Development of CNT-polysiloxane composites for spacecraft applications

In geostationary orbit, thermal control coatings are exposed to a continuous bombardment of electrical particles, which have the capability to charge the external surface of the satellite. The accumulation of implanted charges leads to differences of potential between many parts of the satellite and can induce electrostatic discharges, which are detrimental to electronic equipment. To prevent this, coatings should have normalized characteristics like surface resistivity lower than 10⁹ Ω/□ and bulk resistivity lower than 10⁹ Ω.m. The Materials and Coatings Laboratory of the Thermal Control Service of the CNES Toulouse Space Centre has already developed low cost cold coatings called solar reflectors (SR) to replace current space coating named optical surface reflectors (OSR) and second surface mirrors (SSM). SR have been qualified only for low earth orbit applications because they do not evacuate space charges. Today the laboratory is looking for a solution to be able to use SR in geostationary orbit. This paper describes the effects of the incorporation of carbon nanotubes (CNTs) in a polysiloxane matrix, on thermo-optical and electrical properties.