Landsat

Some of the most popular and valued remote sensing images of the Earth are obtained from the Landsat satellites which have been orbiting the Earth for over 40 years. Landsat is a joint venture between NASA and the U.S. Geological Survey that began in 1972 with the launch of Landsat 1.

Previous Landsat Satellites

Originally known as the Earth Resources Technology Satellite 1, Landsat 1 was launched in 1972 and deactivated in 1978. Landsat 1 data was used to identify a new island off the coast of Canada in 1976, which was subsequently named Landsat Island.

Landsat 2 was launched in 1975 and deactivated in 1982. Landsat 3 was launched in 1987 and deactivated in 1983. Landsat 4 was launched in 1982 and stopped sending data in 1993. 

Landsat 5 was launched in 1984 and holds the world record for being the longest-serving Earth-observing satellite in operation, serving for more than 29 years, until 2013. Landsat 5 was utilized for longer than expected because Landsat 6 was unable to attain orbit following the launch in 1993.

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An Overview of Remote Sensing

By Amanda Briney

Landsat 6 was the only Landsat to fail before sending data to the Earth. 

Current Landsats

Landsat 7 remains in orbit after having been launched on April 15, 1999. Landsat 8, the newest Landsat, was launched on February 11, 2013. 

Landsat Data Collection

The Landsat satellites make loops around the Earth and are constantly collecting images of the surface through the use of a variety of sensing devices. Since the beginning of the Landsat program in 1972, the images and data have been available to all countries around the world. Landsat data is free and available to anyone on the planet. Images are used to measure rainforest loss, assist with mapping, determine urban growth, and measure population change.

The different Landsats each have different remote-sensing equipment. Each sensing device records radiation from the surface of the Earth in different bands of the electromagnetic spectrum. Landsat 8 captures images of the Earth on several difference spectrums (visible, near-infrared, short wave infrared, and thermal-infrared spectrums). Landsat 8 captures about 400 images of the Earth each day, far more than the 250 a day of Landsat 7. 

As it orbits the Earth in a north-south pattern, Landsat 8 collects images from a swath about 115 miles (185 km) across, using a push broom sensor, which captures data from the entire swatch at the same time. This is different than the whiskbroom sensor of Landsat 7 and other previous Landsat satellites, which would move across the swath, more slowly capturing imagery. 

The Landsats orbit the Earth from the North Pole to the South Pole on a continual basis. Landsat 8 captures imagery from approximately 438 miles (705 km) above the surface of the Earth. Landsats complete a full orbit of the Earth in about 99 minutes, allowing the Landsats to achieve about 14 orbits per day. The satellites make a complete coverage of the Earth every 16 days. 

About five passes cover the entire United States, from Maine and Florida to Hawaii and Alaska. Landsat 8 crosses the Equator every day at approximately 10 a.m. local time.

Landsat 9 

NASA and the USGS announced in early 2015 that Landsat 9 is being developed and scheduled for launch in 2023, ensuring that data will be collected and made freely available about the Earth for another half-century. 

All Landsat data is available to the public free of charge and is in the public domain. Access Landsat imagery through NASA's Landsat Image Gallery. The Landsat Look Viewer from the USGS is another archive of Landsat imagery.