In my earlier entry "Forests Also Casualties of Katrina," I mentioned that scientists looked at satellite imagery to determine the amount of damage done by Hurricane Katrina. Following up on that entry, I wanted to spotlight the technology used by those scientists.

The source of the satellite imagery was the government's Landsat program. Since 1972, through a series of launched satellites, Landsat has been gathering information on Earth from above. The field of remote sensing was just emerging in 1972, but as of 2006, the program had accumulated more than 1.7 million "scenes."

Its collection continues to grow by more than 320 gigabytes every day. (Consider that a single-sided, single-layer DVD can hold 4.7 gigabytes, enough for most feature-length movies.) Landsat is jointly managed by NASA and the U.S. Geologic Survey (USGS).

The website Our Earth As Art hasn't been updated in awhile, but it allows visitors the chance to view the planet's magnificence as seen from space. Other images can be seen on NASA's and the USGS's Landsat websites.

Links:
The Landsat Program (NASA)
Landsat Satellites (USGS)
The Future of Land Imaging federal interagency study

Image: Greenland Coast, taken Sept. 3, 2000, by the Landsat-7 satellite. Image courtesy of USGS National Center for EROS and NASA Landsat Project Science Office.