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Tom Mueller

Thomas John Mueller is an American aerospace engineer and rocket engine designer renowned for his pioneering work in propulsion systems, including as the first employee and co-founder of SpaceX's propulsion division, where he led the development of engines that revolutionized reusable rocketry, and as the founder and CEO of Impulse Space, a company focused on in-space transportation. Born and raised in Saint Maries, Idaho—a rural town with a population of about 2,500—Mueller developed an early passion for rocketry, building model rockets starting at age 14 while working summers as a lumberjack to support his family. As the first in his family to attend college, he earned a Bachelor of Science in mechanical engineering from the University of Idaho in 1985, followed by a Master of Science in mechanical engineering from Loyola Marymount University in 1992, where his thesis designed a 50-pound-thrust bipropellant engine using liquid oxygen and kerosene. After graduation, he relocated to Los Angeles, joining Hughes Aircraft and later TRW Inc., where he contributed to satellite propulsion projects, and became active in the amateur rocketry group Reaction Research Society, launching experimental engines in the Mojave Desert. In 2002, Mueller met through mutual contacts in the rocketry community and became 's inaugural employee (employee No. 1), serving as of propulsion engineering and later as of propulsion from 2014 onward. Over nearly two decades at the company, he spearheaded the design and development of critical engines, including the family for the , , and rockets—enabling reusable first-stage landings and drastically reducing launch costs—and the thrusters for the spacecraft's maneuvering systems. His innovations transformed from a startup facing early failures into a leader in commercial , with rockets achieving over 560 successful launches as of November 2025. Mueller left in late 2020 to found Impulse Space in 2021, where as CEO he has advanced in-space logistics, including the development of the vacuum-optimized thruster for high-efficiency orbital maneuvers. The company has secured substantial funding—$30 million in 2022, $45 million in 2023, $150 million in 2024, and $300 million in 2025—and executed missions like in 2023 and 2025, aiming to deliver payloads to Mars by 2026 and establish infrastructure for economies. Widely regarded as one of the world's leading experts, Mueller's career bridges amateur experimentation with industrial-scale innovation, making space more accessible and sustainable.

Early life and education

Early life

Thomas Mueller was born in St. Maries, , a small rural logging community with a population of about 2,500 people. He grew up in a family deeply rooted in the local industry, as his father worked as a logger and second-generation member of the trade. Mueller's early years were shaped by the rugged, forested environment of northern , where outdoor labor and self-reliance were everyday realities. He graduated from St. Maries High School in 1979. As a teenager during high school and in the years immediately following, Mueller gained practical mechanical experience by working as a logger in the woods, felling trees and operating during summers and off-seasons. These hands-on jobs, often physically demanding and isolated, honed his problem-solving skills and familiarity with machinery, traits that later proved invaluable in . Despite the blue-collar surroundings, Mueller stood out as somewhat unconventional among his peers, showing early curiosity beyond typical rural pursuits like dirt bikes and sports cars. From a young age, Mueller nurtured a passion for rocketry through childhood hobbies, building and launching model s purchased from local hobby shops, including dozens of Estes kits. He advanced his experiments by inheriting his uncle's , which he used to create homemade solid-fuel rocket propellants and more powerful engines. In one notable project during junior high, he launched an Estes rocket carrying crickets for a to study acceleration effects. The lack of formal resources in his remote setting only amplified his self-taught approach, fueled by books, media, and personal tinkering that ignited a lifelong drive toward . This foundation eventually propelled him toward formal studies at the .

Education

Mueller earned a in from the in 1985. His coursework included foundational topics in and , which laid the groundwork for his later work in propulsion systems. To finance his undergraduate studies, Mueller worked summer jobs as a logger in , becoming the first in his immediate family to attend . Building on his early interest in model rocketry, Mueller pursued advanced studies while employed in the aerospace sector. He completed a in from in 1992, balancing part-time graduate coursework with his full-time professional responsibilities. For his master's thesis, Mueller designed a small bipropellant using (LOX) and RP-1 (refined petroleum), producing approximately 50 pounds of ; the project involved detailed engineering calculations for optimization and performance. This work represented one of the smallest LOX-fueled amateur rockets at the time and demonstrated practical applications of principles.

