Landsat 5 Turns 25: Earth Image of the Week

A scar left in the Alabama landscape by a 1998 F5 tornado can be seen is this image — more than 700,000 taken by Landsat 5 over the past quarter century.

When Landsat 5 was launched from California’s Vandenberg Air Force Base on March 1, 1984, none involved in the mission expected that the plucky satellite would still be capturing images of planet Earth 25 years later.

After more than 133,000 orbits, it has survived 22 years longer than it was originally designed for. NASA attributes the longevity to “over-engineering” along with a healthy measure of good luck.

That luck helped fill a gap between the launch failure of Landsat 6 in 1993 and the successful launch of Landsat 7 in 1991, when no other instruments in the series were available to take observations.

"Such a gap would have been a scientific disaster," said Darrel Williams, Landsat project scientist at NASA's Goddard Space Flight Center, Greenbelt, Maryland. "The images derived from Landsat are like a family photo album," he added. "Just as we change over time, so, too, does Earth's surface."

The image to the upper right was taken shortly after an F5 tornado tore through parts of metropolitan Birmingham, Alabama, on April 8, 1998. It clearly shows a wide path of destruction stretching from southwest to northeast in the image.

It’s just one of more than 700,000 images Landsat 5 has taken in a "sun-synchronous" orbit, which guarantees it will observe the same location on Earth at the same time of day every 16 days. This makes it easy to detect changes in Earth’s landscape and plot things like urban growth, deforestation and erosion.

Full story and image: NASA