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Sanjayan Muttulingam, a leading scientist with The Nature Conservancy studies December 2004 tsunami destruction to southern coastal regions of Sri Lanka near Yala National Park. © Mark Godfrey, 2005 The Nature Conservancy

"Satellite imagery is the most essential applied tool for conservation because it allows us to see a landscape—and the threats to it—at the proper scale."

Sanjayan, Conservancy lead scientist

By Sanjayan

I am standing in the depths of a bunker-like building that sprawls beneath the farmland just outside of Sioux Falls, South Dakota.

Aboveground, the building is nondescript, Wal-Mart-like — except for the giant dish antennae that point to the skies and the United Nations flag that flutters alongside the Stars and Stripes, hinting at the global significance of this monolith.

This is the center for Earth Resources Observation and Science (EROS), run by the U.S. Geological Survey. EROS is the place to which Earth-imaging satellites transmit their data.

As a conservationist, I use these images all the time.

'Family Photo Album of Planet Earth'

Satellites have been taking pictures of us from God's perspective since the 1960s. Though satellites were first controlled by the military, more recent ones — like Landsat, Terra and Aqua — have been launched for scientific and public-use purposes.

Sweeping north to south in polar orbits, they image the globe in huge swaths; over a few days, nearly every corner of the planet is exposed. EROS holds the largest collection of such images. Eric Clemons, the center's director, calls it the "family photo album of planet Earth."

And I'm here to flip through the pictures. But where to start?

Seeing Where Man First Walked

When asked to choose, I pick not my home in Missoula, Montana, or my country of birth — Sri Lanka — or even my favorite fishing spot (it's a secret), but rather a place I've visited in northern Tanzania: Laetoli.

From space, it turns out, Laetoli is not much to look at — a smudge of green and gold. To be honest, it's also disappointing from the ground, just scrubby savanna, thorny acacias and rocks, unremarkable but for one thing: At Laetoli, two pairs of fossilized footprints, some 3.7 million years old, mark the time when our ancestors first stood upright — and walked.

It takes imagination to work out the scene. Two individuals — the larger, male — move leisurely on parallel paths on a drizzly day. The tilt of the smaller prints may indicate a female, carrying an infant on her hip.

What were these humanlike primates looking for? Opportunity perhaps in the form of a recent animal kill. Or maybe approaching danger. Stand on your hind feet and you get an advantage over quadrupeds. You know a bit sooner what the future holds.

Can Satellite Imagery Help Us Be Better Conservationists?

Now, here in Sioux Falls, looking at an image of Laetoli, it occurs to me that for a few million years, human experience was limited to a 2-mile radius. That's about as far as we can see before the ground falls away with the curvature of the Earth.

Then, in virtually one human generation, we overcame this limitation. Now we can see the entire planet at once.

Scientists of my generation have grown up using satellite imagery. It is the most essential applied tool for conservation because it allows us to see a landscape — and the threats to it — at the proper scale.

If you are working to reduce deforestation of the Amazon or estimate carbon emissions from forest fires or design protected areas, satellite images are indispensible.

We have entered a new period of human understanding, one in which extrapolating our understanding of what's beyond our sight has given way to whole-Earth analysis. We know what's coming around the corner.

Now we must find bold solutions to what we see — to realize the full potential of our upright stance first begun in East Africa and culminating here in this planetary library.

The opinions expressed in "Wild Life" are the author's. They should not be construed as the position of The Nature Conservancy.