Propulsion - Junior Propulsion Engineer

At Orbital Paradigm, we design, develop, manufacture, and operate reusable orbital logistics systems. Our spacecraft perform multiple orbital mission profiles and return safely to Earth through hypersonic atmospheric reentry and landing with pinpoint accuracy for rapid refurbishment and reuse. Role Description We are looking for a Junior Propulsion Engineer to support the design, development, integration, and testing of chemical propulsion systems for reusable orbital logistics vehicles. The role focuses on HTP-based propulsion systems, including thrusters, tanks, feed systems, valves, regulators, pressurization systems, fluidic components, additive manufacturing, test hardware, and propulsion test campaigns. The engineer will work closely with propulsion, systems, GNC, avionics, mechanical, thermal, manufacturing, AIT, and quality teams to develop reliable spacecraft propulsion hardware from early design through testing. This role is suited for an early-career engineer with strong fundamentals, hands-on project experience, and clear motivation to work on spacecraft propulsion systems. Key Responsibilities Support the design, development, and testing of HTP-based chemical propulsion systems. Assist with propulsion system architecture, sizing, trade studies, and component selection. Support the design of thrusters, tanks, feed systems, pressurization systems, valves, regulators, lines, fittings, and fluidic components. Contribute to CAD models, drawings, interface documentation, BOMs, and technical documentation. Support additive manufacturing activities for propulsion hardware, including design reviews, supplier coordination, inspection, and test preparation. Assist with propulsion analyses, including performance estimates, pressure drop calculations, thermal assessments, and operational scenario analysis. Support preparation and execution of propulsion test campaigns, including pressure tests, leak tests, functional tests, component tests, and hot-fire tests. Assist with test setup, instrumentation, data acquisition, test procedures, safety checks, and post-test inspections. Analyze propulsion test data and document results, anomalies, and technical findings. Support troubleshooting, root-cause analysis, and design iterations based on manufacturing, integration, and test results. Work with suppliers, manufacturing partners, test facilities, and internal teams under the guidance of senior engineers. Contribute to design reviews, test readiness reviews, and qualification reviews. Required Qualifications 0–1 years of professional experience in propulsion, aerospace, mechanical systems, fluid systems, thermal systems, or related technical fields. Degree in Aerospace Engineering, Mechanical Engineering, Chemical Engineering, Propulsion Engineering, or a related technical field. Hands-on technical experience through a rocketry team or propulsion project, or equivalent engineering club, or applicable internship at a relevant aerospace company or startup. Strong fundamentals in propulsion, fluid dynamics, thermodynamics, heat transfer, mechanics, materials, and system-level engineering. Basic understanding of chemical propulsion systems, pressure systems, feed systems, tanks, valves, regulators, lines, fittings, seals, and fluidic components. Basic familiarity with propulsion testing, instrumentation, data acquisition, test procedures, and test safety. Exposure to CAD, mechanical design, manufacturing drawings, or mechanical documentation. Exposure to propulsion, fluid, thermal, or structural analysis tools. Ability to write clear technical documentation, test notes, procedures, and reports. Strong problem-solving skills and willingness to work hands-on during design, integration, and testing activities. Ability to work effectively in multidisciplinary engineering teams. Full proficiency in English, written and spoken. Preferred Qualifications Internship experience in aerospace, propulsion, mechanical systems, fluid systems, automotive, energy, or another high-performance engineering environment. Experience in a startup, student team, laboratory, or small engineering team with fast design-build-test iterations. Exposure to HTP systems, monopropellant systems, bipropellant systems, cold gas systems, RCS, or other chemical propulsion systems. Familiarity with spacecraft propulsion, launch vehicle propulsion, reentry vehicle propulsion, or orbital maneuvering systems. Exposure to additive manufacturing for propulsion, fluidic, thermal, or high-performance mechanical hardware. Exposure to with materials compatibility, contamination control, pressure systems, hazardous operations, or propellant handling. Basic knowledge of propulsion design and analysis tools for CAD, CFD, FEA, system simulation, performance modelling, and test data analysis, such as CATIA, Siemens NX, ANSYS, STAR-CCM+, OpenFOAM, EcosimPro/ESPSS, Simulink/Simscape, NASA CEA, Python, MATLAB, or equivalent. Basic proficiency with one or more programming languages such as Python and MATLAB. Basic awareness of aerospace industry standards such as ECSS, NASA, or MIL. Good proficiency in Spanish. What We Value Excellence in technical work, execution, and professional conduct Strong ownership mindset, with the ability to drive activities to clear outcomes through accountability, proactivity, and resourcefulness Clear, efficient, direct, and constructive communication Team-first attitude with low ego and strong cross-functional collaboration What We Offer Location: Madrid, Spain (office-first) Flexible hybrid work (2 days/week from home + 2 fully remote weeks/year) 30 vacation days (23 flexible, +7 during holidays). Salary depending on experience and profile Relocation package depending on seniority and profile Flexible compensation (meal vouchers, health insurance, public transport) Company shares plan