Fiona A. Harrison is the Kent and Joyce Kresa Leadership Chair of the Division of Physics, Mathematics and Astronomy at Caltech, Harold A. Rosen Professor of Physics at Caltech and the Principal Investigator for NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) mission.

As the Principal Investigator for NuSTAR, the first focusing telescope in orbit operating in the high energy part of the X-ray spectrum (3 – 79 keV), she led an international team to propose, develop and launch the mission.

Harrison's observational research showed that the afterglows of gamma-ray bursts exhibit breaks in their decay rate due to collimation of the ejecta.

[3] Scientific highlights from the NuSTAR mission include mapping the radioactive debris in the Cassieopeia A supernova remnant to constrain the core collapse explosion mechanism,[4][5] measurement of the spin of supermassive[6] and stellar mass[7] black holes, the discovery of a magnetar in the Galactic Center,[8] and the discovery of an ultra luminous pulsar.

[13] She is a fellow of the American Physical Society,[14] the American Academy of Arts and Sciences, an honorary fellow of the Royal Astronomical Society, and honorary degree Doctor Technices Hornoris Causa from the Danish Technical University, and a member of the National Academy of Sciences.