Remote Sensing Systems
Early Satellite Sensing
• Spy satellites gave exquisite but very local
views and were classified
• Even before satellites were launched, it
was clear that color imaging was essential
• Best images were from manned
spacecraft
– Low latitude
– Limited coverage in space and time
– Almost all oblique
Gemini XII,
1968
(410 miles)
Early Satellite Sensing
• Meteorological satellites gave hints of
what might be possible
– Snow coverage
– Sea ice
– Glaciers
– Gross geological structures
Nimbus I image
1964
Landsat
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Landsat 1 1972-1978
Landsat 2 1975-1981
Landsat 3 1978-1983
Landsat 4 1982-1993
Landsat 5 1984, still functioning
Landsat 6 1993, failed to reach orbit
Landsat 7 1999, still functioning, but with
faulty scan line corrector (May 2003)
• Landsat Data Continuity Mission,
scheduled for 2012
Two Key Features of Landsat
• Orbits are sun synchronous: satellite
crosses equator southbound on day side
at about 10 AM local time
• Orbits repeat ground track precisely every
14-18 days (Revisit period)
• A term to know: Nadir = point directly
below (opposite of Zenith)
Early Landsat
• Originally modeled on Nimbus weather
satellite system
• Landsat 1 observed in Green, Red and
two IR bands with 80-m resolution
• Landsat 3 had 30-m resolution
• Landsat 3 added a fifth thermal IR band
but it failed
• Landsat 4: 7 bands
• Landsat 7: 15 m resolution panchromatic
Failed Experiment
• President Jimmy Carter recommended private
sector operation of Landsat, 1979
• Earth Observation Satellite Company (EOSAT),
a partnership of Hughes Aircraft and RCA, was
awarded ten year contract to operate Landsat,
1985
• EOSAT operated Landsats 4 and 5 and had
exclusive rights to market Landsat data.
• EOSAT needed repeated bailouts
• Congress passed Land Remote Sensing Policy
Act (Public Law 102-555) and returned Landsat
to public domain, 1992
Landsat 7 Bands
1 0.45-0.52µm
Blue-Green
30 m
2 0.52-0.60 µm
Green
30 m
3 0.63-0.69 µm
Red
30 m
4 0.76-0.90 µm
Near IR
30 m
5 1.55-1.75 µm
Mid-IR
30 m
6 10.40-12.50 µm
Thermal IR
60 m
7 2.08-2.35 µm
Mid-IR
30 m
Panchromatic
15 m
0,52-0.90 µm
Uses of Landsat 7 Bands
1. Coastal water mapping, soil/vegetation discrimination,
forest classification, man-made feature identification
2. Vegetation discrimination and health monitoring, manmade feature identification
3. Plant species identification, man-made feature
identification
4. Soil moisture monitoring, vegetation monitoring, water
body discrimination
5. Vegetation moisture content monitoring
6. Surface temperature, vegetation stress monitoring, soil
moisture monitoring, cloud differentiation, volcanic
monitoring
7. Mineral and rock discrimination, vegetation moisture
content
False Color Images
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Near IR (ETM+ band 4)  Red
Red (ETM+ band 3)  Green
Green (ETM+ band 2)  Blue
Colors on image are shifted one band
toward blue compared to real scene
Making a False-Color Image
Landsat 7 Facts
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Altitude: 705 kilometers
Period: 98.9 minutes
Inclination: Sun-synchronous, 98.2 degrees
Equatorial crossing: Southbound 10:00AM +/15 min.
• Repeat coverage interval: 16 days (233 orbits)
• Swath width: 185 kilometers
• On-board data storage: ~375 Gb (solid state)
See SPOT. See SPOT See
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Satellite Pour l'Observation de la Terre
Sun-synchronous
Altitude: 832 kilometers,
Inclination: 98.7
Revisit period: 26 days
Uses CCD’s and stare mode; no scanning
SPOT 5 Bands
Band (microns) Colors
Resolution
0.51 - 0.73
Panchromatic
2.5 & 5m
0.50 - 0.59
Green
10m
0.61 - 0.68
Red
10m
0.79 - 0.89
Near IR
10m
1.58 - 1.73
Mid IR
20m
SPOT
Image of
Kuwait
City,
2004
IKONOS
• 1992 Land Remote Sensing Policy Act
permitted private companies to enter the
satellite imaging business.
• Lockheed Martin
• Launched 2000
• 1 m resolution
• Bands: Blue, Green, Red, Near IR
• Now operated by GeoEye Inc., Dulles VA
Burj Khalifa by IKONOS
Terra
• Part of NASA EOS (Earth Observation System)
• Partnership of U.S., Canada, Japan
• Instruments
– ASTER (Advanced Spaceborne Thermal Emission
and Reflection Radiometer)
– CERES (Clouds and Earth's Radiant Energy System)
– MISR (Multiangle Imaging Spectroradiometer)
– MODIS (Moderate-Resolution Imaging
Spectroradiometer)
– MOPITT (Measurements of Pollution in the
Troposphere)
ASTER
• U.S. – Japan joint mission
• Three Subsystems, each with own
telescopes
• VNIR: Four visible and near-IR channels,
15-m resolution
• SWIR: Six short wave IR channels, 30-m
resolution
• TIR: Five Thermal IR Channels, 90-m
resolution
– IR sensors use Stirling Cycle coolers
MODIS
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Resolutions 250, 500 and 1000 meters
Ten visible bands (250 and 500-m)
Ten Near IR bands (500 and 1000 m)
16 Medium and Thermal IR bands
(1000 m)
• Bands are narrow and tailored to specific
emissions and absorptions (ocean color,
aerosols, ozone, water vapor, cloud
temperature)