When NASA’s Messenger space probe swung past Mercury on
September 29, it snapped this picture of the innermost planet’s
barren and strange landscape. The $446 million probe’s third
flyby brought it within 142 miles (228 km) of Mercury’s surface
to cover more uncharted terrain, leaving 98 percent of the
planet now mapped [SPACE.com]. The images taken and the data
recorded during the flyby are the last that will be acquired
until Messenger finally slips into orbit around Mercury in 2011.
The probe has now completed about three-quarters of its swooping
4.9-billion-mile journey that will eventually bring it into
orbit. Researcher Brett Denevi explains that this enhanced color
shot shows a bright area surrounding an irregular depression,
with steep sides and an odd shape, “all of which are hallmarks
of something like a volcanic vent,” Denevi said [SPACE.com]. The
double-ring basin in the center of the photo measures about 180
miles in diameter. It appears to be a relatively young impact
crater–researchers believe