Physical Design Engineer Intern Jobs in New Mexico

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.

Castelion is designing and building next‑generation hypersonic weapon systems that restore stability through credible deterrence. We are seeking a hands‑on, mission‑driven Senior Warhead Design Engineer to lead the design, development, and integration of advanced next‑generation systems for our long‑range hypersonic strike vehicles.

This is a high‑impact role for someone with deep expertise in energetic devices and safe & arm mechanisms, who thrives in a fast‑paced, hardware‑rich development environment.

• Own the design, development, and qualification of ordnance systems, including: Initiators, detonators, transfer charges, explosive bolts, safe & arm devices.
• Define requirements and interface specifications across mechanical, electrical, and software boundaries.
• Lead supplier engagement, component selection, and build‑to‑print efforts with a focus on manufacturability, cost, and performance.
• Drive development test planning, execution, and analysis for ordnance systems (including arena testing, function testing, and environmental qualification).
• Work closely with systems, propulsion, avionics, and GNC teams to ensure ordnance components integrate safely and effectively into the full weapon system.
• Support FMEA, fault‑tree analysis, and safety case development.
• Own documentation and compliance to MIL‑STD‑1316, MIL‑STD‑1910, AFSPCMAN 91-710, and other relevant standards.

• B.S. or M.S. in Mechanical Engineering, Aerospace Engineering, or related field.
• 5+ years of experience in ordnance or energetics design, analysis, and test
• Familiarity with relevant DoD and NASA standards (e.g., MIL‑STD‑1316, MIL‑STD‑1901A, etc.).
• Hands‑on test experience in high‑consequence environments.
• Strong communication and documentation skills.
• Active or eligible for a U.S. security clearance.

• Experience working with DoD customers and navigating military qualification processes.
• Background in hypersonics, missile systems, or space launch vehicles.
• CAD and mechanical analysis experience (e.g., SolidWorks, FEA tools).
• Experience with additive manufacturing tools and capabilities. Prior experience working at a defense startup or fast‑moving development organization.

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.

All full‑time employees are granted meaningful long‑term equity, sharing in the company's significant growth trajectory. We offer four (4) weeks of paid time off, ten (10) company‑paid holidays, and comprehensive health benefits - including 100% employee‑covered medical and strong dependent coverage, along with dental and vision plans. We also provide paid parental leave to support growing families, a $100 monthly fitness stipend to promote health and performance, and onsite EV charging for convenience. In addition, employees enjoy perks like catered meals, company‑covered food during high‑demand periods, and a fully stocked kitchen to stay fueled throughout the day.

While this position does not currently require a U.S government‑issued security clearance, it may in the near future. Therefore, the ability to obtain and maintain a U.S. government‑issued security clearance is required. U.S. citizenship is required, as only U.S. citizens are eligible for a security clearance.

Employment with Castelion is governed on the basis of competence and qualifications and will not be influenced in any manner by race, color, religion, gender, national origin/ethnicity, veteran status, disability status, age, sexual orientation, gender identity, marital status, mental or physical disability or any other legally protected status.