Career

TRW Inc.

Mueller joined TRW Inc. in 1987 as a propulsion test engineer, two years after earning his bachelor's degree in mechanical engineering from the University of Idaho in 1985, marking his entry into the aerospace industry. Over the course of 15 years at the company, he progressed from entry-level testing roles to managing the Propulsion and Combustion Products department, overseeing liquid rocket engine development for various applications. A key achievement during this period was his leadership as lead engineer on the engine, a throttleable, low-cost /hydrogen upper-stage designed to deliver 650,000 lbf of . The project originated in the 1990s as part of NASA's Initiative to reduce launch costs, progressing through , component testing, and full-scale hot-fire demonstrations by the early 2000s. In parallel with his professional duties, Mueller pursued his lifelong passion for rocketry by building amateur liquid-fueled engines on evenings and weekends, including a 13,000 lbf LOX/RP-1 engine developed in his garage in 2001—the largest such amateur project at the time—tested at private facilities. As head of the propulsion department, Mueller contributed to TRW's systems by directing efforts to enhance reliability in bipropellant thrusters and attitude control used in military and commercial , drawing on his expertise in combustion stability and design to minimize failure rates in operational environments.

SpaceX

Tom Mueller joined in May 2002 as its first employee, personally recruited by founder to lead propulsion development as the startup grappled with foundational technical and financial hurdles in building reusable launch systems. Leveraging his prior experience at TRW Inc. managing large-scale liquid rocket engine projects, Mueller directed the iterative design of the Merlin engine family, which became the core propulsion for Falcon rockets and Dragon spacecraft. The Merlin 1A prototype, developed starting in 2002, delivered an initial vacuum specific impulse of approximately 289 seconds. By 2006, the refined Merlin 1C achieved a vacuum specific impulse of 311 seconds, enabling reliable upper-stage performance. The Merlin 1D, introduced in 2012, incorporated thrust vector control for precise steering and maintained a sea-level specific impulse of approximately 282 seconds while scaling thrust to support Falcon 9's reusability goals; its vacuum-optimized variant further enhanced efficiency for second-stage operations. Complementing this, Mueller oversaw the 2006 development of the Kestrel engine, a pressure-fed upper-stage design producing 6,900 lbf of thrust for the Falcon 1, emphasizing simplicity and low cost over turbopump complexity. Mueller also led the creation of hypergolic thrusters for spacecraft maneuvering and abort systems. The thruster, qualified in 2008, provided 90 lbf (400 N) of thrust using and nitrogen tetroxide propellants for reaction control. In 2014, the scaled-up engines, each generating 16,000 lbf of thrust, were integrated into Crew Dragon's , featuring advanced health monitoring for real-time diagnostics and multiple restarts to ensure crew safety during ascent. Under Mueller's leadership as Vice President of Engineering, adopted a strategy centered on reusability, with cycles—often iterating designs in weeks—that accelerated reliability improvements and culminated in the Falcon 9's first successful orbital launch on June 4, 2010. This approach transformed from a high-risk venture into a dominant launch provider, with engines enabling over 300 missions by enabling booster landings and refurbishment. Mueller retired from his role on November 30, 2020.

