Principal Thermal Design Engineer

K2 is building the largest and highest-power satellites ever flown, unlocking performance levels previously out of reach across every orbit. Backed by $450M from leading investors including Altimeter Capital, Redpoint Ventures, T. Rowe Price, Lightspeed Venture Partners, Alpine Space Ventures, and others – with an additional $500M in signed contracts across commercial and US government customers – we’re mass-producing the highest-power satellite platforms ever built for missions from LEO to deep space. The rise of heavy-lift launch vehicles is shifting the industry from an era of mass constraint to one of mass abundance, and we believe this new era demands a fundamentally different class of spacecraft. Engineered to survive the harshest radiation environments and to fully capitalize on today’s and tomorrow’s massive rockets, K2 satellites deliver unmatched capability at constellation scale and across multiple orbits. With multiple launches planned through 2026 and 2027, we're Building Bigger to develop the solar system and become a Kardashev Type II (K2) civilization. If you are a motivated individual who thrives in a fast-paced environment and you're excited about contributing to the success of a groundbreaking Series C space startup, we’d love for you to apply. The Role You will be a core driver of the detailed thermal design of spacecraft subsystems by running thermal analysis at both the component and spacecraft level. You will also be involved in exploring different thermal management strategies and demonstrating them through test campaigns. Our ideal candidate has experience with in-orbit integrated thermal analysis of spacecraft components using both first principles as well analytical models using software tools (such as Thermal Desktop, Ansys IcePak, and Python for automation purposes). Hands-on experience with thermal testing for spacecraft components such as thermal cycling and TVAC is highly preferred. Responsibilities Collaborate with Mechanical teams to develop passive and active thermal control hardware for the spacecraft including radiators, heaters, heat pipes, and surface coating Partner with Avionics teams to develop thermal models and thermal tests for electronic assemblies Work with the GNC teams to define and thermally analyze nominal and contingency cases for in-orbit operations of the spacecraft Develop and maintain thermal models for spacecraft and sub-components using Thermal Desktop and Ansys Interface with vendors and launcher providers to understand their design and translate it into thermal-related requirements Automate data analysis to support architectural trades effectively Set up and execute thermal testing ranging from development to qualification Qualifications 8+ years of experience with satellite thermal design and analysis Demonstrated experience with radiative and conductive thermal modeling of spacecraft systems using Thermal Desktop Experience with selection, sizing, and design of thermal control hardware including heat pipes, heaters, stickers, OSR, thermal straps, thermal paints, tapes, MLI, TEC Experience with thermal cycling and thermal vacuum testing including predictions, setup, instrumentation and thermal model correlation Nice to Have Experience with full-vehicle thermal vacuum testing and model correlation Experience with spacecraft thermal design optimized for cost, reliability, performance and manufacturability Experience with integrated thermal analysis of spacecraft and rocket Experience with solar panel thermal modeling Experience with electrical PCBA thermal modeling and thermal interface materials (thermal grease, gap pads, etc.) Experience with spacecraft primary radiator design and analysis Familiarity with SMC-S016 standard or equivalent Experience with Python, C/C++, or Matlab for thermal modeling and automated data analysis Compensation and Benefits: Base salary range for this role is $175,000 - $220,000 + equity in the company ... (truncated, view full listing at source)