Gregory A. Zimmerli

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About

Gregory A. Zimmerli is a pioneering aerospace engineer at NASA’s Goddard Space Flight Center, whose research focuses on in-space cryogenic fluid management and robotic servicing technologies critical to the future of deep-space exploration. His most significant contribution is leading the Robotic Refueling Mission-3 (RRM3), a landmark external payload on the International Space Station that successfully demonstrated the first-ever storage and transfer of liquid methane—a cryogenic propellant—in orbit. This achievement, documented in his highly cited 2020 overview paper (20 citations), directly addresses one of NASA’s greatest technical challenges: enabling spacecraft to refuel and extend their operational lifetimes beyond Earth orbit. Zimmerli’s work on RRM3 has profound implications for sustainable lunar missions, Mars transit vehicles, and orbital refueling depots, effectively laying the groundwork for a new era of reusable space architectures. By proving that cryogenic fuels can be handled in microgravity without significant boil-off loss, his research has become foundational for future human exploration. Zimmerli’s contributions exemplify how targeted, high-risk engineering demonstrations can transform theoretical concepts into operational reality, making him a key figure in advancing NASA’s Artemis program and long-duration spaceflight capabilities.