Lead, Mission Software Engineer

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.

Castelion is seeking a Lead, Mission Software Engineer to help define and build the software that connects our products into an integrated mission capability.

Mission Software spans Castelion’s full product portfolio, including weapons, launchers, command‑and‑control systems, sensors, mission planning tools, and external platforms
. Engineers on this team build the software that allows operators and systems to plan missions, exchange targeting and sensor data, command assets, initialize and employ weapons, and execute missions end to end.

As a Lead Mission Software Engineer, you will own major software capabilities and technical architecture across this mission stack. You will work across product boundaries, drive interfaces between systems, and help establish the software patterns that allow Castelion’s products to operate together as a cohesive system.

This is a hands‑on technical leadership role
. You will write, review, test, and commit production code while also leading architecture, mentoring engineers, and driving complex integrations from concept through flight test and fielding.

• Lead the architecture, development, integration, and deployment of mission software across weapons, launchers, C2 systems, sensors, and mission planning
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• Own major software capabilities from early requirements and architecture through implementation, integration, test, and operational deployment.
• Develop and integrate command‑and‑control software connecting operators, sensors, weapons, launchers, tactical networks, and external platforms.
• Define software architectures, APIs, data models, and interfaces that allow Castelion products to operate together as an integrated mission system.
• Develop software interfaces between Castelion products and aircraft, launchers, mission computers, fire‑control systems, sensors, and government C2 systems.
• Implement communications across interfaces and protocols such as Ethernet, TCP/UDP, CAN, MIL‑STD‑1553, MIL‑STD‑1760, and other tactical interfaces
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• Translate operational concepts, system requirements, and ICDs into scalable software architectures and production implementations.
• Build tools, simulators, and test infrastructure for software‑in‑the‑loop, hardware‑in‑the‑loop, and system‑level testing
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• Lead debugging and root‑cause efforts for complex issues spanning application software, embedded systems, networks, avionics, sensors, and hardware.
• Write and review production code using modern Git‑based workflows, automated testing, and continuous integration
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• Establish strong software engineering practices around code quality, testability, interfaces, and system architecture.
• Mentor software engineers and provide technical guidance across mission software efforts.
• Partner closely with flight software, avionics, guidance and navigation, vehicle engineering, test, and integration teams.
• Work directly with government customers, platform partners, operators, and external engineering teams during integration and fielding.
• Support integration and test activities from laboratory testing through ground and flight test.

• Bachelor’s degree in Computer Science, Computer Engineering, Electrical…