Sensors: Image Processing Library
| LANDSAT MSS / TM |
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Sample of LANDSAT Image: Bands 4,3 &2
| TM | MSS | ||
| SPECTRAL REGION: |
Visible & Reflected IR: |
450-2350 nm | 500-1100 nm |
| Thermal IR (TM Band 6): |
10.5-12.5 | - | |
| Spectral Bands: |
7 | 4 | |
| TERRAIN COVERAGE: |
East-West direction: |
185 km | 185 km |
| North-South direction: |
170 km | 185 km | |
| INSTANTANEOUS FIELD OF VIEW: |
Visible & Reflected IR: |
0.043 mrad | 0.087 mrad |
| Thermal IR (TM Band 6): |
0.17 mrad | - | |
| GROUND RESOLUTION CELL: |
Visible & Reflected IR: |
30m x 30m | 79m x 79m |
| Thermal IR (TM Band 6): |
120m x 120m | - |
The LANDSAT Concept
Background
The first Landsat satellite was launched in July of 1972. At that time the satellite was known as ERTS-1 (Earth Resources Technology Satellite) yet was later re-named Landsat-1. In January of 1975 and March of 1978 two additional satellites with similar sensors, Landsat-2 and -3, were successfully launched. Landsat-1, -2, and -3 were operational until January 1978, February 1982, and March 1983, respectively. On July 16, 1982, NASA launched a second generation of the Landsat satellite, beginning with Landsat-4, and followed by Landsat-5 on March 1, 1984.Sensors
Landsat-1,-2, &-3 carried two primary sensors: a Return Beam Vidicom (RBV) camera system and the Multispectral Scanner (MSS). These spaceborne sensors observed the earth and transmitted information by microwave signals to ground stations that received and processed data to produce both images and digital information for the user. The RBV was designed to provide, relative to MSS, high geometric accuracy but lower spectral and radiometric detail. In contrast, the MSS was designed to provide finer detail concerning the spectral characteristics of the earth but less positional accuracy. Because technical difficulties restricted RBV operation, Landsat-4 and -5 employed the MSS(the primary LANDSAT sensor) and the Thematic Mapper (TM), a more sophisticated version of the MSS, instead of the RBV.-MSS-
The Multispectral Scanner is a 4-channel whisk-broom optical scanner that provides 80m spatial resolution on a 16-18 day revisit cycle. MSS images in four spectral bands (called Bands 4-7 on LS1,2&3 and 1-4 on LS 4&5) covering the visible and near infrared regions of the electromagnetic spectrum. The MSS ground swath is 185 kilometers wide, with a nominal 80 meter pixel resolution. Although based on 1960s technology, it provided human kind's first synoptic imagery of the globe from low Earth orbit.-Thematic Mapper-
Thematic Mapper is a 7-channel whisk-broom scanner providing 30m spatial resolution. It offers an order-of-magnitude improvement in spectral and spatial data collection for Earth resources. Thematic Mapper imagery is widely used today for mapping the Earth's resources. The TM operates in the visible, infrared portions of the EM spectrum as well as collecting a thermal band. The specific bands for TM and their applications are listed in the table below. ETM and ETM+: Enhanced Thematic Mapper was designed as a sensor improvement for Landsat-6, but never achieved orbit. Its conceptual successor, ETM+, is designed as a 4-channel VNIR and 2-channel SWIR sensor having 30m ground resolution; a panchromatic, 15m channel; and a 2-channel LWIR having 60m resolution.Orbital Characteristics
| Landsat-4 and -5 | Landsat-1, -2, and -3 | |
| Orbits | Circular,sun-synchronous | Circular, sun-synchronous |
| Inclination angle | 98.2 degrees | 99 degrees |
| Altitude | approx 705 km | approx 900 km |
| Orbital period | 99 minutes | 103 minutes |
| Orbits per day | 14.5 | 14 |
| Orbital repeat cycles | 16 days | 18 days |
| Equatorial Crossing Time (ECT) | 9:45 am local time | 9:42 am local time |
| Swath | 185 km | 185 km |
| Weight | 2000 kg | 800 kg |
Band Characteristics
| Band | Wavelength (microns) | Spectral Location | Principal Applications |
| 1 | 0.45-0.52 | Blue | Designed for water body penetration, making it useful for coastal water mapping. Also useful for soil/vegetation discrimination, forest type mapping, and cultural feature identification. |
| 2 | 0.52-0.60 | Green | Designed to measure green reflectance peak of vegetation for vegetation discrimination and vigor assessment. Also useful for cultural feature identification. |
| 3 | 0.63-0.69 | Red | Designed to sense in a chlorophyll absorption region aiding in plant species differentiation. Also useful for cultural feature identification. |
| 4 | 0.76-0.90 | Near infrared | Useful for determining vegetation types, vigor, and biomass content, for delineating water bodies, and for soil moisture discrimination. |
| 5 | 1.55-1.75 | Mid-infrared | Indicative of vegetation moisture content and soil moisture. Also useful for differentiation of snow from clouds. |
| 6 | 10.4-12.5 | Thermal infrared | Useful in vegetation stress analysis, soil moisture discrimination, and thermal mapping applications. |
| 7 | 2.08-2.35 | Mid-infrared | Useful for discrimination of mineral and rock types. Also sensitive to vegetation moisture content. |
Sensors
Last Modified: Wed Apr 14, 1999
CSR/TSGC Team Web