Systems Engineer, Spacecraft Design & Simulation

Vast is seeking a Systems Engineer, Spacecraft Design & Simulation to own the spacecraft simulation toolchain that is the foundation of our mission factory the software infrastructure that will enable us to scale from our first 10-satellite demo launch to hundreds of spacecraft per year.

This will be a full-time, exempt position located in our Long Beach location.

About the role:

We're building a mission factory software infrastructure that dramatically reduces the time from customer contract to payload on orbit. The foundation is a simulation and digital twin toolchain that serves as the primary engineering record. Requirements, budgets, design parameters, and trade study results all live in this toolchain. It includes spacecraft power/thermal/ADCS simulation, orbital constellation analysis, communications link budgets, and actuator trade studies. This is model-based systems engineering as it should work requirements, budgets, and design parameters live in executable models that compute and validate, not in static documents. A working prototype exists today you'll evaluate it, determine whether to extend it or redesign it, and own the toolchain as we scale from our first 10-satellite demo launch to hundreds of spacecraft per year.

This is a spacecraft systems engineering role, not a software engineering role. You define the governing equations, boundary conditions, and expected behavior for each model. You build and maintain a rigorous validation suite hand calculations, independent tool cross-checks, and edge case analysis that serves as the quality gate for every change. We use AI code generation tools to accelerate implementation, but the engineering judgment, validation methodology, and physics expertise are yours.

Responsibilities:

• Own and evolve the spacecraft design, simulation, and digital twin toolchain power, thermal, ADCS, orbital mechanics, constellation coverage, link budgets, mass and design margin tracking
• Make the toolchain the hub of the engineering organization every discipline (thermal, GNC, power, structures) should be able to run trade studies and assess design changes quickly as the program evolves
• Drive design trades and architecture decisions through analysis your models are how the team knows whether the power budget closes, whether the thermal architecture works, and whether we meet customer requirements
• Enable rapid iteration as customer requirements and the design evolve the toolchain must keep pace with the program so engineers can assess impact immediately, not wait weeks for analysis
• Maintain the digital twin as the program's engineering record requirements, budgets, design parameters, and trade study results live here
• Build and maintain a rigorous validation suite hand calculations, independent tool cross-checks, edge case analysis, and regression testing for every physics model
• Train and support the engineering team so they can self-serve on trade studies and analysis

Minimum Qualifications:

• Bachelor's degree in Aerospace Engineering, Mechanical Engineering, Electrical Engineering, Physics, or a related technical discipline
• 4+ years of spacecraft systems engineering or mission analysis experience
• Spacecraft systems engineer with broad subsystem knowledge you understand power, thermal, ADCS, and orbital mechanics well enough to catch errors in a simulation
• Strong analytical skills you can set up a hand calculation for a thermal equilibrium problem, a power budget across an orbit, or a pointing error budget
• Rigorous validation mindset you're the person who asks how do we know this is right? and builds the test to prove it
• Comfortable with AI-assisted development workflows
• Generalist background prior experience at a small-sat company, research lab, or mission design role where you touched multiple subsystems
• Cross-functional collaboration skills you'll work with every discipline lead to capture their domain knowledge and translate it into validated models
• Comfortable reading and reviewing code you don't need a software engineering background, but you should be able to understand what code is doing and catch errors

Preferred Skills & Experience:

• Able to obtain a security clearance
• Experience building or maintaining spacecraft simulation tools
• Familiarity with orbital mechanics (Kepler solver, J2 perturbations, eclipse geometry)
• Familiarity with CMG dynamics, quaternion attitude propagation
• Experience with data visualization tools or libraries
• Demonstrated use of AI-assisted code generation tools on an engineering project show us what you built
• Requirements management and verification experience on a spacecraft mission
• Experience with MBSE tools or model-based development methodologies
• Experience scaling engineering tools or analysis workflows across a growing team
• Experience developing validation and verification test suites for engineering tools