NanoBlack coating could soon be used in space applications

Scientists researching the ‘darkest material known to man’ are hoping a new manufacturing process will enable them to create more accurate space instruments.

The British companies developing the production method say it could make NanoBlack — a coating based on carbon nanotubes — more flexible and widely used, following a new research project match-funded by the government.

The carbon nanotube coating, which was demonstrated by NASA last year, absorbs more than 99 per cent of the visible, infrared and ultraviolet light that hits it, making it ideal for sensitive optical instruments on board satellites and other spacecraft.

ABSL Space Products and Surrey Nanosystems, along with measurement institute National Physical Laboratory (NPL), are developing a particular kind of vertically aligned nanotube coating to enable its use in space applications.

‘This material has been shown to be the darkest material known to man, both in the visible and particularly in the infrared,’ said Dr Theo Theocharous, principal research scientist at NPL’s optical radiation measurement group.

‘[Most] materials that are very black in the visible become reflective in the infrared simply because the structure of the surface that gives us the absorbance is actually not large enough to enhance the absorbance in the infrared.’

Because nanotube coatings absorb such a high proportion of the electromagnetic spectrum, they could be used to calibrate optical equipment by providing a precise reference, as well as being used in light detectors and to limit light scattering within the equipment.

NanoBlack can be applied at a lower temperature than other nanotube coatings and so can be used with a wider range of materials, opening up the coating to commercial space applications.

Once the coating technology has been readied by Surrey Nanosystems and proven and characterised by NPL, project leader ABSL plans to test it ready for space applications, creating a near-commercially ready product by the end of the year.

NanoBlack can be applied at lower temperatures than other coatings

Ben Jensen, chief technical officer at Surrey Nanosystems, said: ‘To get the kind of optical effects we need, the material would [previously] need to be grown at about 600–700ºC.

‘The technology we apply allows us to grow the materials with a suitable structure at a much lower temperature, thereby applying it to lightweight materials that would be flight qualified.

‘That technology involves specific wavelengths of energy delivered to a novel catalyst and interface materials that allow us to limit the temperature rise on the substrate during the growth process.

‘Some coatings involving nanotubes have been spray applied or delaminated on. Our process involves growing the material onto the structure directly, so that allows us to do novel shapes and sizes, and get round some of the problems of other coatings.’

The Technology Strategy Board, the UK Space Agency and the South East England Development Agency are providing £100,000 to fast-track the technology to commercial readiness, as part of the National Space Technology Programme.