November 06, 2014
Image Mission Elapsed Time (MET):
Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
The crater in the center left of the scene is about 22 km (14 mi.) in diameter
North is to the left in this image.
Why not, indeed?
The cliff-like feature crossing today's image from top to bottom is one of Mercury's famed lobate scarps
, and is called Pourquoi-Pas Rupes
. Lobate scarps (termed "rupes" in geologic nomenclature, pluralized as "rupÄ“s") on the innermost planet are named for ships of discovery, and this scarp takes its name from Pourquoi-Pas
, the fourth ship built for the French polar scientist Jean-Baptiste Charcot. "Pourquoi pas?" is the French term for "why not?"°a fitting attitude for an explorer, be it of Earth's polar regions or the distant reaches of the Solar System.
Mercury's lobate scarps are thought to be the result of the planet's shrinking
as its interior cooled and contracted. Pourquoi-Pas Rupes is one of the largest examples on Mercury, with vertical relief of up to 1.5 km (about 1 mile) in places.
This image was acquired as a high-resolution targeted observation. Targeted observations are images of a small area on Mercury's surface at resolutions much higher than the 200-meter/pixel morphology base map. It is not possible to cover all of Mercury's surface at this high resolution, but typically several areas of high scientific interest are imaged in this mode each week.
The MESSENGER spacecraft is the first ever to orbit the planet Mercury, and the spacecraft's seven scientific instruments and radio science investigation
are unraveling the history and evolution of the Solar System's innermost planet. In the mission's more than three years of orbital operations, MESSENGER has acquired over 250,000 images and extensive other data sets. MESSENGER is capable of continuing orbital operations until early 2015.
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
For information regarding the use of MESSENGER images, see the image use policy.