Geosynchronous Orbit A satellite in geosynchronous orbit circles the earth once each day. The time it takes for a satellite to orbit the earth is called its period. To stay over the same spot on earth, a geostationary satellite also has to be directly above the equator. Otherwise, from the earth the satellite would appear to move in a north-south line every day.

Sun-Synchronous Orbit Because the valid comparison of images of a given location acquired on different dates depends on the similarity of the illumination conditions, the orbital plane must also form a constant angle relative to the sun direction. This is achieved by ensuring that the satellite overflies any given point at the same local time, which in turn requires that the orbit be sun- synchronous The satellite crossed the equator at approximately the same local sun time (9:42) every day

Earth Resource Satellites Operating in the Optical Spectrum Landsat SPOT Meteorological Satellites –NOAA satellites –GOES satellites Ocean Monitoring Satellites –Radar Satellites –Seasat –ERS-1 –JERS-1 –Radarsat

Landsat-7 This program is jointly managed by NASA and USGS ( pdate.html) Launched on April 15, 1999 ( A new sensor : Enhanced Thematic Mapper Plus (ETM+) Same swath as ETM, similar orbits and characteristics Swath: The area imaged on the surface.

ETM+ Resolution –Bands1-5, 7: 30 meters –Band 6 (Thermal band): 60 meters –Band 8 (Panchromatic band): 15 meters Complete global view four times a year

ETM+ Ground transmission of data either directly or stored onboard for later transmission GPS is included for subsequent geometric processing of the data Primary receiving station: EROS Dara Center, SD

ETM+ Spectral Bands

Landsat 7 +ETM Spectral Bands

Landsat Resources Data acquisition (

Enhanced Thematic Mapper Plus (ETM+) 8 8-bit bands: bands 1-7 are the same as TM; additional panchromatic band 8, μm IFOV 30 x 30m (bands 1-5 and 7), 60 x 60m (band 6), 15 x 15m (band 8); swath width 185 km. Images the earth once every 16 days; 1999 to present

EOS Terra ASTER –The ASTER is a cooperative effort between NASA and Japan’s Ministry of International Trade and Industry –Primary applications include study vegetation, rock types, volcanoes, clouds, and produce DEM’s – 6 SWIR bands: band 6 centered at the clay absorption feature and band 8 at the carbonate absorption feature – 5 TIR bands: bands 10, 11, and 12 at sulfate and silica absorption features

ASTER Characteristics Wide Spectral Coverage 3 bands in VNIR (0.52 – 0.86 μm) 6 bands in SWIR (1.6 – 2.43 μm) 5 bands in TIR (8.125 – μm) High Spatial Resolution 15m for VNIR bands 30m for SWIR bands 90m for TIR bands Quantization (bits) 8 for VNIR AND SWIR 12 for TIR Swath width 60 km Images are not acquired based on researcher scheduling 1999 to present

ASTER consists of 3 subsystems: VNIR, SWIR and TIR

ASTER TM Repeat Orbit: 16 d16 d Scene60 km185km Bands: Pan01 15m VIS2 15m3 30m NIR1 30m1 30m SWIR 6 30m 2 30m TIR5 90m1 90m

ASTER Images of San Francisco Bay False Color Image (VNIR) Sediment Load (VNIR) Water Temperature (TIR)

Land Observing Sensors and their Features Weather, Global Coverage Satellites Sensor NamePixelSwathNo. SpectralSpectralTemporal ResolutionWidth, kmBandsCoverageRepeat, days AVHRR1.1km27005VNIR, TIR4*day SPOT Vegetation1.15km22504VNIR, SWIR26 MODIS0.25,0.5,1km233036VNIR, SWIR, TIR2* day Regional Satellites SensormkmbandsSpectralRepeat ASTER15, 30, VNIR, SWIR, TIR16 Landsat ETM+30, 60, Pan + TM16 SPOT HRV10, 20604Pan, VNIR26 SPOT HRVIR10, 20605SWIR + HRV26 Local Coverage Satellites SensormkmbandsSpectralRepeat Quickbird0.61 Pan, Pan, VNIR2 to 11 IKONOS1.0 Pan, Pan, VNIR3

Medium and coarse resolution sensors SensorPixel Size, m ‘blue’ nm ‘green’ nm ‘red’ nm ‘NIR’ nm ‘SWIR’  m ‘Thermal’  m SPOT- VEGETATION Swath 2250 km NOAA- AVHRR Swath 2700 km MODIS (Terra, Aqua) Swath 2330 km

Medium and coarse resolution sensors Ikonos Swath 13 km 4 1 (pan) QuickBird Swath 16.5 km (pan) SensorPixel Size, m ‘blue’ nm ‘green’ nm ‘red’ nm ‘NIR’ nm ‘SWIR’  m ‘Thermal’  m