NASA orbited the Terra (EOS-AM1) spacecraft and EO-1 in formation with Landsat 7 to take advantage of this enhanced calibration. These features, combined with all the traditional utility of Landsat data proven over 40 years, makes Landsat 7 data important for a wide and diverse remote sensing community.
However, the malfunction has impacted the imagery of Landsat 7. Specifically, the ETM+ optics contain the Scan Mirror and Scan Line Corrector assembly among other components. The Scan Mirror provides the across-track motion for the imaging, while the forward velocity of the spacecraft provides the along-track motion.
In October 2008, USGS made all Landsat 7 data free to the public (all Landsat data were made free in January 2009 leading to a 60-fold increase of data downloads).
The final such maneuver took place on February 7, 2017. From that point forward, the satellite's orbit began to slowly degrade (lower) such that by 2021 it had faded from the desired 10:00 AM LMT to about 9:15 AM. With the September 27, 2021 launch of Landsat 9, Landsat 7 is to be decommissioned.
Landsat-9 has been authorized and is proceeding towards a December 2020 launch.
Landsat 7 Scan Line Corrector (SLC) Failure On May 31, 2003, the Scan Line Corrector (SLC), which compensates for the forward motion of the satellite, failed. Subsequent efforts to recover the SLC were not successful, and the failure is permanent.
The Landsat 7 ETM+ instrument is currently operating in SAM (Scan Angle Monitor) mode to control the motion of the scan mirror during imaging.
Currently orbiting and active satellites are Landsat 8, and Landsat 9.
Landsat 9—a partnership between the USGS and NASA—was launched from Space Launch Complex 3E at Vandenberg Air Force Base in California upon a United Launch Alliance Atlas V 401 launch vehicle on September 27, 2021.
30 metersLandsat 7 ETM+ images consist of eight spectral bands with a spatial resolution of 30 meters for bands 1 to 7. The panchromatic band 8 has a resolution of 15 meters.
Landsat 7 Enhanced Thematic Mapper Plus (ETM+) images consist of eight spectral bands with a spatial resolution of 30 meters for Bands 1 to 7. The resolution for Band 8 (panchromatic) is 15 meters.
The Landsat-8 Operational Land Imager (OLI) has improved calibration, signal to noise characteristics, higher 12-bit radiometric resolution, and spectrally narrower wavebands than the previous Landsat-7 Enhanced Thematic Mapper (ETM +).
Landsat 7 at the time was the most accurately calibrated Earth-observing satellite, i.e., its measurements are extremely accurate when compared to the same measurements made on the ground.
Landsat 7 satellite is equipped with Enhanced Thematic Mapper Plus (ETM+), the successor of TM. The observation bands are essentially the same seven bands as TM, and the newly added panchromatic band 8, with a high resolution of 15-meters was added.
The only commercial launch of the Landsat program, Landsat 6 never achieved orbit. Sources/Usage: Public Domain. A sketch of what the Landsat 6 satellite would have looked like in orbit. Landsat 6 launched on October 5, 1993 on a Titan II rocket from Vandenberg Air Force Base, California, but did not achieve orbit.