by Lee Smith, thermal insulation business development manager, Web Industries (CSA CSM), LSmith@webindustries.com,
Needs for custom-made, space proven components and systems take on added urgency as launch dates proliferate and space facilities around the world hum with activity. Supply partners like Web Industries (CSA CSM) that offer such components can support space initiatives and help space and satellite companies meet ever-tightening launch deadlines.
One component that requires a custom-fabricated approach is multilayer insulation (MLI), often called MLI blankets. They provide passive thermal management during the mission, protecting passengers and on-board equipment. The blankets are composed of multiple layers of reflective, metalized plastic film, alternated with spacer materials that prevent conduction between the layers. MLI blankets for space applications have up to 30 layers, with each successive layer adding to the blanket’s overall insulating effectiveness.
Although initially the design of other vehicle systems takes priority, MLI blanket design can hardly be considered an afterthought. Well designed and manufactured blankets contribute to a mission’s success, while poorly designed ones can result in deficient fit, excess weight and slower integration times.
Space vehicles and satellites come in all shapes and sizes, including 1U, 50kg, 500kg and up. They carry different payloads, follow different orbital paths and vary widely in weight. After liftoff, they are exposed to varying amounts of thermal radiation from sunlight and other sources. Accordingly, MLI blankets must be designed and custom-fabricated with their specific application in mind to function effectively. There are no off-the-shelf solutions.
MLI blanket production is a mix of automation and craftsmanship. Space companies should partner with MLI providers that have a track record of successfully making MLI blankets for space applications with flight heritage. These providers typically have advanced software programs like CREO Design Essentials that automatically convert complex 3D models into flat patterns for fast iteration and efficient assembly, and automated cutting tables that create clean blanket edges.
Precision sewing in MLI blanket construction is essential. Skilled technicians securely sew blanket layers together via small holes along the edges using thread made from strong synthetic fibers such as Kevlar® or ceramic materials. The stitches must pass through film, fabric or nonwoven materials and hold them securely in place. This operation requires expert craftsmanship. Poor sewing practices can cause threads to break, and shrinkage of the overall blanket dimension.
Experienced MLI blanket suppliers have developed sewing and fabrication techniques that promote superior blanket construction and performance. These include automated hole punching and film overlays. Stitch holes, for example, can be punched beforehand to give predefined locations for hand stitching. Attention must be paid to small details, such as determining the right number of holes along the blanket’s edges. Too many holes can introduce additional possible failure points during use. Film overlays from blanket suppliers allow easy inspection of sewn features, eliminating the need for multiple measurements.
Further customization occurs upon MLI blanket prototype production. The blankets normally undergo testing at space facilities and are modified based on test results. Initial telemetry data from constellations provides additional feedback that helps further optimize MLI blanket design.
Many space and satellite companies maintain existing in-house MLI production operations. They can benefit by forming co-sourcing partnerships with outside MLI blanket suppliers. Co-sourcing supports internal operations with application engineering and technical support and reduces the time required to fabricate completed blankets. This can relieve deadline pressures and allow companies to respond more quickly to tight launch windows. Further, purchase can be made of a finished and fully inspected MLI blanket including FAI (first article inspection) with one purchase order.
MLI blankets play an unheralded but critical role on space missions. They are customized for diverse applications and varying space conditions and contribute to overall mission success. http://www.webindustries.com ■