Spacecraft represent the most pressing unmet need across the entire aerospace industry. As more launch vehicles come online and the cost to orbit decreases, more companies launching payloads to space continue to emerge. For the first time in history, this influx of payload companies combined with reduced launch costs has resulted in a massive increase in need for commercial spacecraft platforms, known as satellite buses. These buses hold the payloads of our customers and are flown on launch vehicles. Apex manufactures these satellite buses at scale using a combination of software, vertical integration, and hardware that is designed for manufacturing. Our spacecraft enable the future of society: ranging from earth observation to communications and more. We’d love for you to join us on our mission of providing humankind access to the galaxy beyond our planet. About the Role Apex is seeking a Staff Electric Propulsion Engineer with deep expertise in Hall-effect thrusters to serve as the technical authority for our Hall thruster development and production. Building on Apex's in-house Hall-effect thruster capability, you will own the thruster from plasma physics and discharge channel design through qualification, flight integration, and design-for-manufacturing at rate. This is a Staff-level individual-contributor role with broad technical leadership scope. You will set the Hall thruster technical roadmap, drive key architecture and design trades, lead test and qualification campaigns, and mentor propulsion engineers as we scale our EP capability. As a technical anchor of Apex's EP team, you'll shape how high-performance Hall thrusters are designed for serial production and flown across our spacecraft platforms. Responsibilities • Own the end-to-end design of Apex's Hall-effect thrusters, including discharge channel geometry, magnetic circuit design, anode and gas distributor design, and thermal-mechanical packaging. • Lead the plasma physics and performance modeling that drives thruster design, including ionization and acceleration behavior, magnetic field topology, efficiency, thrust-to-power, and specific impulse across the operating envelope. • Define and execute thruster test and life-qualification campaigns, including performance mapping, plume characterization, thermal testing, oscillation and stability characterization, wear testing, and long-duration life testing in vacuum facilities. • Establish erosion, degradation, and life models for the discharge channel and pole pieces, and demonstrate compliance with mission life and propulsion budgets for power, thermal, throughput, and leak. • Drive cathode-thruster coupling and overall EP system integration in partnership with cathode, propellant feed-system, and PPU owners. • Select materials and processes, including ceramics, magnetic materials, and refractory metals, and qualify them for spaceflight and high-rate production. • Optimize thruster designs for performance, mass, cost, manufacturability, and repeatability, and develop the work instructions, process flows, and AI&T procedures required to build them at rate. • Partner with systems, power electronics, thermal, structures, and avionics teams to define interfaces, including PPU/thruster operating points and gimbal integration, and verify requirements. • Support the build, integration, and test of flight hardware, as well as launch campaigns, on-orbit performance evaluation, and anomaly resolution. • Lead failure analysis, root-cause investigations, and continuous design improvements to support future builds and scalable production. • Provide technical leadership and mentorship across the propulsion team and help build Apex's Hall thruster capability, team, and infrastructure. Requirements • Must be a U.S. Person (U.S. citizen, lawful permanent resident, or protected individual) as defined by ITAR (22 CFR §120.15) • Bachelor's degree in aerospace, mechanical, electrical, plasma/propulsion engineering, applied physics, or a related field. • 10+ years of relevant electric propulsion experience with a Bachelor's or Master's degree, OR a Ph.D. in electric propulsion, plasma physics, applied physics, or a closely related field with 3+ years of relevant industry experience, with substantial and demonstrable focus on Hall-effect thruster design, development, and testing. • Deep, hands-on knowledge of Hall thruster physics and design, including discharge channel design, magnetic circuit layout, anode and gas distribution, cathode coupling, and thermal management. • Experience planning and executing Hall thruster or EP test campaigns in vacuum facilities, including plasma/plume diagnostics, performance measurement, and long-duration life/wear testing. • Strong understanding of the failure and degradation mechanisms that drive Hall thruster life, including channel and pole erosion, thermal limits, and discharge instabilities, and how to design and test against them. • Working knowledge of spacecraft propulsion system architecture, propellant feed systems, PPU interaction, and range safety requirements (e.g., SSCMAN 91-710). • Demonstrated technical leadership, including setting technical direction, driving complex design trades, and mentoring engineers. • Ability to decompose requirements and ICDs and communicate clearly across engineering disciplines. Preferred Requirements • Direct experience taking a Hall thruster from clean-sheet design through flight qualification and on-orbit operation. • Experience with magnetically shielded, wall-less, and/or unshielded Hall thruster architectures. • Experience with alternative propellants, including krypton and other non-xenon EP propellants, and their effects on thruster performance and life. • Familiarity with Hall thruster plasma simulation tools, including particle-in-cell and hybrid codes, and magnetic FEA. • Familiarity with PPU/thruster drive electronics and power interface definition. • Design-for-manufacturing experience bringing propulsion