Masatoshi "Toshi" Hirabayashi
Dr. Masatoshi (Toshi) Hirabayashi bridges planetary science mission technologies and planetary science to harmonize them on planetary science exploration missions. His expertise is in space operations, particularly exploring techniques to achieve both engineering and science requirements under mission constraints. His engineering targets are orbiter/lander design and navigation techniques enabling scientific infestations, while his scientific focuses are on the origin and evolution of small bodies, moons, and terrestrial bodies to explore planetary volatiles. His academic efforts propel planetary science exploration missions.
He was involved in a series of planetary missions, including JAXA/IKAROS (solar sail mission), JAXA/Hayabusa 1 and 2 (small body sample return mission), NASA/OSIRIS-REx (small body sample return mission), and ESA/JAXA/Bepi-Colombo (Mercury orbiter mission). Recently, he was a Co-I of NASA/DART (planetary defense mission). He currently serves as a Co-I of NASA/VIPER (lunar rover mission). He also leads Hayabusa 2# as a Science Integration Lead. 11471 Toshihirabayashi is named after him for his contribution to small-body research.
Professor Hirabayashi teaches astrodynamics and space flight technologies, including navigation and operations. He engages students at both undergraduate and graduate levels, emphasizing fundamental principles and practical applications in space exploration missions. He handles courses across a broad spectrum, from theoretical characterizations in astrodynamics, such as Hamiltonian mechanics, to practical, hands-on applications in space. With these different types of courses, he encourages students to foster deeper but broader knowledge of space systems, particularly helpful for future space exploration missions.
Professor Hirabayashi’s research focuses on astrodynamics and its applications to space missions. He has been engaged in detailed theoretical and numerical characterizations of complex dynamical behaviors of space objects. Extending such skills, he has also attempted to improve navigation techniques. Recent efforts include imaging data processing to extract geometric information and support navigation techniques. He is also interested in characterizing thermal and structural properties of planetary bodies, particularly icy objects. With these targets and experiences, he has been part of various space exploration missions. He was part of JAXA/IKAROS, ESA/BepiColombo, JAXA/Hayabusa and Hayabusa2, and NASA/DART. He is currently involved in NASA/Lucy, NASA/VIPER, and ESA/Hera. He also serves as the Interdisciplinary Science Lead of JAXA/Hayabusa2#, leading science investigation on the mission. His key efforts directly contribute to Planetary Defense and In-Situ Resource Utilization (ISRU), interdisciplinary fields that have led recent planetary exploration missions.
Space operations, celestial mechanics, planetary science, and design & navigation.
- Ph.D., Aerospace Engineering, University of Colorado Boulder, 2014
- M.S., Aerospace Engineering Sciences, University of Colorado Boulder, 2012
- M.S., Aeronautics and Astronautics, University of Tokyo, 2010
- B.S., Mechanical and Aerospace Engineering, Nagoya University, 2007
- 2023, Finalist of PROSE Award for Excellence in Physical Sciences and Mathematics of the Association of American Publishers, in the Chemistry, Physics, Astronomy, and Cosmology area
- 2022, NASA Group Achievement Award through the Lunar Dust Science Definition Team
- 2022, Auburn University College of Engineering Journal Faculty Research Award
- 2021, Hayabusa2 Honor Award, Hayabusa2 team
- 2019 – present, Adjunct professor appointment in the Geoscience department
- 2017, Asteroid 1981 EH48 was named after myself, 11471 Toshihirabayashi
- Z. Huang, M. Hirabayashi, and T. M. Orlando, “Micrometeoroid Impacts: Dual Pathways for Iron Reduction and Oxidation on Lunar and Asteroidal Surfaces,” Astrophysical Journal, 994, 240, doi:10.3847/1538-4357/ae19e6.
- A. Daca, M. Hirabayashi, et al., “The Caltech Mission to Apophis: Accelerating Planetary Science and Planetary Defense,” Planetary Science Journal, 6, 253, 2025, doi: 10.3847/PSJ/ae0caf.
- M. Hirabayashi, “Prediction of Apophis’s deformation-driven rotational evolution during its closest encounter to the Earth in 2029,” Icarus, 443, 116754, 2025, doi: 10.1016/j.icarus.2025.116754.
- M. Hirabayashi, et al., “Kinetic deflection change due to target global curvature as revealed by NASA/DART,” Nature Communications, 16, 1602, 2025, doi:10.1038/s41467-025-56010-w
- M. Hirabayashi, et al., “Crater Equilibrium State Characterization given Crater Production from a Single Power Law,” The Planetary Science Journal, 5, 250, 2024, doi: 10.3847/PSJ/ad8883