Interesting video of Rover Curiosity pics. Probably will be no real definitive answer to the question, but interesting none the less.
"UFO hunters believe that may have found evidence of a UFO streaking through the sky – on Mars.
They claim a picture taken by the Curiosity rover shows a possible extra terrestrial craft.
In the image, a bright object can been seen appearing to leave a trail in the Martian sky".
http://mysticalfiles.com/has-nasas-curiosity-rover-spotted-a-ufo-on-mars/
http://www.youtube.com/watch?v=NAq5u5gfFbg
A look at the original Front HazCam image of this shows the object in question to be, literally, 6 or 7 pixels long. The Inset "enlarged image" is really very misleading. Really cool, but there's so little to go on here in terms of evaluation...
I wish it was higher res!
Paulie
Its a bug in front of the lens :P
http://www.youtube.com/watch?v=T0sjZz9-Ebg
http://www.youtube.com/watch?v=T0sjZz9-Ebg
(http://mars.jpl.nasa.gov/msl-raw-images/proj/msl/redops/ods/surface/sol/00504/opgs/edr/fcam/FLB_442235847EDR_F0250000FHAZ00323M_.JPG)
Original image link
http://mars.jpl.nasa.gov/msl-raw-images/proj/msl/redops/ods/surface/sol/00504/opgs/edr/fcam/FLB_442235847EDR_F0250000FHAZ00323M_.JPG
Raw images
http://mars.jpl.nasa.gov/msl/multimedia/raw/?s=#/?slide=528