Since 1972, the joint NASA/USGS Landsat program is the only U.S. satellite system designed and operated to repeatedly make multi-spectral observations of the global land surface at a moderate scale that shows both natural and human-induced change. Landsat data helps land managers and policymakers make informed decisions about our natural resources and the environment.
History of Landsat
When astronauts returned from circling the Moon, they took the first pictures of Earth. One such picture was nicknamed “The Blue Marble,” shown to the left. These were among the first images that captured our entire planet into one frame. Enthusiasm to view Earth from a global perspective grew, especially in the U.S. Geological Survey/Department of the Interior (USGS/DOI). Scientists encompassed a variety of science applications that would benefit from a remote sensing platform other than aerial photography.
Although remote sensing technology was in its infancy in the 1960s, the idea of acquiring information about an event or object without physically being present wasn’t novel. Military strategists used aerial photography from airplanes in World War I & II, but later the practice branched into civilian uses like mineral exploration, crop analyses, and timber surveys. What was now possible in the space age was a novel technology to collect a large volume of data about our ever-changing planet for non-defense science applications from a spaceborne platform. Geography, geology, hydrology, and natural resources management could all benefit from the synoptic views of Earth.
Early Champions of Landsat
Knowing the benefits of viewing the Earth from space, USGS urged NASA to create an Earth observing satellite in 1965. NASA was firmly focused on crewed spaceflight and outer space exploration. The agency argued that current remote sensing technology wasn’t strong enough. They continued to contribute to developments of remote sensing, albeit at a slow pace. In 1966, a group of USGS scientists led by Photogeologist William A. Fischer and Hydrologist Charles J. Robinove were convinced that current sensors were good enough to start such a project. Fischer and Robinove jumped into action, presenting their case to USGS Director William T. Pecora. The two scientists suggested that USGS immediately develop their own remote sensing satellites.
“The course seemed clear; we must make and execute bold plans to gather data on the Earth’s resources,” Pecora shared in 1966. He joined the scientists’ cause.
From there, the trio shared the proposal of the Earth observing satellite program with the Secretary of the U.S. Interior, Stewart L. Udall. Secretary Udall was a strong advocate for the environment and justice, including removing ethnic slurs from topographical maps. Udall oversaw the addition of 103 protected areas during his tenure including national parks, national historic sites, and national wildlife refuges. In 1963 he wrote a book, “The Quiet Crisis,” about the dangers of pollution, overusing natural resources, and the decline of wide, open spaces. Udall was convinced of the necessity of such a satellite program.
On September 21, 1966, Udall announced at a press conference that the DOI was launching a new program called Project EROS. The Earth Resources Observation Satellites (EROS) program focused on Earth orbiting satellites using sophisticated remote sensing technology to gain valuable information about our planet. The announcement shocked the remote sensing community.
The South Dakota Connection
By 1968, NASA was building the first Landsat satellite, targeted to launch in late 1971. The EROS Program now turned to the next step: handling and distributing the exorbitant amounts of data and image products Landsat would collect. NASA wasn’t interested in managing millions of images or distributing science products to the world that would come from the EROS project.
Building a data center became the next priority for the USGS. The agency contracted a study for where the best location would be to receive transmissions for satellites passing overhead within the US. The result was a 350-by-150 mile zone from Topeka, Kansas, to Sioux Falls, South Dakota. Any land selected would need 100 acres in size and a 200-acre buffer zone. Ideally, the Data Center would need to be 10 miles or less from an airport and intersect near major US highways. Let’s not forget that eventually a large antenna would need to be constructed to receive incoming data, so stable soil and relatively low radio interference was a must as well. With so many requirements, the elliptical zone shrunk considerably.
One savvy senator and congressman duo noticed that a major city in their state could match each necessity laid out by the study. Senator Karl E. Mundt and Congressman Ben Reifel, both from South Dakota, eyed Sioux Falls as a match for the anticipated EROS Data Center (EDC). Community members and advocates from the area joined the politicians. The Office of Bureau Management and Budget was wary to the idea. When the director of the Bureau asked, “Why Sioux Falls?,” Businessman and Sioux Falls Representative Al Schock simply said that the city would donate the land for EDC. The Sioux Falls Development Foundation purchased 318 acres of farmland 16 miles north of Sioux Falls and the EDC site was secured for further development.
