Senior Mechanical Design Engineer - Space
Confirmed on the employer's own hiring board on Nov 1, 2026. First seen by Alion on Oct 23, 2026. Antares Nuclear scores A on the Alion truth index.
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 Role
As a Mechanical Design Engineer in the Mission Engineering team, you will primarily own hardware associated with nuclear power systems in space and on the surface of the Moon and Mars. As the Responsible Engineer (RE) on space with the expectation of taking hardware from clean sheet design to build, dev test, qualification, and integration. You will be responsible for the entire life cycle of your hardware and system, interfaces to and from other systems, how your hardware fits into the larger system, sourcing, building, testing, and designing improvements for a first of a kind system. You’ll drive trades on system layout, interfaces, packaging, working closely with cross-disciplinary teams to refine configurations and close design loops. Your responsibilities will span CAD design, system analysis, leading design reviews, precise definition of thermal and mechanical interfaces, requirements ownership and decomposition, and manufacturability / scalability of your design.
Roles and Responsibilities:
Own a subsystem and related hardware as part of the larger space nuclear system.
Drive system-level layout, requirements definition/decomposition, build/test cycles, defend decisions across all phases of design, take concept through CDR and onward.
Own CAD models, manage configurations, produce drawings, DFMEA, etc.
Drive cross-discipline alignment and trade studies.
Coordinate closely with other teams/people (nuclear, thermal, structures, manufacturing, quality) to ensure a system architecture that satisfies mission/product requirements.
Develop a clean sheet design through hardware procurement and dev/qual testing.
Support design reviews and integration/test planning for hardware, define manufacturing plan and generate work instructions as needed.
Basic Qualifications:
Bachelor’s degree in mechanical or aerospace engineering, or a related physics-based field.
5+ years of experience in space system/product mechanical design, system configuration and layout.
Expertise with CAD (e.g., NX, CATIA) and past experience with PLM and other manufacturing planning and management systems.
Preferred Skills & Experience:
Master’s or PhD in mechanical or aerospace engineering, or a related physics-based field.
Expertise in the design, analysis, and integration of nuclear or space nuclear systems.
Leadership experience on a project or research team.
Strong project management skills, cross discipline communication, and interpersonal and collaborative skills.
Exceptional communication skills to work effectively across teams and convey technical information to non-specialists.
Understanding of fundamental principles in fluid systems and solid mechanics.
Demonstrated track record of initiative and high impact / ROI contributions.
Broad knowledge of materials science and material selections, especially for nuclear applications.
Ability to conduct complex design trades, system sizing, and first-order engineering analyses while clearly identifying analysis limitations and associated design risks.
Very strong design skills and GD&T/ drawings experience; take a design into production.
Additional Requirements:
Ability to work long hours and weekends as necessary to support critical milestones
Willingness and ability to obtain and retain a security clearance
Location
We are located in Torrance, CA in a 322,000 square foot, brand new facility featuring large open spaces for team collaboration, R&D, and production, as well as easy access to the 405, 105, and 110 freeways. Our facility is in the heart of Los Angeles' vibrant emerging tech ecosystem alongside many other high growth startups and enterprises.
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:
Think in Systems - Energy and Defense are complex ecosystems with numerous stakeholders with competing priorities, conflicting policies, perverse incentives, and emergent and path-dependent properties. First principles thinking alone is insufficient. Think probabilistically and then take action. “If you want to be certain, then you are apt to be obsolete.” Over-optimizing the components often degrades the system
Obsess over the End User - The customer and end user are often not the same. We will never build globally competitive commercial products if we lose sight of our end users and their entire interaction with the product life cycle
Be Unconstrained by Convention - Our only limits are the laws of physics. Many, even experts, will say what we are working on is impossible. They said the same about SpaceX reusing rockets. Generationally impactful companies, by definition, must accomplish the seemingly impossible. If it were easy, it would have already been done. Never shy away from a solution because it has never been tried before, and never choose to do something because that's “how it's always been done”
Go Where the Work Is - Never miss a chance to meet a customer, user, or stakeholder face to face, even if that means hopping on a plane. If you can’t make it, find a teammate who can channel your intentions and go in your place. Deep work can be done from anywhere, but we believe teams are built in person, and aim to maximize our time together
Operate in the Grey - Embrace nuance in pursuit of truth. Question every fundamental assumption
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.