Olinto studies the unknown origins of both ultra-high-energy cosmic rays and of the magnetic fields that pervade all objects in the universe. Ultra-high-energy cosmic rays enter the atmosphere with so much energy that they produce a giant cascade of many tens of billions of secondary particles that can be observed by large detectors on Earth. She is investigating multiple possibilities, including the proposal that they come from supermassive black holes in the centers of nearby galaxies, or that they are decaying particles left over from the big bang. Olinto also has developed theories about how magnetic fields are generated and how they evolved at the beginning of the universe. Olinto leads the U.S. collaboration of an international project to help build a new cosmic ray telescope for deployment on the International Space Station.