"Billions and Billions" was a phrase, fantastic at the time, that made Carl Sagan famous. At the time he was talking about the stars in the Milky Way, how many there were.
Next week, Mars Recon Orbiter, will be marking it's 4th anniversary orbiting Mars. It also has another milestone to celebrate: MRO has brought back more data to Earth from Mars… than *all* deep space missions combined. Not just missions to Mars, but all deep-space missions!