An 8-kilometer (5-mile) wide crater of possible impact origin is shown in
this view of an isolated part of the Bolivian Amazon from the Shuttle Radar
Topography Mission (SRTM). The circular feature at the center-left of the image, known
as the Iturralde Structure, is possibly the Earth’s most recent “big” impact
event recording collision with a meteor or comet that might have occurred
between 11,000 and 30,000 years ago.
Although the structure was identified on satellite photographs in the
mid-1980s, its location is so remote that it has only been visited by scientific
investigators twice, most recently by a team from NASA’s Goddard Space Flight
Center in September 2002. Lying in an area of very low relief, the landform is a
quasi-circular closed depression only about 20 meters (66 feet) in depth, with
sharply defined sub-angular “rim” materials. It resembles a “cookie cutter” in that its appearance “cuts” the heavily vegetated soft-sediments and pampas of this part of Bolivia. The SRTM data have provided investigators with the first
topographic map of the site and will allow studies of its three-dimensional
structure crucial to determining whether it actually is of impact origin.
Two visualization methods were combined to produce this image: shading and
color coding of topographic height. The shade image was derived by computing
topographic slope in the northwest-southeast direction. North-facing slopes
appear bright and south-facing slopes appear dark. Color coding is directly
related to topographic height, with brown and green at the lower elevations,
rising through yellow and brown to white at the highest elevations.
Size: 1 degree latitude by 1 degree longitude (about 111 by 111 kilometers or
69 by 69 miles)
Location: 12.5 degrees South latitude, 67.5 degrees West longitude
Orientation: North at top
Image: Elevation data, colored height with shaded relief
Original Data Resolution: SRTM 1 arcsecond (about 30 meters or 98 feet)
Date Acquired: February 2000 (SRTM)
Compare this topographic image with a Landsat image made with spectral (light) information.