His research interest includes the study of lightning storms at Earth and the planets, the dusty plasma environment at planetary moons and asteroids, the space environment at our own Moon, and planetary auroral & magnetospheric processes. He is a co-investigator on the Cassini mission to Saturn, the Solar Probe Plus mission, and Wind spacecraft. His instrument team has built numerous radio hardware components to fly on rockets, balloons, in remotely piloted vehicles, and for space flight. He owns a patent on a lightweight magnetic antenna that will be flown on an upcoming USAF space mission. Dr. Farrell continues to be a scientific reviewer on AGU, EGS, and IEEE journals and he has authored/co-authored over 180 journal articles & book chapters on space science topics.