Mission Design Engineer

About the role

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 and technical excellence are decisive advantages - and we are building a team that can deliver real capability, not just concepts. This is a rare opportunity to join at an early stage, where your work will directly shape critical systems, influence major technical decisions, and have immediate, real-world impact.

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.

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.
• 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.
• U.S. citizenship is required, as only U.S. citizens are eligible for a security clearance.

Benefits and Perks

• Meaningful long-term equity for all full-time employees.
• Four (4) weeks of paid time off.
• Ten (10) company-paid holidays.
• Comprehensive health benefits – including 100% employee-covered medical and strong dependent coverage, plus dental and vision plans.
• Paid parental leave.
• $100 monthly fitness stipend.
• Onsite EV charging.
• Catered meals, company-covered food during high-demand periods, and a fully stocked kitchen.