Per Diem Simulation Engineer Jobs in California (NOW HIRING)

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