Next month’s launch marks the ninth iteration of a 50-year mission that has transformed earth science.
Nearly 50 years after launching its first satellite in 1972, the Landsat mission, a joint effort by NASA and the U.S. Geological Survey to monitor the Earth’s surface, is scheduled to launch its ninth satellite into space on September 16. Landsat 9, which will lift off from Vandenberg Space Force Base in California, is the next installation in the longest continuous space-based record of Earth’s land in existence.
Once in orbit, Landsat 9 will replace Landsat 7 and join Landsat 8. Together, they will collect images that capture Earth’s land surfaces every eight days.
“Landsat’s data of Earth’s surface as seen from space have transformed scientists’ understanding of regional, national, and global-scale changes in land use and land cover, providing information for sectors including agriculture, forestry, urbanization, hydrology, and homeland security and disaster mitigation,” NASA said in a public statement. “Landsat 9 will continue this record of monitoring key natural and economic resources, as well as global environmental changes into the future.”
15-feet tall and about the length of a school bus, each satellite orbits the Earth every 99 minutes, snapping photos with every pass. Every few hours, they contact a ground station to offload their data.
The Landsat archive now contains over eight million images adding up to a 50-year historical survey of the Earth’s surface, but the data was not always accessible. In 1990 Landsat data cost as much as $4,000 per scene, and scientists often required several scenes to complete their work. In 2008, however, the archive was opened to the public, free of charge. That year, Landsat had over a million downloads, and today, that number typically lands in the ballpark of 15 to 20 million.
As a public good, the data has been used in more than 18,000 peer-reviewed research papers, and many public and private programs use it to support agriculture, forest management, urban development and wildfire-damaged vegetation recovery, among other applications. Researchers can determine whether a piece of Earth has changed from wetlands to suburban housing, if a forest has become stressed due to insect damage or if a group of farm fields are suffering from drought.
Landsat 9’s launch next month will be the first such event since the previous satellite, Landsat 8, went into orbit over eight years ago. It will hitch a ride on one of United Launch Alliance’s spacecraft, and the U.S. Geological Survey Earth Resources Observation and Science Center will operate the mission and manage the ground system, including maintaining the Landsat archive. The satellite itself was built by Northrop Grumman, which also integrated it with instruments, and tested the observatory.
Landsat 9 uses similar instrument technology to Landsat 8. Carrying two sensors, the Operational Land Imager-2 (OLI-2), built by Ball Aerospace & Technologies Corporation, and the Thermal Infrared Sensor-2 (TIRS-2), built at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, it will detect the reflected light and heat emitted from Earth’s surface across the visible, near infrared, shortwave infrared, and thermal infrared wavelengths.
The instruments will capture more than 700 new images daily across 11 wavelengths at 30-meter resolution. This resolution is fine enough to detect even small agricultural fields, buildings, forest stands, and lakes, while still providing a broad enough swath to cover large areas of terrain. With its 11 wavelengths, the instruments will capture information about Earth, including data related to coastal waters, forests, healthy and unhealthy plants, and wildfire scars in the visible light to thermal infrared ranges.
NASA created an interactive webpage for interested members of the public to learn about the Landsat mission and its history.