BALTIMORE (WJZ)– Forty years of looking down has captured a lot of change here on earth.

Alex DeMetrick reports the images taken by the National Aeronautics and Space Administration’s (NASA) Landsat Program show past and present as a way to plan for the future.

Forty years ago, NASA launched its first Landsat satellite with telescopes and cameras pointed down. And as one satellite was replaced by another, four decades worth of flyovers showed the earth as never before seen.

“The most amazing thing was the revelation of the beauty of the land surface, where we could first see the landscape at that scale,” said Dr. James Irons of the Goddard Space Flight Center.

Irons has worked the Landstat project for much of its existence.

“The planet’s dynamic and land surface change goes on continuously,” he said.

It captures the before-and-after of natural disasters like forest fires or rivers suddenly swelling into floods.

There is also human change as the earth’s population moves into cities.

“As that happens, we watch cities all over the world expand into the surrounding regions,” Irons said.

While Landsat’s mission is global, images are zooming in to help the Chesapeake Bay.

When rain hits like it did Thursday in Baltimore, it washes pollutants into waterways leading to the Bay. Scientists and engineers use Landsat images to track the growth of development and to find ways to slow that runoff from hard surfaces like roads and parking lots.

“Instead of being absorbed by the soil and filtered by the soil before it reaches the Bay,” Irons said.

And after tropical storms last year, Landsat captured just how far uncontrolled runoff can spread.

Landsat will launch the program’s eighth satellite next year.