Landsat-9 is a continuation of a series of Earth-observing spacecraft that started almost 50 years ago. No other remote-sensing system has kept a longer, continuos record of the changing condition of our planet.
Landsat has catalogued the growth of megacities, the spread of farming and the evolving outlines of forests, deserts, coasts and glaciers.
“We’ve assembled an amazing history of how the planet has changed over the last half century,” said Dr Jeff Masek, Nasa’s Landsat-9 project scientist.
“For example, we’re able to see the natural disturbances that occur, (such as) fires, hurricanes, and insect outbreaks; and then the long-term recovery of ecosystems that takes place for decades after that.
“And we’re able to look specifically at climate and climate-change impacts on ecosystems. We’ve mapped areas of increased plant cover at high latitudes due to a warming climate. We’ve also seen areas of vegetation decline in water-limited semi-arid environments.”
Since 1982 with Landsat-4, the system has been able to resolve features on the ground as small as 30m across. Although there are now plenty of other imaging spacecraft up there that can boast a much sharper view (in the tens of centimetres), none comes close to Landsat for longevity.
This enables scientists to pull out the real trends in time. Also, the data is free and open so anyone anywhere can access and use Landsat pictures at no cost.