Ralph McNutt Jr.

APL Research Scientist, Space Science

Johns Hopkins APL

Ralph L. McNutt Jr., Ph.D. is an APL Research Scientist for Space Science at the Johns Hopkins University Applied Physics Laboratory (APL) and one of the nation’s leading voices in planetary science, deep-space exploration, and advanced mission architecture.

A physicist by training, Dr. McNutt has played pivotal leadership roles across some of NASA’s most ambitious missions. He serves as Project Scientist and Co-Investigator for NASA’s MESSENGER mission to Mercury, Principal Investigator for the PEPSSI instrument aboard New Horizons to Pluto and the Kuiper Belt, Co-Investigator for Solar Probe Plus (now Parker Solar Probe), and has contributed to both the Voyager and Cassini missions. He has also been a leading advocate for the development of an Interstellar Probe, advancing concepts for humanity’s first mission beyond the heliosphere.

Throughout his career, Dr. McNutt has supported numerous NASA science and technology definition teams, strategic review panels, and mission planning efforts, helping shape the future of solar system exploration and the role of advanced nuclear power and propulsion in enabling it.

He has authored more than 150 scientific and engineering papers, over 250 technical abstracts, and delivered more than 150 professional and public presentations. He earned his B.S. in Physics from Texas A&M University and his Ph.D. in Physics from the Massachusetts Institute of Technology. He joined APL in 1992 after previous roles with MIT, Sandia National Laboratories, and Visidyne, Inc.

Known for his visionary thinking and ability to connect technical innovation with humanity’s long-term future in space, Dr. McNutt continues to shape how we think about exploration beyond the planets—and beyond the Sun itself.