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A Martian bull's-eye ... and more!

The central pit within this Martian crater may have been caused by unusual surface layering or a second impact.
The central pit within this Martian crater may have been caused by unusual surface layering or a second impact.NASA / JPL / Univ. of Arizona

Does lightning strike twice in the same place? How about meteors striking Mars? This image, captured by NASA's Mars Reconnaissance Orbiter, suggests that a cosmic bullet could have hit almost smack-dab in the center of a crater created by an earlier impact. Or it could be the result of just one impact messing around with the Red Planet's layered terrain. Either way, the picture adds to the orbiter's store of weird and wonderful pictures from Mars. The team behind the orbiter's High Resolution Imaging Science Experiment, or HiRISE, says the crater's concentric circles were probably created when something went splat into a section of layered hard-and-soft ground. The crater's central pit may be slightly offset because of uneven melting and erosion. The other explanation would be the crater-within-a crater scenario. A cosmic bull's-eye! That's not the only weirdness turned up by the Mars Reconnaissance Orbiter recently. Here's just a smattering of images from the HiRISE team's latest data dump:

Meanwhile, other Mars probes are keeping busy as well. NASA's Spirit rover may be down for the count - but Opportunity, its twin on the other side of the planet, is chugging along toward Endeavour Crater. Oppy's recent images include faraway views of the crater's rim and a close-up view of Martian blueberries. The Planetary Society's Emily Lakdawalla offers up a cool 3-D image of Acidalia Planitia, captured by the Context Camera aboard the Mars Reconnaissance Orbiter. You'll need red-blue glasses to get the 3-D effect, and it's really fun if you make the image as big as you can. I'd almost swear I could see tire tracks inside some of those troughs, but they're merely dune patterns. As long as you've got your 3-D glasses at the ready, click on over to Cumbrian Sky for this week's Carnival of Space, which features more stereo imagery from Mars. Join the Cosmic Log corps by signing up as my Facebook friend or hooking up on Twitter. And if you really want to be friendly, ask me about "The Case for Pluto."