Go for Launch
NASA and USGS finally entered a partnership together for the EROS project. NASA would fund and launch the first three satellites as research missions, and USGS would store and process the data that came from the EROS program. Since the EROS Data Center near Sioux Falls didn’t have an antenna yet, NASA Goddard Space Flight Center in Maryland retrieved the data from both sensors then mailed physical film rolls and tapes to EDC to be fully processed and archived.
The first three satellites were of the same design. Each one carried the same type of imaging instruments and sensors: a primary Return Beam Vidicon (RBV) and an experimental Multi-Spectral Scanner (MSS). The RBV assembly was three film cameras on Landsat 1 & 2 that shuttered to freeze an imaged area in one moment in time. Each camera was filtered to a different part of the electromagnetic spectrum: red, green, and infrared. Essentially, the RBV was a highly sophisticated television camera, even compared to present day. The other sensor, MSS, scanned one pixel at a time, scanning the planet line by line. The sensor could image six lines at a time using a rotating mirror system to scan the land surface. The MSS recorded in green, red, and two infrared portions of the spectrum. Quickly, the MSS data was found superior and more favorable to the RBV data.
The Earth Resources Technology Satellite-1 (ERTS-1), later renamed Landsat 1, launched in 1972 and became the first civilian sensor to send real-time data in the world. The first MSS image taken with the satellite was of the Dallas-Fort Worth area in Texas on July 23, 1972.
In 1974, the first annual Landsat symposium was created, known as the Pecora Symposium, to honor William T. Pecora who led the Landsat mission as the USGS director during its early years. These annual symposia continue to this day. At each Pecora symposium, researchers from a variety of professional backgrounds discuss innovations, discoveries, and applications for the valuable geospatial remote-sensing data Landsat produces.
The ERTS-B satellite, renamed Landsat 2, launched in 1975. Landsat 3 blasted off into space in 1978 with a two camera RBV array to improve data quality & sensor reliability, and Landsat 1 retired the same year.
Rocky Times Ahead
As more remote-sensing satellites went up, the older ones were decommissioned. Landsat 2 was retired after the launch of Landsat 4 in 1982. Landsat 4 was the first civilian satellite with global positioning systems (GPS). It took a truly collaborative effort, as it was funded by NOAA, built by NASA, and operated by EOSAT with operational support from USGS.
Landsats 4 and 5 carried a MSS and a Thematic Mapper (TM) instrument. Based on learned lesson from the MSS, TM used seven spectral bands, adding thermal infrared radiation. This added the capability to acquire night scenes and calculate land surface temperatures. With the increased spatial and radiometric resolutions, the TM could transmit data six times greater than MSS.
Launching Landsat aboard Titan rockets from Vandenburg Airforce Base into an exosphere near polar orbit wasn’t cheap. In the 1980s, those who operated the program began to raise fees associated with the imagery, in hopes for better economical return on the satellite endeavor. In 1983, NASA transferred Landsat operations to NOAA, where they first increased the price of Landsat products. Attempts to fully commercialize the EROS program began in 1985, the year after Landsat 5 was launched, and as a problem on Landsat 4 threaten to end its mission prematurely. Eventually the program was transferred to the Earth Observation Satellite Company (EOSAT). Further increased prices resulted in a drop of user demand. Few could afford the new prices for Landsat that peaked at $4,400 per scene. Scientists world-wide simply went without and shared copies of Landsat data they already had purchased among themselves.
Landsat 6 was the only satellite built under EOSAT and NOAA leadership. Landsat 6 failed to achieve orbit due to a payload separation problem, leaving Landsat 5 alone to survey our planet. Budget driven decisions almost led to an EROS program shut down. In the early 1990s, the U.S. government stopped trying to commercialize the Landsat program and returned it to DOI/USGS via Public Law 102-555. Through the Land Remote Sensing Policy Act of 1992, the USGS established a permanent Government archive containing satellite remote sensing data of the Earth's land surface and to make this data easily accessible and readily available. The National Satellite Land Remote Sensing Archive (NSLRSDA) is one of the only data archives authorized by Congress. In 1988, NOAA withdrew itself from the program, and the USGS set lower prices in place for their Landsat products.
