The visits of the first robotic missions to the icy moons radically changed scientists' conceptions of the suitability of these worlds to host life. Which of the following statements about this change in perception is true? Select each true statement (there may be several).
A) Detection of radioactivity confirmed that radioactive decays were providing significant heat to some of the moons.
B) A key sign of youth for the surface of some of the moons was provided by their heavily cratered surfaces.
C) Images from the first robotic missions showed surprisingly young surfaces on some of the moons.
D) If the moons were experiencing significant heating, then they might have liquid water.
E) Prior to the first robotic missions, the moons (except Titan) were presumed to be dead, frozen worlds.
F) Careful analysis of the moons' masses and orbits confirmed that strong tidal forces were providing significant heat to some of the moons.