Sr. Thermal & Propulsion Engineer

Company Overview Fortastra designs and delivers resilient, high-performance spacecraft that safeguard critical orbital assets and ensure freedom of action in space. We integrate advanced autonomy, sensing, and control into systems engineered for reliability, speed, and scale. Our culture values simplicity, accountability, and disciplined execution. We expect leaders to think systemically, act decisively, and take ownership of mission outcomes. Aggressive innovation. Disciplined execution. Strength among the stars. We recently closed a $30M Series A to build the future of on-orbit security and we’re just getting started! Our Engineering Team You will join Fortastra’s Engineering Division, working at the intersection of propulsion, thermal control, and spacecraft systems. The team is responsible for the design, integration, and flight readiness of core vehicle subsystems that directly determine mission reliability and on-orbit performance. The Role Fortastra is seeking a Sr. Thermal & Propulsion Engineer to own the design and implementation of our bipropellant propulsion hardware and Thermal Control Systems (TCS). This is a hardware-focused role: you will architect, design, and build propulsion and thermal-fluid systems including thrusters, feed systems (tanks, valves, lines), and thermal management hardware that must operate reliably in the space environment. You will be responsible for taking systems from concept through detailed design and into assembly and integration, with less emphasis on pure analysis or simulation and more on practical, flight-ready hardware. The ideal candidate brings deep hands-on experience with propulsion and thermal-fluid systems, strong mechanical design instincts, and a track record of delivering hardware that works on the vehicle. Key Responsibilities Own the end-to-end design of bipropellant propulsion hardware, including thrusters, tanks, valves, regulators, filters, and feed system plumbing. Architect and implement Thermal Control Systems (TCS) for propulsion and related spacecraft subsystems, focusing on thermal-fluid behavior and hardware-level solutions. Define fluid and thermal architectures that ensure reliable performance across all mission phases, including start-up, steady-state, transients, and off-nominal conditions. Create detailed CAD models, assemblies, and drawings for propulsion and thermal hardware, including routing, brackets, manifolds, and integration hardware. Select, specify, and qualify propulsion and thermal components (valves, sensors, heaters, fittings, insulation, etc.) and drive supplier engagement and design-for-manufacture decisions. Work hands-on with technicians and manufacturing partners to build, assemble, and integrate propulsion and TCS hardware into the spacecraft. Collaborate with systems, structures, avionics, and GNC teams to define interfaces, loads, and constraints, ensuring robust mechanical and functional integration. Support test planning and execution for propulsion and thermal systems as needed, with a primary focus on designing hardware that is robust, testable, and flight-ready from the outset. Qualifications and Skills B.S. in Mechanical Engineering, Aerospace Engineering, or a closely related field (M.S. is a plus but not required). 5+ years of industry experience working on propulsion and/or thermal-fluid systems for spacecraft, launch vehicles, or similar aerospace hardware. Demonstrated, hands-on experience designing and developing propulsion hardware, including bipropellant thrusters and feed systems (tanks, valves, tubing, regulators, fittings). Experience designing Thermal Control Systems (TCS) for complex aerospace hardware, with practical application of thermodynamics and heat transfer to hardware-level solutions. Proficiency with CAD tools for mechanical design, layout, and integration of propulsion and thermal hardware. Strong understanding of fluid dynamics and thermal-fluids as applied to propellant management, feed systems, and thermal control, with a bias toward implementable, hardware-centric designs. Proven ability to take systems from concept through detailed design, fabrication, assembly, integration, and troubleshooting on real hardware. Preference for engineers who gravitate toward hardware design and build rather than primarily analysis or simulation roles. Strong communication and collaboration skills, with the ability to operate in a small, fast-moving, highly integrated engineering team. Requirements 5 days on-site in Torrance, CA U.S. Citizenship required Why Fortastra We are a small, high-impact team building the next generation of autonomous orbital control systems for national security space. At Fortastra, leaders own outcomes from first principles through flight and directly shape the future of resilient, mission-critical spacecraft autonomy. FORTASTRA TALENT & CULTURE PRINCIPLES Values Driven by First Principles We value engineers and operators who prioritize sound judgment, candor, technical rigor, bias for action, and intellectual honesty over corporate consensus. We care about the caliber of the system you build and the speed at which you solve problems. Talent Density Over Headcount A high-performing startup is built on dense talent, not organizational bloat. A single exceptional engineer designs, tests, and delivers faster than a bloated committee. We intentionally maintain a lean, elite engineering crew where every contributor directly moves the needle on the mission. High Autonomy, High Ownership We hire domain experts to execute, not to micromanage them. You own your systems end-to-end, from initial architecture and hardware design to testing and deployment. With absolute ownership comes the responsibility to deliver mission critical reliability. Mission Context Over Bureaucracy The best execution happens when teams are provided clear technical objectives, constraints, and operational context, rather than rigid top-down policies. We strip away red tape so builders can iterate, make decisions, and push hardware and flight software forward rapidly. Disciplined Speed & Flight Rigor We move fast because we test often and kill artificial bottlenecks, not because we cut corners. Rapid iteration on the test stand and in simulation is how we learn; an uncompromising flight-readiness bar is how we earn trust. Precision without friction, speed without recklessness. Direct Impact, Not Career Bureaucracy You don’t come to Fortastra to climb a corporate ladder or manage slide decks; you come to build complex, flight-ready systems from day one. Growth here is organic, driven by the magnitude of technical challenges you solve and the trust you build across the team. Benefits Unlimited Paid Time Off so that you have the time you need to rest and recharge. Comprehensive Healthcare: Medical, dental, and vision coverage for you and your dependents, because peace of mind starts with feeling cared for. Equity: Share in Fortastra's success with equity in the company you're helping build. 401(k): A 401(k) plan to help you invest in your future and plan for what's ahead. Social Events: Regular social events, team outings, and company-sponsored activities that make this a place people are glad to be part of. The pay range for this role is $130,000.00 - $220,000.00. Where an offer falls within that range depends on factors like your qualifications, experience, location, and interview performance, which we weigh against the market rate for the position. Recruiters & Agencies Fortastra does not accept unsolicited resumes or candidate submissions from recruiters, agencies, or third parties. Any candidate submitted without a signed agreement and prior written authorization from Fortastra will not be subject to any fee, and no relationship is implied. Please do not contact Fortastra employees, hiring managers, or recruiting team directly. #J-18808-Ljbffr Fortastra