Project for the Science and Technology Facilities Council – Rutherford Appleton Laboratory (RAL Space)
Overview
Green Resource Engineering (GRE) was awarded a contract by the UK’s Science and Technology Facilities Council (STFC) to design and manufacture two sets of 46 thermal shrouds (radiators). These systems enable precise temperature control inside two large vacuum space/satellite test chambers at Harwell, UK—each measuring 5m in diameter and 8m in length.
The shrouds allow the chambers to replicate the extreme thermal conditions experienced in space, ranging from 80K (–193.15°C) to 400K (+120°C). This capability is essential for testing satellites and space‑bound equipment.
Project Challenges
Traditional temperature-control methods—often using a combination of liquid and gaseous cryogens—were unsuitable for this project due to cost, complexity, and the scale of the chambers. Additionally, prior contractors had attempted to build similar systems, but both previous solutions were plagued by technical or structural failures and had to be scrapped.
GRE set out to create a long‑lasting, reliable, and technically superior system using carefully selected materials and rigorously engineered designs.
The goal was to create a robust, high‑precision thermal shroud system capable of operating in large‑scale vacuum environments. With the rapid growth of the global space industry and increasing demand for spacecraft testing, GRE aimed to push forward the engineering and scientific capabilities available for thermal‑vacuum testing.
The solution required:
- Excellent thermal control
- Long-term mechanical stability
- Scientifically verified material choices
- Repeatable, highly accurate manufacturing techniques
Key Project Considerations
- Materials & Outgassing
Materials had to be researched extensively due to strict requirements around outgassing. Many common engineering materials release contaminants that can damage sensitive components such as turbomolecular pumps or spacecraft hardware.
- Structural Integrity
Most panels exceeded 3m² and weighed around 100kg. After a previous contractor experienced catastrophic panel failure, GRE had to perform deep structural analysis and physical testing to ensure long‑term reliability.
- Extreme Temperature Cycling
The system needed to handle a thermal swing of over 320K. GRE had to model and test how materials expanded and contracted—both individually and as combined assemblies—to guarantee performance and structural soundness.
- Complex Geometry & Precision Manufacturing
Because the chambers are cylindrical with concave access doors, GRE had to develop manufacturing methods that could accommodate precise curvature and repeatability across dozens of unique panels.
- Performance Testing & Validation
To ensure consistent quality, GRE needed a structured, scientifically robust testing methodology that could be applied to all panels, regardless of size or configuration.
Solutions presented
Design & Materials Research
GRE engineers conducted comprehensive material studies using NASA’s outgassing database and consulted with specialist partners, including Monroe Brothers and Aeon Engineering. Solutions were cross‑checked against previous failed attempts to avoid repeating past issues.
Structural Engineering & Analysis
New jointing and fastening systems were developed, including a specialised combination of fixings with flat and sprung washers. This assembly allowed controlled movement during thermal expansion and contraction while maintaining constant clamping force—critical for maintaining structural integrity.
Testing included:
- Computational stress analysis
- Empirical testing on prototypes
- Evaluation of combined material behaviour
Thermal Modelling & Prototyping
Initial finite element analysis (FEA) provided a starting point for predicting thermal behaviour. However, physical prototypes revealed performance issues. GRE adapted the design—modifying base material thickness—and validated improvements through further modelling and a second prototype, which delivered the required thermal performance.
Manufacturing Innovation
GRE developed detailed manufacturing procedures including:
- Repeatable sub-assembly processes
- Thermal cycling tests to validate rigidity
- Carefully controlled painting and finishing processes
- A specialised heated vacuum outgassing method using thermoelectric quartz crystal monitoring to ensure panels were molecularly clean
Testing, Validation & Quality Assurance
To ensure consistency and long-term reliability, GRE created a complete suite of testing methodologies. In collaboration with STFC and the European Space Agency, GRE also helped develop a mathematical formula to determine when outgassing levels were sufficiently low for safe installation within the client’s clean vacuum environment.