Archive September 2010
This is a mosaic of the Viking 1 Orbiter images f022a94 (taken on July 12, 1976), f034a11 to 16 and f034a34 (taken on July 24, 1976), and f040a04 (taken on July 30, 1976) and shows the Argyre impact basin in the southern highlands of Mars.
The basin, which is approximately 1,300 kilometers in diameter, was formed about 4 billion years ago during the Heavy Bombardment Period of the early Solar System when an asteroid or comet roughly 50 kilometers across impacted Mars.
Argyre is believed to be the second-largest impact basin on Mars after Hellas Planitia and may be one of the best preserved ancient impact basins from the Heavy Bombardment Period.
Argyre is surrounded by rugged massifs which form concentric and radial patterns around the basin. Several mountain ranges are present, including Charitum and Nereidum Montes.
The 230 km wide Galle Crater, located on the eastern rim of Argyre, strongly resembles a smiley face.
Above the horizon are detached layers of haze 25 to 40 km high, thought to be crystals of carbon dioxide.
Image Credit: NASA/JPL/Arizona State University/Mosaic by astroarts.orgoff