Celebrating 50 years of continuous Earth observation, the joint U.S. Geological Survey/NASA Landsat program of Earth observation satellites has provided a broad range of scientists, professional analysts, and ordinary citizens around the globe with accurate and impartial Earth imagery and data.
Fifty Years of Landsat: Pioneer in Promoting Food Security from Space
Landsat’s power to systematically observe the Earth’s land surfaces from 400 miles aloft in space supplies a nearly comprehensive portrait of Earth stretched across five decades of time, enabling specialists to detect and monitor critical changes in the land and its resources. One of the most beneficial applications of this power of observation has been the ability to address the relentless issue of food security.
With the world’s population predicted to increase from 7.9 billion in 2022 to over 9.6 billion people by 2050, and with the added stress of a changing climate, increasing agricultural output is one of the biggest challenges society faces today. Currently, 1 in 9 people are defined as chronically hungry, and chronic hunger disproportionately impacts the world's poorest people.
A vital aspect of food security is the development of a generally accurate forecast of agricultural production and food availability within a country or region. A reliable outlook of food availability during a critical timeframe enables governments and humanitarian organizations to make the most of the food resources at hand and to devise effective strategies to reduce the risk of future famine and potential disease outbreaks.
The origin of Landsat
In September 1966, then Secretary of the Interior Stewart Udall, announced that the U.S. Department of the Interior was launching "Project EROS” (Earth Resources Observation Satellites) to collect vital information about Earth through remote sensing by satellites. This remarkably ambitious project, later renamed Landsat, supported the mandate that Congress set for the USGS 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."
Surveying agricultural conditions since 1972
Following the launch of Landsat 1 by NASA on July 23, 1972, the Foreign Agricultural Service of the U.S. Department of Agriculture began using Landsat imagery and data to monitor global agricultural production from space. The experimental stages of this new capability followed on the heels of the Soviet Union’s grain crop failure of 1972. Although the crop failure was widespread throughout the USSR, the extraordinary extent of the shortfall remained unknown to U.S. officials until months later. This lack of timely global production estimates meant that the USSR was able to purchase massive quantities of U.S. wheat at substantially lower prices than the true market value.
The first large scale program for monitoring global crop production using Landsat imagery was USDA’s Agriculture and Resource Inventory Surveys through Aerospace Remote Sensing (AgRISTARS), launched in 1979. The primary focus for AgRISTARS was on early warning and crop condition assessments in support of foreign commodity production forecasting.
In 1997, the USDA Cropland Data Layer program for tracking U.S. agricultural conditions began as an experiment to use data from Landsat 5 to produce a crop-specific land cover map. From the initial coverage of North Dakota, the program expanded to include coverage from additional satellites as well as the classification of additional states. Landsat’s detailed data, combined with on-the-ground surveys and other tools, helps the USDA to tally crop type and acreage, by county, and state-by-state for the entire contiguous U.S., an effort that continues today.
A long look is a good look
Monitoring and forecasting crop and rangeland conditions is critical for early warning and response planning in food insecure areas of the world. Satellite remote sensing can relay relevant and timely information in areas where ground data are scattered or frequently unavailable. Rainfall estimates from dispersed rain gauges can supply a rough outlook on the drivers of vegetation growth, whereas satellite-based, time series of biophysical indicators provide key information about actual vegetation status in near real-time over large areas.
The main advantage of using Landsat for crop monitoring across several decades, according to FAS sources, is that the imagery provides an objective and unbiased assessment of farm-level crop production. The calibrated stability of spectral and spatial resolution across Landsat satellites as well as consistently high levels of image positioning and production have helped establish Landsat as a gold standard among earth observation satellites. The sheer length of the Landsat data record – approaching half a century in some areas – adds certainty to regional vegetation assessments and harvest forecasts. Since 2008, Landsat data has been freely available, an important benefit for governments and humanitarian agencies around the globe which may have limited budgets for purchasing satellite imagery from commercial sources.
Global supply and demand estimates developed by USDA’s FAS and the World Agricultural Outlook Board, based in part on Landsat observations of agricultural conditions, contribute to broader assessments of global commodity intelligence. The ability to rapidly assess changes in a region’s agricultural status, whether due to natural disaster, drought, or political unrest, is crucial for anticipating market impact, food shortages, and humanitarian needs.
How does your garden grow?
With the capability to “see” detail on the land to approximately the size of a baseball diamond (30-meter resolution), Landsat satellites can image individual farm fields planted with major global crops, like corn and wheat, to regional crops, like rice and citrus. Because the complex sensors onboard Landsat satellites can see spectral ranges of light far beyond human vision, they are able to measure the wavelengths of light absorbed and reflected by green plants and thus monitor plant growth and health.
Using 30-meter resolution imagery from Landsat, vegetation evaluations are nearly 70 times more detailed than vegetation condition measurements from coarser resolution satellites. Of course, more detail requires more data. In early 2020 USGS, as part of its ongoing effort to improve access to the Landsat data archive, began data migration of the Landsat archive so that it would be accessible through the Amazon web services data cloud infrastructure. Cloud access, made possible by the 2008 DOI decision to release Landsat satellite data free to the public, enables large-scale data processing by Google Earth Engine and others. As a result, the analysis of massive Landsat datasets of crop conditions can proceed much easier and more productively than ever before.
By combining Landsat data with data from other satellite systems and augmented by ground observations as needed, the Landsat program provides decision makers with vital information on crop conditions, natural vegetation, and, crucially, water availability. In recent years, the compatibility of the European Space Agency’s Sentinel-2 satellite with Landsat satellites 8 and 9 means that imaging revisit times are more frequent. No-cost, cloud-based accessibility to Landsat data around the globe helps agencies in prioritizing where to direct food assistance, relief efforts, and support by identifying where one area may be in worse condition than another area because of flooding, drought, or political unrest.
Cultivating food knowledge from space
Today there are many earth observing systems operated by dozens of nations and consortiums that monitor agricultural conditions and production. Examples include: the Global Information and Early Warning System of the United Nations Food and Agriculture Organization (FAO); the Famine Early Warning Systems Network from the U.S. Agency for International Development; China’s CropWatch; the Monitoring Agriculture with Remote Sensing system from the European Commission; the Group on Earth Observations initiative GEOGLAM (GEO GLobal Agricultural Monitoring); and NASA Harvest Mission.
In 1972, Landsat was the pioneer for this technology. The Landsat program, by example and through cooperation, led the way for other technical efforts in assessing food production by means of earth observation, thus promoting food security. If Landsat were a person, perhaps it would take a measure of pride in knowing it contributed – behind the scenes – to the success of the winner of the 2020 Nobel Peace Prize, the United Nations World Food Programme.
The Landsat program, a joint mission of the U.S. Geological Survey and NASA, has provided continuous global coverage of landscape change since 1972. Landsat’s unique long-term data record provides the basis for a critical understanding of environmental and climate changes occurring in the United States and around the world.
Landscapes of West Africa, A Window on a Changing World (USGS, USAID, et al)