“If you think back to the mid-’60s, the space race was on, the American public was enamored of what was going on, and it was a unique idea to use that technology, and not just for military applications. , but rather to turn on those cameras and see what happens on the surface of the Earth,” says Sohal. “People didn’t really know what to expect.”
Since 1972, nine Landsat satellites have populated Earth’s sky (though one, Landsat 6, did not reach orbit). Currently, three of them circle the planet in polar orbits, observing strips of land up to 185 kilometers wide and making very detailed measurements. Every 16 days the same satellites return to observe the same location. Thus, during five decades of observing Earth, Landsat has compiled the most detailed record ever of the changing face of our planet.
“It’s been a great discovery program,” says NASA’s James Irons, who has led the Landsat program for decades. “At the time of Landsat 1’s launch, the entire Earth was not well mapped: the data was sparse.”
And it set the stage for cartographer and pilot Elizabeth Fleming to use Landsat data to make an unusual mark on history.
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the pixel that made canada big
In 1973, a Canadian Coastal Survey decided to use Landsat data to better map the country’s under-represented northern coastlines. While inspecting satellite data, Fleming detected a telltale signature in the spectrum of light bouncing off Earth’s surface. They concluded that it came from an island, not an iceberg.
The rocky atoll, only 24 meters wide and 45 meters long, reflects infrared light rather than absorbing it like the surrounding seawater. The island was too small to be seen correctly, but it significantly changed the average reflectance of the pixels it occupied.
“That pixel is a mixture of water and soil,” explains Sohal. “So you see a great contrast to the surrounding area.”
In 1976, a team from the Canadian Hydrographic Service took to the skies over northern Labrador to verify the island’s existence and fix its position on the map; After all, it was only observed in a single pixel of satellite data. About 12 miles in, the desolate portion of the rock juts out into the foam in an area known as the he pretends (bar), a treacherous set of reefs, shoals and underwater rocks that sailors avoid. Fleming’s discovery stuck: the island did exist.
As reported in the Canadian Parliament, when hydrographer Frank Hall was helicopter-dropped onto an ice-covered island, he narrowly escaped the fatal claw blow of a hiding polar bear.
“I still remember listening to the radio as a child and with some excitement, because when I grew up I dreamed of being an explorer, discovering new islands off the east coast of Canada,” said Scott Reid, MP Said 2001.
“This was a discovery of practical importance to Canada as it allowed it to expand its territorial waters.”
Landsat’s legacy
The latest members of the Landsat fleet (Landsat 9, launched in September 2021) are more advanced iterations of Landsat 1. They study our planet in longer wavelengths of light, their eyes are sharper, and they carry thermal cameras on board.
From their orbiting sites, these satellites measure coastal retreat, characterize urban heat islands, monitor the Amazon Gold Rush, and even track water consumption within 50 miles of California wine country. Are.
“Remote sensing applications, whether it’s in vineyards or agriculture, or helping people fight fires in the West, are great,” Sohal says.
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Currently, there are hundreds of Earth observation satellites, both government and commercial, including Landsat. This constellation makes important observations that help in making decisions about the management of our planet’s dwindling resources.
“In all of our observations of Earth, we are seeing the effects of a growing population,” says Irons. Less than 4 billion people lived on Earth when Landsat 1 was launched, a number that has since doubled.
“It is becoming increasingly difficult for the Earth’s resources to sustain us under these conditions,” he says. “But I try to be optimistic, and my hope is that with accurate information, people are in a better position to make better decisions.”
(tags to translate) space
