Landsat program

The Landsat program is a long project that has taken pictures of Earth from space. It is a joint effort by NASA and the USGS. It began on 23 July 1972, when the Earth Resources Technology Satellite was launched. This satellite was later renamed Landsat 1. The most recent satellite, Landsat 9, was launched on 27 September 2021.

Landsat 7, launched in 1999, is the 7th of 9 satellites in the Landsat program.

The instruments on Landsat satellites have captured millions of pictures. These pictures are stored in the United States and at Landsat stations around the world. They are useful for studying changes on Earth and for many things, such as agriculture, cartography, geology, forestry, regional planning, surveillance, and education. People can see these pictures on the U.S. Geological Survey's "EarthExplorer" website.

Landsat 7 can capture data in eight different colors of light, with details as small as 15 to 60 meters across. It takes pictures of the same area every 16 days. Landsat pictures are usually split into parts called scenes, each covering an area about 115 miles long and wide.

History

Virginia Norwood, "The Mother of Landsat", designed the multispectral scanner.

In 1965, William T. Pecora, the director of the United States Geological Survey, suggested using satellites to study Earth's natural resources. At that time, weather satellites had been watching the atmosphere since 1960, but no one had thought about watching land from space.

Landsat began in 1966 when the Department of the Interior (DOI) decided to create an Earth-observing satellite. NASA started building the first satellite, and by 1972, Landsat 1 was launched, starting a new way to watch Earth from space. The program helped scientists study crops, forests, and many other parts of our planet.

Satellite chronology

Timeline

Instrument	Launched	Terminated	Duration
Landsat 1	23 July 1972	6 January 1978	5 years, 6 months and 14 days
Landsat 2	22 January 1975	25 February 1982	7 years, 1 month and 3 days
Landsat 3	5 March 1978	31 March 1983	5 years and 26 days
Landsat 4	16 July 1982	14 December 1993	11 years, 4 months and 28 days
Landsat 5	1 March 1984	5 June 2013	29 years, 3 months and 4 days
Landsat 6	5 October 1993	5 October 1993	0 days
Landsat 7	15 April 1999	4 June 2025	26 years, 1 month and 20 days
Landsat 8	11 February 2013	Active	13 years, 3 months and 6 days
Landsat 9	27 September 2021	Active	4 years, 7 months and 20 days

Spatial and spectral resolution

Landsat satellites use different tools to take pictures of Earth. Landsat 1 through 5 used a tool called the Multispectral Scanner. Landsat 4 and 5 used that scanner and another tool called the Thematic Mapper. Landsat 7 used an improved version called the Enhanced Thematic Mapper Plus. Landsat 8 uses two tools: the Operational Land Imager for normal light and the Thermal Infrared Sensor for heat images.

Each picture piece, or pixel, can be different sizes depending on the tool. Older pictures from the Multispectral Scanner were a bit blurry, but systems now make them clearer. Other tools also adjust their pictures to be easier to use.

Landsat images can show the whole Earth in ways that ground measurements cannot. However, Landsat images are not as detailed as pictures taken from airplanes, and they do not visit the same spot as often as some other satellites.

The spectral band placement for each sensor of Landsat

Landsat 1–5 Multispectral Scanner (MSS)
Landsat 1–3 MSS	Landsat 4–5 MSS	Wavelength (micrometers)	Resolution (meters)
Band 4 – Green	Band 1 – Green	0.5 – 0.6	60*
Band 5 – Red	Band 2 – Red	0.6 – 0.7	60*
Band 6 – Near Infrared (NIR)	Band 3 – NIR	0.7 – 0.8	60*
Band 7 – NIR	Band 4 – NIR	0.8 – 1.1	60*

Landsat 4–5 Thematic Mapper (TM)
Bands	Wavelength (micrometers)	Resolution (meters)
Band 1 – Blue	0.45 – 0.52	30
Band 2 – Green	0.52 – 0.60	30
Band 3 – Red	0.63 – 0.69	30
Band 4 – NIR	0.76 – 0.90	30
Band 5 – Shortwave Infrared (SWIR) 1	1.55 – 1.75	30
Band 6 – Thermal	10.40 – 12.50	120* (30)
Band 7 – SWIR 2	2.08 – 2.35	30

