Senior Simulation and Modeling Engineer

About the role

In this role, you will design and maintain the simulation frameworks that define how the Terran R vehicle navigates from launch to orbit, ensuring that every trajectory prediction is grounded in rigorous analysis. You will build high-fidelity models and software tools that directly influence flight performance, structural loading assessments, and mission success across multiple vehicle phases. The position requires close collaboration with the Guidance, Navigation, and Control (GNC) and Performance teams to translate complex mission requirements into executable simulation logic. You will own the architecture of numerical solvers and physics-based models so that they remain scalable, maintainable, and accurate as vehicle designs evolve. This role involves establishing robust interfaces between simulation software and GNC algorithms, enabling real-time testing and rapid iteration. You will also create tools for simulation configuration, logging, scheduling, and Monte Carlo execution to streamline analysis workflows. In addition, you will support the development environment for simulation users and contribute to broader cross-functional software packages that integrate simulation, data visualization, and reporting. Your work will directly support trade studies, failure mode analysis, and certification activities by providing reliable simulation evidence.

Key facts

What you'll do

• Build and maintain 6DOF simulations for GNC algorithm development, Monte Carlo analysis, and hardware-in-the-loop (HITL) testing, ensuring that models accurately represent vehicle dynamics across all flight regimes.
• Integrate subsystem models into the primary 6DOF simulation environment, managing interfaces for propulsion, aerodynamics, guidance, and navigation components with strict attention to data consistency.
• Develop and implement numerical solvers and physics-based models that are efficient, stable, and capable of handling the nonlinearities inherent in launch vehicle trajectories and attitude dynamics.
• Create tools for simulation configuration, logging, scheduling, and Monte Carlo execution, enabling automated workflows that reduce manual setup time and improve reproducibility.
• Establish interfaces between simulation software and GNC algorithms, facilitating real-time testing, rapid prototyping, and validation of control strategies under diverse scenarios.
• Support the development environment for simulation users by providing documentation, templates, and utilities that lower the barrier to entry for new analysts and engineers.
• Contribute to broader cross-functional software packages by collaborating with software, systems, and integration teams to align simulation capabilities with overall product objectives.
• Optimize simulation performance for high-throughput analyses, leveraging efficient data structures and parallelization strategies to meet demanding turnaround times.
• Validate simulation outputs against analytical benchmarks, subsystem tests, and flight data to ensure that models remain accurate as vehicle designs mature.
• Drive best practices in version control, testing, and modular design so that simulation frameworks can be reused across programs and adapted to future vehicle architectures.

Requirements

• Undergraduate or graduate degree (BS, MS, or PhD) in physics, mathematics, engineering, or a related field.
• Minimum of 5 years of professional experience in a relevant role involving simulation, modeling, or analysis for aerospace systems.
• Proficiency in scripted languages (Python) and compiled languages (C++ or Rust) to develop high-performance simulation components and integrate them into larger workflows.
• Proven experience creating physics-based simulations for aerospace vehicles, including trajectory, attitude, and structural or loading analyses where applicable.
• Ability to work independently on end-to-end projects within a fast-paced startup environment, taking ownership from requirements capture through delivery.
• Strong understanding of numerical methods, discretization schemes, and stability considerations for dynamic system simulations.
• Experience with version control, debugging, and performance profiling to maintain high-quality, reliable simulation codebases.
• Demonstrated ability to communicate technical concepts clearly to both technical and non-technical stakeholders during design reviews and decision-making processes.

Nice to have

• Experience with launch vehicle or space system design and analysis, including familiarity with stages, propulsion, and orbital mechanics.
• Background in aerospace simulation development involving GNC algorithms or HITL testing, with an understanding of control loops, sensor processing, and actuator dynamics.
• Proficiency in high-performance computing (HPC) implementations, including parallelization techniques and usage of computing clusters for large-scale analyses.
• Experience with modern software workflows including Docker, continuous integration (CI), and continuous deployment (CD) to ensure reproducible environments and reliable delivery of simulation tools.

Practical notes

Relativity provides a comprehensive benefits package including equity, PTO, sick leave, parental leave, and an annual learning and development stipend. The company is an equal opportunity employer. For accommodation requests, contact accommodations@relativityspace.com. Unsolicited resumes from recruitment agencies are not accepted.