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.