Landsat 7 Enhanced Thematic Mapper Plus (ETM+)
Bands	Wavelength (micrometers)	Resolution (meters)
Band 1 – Blue	0.45 – 0.52	30
Band 2 – Green	0.52 – 0.60	30
Band 3 – Red	0.63 – 0.69	30
Band 4 – NIR	0.77 – 0.90	30
Band 5 – SWIR 1	1.55 – 1.75	30
Band 6 – Thermal	10.40 – 12.50	60* (30)
Band 7 – SWIR 2	2.09 – 2.35	30
Band 8 – Panchromatic	0.52 – 0.90	15

Landsat 8 Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS)
Bands	Wavelength (micrometers)	Resolution (meters)
Band 1 - Ultra Blue (coastal/aerosol)	0.435 – 0.451	30
Band 2 - Blue	0.452 – 0.512	30
Band 3 - Green	0.533 – 0.590	30
Band 4 – Red	0.636 – 0.673	30
Band 5 – NIR	0.851 – 0.879	30
Band 6 – SWIR 1	1.566 – 1.651	30
Band 7 – SWIR 2	2.107 – 2.294	30
Band 8 – Panchromatic	0.503 – 0.676	15
Band 9 – Cirrus	1.363 – 1.384	30
Band 10 – Thermal 1	10.60 – 11.19	100* (30)
Band 11 – Thermal 2	11.50 – 12.51	100* (30)

MultiSpectral Scanner (MSS)

The Landsat program used the Multispectral Scanner (MSS) from its first mission up to its fifth. The MSS helped the United States stay ahead in satellite imaging, allowing Landsat to launch before the French SPOT satellite.

The MSS was special because it used a moving mirror instead of a regular camera. This mirror captured images of Earth in four different colors of light, showing how much sunlight reflected from the Earth there was.

The MSS was known for taking clear and consistent pictures. Each picture showed an area about 83 meters long and 68 meters wide. The system was set up to keep moving smoothly, covering a path 185 km wide on Earth's surface.

Uses of Landsat imagery

Landsat data helps scientists learn about animals and how places change over time, both naturally and because of humans. The Landsat satellites can see Earth in different colors, which helps with many jobs, like studying plants and animals or looking at land use.

Landsat imagery has been taken since 1972, giving us a long record of how Earth looks from space. In 2021, Landsat 9 was launched, so we can keep learning about our planet for many years to come.

One year after launch, Landsat 8 imagery had over one million file downloads by data users.

Landsat imagery helps save money. In 2015, it was found that the top 16 ways people use Landsat data save governments, groups, and businesses a lot of money each year. These uses include helping farms, mapping for the government, watching over forests, and planning for fires. Other uses include studying fish, watching glaciers, and finding new animals.

Landsat imagery has helped us learn about big changes on Earth, like how some lakes are getting smaller or how forests are changing. It has also helped us understand big fires, like the ones in Yellowstone National Park in 1988. By looking at pictures from space, scientists can see how different places react to fires.

Landsat imagery also helps us see how cities grow and change over time. For example, in Beijing, we can watch how new roads and buildings appear after important changes in how the city is managed. In 2005, Landsat pictures helped a scientist find a new area in Mozambique that turned out to be home to many new kinds of animals, including butterflies and a snake.

Recent and future Landsat satellites

Landsat 8 launched on February 11, 2013. It was sent into space on an Atlas V rocket from Vandenberg Air Force Base. This satellite helps us learn about farming, teaching, business, science, and more. It was built in Arizona.

Landsat 9 launched on September 27, 2021. Plans for this satellite started a few years earlier. In the future, Landsat may work together with other satellites like the ESA's Sentinel-2.

Landsat Next is expected to launch around late 2030 or early 2031. It will collect information in 26 different ways, more than the 11 ways used by Landsat 8 and 9 today.