Senior Mechanical Engineer; Propulsion

Position: Senior Mechanical Engineer (Propulsion)

Location

Los Angeles

Employment Type

Full time

Department

Engineering

Compensation

• $150K – $187K

The stated compensation range reflects only the targeted base salary range and excludes additional benefits. If your salary requirements fall outside of the range, we still encourage you to apply.

About the Role

Apex is seeking a Propulsion Mechanical Engineer to own mechanical designs for our spacecraft propulsion systems. You will drive the design, analysis, and qualification of propulsion hardware that must perform reliably through launch environments and long‑duration on‑orbit operations. This role spans mechanical design, fluid system development, thermal interfaces, and flight hardware qualification, with end‑to‑end ownership from early concept through flight readiness and operational performance.

You will work closely with propulsion, thermal, avionics, and systems engineering teams to deliver robust, repeatable propulsion hardware designed for production spacecraft.

Responsibilities

• Own the mechanical design of propulsion system hardware and its integration into propulsion modules, including thrusters, PPUs, manifolds, flow control hardware, high‑pressure propellant lines, and tanks.
• Perform analysis and testing to satisfy propulsion subsystem requirements across performance, safety, and environmental constraints.
• Design propulsion module structures and housings, plasma‑facing components, mounts, thermal straps, and mechanical interfaces.
• Perform structural and vibration analyses to support launch loads, thermal cycling, and long‑duration on‑orbit operation.
• Generate and maintain CAD models, drawings, and GD&T for flight hardware.
• Support manufacturing, assembly, and integration of propulsion and fluid hardware.
• Plan and execute propulsion hardware testing, including vacuum testing, performance testing, leak testing, proof pressure testing, vibration, and thermal vacuum qualification.
• Diagnose test anomalies related to propulsion system testing and drive corrective action and design iteration.
• Partner with systems engineering on requirements, margins, and subsystem interfaces.
• Support launch campaigns, on‑orbit performance evaluation, and anomaly resolution.
• Contribute to failure analysis and continuous design improvements to support future builds and scalable production.

Requirements

• Bachelor’s degree in Mechanical Engineering, Aerospace Engineering, or a related field.
• 8+ years of experience delivering mechanical and/or fluid system hardware.
• Strong foundation in fluid mechanics, including compressible and/or rarefied gas flow, pressure‑drop/flow control, and cleanliness/contamination control.
• Experience designing and developing pressurized fluid systems.
• Proficiency with CAD tools (NX preferred).
• Comfortable owning hardware from concept through qualification and flight.
• Strong interpersonal skills and ability to work effectively across multidisciplinary teams.

Preferred but not required

• Experience with electric propulsion systems (Hall thrusters, ion thrusters, or related EP).
• Experience with spacecraft propellant feed systems and/or xenon (or alternative EP propellants).
• Familiarity with propulsion testing in vacuum facilities and vacuum system gas behavior.
• Prior flight hardware experience.

Why Join Apex?

Apex believes in creating a work environment that you look…