Principal Payload Engineer

Antares Nuclear · Los Angeles

Mechanical & AerospaceMission EngineeringFullTime

Antares Nuclear is hiring a Principal Payload Engineer in Los Angeles, California (full-time). Posted 21 September 2026. Apply directly on Antares Nuclear's own careers site — no account needed.

About Us

At Antares, our long-term mission is to make clean energy abundant from Earth to the Asteroid Belt. We’re fueled by the belief that advanced nuclear energy can strengthen our military, solve the climate crisis, elevate global living standards, and expand humanity's presence in outer space. To achieve our mission, we’re building mass-producible, inherently safe, deployable microreactors that can be used terrestrially, underwater, and in space.

The Antares team hails from SpaceX, the White House, the Pentagon, the Department of Energy, MIT, Rigetti Computing, General Atomics, Relativity Space, Ursa Major, and National Laboratories like Idaho, Oak Ridge, Los Alamos, and Savannah River. Antares has raised over $600M in venture capital from top-tier investors and has hundreds of million-dollars on contract with the military services, NASA, and the Department of Energy.

About the Team

As a key member of the Mission Engineering team, you will lead the development of novel effectors, sensors, and instruments needed to unleash nuclear-enabled missions in all domains. You will serve as a primary technical point of contact for customers and stakeholders during the mission development phase of projects, driving the development mission concepts that are grounded by our ability to project payload performance. You will lead trade-off decisions on which payload projects to pursue, as well as “make v. buy” decisions for integrating technologies. Finally, you will be responsible for executing technical projects to develop payloads, with the ultimate goal of building teams to carry out the development of these products to take to market. You understand everything from how on-orbit nuclear detection is achieved, to bespoke mechanisms for space control.

You will operate at the intersection of engineering, product development, customer program engagement, and mission integration, owning how the complete product is applied to real-world missions from concept through end of life.

You need to have strong engineering and physics fundamentals – particularly in particle physics, optics, condensed matter physics (materials interactions), remote sensing, thermodynamics, heat transfer, fluid mechanics, energy and power systems, and engineering economics – with demonstrated ability to reason from first principles, develop quantitative models to simulate payload (and thus mission) performance, and maintain high technical rigor across disciplines. You will own product integration into operational end-user environments.

The ideal candidate is a technical expert who understands space-domain awareness and space control concepts, yet is able to flex a generalist skillset, comfortably moving between various relevant payload technologies, engineering disciplines, hands-on analysis, hardware, program execution, and customer-facing work. They can rapidly develop depth in unfamiliar areas, communicate effectively across engineering teams, and drive ambiguous problems to closure. Experience with DOW, DOE, IC, NASA, or other government sponsors and procurement processes is preferred.

 

Roles and Responsibilities:

You will be responsible for:

Basic Qualifications:

 

Preferred Skills & Experience:

Culture

At Antares, we like to specifically tie each role to our founding document’s set of values–here are the top five cultural values we think you should believe at your core to be successful:

Equal Opportunity

Antares is an Equal Opportunity Employer. Employment decisions are based solely on merit, competence, and qualifications, without regard to race, color, religion, gender, national origin/ethnicity, veteran status, disability status, age, sexual orientation, gender identity, marital status, mental or physical disability, or any other legally protected status.

ITAR Requirements

To conform to U.S. Government export regulations, applicant must be a (i) U.S. citizen or national, (ii) U.S. lawful, permanent resident (aka green card holder), (iii) Refugee under 8 U.S.C. § 1157, or (iv) Asylee under 8 U.S.C. § 1158, or be eligible to obtain the required authorizations from the U.S. Department of State. Learn more about the ITAR here.

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