Using flax fibres to build structures in space

In recent years, the interest in the development of bio-composite materials for space applications has increased.

Under the CleanSpace Framework, ESA plans to make a set of bio-composite materials, to try to fulfil a search for more sustainable and more demiseable materials suitable for space applications.

The next logical step in this goal is to consider a specific space application and verify the applicability of such materials for a generic LEO mission.

As such, a GSTP contract with Bcomp in Switzerland along with RUAG Space, has developed bio-composites flax fibres and epoxy resin into a viable material for spacecraft structures.

Specifically, the activity aimed to develop and produce a demonstrator flax fibre-reinforced thermoset (FFRP) spacecraft structure for a generic LEO mission with a low environmental impact, that could be well-demisable at re-entry.

By the end of the activity, Bcomp’s bio-composites solutions reached TRL 6 at material level, and TRL 5 at component level.

The activity designed and built a spacecraft structure demonstrator panel from ampliTex™ flax fibre-reinforced composite facesheets (FFRP) and aluminium honeycomb core (AHC) under the same specifications as a standard aluminium panel. The reference design, structural and environmental requirements were taken from the Copernicus Sentinel-1 satellite’s secondary structure for LEO missions.

Novel design features were introduced as a new opportunity for Design for Demise, allowed by the natural fibre-based ‘power ribs’ (thin-shell composite reinforcement technology) and single-shelled recessions built into the sandwich panel surface, intended to act as targeted demisable points allowing the early ingress of heat fluxes into the satellite’s internal structure upon re-entry. This good demisability behaviour was demonstrated in plasma wind tunnel testing.

Besides providing an in-depth understanding of their mechanical properties for analysis and simulation, key assets of these materials were revealed, such as relatively good mechanical fatigue endurance, high UV/VUV resilience, and a very low RF attenuation at all relevant frequencies for radio-communication (up to Ka band).

Future developments shall focus on making the best of the assets of FFRP.

G61C-039MS closed in October 2020.