PIA00473: Venus - Sag Caldera 'Sachs Patera
 Target Name:  Venus
 Is a satellite of:  Sol (our sun)
 Mission:  Magellan
 Spacecraft:  Magellan
 Instrument:  Imaging Radar
 Product Size:  480 x 591 pixels (w x h)
 Produced By:  JPL
 Producer ID:  P38284
 Addition Date:  1996-11-20
 Primary Data Set:  Magellan MIDRs
 Full-Res TIFF:  PIA00473.tif (208 kB)
 Full-Res JPEG:  PIA00473.jpg (116.5 kB)

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Original Caption Released with Image:

This image of Sachs Patera on Venus is centered at 49 degrees north, 334 degrees east. Defined as a sag-caldera, Sachs is an elliptical depression 130 meters (81 feet) in depth, spanning 40 kilometers (25 miles) in width along its longest axis. The morphology implies that a chamber of molten material drained and collapsed, forming a depression surrounded by concentric scarps spaced 2-to-5 kilometers (1.2- to-3 miles) apart. The arc-shaped set of scarps, extending out to the north from the prominent ellipse, is evidence for a separate episode of withdrawal; the small lobe-shaped extension to the southwest may represent an additional event. Solidified lava flows 10-to-25 kilometers (6-to-16 miles) long, give the caldera its flower-like appearance. The flows are a lighter tone of gray in the radar data because the lava is blockier in texture and consequently returns more radar waves. Much of the lava, which was evacuated from the chamber, probably traveled to other locations underground, while some of it may have surfaced further south. This is unlike calderas on Earth, where a rim of lava builds up in the immediate vicinity of the caldera.

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