We are seeking a highly capable Thermal Test Engineer to join our satellite design and manufacturing team in the UK. This role is central to the verification and validation of spacecraft thermal performance across the full development lifecycle, from subsystem qualification through to full satellite environmental test campaigns. You will be responsible for planning, delivering, and analyzing a range of thermal test campaigns for spacecraft and payload hardware. Working closely with thermal analysts, systems engineers, AIT teams, and customers, you will ensure our satellites meet mission thermal requirements and perform reliably in the space environment. This position offers a unique opportunity to play a key role in delivering mission-critical thermal solutions ; you'll solve complex analytical challenges, influence design decisions, and contribute to next-generation satellite platforms. This is an excellent opportunity for an engineer with hands-on environmental test experience who is passionate about spacecraft verification and enjoys solving complex thermal challenges. This role doesn’t necessarily require prior Space Engineering experience provided you have a strong background in Thermal Design & Testing from a relatable industry. Scope of the role: Lead the planning, preparation, and execution of various types of thermal testing of Spacecraft Systems including: Thermal Vacuum Testing (TVAC) Thermal Balance and Characterization Tests Thermal Characterization of components, coatings, and interfaces Work closely with thermal analysis teams to ensure robust test-to-model correlation of spacecraft thermal models. Specify and configure thermal test hardware such as thermocouples, heaters, cold plates, data acquisition systems, and chamber instrumentation. Support root-cause analysis of unexpected thermal behavior or Non-Conformances during TVAC and Thermal Balance campaigns. Prototyping of new Thermal Management Systems. Contribute to the design of Satellite Thermal Management and other Mechanical systems onboard the Spacecraft. Contributing to On-Orbit verification of satellite Thermal Systems. Provide production support to the manufacturing team. Drive continuous improvement in thermal test methods, instrumentation standards, and campaign efficiency. Assisting other team members from multiple disciplines achieve their goals. Basic Qualifications / Experience: Degree in Mechanical, Aerospace, Physics, Systems Engineering or equivalent course or work experience Proven experience planning and carrying out thermal testing in an industry such as Aerospace, Aviation, Automotive, or another relatable industry. Experience working with equipment such as Thermal test chambers, Vacuum instrumentation, N2 & LN2 systems, and thermal data acquisition systems (DAQ). Ability to interpret spacecraft thermal requirements and translate them into practical test methods. Excellent data analysis and reporting skills using tools such as Excel, Python, MATLAB, or LabVIEW. Excellent written and verbal communication Preferred Qualifications / Experience: Thermal environmental testing of Spacecraft Experience with thermal modelling of satellites (Using packages such as Siemens NX TMG, ESATAN, Thermal Desktop etc.) Experience with common spacecraft thermal control measures (e.g. MLI, Thermal paints, heatpipes, radiators, cryo-cooling) Familiarity with ECSS environmental test standards and spacecraft verification philosophy. Knowledge of spacecraft systems engineering and mission operations constraints. Design and drafting experience (preferably in Solidworks) Basic software skills (C, python, scripting) What Success Looks Like: Safe and efficient delivery of TVAC and thermal balance campaigns to schedule. High-quality test data enabling rapid thermal model correlation. Clear identification and resolution of thermal performance issues before launch. Strong collaboration between test, design, systems, and analysis teams. Continuous improvement in test quality, repeatability, and facility utilization. Spire operates a hybrid work model, and this position will require you to work a minimum of three days per week in the office. Access to US export-controlled software and/or technology may be for this role. If needed, Spire will arrange the necessary licenses—this is not something candidates need to have before applying. LI-MI1LI-MI