Monday, April 19, 2010

LOLA's Orientale

In our renewed era of lunar exploration, much attention has been given Mare Orientale, which dominates the Moon's western hemisphere, it's "leading edge" facing the forward direction of it's orbit (in relation of the elusive barycenter of the Earth-Moon system - a third of the way to Earth's center). At first glance this latest pretty definitive "false color" crop from the LOLA Image of the Week (centered on 19.9°S, 270°E) might seem little different than that from Japan's SELENE-1 ("Kaguya") and its laser altimeter digital terrain model (DEM). A closer look, plus the time needed to download, shows a lot of information is densely packed in this representation of hundreds of thousands of laser datapoints [NASA/GSFC].

GSFC Only partially visible to Earth-bound observers, a lava-filled target encircled by three mountain ranges peeks over the Moon's western horizon. Orientale, the lunar bull's eye, is considered to be the youngest, most well-preserved multi-ringed impact basin on the Moon. The ring structures surrounding the ~330-km-diameter central mare include the Inner and Outer Montes Rook, each progressively further from the interior basin, followed by the Montes Cordillera (~920-km-diameter).

Over 9 km of elevation are encompassed within Orientale, with the basin floor lying ~3 km below the lunar mean elevation level (R = 1737.4 km), and the western Cordilleras attaining elevations over 6 km above this elevation. The 55-km-diameter Maunder crater, located just south of the northernmost Inner Montes Rook, carves an additional 3 km out of the basin floor, revealing even deeper lunar crustal material at the surface. Lineations radiating from Orientale, likely formed in association with the basin-forming impact event, are also visible in the LOLA altimetry data.

Orientale is of particular interest to scientists because it is filled by a far lesser quantity of mare basalts than other nearside mare basins, leaving more details of its structure and compositional units exposed for scientific investigation.

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