Senior Thermal Engineer - Space

The posting, as Antares wrote it

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 Senior Space Thermal Engineer at Antares, you will own and drive the thermal design and analysis of a space nuclear vehicle, including the reactor, spacecraft, and heat rejection systems. You will develop, validate, and anchor thermal models to experimental and test data, using those models to guide early architecture decisions, system-level integration, and hardware design trades.

This role will focus primarily on high-temperature thermal management for space nuclear systems, including reactor heat transport and radiator architectures, while also supporting traditional low-temperature spacecraft radiator design where required. You will work closely with reactor, fluids, mechanical, test, and systems engineers to define thermal management architectures, evaluate heat rejection system configurations, identify data gaps, and mature thermal hardware integration approaches from concept through test-informed design.

Role and Responsibilities

• Construct, own, and validate thermal models for the reactor core, spacecraft, radiator systems, and integrated vehicle thermal response.
• Anchor thermal models to experimental, analytical, and test data wherever available; quantify uncertainty and improve model fidelity over time.
• Identify gaps in thermal, materials, coolant-loop, radiator, and reactor heat-transfer data, and work with test engineers to define, execute, and interpret required tests.
• Develop and analyze space nuclear thermal management architectures, including reactor heat transport, coolant loops, radiator systems, and integrated heat rejection systems.
• Generate, compare, and downselect heat rejection system configurations across performance, mass, temperature, integration, reliability, manufacturability, and operational constraints.
• Build system-level thermal models to assess vehicle-level performance, transient response, operating limits, and subsystem integration impacts.
• Create tools, methods, and analysis processes for predicting radiator thermalization behavior, heat rejection system performance, operating chara

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• 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 https://www.pmddtc.state.gov/?id=ddtc_kb_article_page&sys_id=24d528fddbfc930044f9ff621f961987.