Impulse Space

Tom Mueller founded Impulse Space in September 2021 shortly after retiring from , where he had served as a key , and assumed the role of CEO to advance affordable in-space transportation solutions for satellites and missions extending beyond . The company focuses on developing high-thrust systems to enable rapid adjustments and delivery, leveraging Mueller's expertise in chemical engines to reduce costs and timelines for orbital maneuvers. Impulse Space has raised substantial funding to support its growth, including $30 million in 2022, $45 million in 2023, $150 million in , and $300 million in 2025. A cornerstone of Impulse Space's portfolio is the Mira orbital maneuvering vehicle, designed for high-thrust chemical propulsion to perform last-mile transport and orbit raising in low Earth orbit. Mira achieved its first flight on the LEO Express-1 mission, launched November 10, 2023, aboard SpaceX's Transporter-9 rideshare from Vandenberg Space Force Base, where it successfully demonstrated responsive maneuvers, payload hosting, and deorbit capabilities over several months. Subsequent flights, including LEO Express-2 in January 2025 and LEO Express-3 in November 2025, have further validated Mira's agility, with upgrades in 2025 enhancing its thrusters and avionics for extended operations beyond low Earth orbit. Impulse Space introduced the kick stage in January 2024 as a high-performance vehicle for transporting large payloads to , , space, and lunar trajectories, capable of delivering over 5 metric tons from to in under 24 hours using a 15,000 lbf engine. 's design emphasizes rapid transfers and compatibility with medium-lift launchers like , with its debut flight targeted for mid-2026 as part of dedicated rideshare missions. This vehicle powers the company's mission series, an annual rideshare program starting with the fully manifested 1 in the third quarter of 2026, which aggregates multiple small satellites for efficient delivery. In September 2025, Impulse secured a multi-launch agreement with Infinite Orbits to transport several satellite servicing spacecraft to beginning in 2027 via missions, underscoring growing demand for such shared access. In October 2025, Impulse Space announced a proposed lunar mission architecture integrating the kick stage with an in-house developed robotic to enable cost-effective cargo delivery , targeting up to 6 metric tons of across two lander missions per launch by 2028. This system launches to on a medium- or heavy-lift vehicle, where Helios performs to place the lander in for a , each capable of deploying approximately 3 metric tons to the surface to support commercial infrastructure and align with goals for sustained lunar presence. The architecture aims to fill gaps in near-term lunar logistics by offering reliable, multi-ton deliveries without requiring dedicated heavy-lift launches.

Awards and honors

Professional awards

In 2003, Tom Mueller received the Wyld Propulsion Award from the American Institute of Aeronautics and Astronautics (AIAA), recognizing his innovative contributions to liquid technology early in his career. In 2018, Tom Mueller received the (NSS) Space Pioneer Award in the Science and Engineering category, recognizing his pioneering work on reusable engines during his tenure at . The award was presented at the NSS's International Space Development Conference (ISDC) in , where Mueller highlighted his contributions to advancing technologies that enabled cost-effective access. Also in 2018, Mueller was selected as the winner of the Readers' Choice category in the SpaceNews Awards for Excellence & Innovation, honoring his pivotal role in developing SpaceX's Merlin engines and advancing reusable rocketry. During his acceptance speech at the 2018 ISDC, Mueller reflected on the evolution of the Merlin engine family, tracing its development from the initial Merlin 1A version tested in the early 2000s to the more efficient and throttleable Merlin 1D introduced in 2013, which played a key role in achieving rocket reusability. This innovation underscored Mueller's broader impact on aerospace engineering, including his leadership in propulsion systems that supported SpaceX's rapid iteration and commercialization of launch vehicles.

Academic honors

In 2013, Tom Mueller received an honorary doctorate from (LMU), where he also served as the Graduate Commencement Speaker, with the award recognizing the influence of his master's thesis—a project involving the design and flight of one of the smallest rockets ever tested—on advancements in propulsion technology. During his commencement address at LMU, Mueller reflected on his unconventional path, detailing his early summers working as a logger in to fund his education before pivoting to through self-directed studies and hands-on projects. At his , the (), Mueller was inducted into the College of Engineering's Academy of Engineers in 2017 for his distinguished contributions to rocketry as a alumnus. The following year, in 2018, he received an honorary Doctorate in Engineering from during its spring commencement, where he delivered the address honoring his visionary role in innovation. In his 2018 speech, Mueller emphasized the value of self-taught skills, recounting how, as a young mechanic in the early 1990s, he independently learned advanced tools like 3D CAD modeling to advance his expertise in propulsion design. These honors underscore Mueller's inspirational impact on students, bridging his formal education—a bachelor's in from in 1985 and master's from LMU in 1992—with his pioneering career achievements.

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