Senior Modeling & Simulation Engineer: National Security Missions

K2 is building the largest and highest-power satellites ever flown, unlocking performance levels previously out of reach across every orbit. Backed by $450M from leading investors including Altimeter Capital, Redpoint Ventures, T. Rowe Price, Lightspeed Venture Partners, Alpine Space Ventures, and others – with an additional $500M in signed contracts across commercial and US government customers – we’re mass-producing the highest-power satellite platforms ever built for missions from LEO to deep space. The rise of heavy-lift launch vehicles is shifting the industry from an era of mass constraint to one of mass abundance, and we believe this new era demands a fundamentally different class of spacecraft. Engineered to survive the harshest radiation environments and to fully capitalize on today’s and tomorrow’s massive rockets, K2 satellites deliver unmatched capability at constellation scale and across multiple orbits. With multiple launches planned through 2026 and 2027, we're Building Bigger to develop the solar system and become a Kardashev Type II (K2) civilization. If you are a motivated individual who thrives in a fast-paced environment and you're excited about contributing to the success of a groundbreaking Series C space startup, we’d love for you to apply. The Role You will build the modeling and simulation capabilities that let us design, verify, and operate spacecraft for demanding national security missions. You will simulate and verify the software that flies and orchestrates some of the largest satellites ever flown, and model how those systems perform against real mission objectives, threats, and operational constraints. As a senior member of the team, you will drive solutions end-to-end across the software stack, make changes to vehicle control software where needed, set technical direction, and mentor other engineers. In your first 3 months you will generalize our simulation tools to operate in classified contexts, modeling multiple spacecraft and mission profiles, demonstrating robust performance in contested and demanding environments. In your first 6 months you will design many-agent, mission-level simulations and tools for operating entire constellations, directly informing mission assurance and critical company and program decisions. This role supports classified national security programs. Work is performed on-site in a secure environment and requires an active TS/SCI clearance and US citizenship. Responsibilities Develop mission-level modeling and simulation of national security space missions, capturing operational objectives, environments, and constraints. Model and analyze constellation-level capability and performance against mission requirements, including network coverage, beam planning, and resilience in contested environments. Support work on classified programs in accordance with all applicable security requirements. Create and maintain simulation software infrastructure for our 20kW+ spacecraft. Develop physics-based software models of spacecraft subsystems, including propulsion, attitude control, power, and communications systems. Create and utilize robust tools to allow for rapid deployment of quality code. Perform data analysis and anomaly investigation to identify and resolve on-orbit problems. Support integration and testing of spacecraft subsystems. Set technical direction, review designs and code, and mentor junior engineers. Qualifications Active TS/SCI clearance, or a TS/SCI held within the last 12 months, and US citizenship. Current or previously held Special Access Program (SAP) access. Prior experience working on classified national security programs and in secure/SCIF environments, including familiarity with handling classified information and program security protocols. Bachelor's degree in physics, aerospace/mechanical/electrical engineering, computer science, math, or a STEM field 5+ years of professional modeling and simulation experience. Development experience in Rust, C++, o…