Make an impact at leading deep tech and American Dynamism Startups

Senior Thermo - Mechanical Engineer (Responsible Heat Pipe Engineer)

Antares

Antares

Other Engineering
Los Angeles, CA, USA
USD 140k-210k / year + Equity
Posted on Dec 17, 2025

Location

Los Angeles

Employment Type

Full time

Department

Engineering

Compensation

  • $140K – $210K • Offers Equity

As a growing Series B startup, the salary range is intentionally wide as we determine the most appropriate package for each individual, taking into consideration: years of experience, educational background, and unique skills and abilities as demonstrated throughout the interview process. Our intent is to offer a salary that is commensurate for the company’s current stage of development and allows the employee to grow and develop within a role.

In addition to the significant stock option package, the estimated salary range for this role is posted

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.

Formed in 2023, the Antares team hails from SpaceX, The White House, MIT, Rigetti Computing, The Air Force, General Atomics, Relativity Space, Ursa Major, and National Laboratories like Los Alamos, Idaho, and Oak Ridge. Antares has raised over $130M in venture capital from top-tier investors and has over $13M in government funding.

About the Role

As the Responsible Engineer for Heat Pipes, you will play a critical role in the development, design, and implementation of advanced heat pipe systems for cutting-edge nuclear microreactors. This position requires a deep understanding of thermal engineering and heat transfer in extreme environments, with a focus on reliability, safety, and efficiency. The ideal candidate will drive innovation and ensure the highest standards in nuclear heat pipe technology, contributing to next-generation sustainable energy solutions

Roles and Responsibilities:

  • Lead the design, modeling, and analysis of heat pipe systems, ensuring compatibility with R1’s core design, primary heat exchanger, and internal interfaces

  • Support development of manufacturing methods for prototyping and mass manufacturing of heat pipes

  • Support development of test articles, stands, and procedures for validating the limits of heat pipe performance and life characteristics

  • Interface with core, reactor vessel, and primary heat exchanger parts and owners to integrate heat pipes into the overall R1 system

  • Define operating procedures and limits for heat pipes to inform reactor control system integration

  • Investigate heat pipe failure and define reliability limits; integrate fixes rapidly

Basic Qualifications:

  • Bachelor's degree in engineering or physics

  • 5+ years of experience in high energy hardware (combustion devices, turbomachines, rankine cycles, hypersonics, etc)

  • Proficiency in thermal modeling software (e.g., COMSOL, ANSYS)

  • Knowledge of materials science as it applies to alloy selection for heat transfer and structural properties

Preferred Skills & Experience:

  • Master’s or PhD in Nuclear Engineering, Thermal Sciences, or Mechanical / Aerospace Engineering

  • Experience focusing on heat pipes or heat transfer systems, preferably in nuclear or high-reliability sectors.

  • Demonstrated knowledge in simulation of high temperature 2-phase flow fields

  • Demonstrated expertise in heat pipe design, analysis, manufacturing, and test

  • Strong understanding of nuclear safety standards, testing protocols, and regulatory requirements

  • Experience in nuclear thermal or other high temperature (500°C+) systems, including prior work with heat pipe technology

  • Experience with sodium purification and material handling

  • Exceptional communication skills to work effectively across teams and convey technical information to non-specialists

Additional Requirements:

  • Ability to work long hours and weekends as necessary to support critical milestones

Location

  • We are located in Torrance, CA in a 145,000 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.

Compensation Range: $140K - $210K