"There’s supposed to be a Mars-shattering Ka-boom!"
Here at Emergent Chaos, we’re big fans of large objects hitting other large objects at high speed. Which is why it’s important to tell you that 2007-WD5 [link to http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2007%20WD5&orb=1 no longer works] is a 50 meter asteroid that’s set to pass within 48,000 kilometers of Mars next month.
“We estimate such impacts occur on Mars every thousand years or so,” said Steve Chesley, a scientist at JPL. “If 2007 WD5 were to thump Mars on Jan. 30, we calculate it would hit at about 30,000 miles per hour and might create a crater more than half-a-mile wide.” The Mars Rover Opportunity is exploring a crater approximately this size right now. (JPL press release [link to http://www.jpl.nasa.gov/news/news.cfm?release=2007-152 no longer works].)
More details about the orbit at the JPL small-body datatbase [http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2007%20WD5&orb=1 no longer works]. Story via VOA news [link to http://www.voanews.com/english/2007-12-22-voa19.cfm no longer works].