Almost a decade ago, Saul Perlmutter discovered something that can't be seen or felt dark energy. Though unseen, the universe apparently consists mostly of this stuff -- and it is causing the universe to expand ever faster. Nobody has a clue as to what this stuff is (or if it is even a "stuff"). In fact, new theoretical papers attempting to explain dark energy have appeared an average of once every few days for the past 10 years. Perlmutter and his colleagues have been collecting the most detailed information ever on supernovas, and developing a new space telescope concept that can use several new methods to study the dark energy, including even better supernova measurements.