The star tracker is a key element of BST's microsatellite design. On previous satellite missions, BST has used a super-black paint on the baffles inside the optical positioning system to minimise internal reflections and provide an accurate position reference based on a map of the stars. Surrey NanoSystems' Vantablack coatings, which utilise an innovative carbon nanotube structure to absorb 99.8% of light hitting its surface, decreases the amount of reflected light by an order of magnitude compared with conventional coatings, and extends the angular range over which the star tracker is able to operate in the presence of bright light sources such as the Sun and Moon. This improves the robustness of the Earth observation instruments on the satellite, and reduces the need for gyroscope-aided position control that can introduce drift errors over time.
"The Vantablack coating was originally developed to improve the efficiency of optical systems in space, and this BST satellite project gives us a very early opportunity to prove its performance," said Ben Jensen, chief technology officer of Surrey NanoSystems. “The material can be used to improve the performance of satellites, but also to dramatically reduce weight and size of optical systems - which could be crucial for future space missions."
Vantablack is claimed to have the highest thermal conductivity and lowest mass-volume of any material that can be used in high-emissivity applications. It has virtually undetectable levels of outgassing and particle fallout, eliminating a key source of contamination in sensitive imaging systems. It withstands launch shock, staging and long-term vibration, and is suitable for coating internal components, such as apertures, baffles, cold shields and micro electro mechanical systems or MEMS-type optical sensors.
Vantablack S-VIS can be applied to most stable surfaces, suiting it to many types of engineering-grade polymers and composite materials. The process is said to be scalable and suitable for high-volume production on a range of substrate sizes.