Observing Earth with
Change is everywhere. We see change best when we can compare things—like before and after images. Landsat helps us do this. Landsat satellites have been imaging our planet over four decades, allowing us to see how the Earth’s land surface has changed. Every day, Landsat images provide important information on February 11, 2013 to people who have to make hard decisions about our resources and our environment.
The Landsat series of satellites is a prime example of American achievement in space. Since the first satellite was launched in 1972, Landsat has become an indispensable part of our national infrastructure, providing a decades-long, unique and invaluable record of our changing landscapes—with lots of practical uses for our lives and livelihoods.
A series of seven Landsat satellites have collected reliable, consistent, and objective observations of the global land surface for over 40 years. The U.S. Geological Survey (USGS) maintains an archive of images from all seven satellites. In 2008 the USGS opened the archive to the public allowing anyone to search, browse and download over 6 million images online for free.
The Power of a Pixel
Landsat provides valuable information by measuring reflected and emitted light energy in both visible and infrared portions of the spectrum. This information is recorded digitally for each 30 square meter area on the ground, called a pixel. Landsat pixels are about the size of a baseball diamond. Pixel-by-pixel, Landsat images of the landscape are built up to provide data at the scale necessary to effectively manage our lands, our cities, and our natural resources over time.
The Just–Right Satellite
Land cover and land use around the globe are changing faster than ever before. This has sweeping consequences. Managing our land and water resources in a sustainable way is important for life on Earth—and if you want to manage something well, you need to be able to map it well. Landsat collects data at the scale of human interactions with the land and with the frequency necessary to detect, monitor, and understand changes in land use and land cover—allowing us to map a better future.
Preserving our shared
The geoheritage of our landscapes is the history of humanity. Therefore, continual study and monitoring is vital if we are to preserve this legacy for future generations. Our landscapes can be studied through human as well as technical senses. We can experience our landscapes in person or remotely through images taken from Earth observation satellites.
A Vision for Earth Observation
Fifty years ago, on September 21, 1966, Secretary of the Interior Stewart Udall announced his vision to create “a program aimed at gathering facts about the natural resources of the Earth from Earth-orbiting satellites.” As a result, since 1972, the Landsat series of satellites have been keeping a watchful eye over our planet. Landsat’s continuous 44-year accumulation of Earth imagery has documented our changing landscapes and provided stunning images of the Earth.
Building a Legacy
NASA builds and launches the Landsat satellites and then the U.S. Geological Survey operates the missions and preserves the data—currently an archive of more than 6 million images. This archive provides the continuity to observe the evolving geoheritage of our landscapes. In late 2008, USGS opened the entire Landsat collection, with free and open access to decades of continuous data. Use of the imagery and data increased exponentially, from approximately 21,000 scenes distributed annually to over 13 million in 2015.
Benefits to Society
Landsat data, used in combination with today’s advanced geographic information systems, image processing software, and cloud computing, enable individual users to process as many scenes as needed for land analysis. For example, many historical images of a single site can now be obtained and analyzed for land-surface change over time, or a user can easily see land-cover or land-use conditions across an entire State or region. Landsat imagery is used in natural resource management, agriculture, disaster management (e.g., wildfire, floods, drought), industry, forestry, human health, climate, energy, urban growth, and ecosystems and biodiversity. All these fields monitor and preserve
the geoheritage of our lands.
Monitoring our Geoheritage
Landsat was the first satellite to keep an eye on our Earth, helping people throughout the world monitor and protect our valuable geoheritage for, as the American Geosciences Institute describes, “scientific, economic, ecological, educational, cultural, aesthetic, artistic, and recreational purposes.”