Normally, asking a person, “Why would aliens want to attack Earth?” would result in a bumbling, confused answer. But pose the same question to Randii Wessen, Deputy Manager of the Project Formulation Office at Caltech’s Jet Propulsion Laboratory (JPL), and you will receive a precise answer: aliens would not bother to attack our puny planet. True, as a consultant for The Exchange, Wessen has had some practice answering that question, but the point is he has taken the time to form a rational answer.