Venus reflectivity     Images are based on Magellan orbiter data, using the MIT Altimetric and Radiometric Global Data Records (GxDR) data sets. Because Venus has a very slow rotation rate and essentially no equitorial bulge, the planetary radius also realistically shows the surface topography (from a geoid or gravitational potential point of view). Areas of "no data" are shown as black, like the south pole (circular area towards the bottom). The rotation of Venus, by the way, is retrograde.

The upper image shows the surface topography of the hemisphere around Artemis Chasma, the large arc-like feature at the center. Artemis Chasma itself is generally lower in elevation than the region immediately on either side of it, and is much lower than the Aphrodite Terra, the east-west trending band of highlands to the north.

The lower image shows the surface radar reflectivity of the same hemisphere. In the mid-latitudes, there is a general correlation between the highest mountains and radar reflectivity — at altitudes above ~4000 meters (~13000 ft), there is a marked increase in reflectivity. The peaks are surprisingly bright. Possible explanations are a very thin deposit of pyrite or tellurium that has condensed out of the atmosphere on the "cooler" peaks — metallic "snow" or "frost" if you will (although the deposit could be as thin as a micron). Unexplained, as far as I can tell, is the even brighter surface towards the south pole where there are no highlands or mountains.

Comments, questions, problems about Jules Verne Voyager? Send mail to Lou Estey
(louunavco.org)