New fibers and composite technologies offer high-tech solutions in Space exploration.
by Marie O’Mahony
In Space, from the needs of humans to rocket engines, advanced textiles are providing some of the most effective solutions in performance and protection. However, to focus on spotting “the next Aerogel” is to risk missing where the real progress is being made. Carbon fiber, Kapton film, low-conducting polyester netting and polymer spacers are just some of the materials being used to provide high performance, light weight and flexibility.
Carbon fiber composites offer the benefit of a high strength-to-weight ratio coupled with thermal protection properties for transport in space. Two examples that demonstrate these qualities are the Dream Chaser spaceplane, designed to deliver cargo to the ISS in low-earth orbit, and the Ingenuity helicopter exploring the possibilities of rotorcraft flight on Mars.
Dream Chaser is a multi-mission space utility vehicle commissioned by NASA, owned and operated by SNC and operating from the Kennedy Space Center’s Shuttle Landing Facility. The primary structure uses an advanced composite 3D woven assembly methods in arguably the most advanced high-temperature composite spaceframe that has been built.
Wing Structure Design Lead, Trent H. describes the operation: “After the launch vehicle separates, the complex Wing Deployment System deploys the wings using components that will ultimately lock the wing in place while the space vehicle is on-orbit. Once deployed, the wings will remain in that configuration until after landing.”
The use of a carbon fiber composite replaces aluminium and titanium alloys reducing manufacturing costs and decreasing the amount of thermal protection needed compared to an aluminium primary structure. The 13-foot-long wings are each made of a single composite structure and attached using titanium components. Each wing has over one hundred and fifty tiles attached acting as a thermal shield and providing protection against micro-meteorite debris.
Eren Ozmen, chair and president of SNC is excited by the achievement, declaring with some justification, “It’s an extraordinary engineering and manufacturing accomplishment.”
A NASA first
NASA’s Ingenuity Mars helicopter is the first aircraft to achieve powered, controlled flight on another planet, successfully landing on February 18, 2021. Its mission was to test the possibility for rotorcraft flight in an extremely thin atmosphere—just 1 percent of the density on Earth—and where temperatures can drop to -130 F (-90 C).
The craft measures just 1.6 feet (0.49m) and weighs 4 pounds (1.8 kg) on Earth and 1.5 lbs (0.68kg) on Mars. From a design perspective, more mass can be carried at a given spin rate because the gravity is about one-third that of Earth’s. Four custom-made blades use carbon fiber, arranged into two 4-foot (2 m.) counter-rotating rotors that spin at around 2,400 rpm.
Carbon fiber composites are also used for the aircraft’s four landing legs that measure just 1.26 feet (0.38 m). (The United States is obliged to avoid causing harmful contamination of celestial bodies under the international 1967 Outer Space Treaty.) NASA’s Planetary Protection office has drawn up cleanliness standards with requirements that include safeguards against Earth-sourced biological material being transported by aircraft including the helicopter.
To ensure hardware is biologically clean, the rover, helicopter and other parts of the spacecraft are assembled in clean room environments. The room is equipped with extremely powerful air filters, the aim being that the entire payload should carry fewer that 500,000 bacterial spores, less than needed to cover the lens of a smartphone.
‘Our products face extreme environments. There is no question about that,” says Brent Anderson, co-owner of Aerospace Fabrication in Farmington, Minnesota. Most of their products have to survive the vacuum of space, various forms of radiation, and other unique effects like atomic oxygen. The Multi-Layer Insulation (MLI) blankets used in spacecraft and launch vehicles, can be required to perform in temperatures ranging from absolute zero to almost 1,000 degrees Celsius.
The blankets are comprised of layers of thin films and foils and advanced textiles. The layering starts with the material for the exterior layer, matching the right material for the environment, then working inwards selecting materials that best address the thermal requirements.
SpaceWrapHT is a prefabricated layup used for high-temperature systems on spacecraft. It uses multiple layers of ultra-thin (0.33mil) Kapton film that are separated by a low-conducting polyester netting to minimize weight and layer-to-layer conductivity. The film is coated on both sides with aluminium to provide high thermal performance.
Anderson sees the current approach continuing into the future: “I think we will always have some form of layering in our products given the driving fundamentals of heat transfer. It’s a tough, tough problem to solve in any environment.”
In response to the growing need to be sustainable in space, Aerospace Fabrication recycles as many materials as possible. “It’s difficult with the nature of some of the extreme environments in which our products have to function,” Anderson says. “The next step really goes up stream to our vendors and we look to them to continue developing more plant-based and recyclable or biodegradable materials. We will do what we can to drive their product development.”
The development of new space vehicles for long duration missions has created the need for improved cryogenic (extreme low temperature) propellant storage and transfer capabilities. Better insulation for cryogenic feed lines has been identified as an important enabling technology that could help NASA meet these cryogenic propellant storage and transfer requirements.
Quest Thermal Group’s Wrapped Multi-Layer Insulation (WMLI) is a high-performance multilayer insulation material that uses an innovative, discrete spacer technology that has been specifically designed for cryogenic piping to reduce heat flux. A discrete spacer technology facilitates the separation of radiant barriers using low thermal conductivity polymer spacers. The polymer spacers allow for a very precise layer spacing, with a unique design that minimizes the contact area/length ratio and reduces solid heat conduction. Prototypes have yielded encouraging test results. Used in the inner insulation of a vacuum jacketed pipe, heat leaks as low as 0.09 W/m have been achieved, compared favourably with the industry standard VJP with 0.31W/m. Quest Thermal is confident that WMLI could enable improved spacecraft cryogenic feedlines as well as industrial hot/cold transfer piping.
The ingenuity that goes into the manufacturing processes is crucial to the performance of these materials. It is through continuous refinements and testing that real progress is being made.
Dr. Marie O’Mahony is an industry consultant, author and academic. She the author of several books on advanced and smart textiles published by Thames and Hudson and Visiting Professor at the Royal College of Art (RCA), London.