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 Landsat Landsat Landsat Landsat Landsat , still functioning Landsat , failed to reach orbit Landsat , 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 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 ) and returned Landsat to public domain, 1992

Landsat 7 Bands µmBlue-Green30 m µmGreen30 m µmRed30 m µmNear IR30 m µmMid-IR30 m µmThermal IR60 m µmMid-IR30 m 0, µmPanchromatic15 m

Uses of Landsat 7 Bands 1.Coastal water mapping, soil/vegetation discrimination, forest classification, man-made feature identification 2.Vegetation discrimination and health monitoring, man- made 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 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 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 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)ColorsResolution Panchromatic2.5 & 5m Green10m Red10m Near IR10m Mid IR20m

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 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 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)