in response to data acquisition requests (DARs) from individual investigators. Regional monitoring and global mapping will be scheduled in response to science team acquisition requests (STARs). Prioritization of data acquisition requests will be done using the factors such as user status and observation categories. Three types of schedules; long term schedule (LTS), short term schedule (STS), and one day schedule (ODS) will be generated for ASTER observation activities.

ASTER science mission overview

The advanced spaceborne thermal emission and reflection radiometer (ASTER) is a research facility instrument to be launched on NASAs Earth Observing System AM1 (EOS AM-1) platform in 1998. ASTER has three spectral bands in the VNIR, six bands in the SWIR, and five bands in the TIR regions with 15, 30, and 90 m ground resolution respectively. The VNIR subsystem has one backward-viewing band for stereoscopic observation in the along-track direction. Because the data will have wide spectral coverage and relatively high spatial resolution, we will be able to discriminate a variety of surface materials and reduce problems resulting from mixed pixels. ASTER will provide the highest spatial resolution surface temperature and emissivity data of all the EOS AM-1 instruments. The primary science objective of the ASTER mission is to improve understanding of the local- and regional-scale processes occurring on or near the Earths surface and lower atmosphere, including surface-atmosphere interactions. Specific areas of the science investigation can be listed as: (1) vegetation and ecosystem dynamics, (2) land surface climatology, (3) volcano monitoring, (4) aerosols and clouds, (5) carbon cycling and in the marine ecosystem, (6) hydrology, and (7) geology and soil. There are four categories of data; global data sets, regional data sets, and local data sets to be obtained by data acquisition requests (DAR) from scientists. Prioritization of data acquisition requests will be done using the factors such as observation category, user category, and science discipline.

Future potential of thermal infrared multispectral data for mapping temperature and emissivity parameters

Abstract The instrument named Advanced Spaceborne Thermal Emission Reflection Radiometer (ASTER) is introduced as the future system for mapping temperature and emissivity parameters. The advanced features of the thermal infrared (TIR) subsystem are the high performance of NEΔT and spatial resolution. The expected data products related to ASTER TIR subsystem are briefly described. The general characteristics of TIR images are examined by the comparison of TIR images in the areas with various land cover. The ability to map thermal conditions on the earth surface are demonstrated but at the same time the necessity of the performance improvement is also indicated so as to detect the subtle spectral difference of the surface especially in vegetated and coastal areas. As to the algorithm development, potential evaluation of temperature estimation has been performed by the airborne field experiments. The resultant temperatures by the different derivation algorithms are quantitatively compared to evaluate the effect of atmospheric profile data such as temperature and humidity profiles. The results show the surface temperature is well derived by the both methods. Finally, the remaining problems are summarized for the development of algorithms.

ASTER early science outcome and operation status

12 The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is a high spatial resolution multispectral imaging radiometer, and is onboard the NASAs Terra spacecraft launched on December 18, 1999. It spectrally covers the visible and near-infrared, short-wave- infrared, and thermal infrared regions with 14 spectral bands, and creates high-spatial-resolution (15-90 m) multispectral images of the Earths surface. The observation performances of the ASTER instrument were evaluated by the early images, e.g. spatial resolution, modulation transfer functions (MTF), signal-to-noise-ratios (SNRs), band-to-band registrations, and so on. It was confirmed that the ASTER instrument generally exceeds the specified observation performance, and the early images exhibit excellent quality even in the preliminary processing level. In the initial check-out phase, ASTER was operationally used for intensive monitoring of volcanic eruptions in Japan, and successfully provided useful information to volcanologists.