Professor Avi Loeb is one of the hardest working astrophysicists in the field, writing a blistering number of academic papers on fascinating topics like the Fermi Paradox, the habitability of other worlds, black holes, and the history of the early universe. He's also one of the people working on the Breakthrough Starshot project to send tiny probes to other star systems. https://www.cfa.harvard.edu/~loeb/