Mission Design Engineer

Why Castelion, Why Now Castelion is moving incredibly fast to develop and deliver advanced defense systems at a time when execution matters more than ever. We believe focus, ownership, and excellence are decisive advantages - and we're building a world-class team to turn bold ideas into real capability. This is a rare opportunity to join at an early stage, where you'll have significant ownership, collaborate with exceptional teammates, and make a direct, measurable impact on our mission and the future of the company - regardless of your function. Mission Design Engineer As a Mission Design Engineer, you will lead mission-level analysis and system design using advanced modeling and simulation tools such as AFSIM and EADSIM. You will evaluate system effectiveness in operational scenarios, translate mission needs into engineering requirements, and inform design decisions through simulation, test, and rapid iteration. In addition to modeling and analysis, you will play an active role in prototype hardware design, integration, and test, working closely with cross-functional teams to ensure mission-driven insights are realized in real-world systems. This role connects operational analysis directly to hardware, ensuring that simulation results drive tangible performance improvements in deployed systems. Responsibilities: Mission Design & Operational Analysis • Develop and execute mission-level simulations using AFSIM and EADSIM to evaluate system performance in contested, multi-domain environments. • Translate operational scenarios and customer needs into system requirements, constraints, and performance metrics. • Conduct trade studies, sensitivity analyses, and campaign-level assessments to inform system architecture and design decisions. • Analyze interactions between sensors, weapons, communications, and threat systems to assess mission effectiveness. Modeling, Simulation & Data-Driven Design • Build, maintain, and extend simulation frameworks representing real-world operational conditions. • Use simulation outputs to guide design trades across propulsion, GNC, avionics, and software. • Correlate simulation results with ground and flight test data to improve model accuracy and predictive capability. • Develop tools and workflows to rapidly evaluate new concepts and configurations. Prototype Development, Integration & Test • Collaborate with hardware and software teams to integrate mission requirements into prototype systems. • Support system-level integration and ensure alignment between modeled performance and actual system behavior. • Participate in flight tests and live-fire events, including pre-test analysis, real-time support, and post-test evaluation. • Use test results to refine both system design and simulation models. Cross-Functional Collaboration • Work across engineering disciplines (GNC, propulsion, avionics, software, manufacturing). • Communicate mission-level insights to inform design tradeoffs and prioritization. • Support design reviews, technical briefings, and customer engagements. Basic Qualifications: • Bachelor's degree in aerospace engineering, mechanical engineering, electrical engineering, physics, or related field. • 2+ years of experience in mission analysis, operational analysis, systems engineering, or aerospace/defense modeling & simulation. • Experience with AFSIM, EADSIM, or similar tools (e.g., STK, MATLAB/Simulink, custom simulation frameworks). • Experience translating mission needs into engineering requirements and design trades. • Familiarity with aerospace or defense systems (missiles, aircraft, spacecraft, or launch vehicles). • Strong analytical and communication skills. • Ability to obtain and maintain a Top Secret/SCI clearance. Additional Requirements: • Ability to put in extended hours, including evenings and weekends, when required to meet aggressive timelines • This role is based in Torrance, CA and requires full-time onsite presence Castelion offers a generous benefits package. Please refer to the bottom of our Careers page for more details. Other Duties Please note this job description is not designed to cover or contain a comprehensive listing of activities, duties or responsibilities that are required of the employee for this job. Duties, responsibilities and activities may change at any time with or without notice. Additional Eligibility Requirements This position may require access to classified information or restricted U.S. Government sites, systems, or information, as determined by the Company and/or applicable U.S. Government requirements. If the position is so designated, your employment in the role may be contingent upon your ability to obtain and maintain the required U.S. Government security clearance or other government authorization, and to satisfy any citizenship or other eligibility requirements imposed by applicable law, regulation, executive order, or government contract requirements. You will be notified if and when such requirements apply. Affirmative Action/EEO Statement Castelion is an Equal Opportunity Employer. We are committed to providing equal employment opportunities to all applicants and employees without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, age, disability, genetic information, protected veteran status, or any other characteristic protected by applicable federal, state, or local law. Castelion is committed to providing reasonable accommodations to qualified individuals with disabilities throughout the application and hiring process. If you require a reasonable accommodation to complete an application, participate in the interview process, or otherwise participate in the hiring process, please contact hr@castelion.com. Requests for accommodation will be considered on an individual basis and handled in accordance with applicable law. Castelion is committed to fostering a workplace where employment decisions are based on qualifications, business needs, and the ability to perform the essential functions of the role, with or without reasonable accommodation. EAR/ITAR Requirements This position requires access to export-controlled information, and as such, employment (or hiring of a contractor) is contingent upon the candidate’s ability to access all applicable export-controlled information without additional export licensing being required by the Bureau of Industry and Security and/or the Directorate of Defense Trade Controls.