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3. LANDSAT-7 
Another long-term U.S. government satellite program which 
began in 1972 is Landsat. Landsat-7, the next planned mission 
after the ill-fated unsuccessful launch of Landsat-6, will be a 
joint venture between NASA, NOAA and the U.S. Geological 
Survey (USGS). It is also a part of NASA's Mission to Planet 
Earth (MTPE) which is dedicated to monitoring the 
environment and assessing global change (Asrar and 
Greenstone, 1995). 
Orbital parameters for Landsat-7 are designed to provide 
continuity of data with those obtained by previous Landsat 
satellites. The primary sensor is the Enhanced Thematic 
Mapper Plus (ETM+) (Table 3). The ETM+ will acquire data 
of increased spatial resolution for panchromatic (15 m) and 
thermal infrared (60 m) bands. This improved resolution will 
permit better characterization and monitoring of land 
cover/processes. Procedures are also in place for more rapid 
data dissemination to the user. 
Table 3. Landsat-7 
Satellite 
1998 launch from 705 km Altitude 
Sun Synchronous Orbit (98°) 
10:00 am Descending Node Orbit 
Ground Track Repeat Interval 16 Days 
Sensor 
Enhanced Thematic Mapper+ (ETM+) 
8 Bands (1 Pan at 15 m, 6 VNIR and SWIR at 30 m, 
1 TIR at 60 m) 
3.8 Gb per Scene (185 x 170 km) 
Solid State On-Board Storage 380 Gb or 100 Scenes 
Data 
USGS EROS Data Center - Process 250 Scenes per Day 
Deliver up to 100 Scenes per Day to User 
Data to be Available for Order within 24 hrs of 
Acquisition 
4. EARTH OBSERVING SYSTEM (EOS) 
The Earth Observing System (EOS) is the centerpiece of 
NASA’s MTPE and a key component of the U.S. Global 
Change Research Program. Beginning in 1998, EOS will 
consist of a series of Earth remote sensing spacecraft, each 
carrying up to six instruments and launched every three to five 
years (Asrar and Greenstone, 1995). In this way, continuous 
data will be provided over the 15 year lifetime of the program 
for observation of the atmosphere, oceans and Earth’s surface. 
EOS AM-1 is scheduled for launch in mid-1998 and will 
include five sensors (Table 4). Of these, the Moderate- 
Resolution Imaging Spectroradiometer (MODIS) and the 
Advanced Spaceborne Thermal Emission and Reflection 
Radiometer (ASTER) sensors are most applicable for land 
resource mapping applications. 
935 
Table 4. Sensors On-Board EOS AM-1 
CERES - Clouds and Earth’s Radiant Energy System 
MISR - Multi-angle Imaging SpectroRadiometer 
MODIS - Moderate Resolution Imaging 
Spectroradiometer 
MOPITT - Measurements of Pollution in the 
Troposphere 
ASTER - Advanced Spaceborne Thermal Emission and 
Reflection Radiometer 
The 36 band MODIS sensor is designed to measure 
biologicaland physical processes (at 250 to 500 m spatial 
resolution) on a global scale every one to two days (Table 5). 
Slated for both EOS AM and PM satellite series, MODIS will 
provide long-term observations of global changes, Earth 
surface processes and the lower atmosphere. 
Table 5. EOS MODIS Sensor 
Satellite 
705 km Altitude 
Sun Synchronous Orbit (98.2°) 
10:30 am Descending Node 
Ground Track Repeat Interval 16 Days 
Sensor 
MODIS - Moderate Resolution Imaging 
Spectroradiometer 
36 Bands (VNIR, SWIR, TIR at 250 m, 500 m or 1 km) 
Share of Solid State On-Board Storage of 140 Gb 
Revisit Time (with cross-track tilt) of 2 Days 
Data 
Primary Data Return via TDRSS 
The Advanced Spaceborne Thermal Emission and Reflection 
Radiometer (ASTER) is a joint venture between U.S. and 
Japanese scientists that will provide data of high spatial 
resolution (15 to 90 m) from visible to thermal infrared 
wavelengths (Kahle, et al., 1991; Table 6). This information 
will be used for long-term monitoring of the land surface, 
water, ice and clouds (Asrar and Greenstone, 1995). A number 
of mapping applications are planned for ASTER data such as 
vegetation, land use patterns, hydrology, geology and surface 
topography. Of primary interest to the mapping community is 
the capability of generating digital elevation models (DEMs) 
from the along-track stereo image data made possible by 
simultaneous acquisition of nadir and aft pointing images 
(Arai, 1992; Welch and Lang, 1994; Welch, 1995). 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B4. Vienna 1996