Senior Thermal Control System (TCS) 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 over $1 billion in total funding from leading investors including Altimeter Capital, ICONIQ, Kleiner Perkins, Lightspeed Venture Partners, Redpoint Ventures, and T. Rowe Price — and with over $1 billion 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 in 2027 and plans to scale to 100 satellites a year, we're Building Bigger — helping develop the solar system and build toward 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 high-growth Series D-funded company, we'd love for you to apply. The Role You will own the success of developing, implementing and testing both R&D and production thermal control systems on the spacecraft. You will be responsible for spearheading the design and verification efforts of active and passive thermal control systems including, but not limited to, pump fluid loops, heat pipes and all of the required ground supporting equipment (test fixtures, diagnostic equipment, instrumentation, software tools etc.). Y our work will require familiarity with pressurized systems (valves, pumps, accumulators, heat exchangers), thermo-mechanical instrumentation (temperature sensors, pressure sensors, flow meters etc.), integrated electronics systems, and secondary satellite structures. You will partner with design engineers early on in the process to ensure manufacturability while building the first prototype, design the build flow, and finalize the process for transition to production. Responsibilities Work with lead engineers to design active and passive thermal control systems using basic heat transfer and mechanical equations to size lines, pumps, accumulators, cold plates etc. Planning and development of thermal cycle and thermal-vacuum testing campaigns Design and develop ment of heater and cooling systems including control architecture Setup, commission, and maintain state-of-the-art test stands and instrumentation Develop data acquisition systems for active and passive thermal control systems Perform tests on novel pump fluid l oop including feed systems, power electronics, and hardware-in-the-loop Develop testing and control scripts to conduct safe and reliable…