On a summer Sunday a half-century ago, a satellite launched into space and opened an eye on Earth that has kept watch over our planet’s immense beauty, and its rapid transformation at the hands of humans, ever since.
The Landsat program, which has produced the longest-running view of Earth from space in existence, turns 50 on Saturday, a milestone that marks the launch of that first space observer, now known as Landsat 1, on July 23, 1972. Since that inaugural mission, Landsat has successfully launched seven other satellites, three of which are still in operation, and experienced one launch failure when Landsat 6 did not reach orbit.
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Managed jointly by NASA and the U.S. Geological Survey (USGS), Landsat has captured more than ten million images, which are available to anyone at no cost, enabling humans to both behold our planet’s grandeur and the pressures we are exerting on it. Landsat has built a mosaic of our planet out of photographic tiles, each capturing an area of Earth that is 115 miles in length and width. These postcards-from-space reveal dune-rippled deserts, remote islands, sprawling cities, and branching river systems that flow through landscapes like veins, among other marvels.
In addition to informing countless scientific disciplines, Landsat’s pictures are just plain gorgeous, which has inspired an “Earth as Art” series that spotlights its most captivating shots. But they are also a stark reminder of the changes that human-caused climate change is wreaking across the globe, as the program’s images have monitored intensifying wildfires, assessed damage from hurricanes, and watched as lakes have dried, coasts have eroded, and forests have been demolished.
For those who have worked on Landsat over the decades, the program is a labor of love that has engaged generations of scientists, including Virginia Norwood, a trailblazing physicist who designed the key imaging instrument used on Landsat 1 and several other early missions in the program.
Landsat 1, which retired in 1978, was a relatively simple spacecraft compared to its modern successors, but many still recognized it as “a wave of the future” at the time, according to Jim Irons, who has been a Landsat leader for decades and currently serves as deputy project scientist for Landsat 7 and project scientist for Landsat 8 at NASA’s Goddard Space Flight Center.
“I think it was clear that it was going to revolutionize the way we observe the Earth over time,” said Irons, who recently retired as director of Earth Science Division at Goddard, in a joint call with fellow Landsat team member Temilola Fatoyinbo.
“Even if we use more high resolution data sets—because now we have all these other really amazing, very high-resolution data—it’s still useful to compare it to Landsat,” added Fatoyinbo, who is a research physical scientist specializing in coastal ecosystems at Goddard’s Biospheric Sciences Lab. “The power lies in the ability to compare and look at the same spot on Earth through time, and we can only do that with Landsat.”
The world that Landsat 1 left all those decades ago was very different from the one that its current operational successors, Landsat 7 through 9, are observing today. Scientists were raising alarms about human-driven climate change, which is caused by greenhouse gas emissions from the consumption of fossil fuels, when the program began, but its 50-year record has documented the disastrous consequences in unprecedented detail.
Because Landsat has provided consistent calibrated coverage at no cost for decades, it is “a really powerful tool for understanding the impacts of climate change in many, many ways,” Irons said, citing observations of “retreating glaciers, Amazonian deforestation and forest disturbance, urban growth, changes in ecosystems” which “are all reflective of climate change—the list is huge.”
“For me, as someone who works in the coastal zone a lot, I see a lot of changes happening,” Fatoyinbo noted. “Both deforestation and coastal change are two really shocking images when you see them.”
Landsat has also tracked the deterioration of wilderness all over the globe as cities, farms, and other human spaces steamroll natural habitats. These frightening changes can be hard to grapple with, but the program’s stunning catalog of Earth imagery presents the ultimate argument for action and resolve in the face of anthropogenic pressures.
Landsat images reveal our familiar home planet as somehow otherworldly when viewed from outer space, and they also expose its fragility—and therefore our own vulnerability—in a cosmic context. The program can make you rethink those little patches of Earth that you may know and love, a power that both Irons and Fatoyinbo reflected on as the program turns 50.
“I grew up in West Africa; I spent a lot of time there and a lot of places you just can’t get to because it’s huge, it’s far, and there might not be transport,” Fatoyinbo said. “In some areas, there might be unrest or you just can’t physically go there, especially in the type of wetlands that I work in.”
“When I saw my first satellite image, which was actually a printout of Africa in front of my future PhD advisor’s office, I felt like my head was about to explode,” she continued. “I hadn’t even thought about the idea that there would be multiple images, and that you could look through time. I hadn’t even digested that yet. But when I ended up doing my PhD, I started working on mapping and working with Landsat data then. I’m still working with it and it keeps getting better.”
Irons also remarked on the interesting experience of beholding familiar stomping grounds from space. When I asked him if he had a favorite Landsat image, he cited an early picture from the program of the Appalachian Mountains around Harrisburg, Pennsylvania. Through Landsat’s perspective, he recognized places he had hiked and identified geological features he had learned about in courses at Penn State.
“To have it presented as an image taken from space, where the textbook discussion of what the Ridge-and-Valley looked like was right there, in a plain image that you could look at, explore, and say ‘oh, I hiked here’— that always struck me,” he said.
“Our focus, appropriately now, is on anthropogenic effects on the land and on the world, and we spend a lot of time looking at the aftermath of disasters, wildfires, and urban growth, but sometimes it’s good just to go back to those ‘Earth as Art’ images and realize the stark beauty of observing the Earth from the high vantage-point of space,” Irons concluded. “We can’t all be astronauts and have that view, but we can all look at Landsat data and imagine what it would look like if we were up in space.”
