The European Space Agency's Rosetta spacecraft is about to attempt something "ridiculously difficult" - landing a probe on the surface of a speeding comet. JPL Rosetta Mission Site - http://rosetta.jpl.nasa.gov/ ESA/Rosetta Mission Site - http://rosetta.esa.int Try your hand at landing a spacecraft on a comet with NASA Space Place's Comet Quest!: http://spaceplace.nasa.gov/comet-quest/

Credit: NASA