Earthshots: Satellite Images of Environmental Change

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» Hailstorm at EROS, Sioux Falls, SD, USA

These images show the location of the USGS Earth Resources Observation and Science (EROS) Center, about 10 miles north of Sioux Falls, South Dakota. On Sunday, July 13, 1997, an unusually severe hailstorm blasted through the area, missing Sioux Falls but hitting EROS head-on. The storm pounded EROS with 20 minutes of baseball- to softball-sized hail. Landsat 5 passed overhead three days later and documented the aftermath.

Healthy crops normally surround Sioux Falls. The healthy crops appear bright red because red represents the near-infrared light (that human eyes can’t see) that is highly reflected by healthy vegetation. Most of the crops grown in this area are soybeans and corn. Some of those fields turned gray in the 1997 image, where the hailstorm converted the cropland into bare soil. The conversion was temporary, however, as the Landsat 5 image from 1998 demonstrates. The cropland is back to the expected red, indicating healthy crops.

Map of the featured area.

The storm cost EROS over $1.2 million in damage. Vehicles were smashed, branches broken, foliage shredded, windows broken, and ground pockmarked. The hail destroyed an array of 512 solar panels, which had heated 60% of the photo lab’s water. Many skylight panels were broken, and the roof sprang leaks. The hail broke concrete paving stones on the roof. The antenna for Landsat 7 (which launched in 1999) was only a month old; the electronics were smashed and the dish had over 2,000 dents. Luckily, no one was injured.

About EROS
The EROS mission is to collect and archive data from Earth-observing satellites, primarily the Landsat satellites. The Center also archives data from other Earth-observing satellites and aerial imagery dating back to the 1930s. EROS is a science center, too; scientists there use the data for research on climate change, landscape dynamics, natural hazards, and many other uses.

What’s EROS doing out there in the middle of cropland anyway? First, it was placed in the center of the continent to receive data from satellites coast-to-coast. So that’s what brought EROS to South Dakota. EROS was built out of town to avoid radio and TV interference and to give the receiving antennas a clear view from horizon to horizon.

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