The Landsat Programme celebrates its fifty year anniversary this year! Landsat is a series of Earth-observing satellite missions jointly managed by NASA and the U.S. Geological Survey (USGS) celebrating its fifty year anniversary in 2022.
On July 23, 2022, Landsat marks fifty years of providing a continuous record of the Earth’s land surfaces. Landsat’s fifty year archive of Earth observation supplies the world with an unparalleled baseline of trusted, empirical evidence to support a shared understanding of how the Earth is changing.
On July 23, 1972, in cooperation with NASA, the Earth Resources Technology Satellite (ERTS-1) was launched. It was later renamed Landsat 1. Additional Landsat satellites have launched to bring the world an archive of remote sensing data. Currently orbiting and active satellites are Landsat 8 and Landsat 9.
NASA and USGS are already planning the development of the follow-on missions, to include Landsat Next, the successor mission to Landsat 9.
Landsat satellites have the optimal ground resolution and spectral bands to efficiently track land use and to document land change due to climate change, urbanization, drought, wildfire, biomass changes (carbon assessments), and a host of other natural and human-caused changes.
Landsat: Fifty Years of Earth Observation
The Landsat Program’s continuous archive (1972-present) provides essential land change data and trending information not otherwise available. Landsat represents the world’s longest continuously acquired collection of space-based moderate-resolution land remote sensing data. Landsat is an essential capability that enables the U.S. Department of the Interior to wisely manage Federal lands. People around the world are using fifty years of Landsat data for research, business, education, and other activities.
Massive volumes of carefully calibrated Landsat data allow observations from one period or one geographic area to be compared to others across time and geographic locations, enabling scientific insights that no other single data source can provide. As a civilian pioneer in land observation from space, and now in partnership with other commercial and international systems, the Landsat program has allowed humanity across the globe to see ourselves – and our actions that affect the Earth – clearly, at length, without political or cultural bias.
An objective view since 1972
Secretary of the Interior Stewart Udall announced in a September 1966 press release that the U.S. Department of the Interior was launching “Project EROS” (Earth Resources Observation Satellites) to collect valuable information about Earth through remote sensing by satellites. This ambitious project, later renamed Landsat, supported the mandate that Congress set for the U.S. Geological Survey when the agency was established in 1879: “classification of the public lands, and examination of the …products of the national domain.” Secretary Udall’s further vision was “to observe the Earth for the benefit of all,” a reference to the concept of the peaceful use of outer space subsequently established in a 1967 United Nations treaty. The first satellite in the Landsat series was launched by NASA on July 23, 1972.
The Landsat program has employed a series of satellites, like relay runners, to carry out 50 years of Earth observation. Landsat 2, Landsat 3, and Landsat 4 followed Landsat 1 in 1975, 1978, and 1982, respectively. Launched in 1984, Landsat 5 set an official Guinness World Record for “longest-operating Earth observation satellite,” delivering high quality, global data for 28 years and 10 months, far beyond its three-year design life. Landsat 6 failed to achieve orbit in 1993. The remainder of Landsat satellites have accomplished successful launches and data collection: Landsat 7 in 1999, Landsat 8 in 2013, and Landsat 9 in September 2021.
In 1972, the world’s population stood at 3.8 billion people; later this year, the world’s population will reach eight billion. Through five decades of population growth, Landsat satellites have systematically recorded changes on the land that have occurred due to agriculture, mining, forest diseases, wildfire, earthquakes, volcanoes, tidal waves, coastal erosion, war, famine, urbanization, and climate change. By design, Landsat has accurately monitored all these changes for the benefit of humankind.
Landsat Then and Now
The Landsat program offers the longest continuous global record of the Earth’s surface; it continues to deliver visually stunning and scientifically valuable images of our planet.
For over 50 years, the Landsat program has collected spectral information from Earth’s surface, creating a historical archive unmatched in quality, detail, coverage, and length.
“It was the granddaddy of them all, as far as starting the trend of repetitive, calibrated observations of the Earth at a spatial resolution where one can detect man’s interaction with the environment,” said Dr. Darrel Williams, the Landsat 7 Project Scientist, states about Landsat as early as in 2012, when celebrating Landsat’s 40 year anniversary.
Free data – open for anyone to use
Previously unimaginable Landsat applications were fostered by a policy change in 2008 that made Landsat data freely available to the global community. Since 2008, not only have individual users had free access to specific Landsat data and imagery, but open public access has encouraged geospatial and data processing firms, such as Amazon, Esri, Google, and Microsoft, to host the entire massive Landsat archive and to develop advanced access, retrieval, and visualization applications for the data.
One theme of these highly developed applications is to rapidly compare land changes over time using temporal layers of Landsat data in a particular place or over broader regions. In recent years, with the development of cloud computing, massive amounts of data can now be processed in hours instead of months. A 2019 USGS study estimated the annual value of Landsat imagery to the American economy at $2.1 billion.
The Landsat story will continue in the next decade with Landsat Next, the newest member of the Landsat family.
The Landsat Next mission is currently in its early phase, with mission designers considering data users’ requests. A wide range of satellite and instrument types are under consideration, but they all have two things in common: They will continue the existing decades-long data record, and they will measure more than twice as many spectral bands as Landsats 8 and 9.
“Spectral bands” refers to the wavelengths of light that Landsat instruments measure. When an instrument measures a range of wavelengths, it provides details about different features on the ground. For example, the visible light section of Landsat 9’s spectral range provides information about dust and smoke in the air and coral in the ocean, while longer infrared wavelengths capture clouds, vegetation health, crop water use and active fires.
Landsats 8 and 9 measure 11 spectral bands from the visible to thermal infrared wavelengths. The goal for Landsat Next is to measure up to 25 spectral bands, unlocking new applications for water quality, plant stress, snow cover, soil health and more.
Landsat Next’s upcoming project design steps are to complete studies on the best mission, instrument and data storage designs to achieve mission goals. The mission is on target to launch in 2029/2030.
Landsat versus Copernicus
In an interview in 2018, ESA’s Josef Aschbacher confirmed that the Landsat and Copernicus programmes are fully complementary, despite some commonalities: “We cannot replace Landsat with Copernicus. In fact the programs complement each other. The world has been benefitting from Landsat data for the past fifty years now. It is really a unique and extremely valuable data source that has provided knowledge and understanding of the planet.
The Sentinel-2 satellites within Copernicus are similar to Landsat in accordance to sensors, with some variations like different numbers of channels and the resolutions. With the Sentinel-2 twins in orbit, we can increase the coverage provided by Landsat, and further with 13 channels increasing the accuracy of the measurements taken with a 10-meter resolution in the best channels.
So, while Landsat has built up a fifty years long history and provides data globally for many applications, Sentinel is going to massively cover the planet regularly every six days. The combination of both will prove to be an extremely good application. In fact, I am working very closely with NASA and USGS in cross-calibrating Sentinel 2 data with Landsat data so that users can use either of them, whichever satellite just happens to fly over.”
Also read: Using historic Copernicus data