Senior People Business Partner

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 The People team at Antares is building the foundation for how we attract, develop, and support exceptional talent as the company continues to grow. We partner closely with leaders across Engineering, Operations, and Corporate functions to create scalable people programs, foster an inclusive and high-performing culture, and ensure employees have the resources they need to do their best work. As a Senior People Team Business Partner at Antares, you'll be a trusted advisor to leaders and employees, helping build an exceptional employee experience while enabling our teams to do their best work. You'll partner with our client groups to support day-to-day people operations, employee relations, organizational effectiveness, talent planning, and change management, while collaborating closely with Recruiting, People Operations, Legal, Finance, and IT. Importantly, you will be a steward of our high-performance culture, implementing inspiring and scalable initiatives to ensure that our employees strive for excellence in everything they do. Startups are hard - it is your job to support our people in embracing the challenge with positivity, teamwork, and humility. This is a high-impact role for someone who thrives in a fast-paced, high-performance environment and is energized by the opportunity to build from an early stage at a company with a global vision. Roles and Responsibilities: - Champion a high-performing, people-first culture that reflects Antares' values and supports employee engagement and business success. - Develop and implement HR policies, compliance practices, and operational processes that are practical and scalable. - Serve as the primary resource for employees and managers on HR policies, employee relations issues, and workplace matters, handling investigations and resolutions with sound judgment and discretion. - Partner with leaders to understand team dynamics, organizational health, and business priorities, providing strategic guidance on talent, performance, organizational design, and change management. - Partner with people leaders to build their coaching and feedback capabilities through leadership development programs, manager training, and ongoing 1:1 support. - Lead and support employee lifecycle processes, including internal mobility, promotions, offboarding, leaves of absence, accommodations, and other People Operations processes while ensuring compliance with federal, state, and local employment laws. - Partner with Finance and business leaders on headcount planning, organizational changes, workforce planning, and job architecture to support business growth and operational efficiency. - Leverage people analytics and workforce metrics—including hiring, retention, engagement, performance, and organizational trends—to identify opportunities and recommend data-informed solutions. - Contribute to cross-functional People initiatives and special projects that support the continued growth and evolution of Antares. Basic Qualifications: - Bachelor’s degree. - 5+ years of progressive HR or People Operations experience in a high-growth…