Carl Sagan

When Carl Sagan's team sent two gold-plated records into space in 1977, it wanted to make alien contact. Forty years later, those time capsules are hurtling beyond the reaches of the Solar System, still seeking intelligent life.

We canvassed the world of the social and behavioral sciences, looking for rising stars whose careers promise to make a lasting mark. We'll be profiling the top 30 throughout the month of April.