(Thought it might be a good time to start a Mars Curiosity Rover thread, seeing as a milestone was reached recently.)
Curiosity departed Earth late last November and is now homing in on it's landing site. The landing site, on Gale Grater, has been narrowed down from an ellipse measuring 20 by 25km to just 7 to 20km.
However, an issue has cropped up. The drill has been shown to potentially introduce contaminants to the very samples it is getting! These come from the teflon seals on the drill motor and from the molybdenum disulfide grease within.
http://www.livescience.com/20886-nasa-mars-rover-contamination-landing.htmlhttp://www.nasa.gov/mission_pages/msl/news/msl20120611.html