The LANDSAT-7 satellite was successfully launched from Vandenburg Air Force Base on April 15, 1999.
The Landsat Project is the longest running enterprise for acquisition of moderate resolution imagery of the Earth from space.
The Landsat 1 satellite was launced in 1972 and the most recent, Landsat 7 was launced in 1999. The instruments on the Landsat satellites have acquired millions of images. The first three satellites caried the Multispectral Scanner (MSS) as the main imaging instrument with a Return Beam Vidicom (RBV) as a subsidiary.
Landsats 4 and 5 had the Thematic Mapper (TM) as the main sensor together with an MSS.
Landsat 6 was unfortunately lost on launch in 1993 however Landsat 5 continued to provide good data until the launch of Landsat 7.
Launched on 15 April 1999, Landsat 7 has the new Enhanced Thematic Mapper Plus (ETM+) sensor. This sensor has the same 7 TM spectral bands as its predecessor, but has an added panchromatic band with 15 metre resolution and a higher resolution thermal band of 60 metres. The ETM+ sensor also has a five percent absolute radiometric calibration.
|Resolution||Landsat 1 (23 Jul 1972-6 Jan 1978) RBV 80 m, MSS 80 m
Landsat 2 (22 Jan 1975-25 Feb 1982) RBV 80 m, MSS 80 m
Landsat 3 (5 Mar 1978-31 Mar 1983) RBV 80 m, MSS 80 m
Landsat 4 (16 Jul 1982-Jan 1986) MSS 80 m, TM 80 m
Landsat 5 (1 Mar 1984-Present) MSS 80 m, TM 30 m
Landsat 7 (15 Apr 1999-Present) Pan 15 m, TM 30 m
|Nominal Swath Width||185 km|
The Multispectral Scanner (MSS) was the main sensor on LANDSATs 1-3. The MSS sensor had a spatial resolution of 56 m x 79 m and collected imagery in 4 spectral bands (from visible green to near infrared) with a range of 128 intensity levels. The MSS sensor became subsidiary to the Thematic Mapper sensor on LANDSATs 4 and 5 and there was no MSS instrument planned for LANDSATs 6 and 7. This meant that the acquisition of MSS was due to cease with the demise of LANDSAT 5, and for technical reasons the MSS instrument was turned off in December 1997.TM
The Thematic Mapper (TM) scanner, which first appeared on LANDSAT 4 in 1982, was designed to provide improved spectral and spatial resolution over the MSS instrument. The use of more sensitive detectors, better optics and a lower orbit enabled the collection of radiation in 7 spectral bands, with a spatial resolution of 30 m, and with a data range of 256 intensity levels. The wavelengths of sensors on the MSS instrument were specifically selected for agricultural purposes, i.e. to highlight vegetation differences. For TM these broad vegetation bands were subdivided to provide more discrimination, and an additional sensor was included to provide geological information.ETM
Launched on 15 April 1999, Landsat 7 is the newest satellite in the series. Landsat 7 carries the Enhanced Thematic Mapper Plus (ETM+) sensor, which replicates the capabilities of the highly successful Thematic Mapper instruments on Landsat 4 and 5 but also includes new features that make it a more versatile and efficient instrument for global change studies, land cover monitoring and assessment and large area mapping. The primary new features are a panchromatic band with 15 m spatial resolution; onblard, full aperture, 5% absolute radiometric calibration; and a thermal infrared channel with 60 m spatial resolution. Unfortunately on 31 May 2003 there was a malfunction of the Scan Line Corrector Mechanism on Landsat 7 resulting in gaps and reptitions in the imagery.
|Archive Availability||Possible from 1972|
|Minimum area of purchase||Varies from source|
|Best Scale||1:50,000 - Landsat 7 Pan-sharpened ETM+
1:100,000 - TM
1:250,000 - MSS
|Bit depth||8 bits|
|Applications||Spectral processing for mineral exploration
Large regional coverage
Extensive archive for change detection
Availability of imagery over cloud affected areas
Minimal expense, medium resolution dataset