WIRED - Way up in the sky and sprinkled across the seas, two of the littlest yet most influential things in the world have stubbornly guarded their secrets: aerosols and phytoplankton. Today, NASA launched its Plankton, Aerosol, Cloud, Ocean Ecosystem mission, or PACE, to unravel their mysteries. The mission’s findings could be a key to understanding how drastically the world is changing as it warms.