Facing the Future
Infrastructure changes began in 1992 as EROS prepared to receive data from satellites directly instead of receiving tapes from NASA from across the country. EDC added another 65,000 square feet to its original 115,000 main floor footprint to accommodate Landsat and other NASA work. The interior featured several new super computers, high volume data storage, analysis equipment, and additional research offices. The building and equipment were completed in 1996.
In June 1997, one last late addition to the facility finally arrived. The long-awaited ground station antennae would allow Landsat satellites to directly communicate with the EDC, justifying the rural eastern South Dakota location. Barely a month after installation, one of the most devastating hailstorms went on record for the Sioux Falls area. The ten-meter articulating dish was battered with over 2,000 baseball-sized hailstone indentations. Along with the once-pristine antennae, the brand-new skylights in the library and atrium were shattered. Less than fifteen minutes of a storm resulted in millions of dollars of damage.
By the end of the year, repairs were made to the building and the Landsat 7 Antennae was replaced. For two years when high winds threatened the facility, personnel carefully re-positioned the dish to minimize damages. In 1999, a dome was installed to protect the satellite dish from the elements including future hail and extreme storms. By that time, the antennae had been downloading data from orbiting Landsat’s for an entire year and continues today with the ability to acquire data from other satellites like SPOT 4 & 5 during the North American data buy program that operated from December 2010 through 2013.
Landsat 7 launched April 15, 1999, and placed a new Enhanced Thematic Mapper Plus (ETM+) sensor into orbit. Although similar to the TM sensor, the ETM+ sensor included the addition of a high-resolution pan-chromatic band (15 m) and an higher resolution thermal band (60m).
In 2008, the USGS declared a commitment to providing free and open Landsat data to the world. Two years later, Landsat data became available to download directly from the internet. This increased access to data allowed greater community awareness and community benefit, akin to providing a library card to the world’s best imagery of the planet Earth. On August 17, 2009, the millionth free scene was downloaded. This started a new trend that brought other nations to allow data free to users. The 10 millionth Landsat scene was acquired and made available to the world at the end of November 2021. The Landsat 7 science mission ended April 6, 2022.
With the Landsat 8 launch in 2013, Landsat 5 was finally able to retire with a Guinness World Record of 28 years orbiting Earth. The new sensors introduced were the Operational Land Imager (OLI) and the Thermal Infrared Sensor (TIRS). TIRS contains two thermal bands that measures the land surface temperature, providing important information about arid lands and urban heat areas. The OLI collects images in nine spectral bands of visible, near-infrared, and shortwave light, allowing us to see wide features of the Earth’s landscape, like farms, forests, and other land uses.
In 2016, the USGS reorganized the Landsat archive into a tiered collection management structure. Landsat data within a collection are consistently calibrated, processed, and retain traceability of data quality origin. Scenes in the Tier-1 category, the highest-quality scenes, are consistent across time. As a result, scientists can use the data for time series analysis with confidence that pixels from 1972 align with current day pixels. This consistency across the Landsat archive has allowed the USGS to develop Landsat Level-2 and Level-3 Science Products. The products are research-quality and application ready, and can be used to monitor, assess, and project how changes in land use, land cover, and land condition affect people and nature.
Landsat 9 launched on September 27, 2021, from Vandenberg Space Force Base, California. Just over a month later, on October 31, 2021, the satellite’s sensors captured first light images across the including the Australian coast, the Himalayas, the Navajo Nation, and Lake Erie. Working in tandem with the Landsat 8 mission, Landsat 9 will provide major improvements to the nation’s land imaging, sustainable resource management, and climate science capabilities Landsat 9 will also ensure continued observation into the era of Landsat-Next. Landsat-Next will have even better improvements over today’s satellites to support better science and public services.
2022 highlights the 50th anniversary of the Landsat program. Over the decades, while technologies advanced, the Landsat program remained true to its mission to build and periodically refresh a global archive of global land surface data. To this day, researchers use the satellites data to understand various processes that occur on Earth. The Landsat program continues to inform managers and scientists in a diversity of disciplines comprising human health, agriculture, climate, energy, fire, natural disasters, urban growth, water management, ecosystems and biodiversity, and forest management.