Astronomers have long been looking for the new black and it looks like they might have found it. Allowing only the desired light to reach the detector of an instrument has been an ongoing battle in astronomy. These days instrument developers apply black paint to instrument components such as spiders, baffles and tubes, to effectively absorb 90 percent of stray light which would otherwise overwhelm the detector. In infrared-sensing, the thermal heat radiated by the detectors can swamp the faint infrared signals so black paint is also used to absorb heat and re-radiate it away from the instruments. However black paint turns shiny when exposed to the super-cold cryogenic temperatures needed for infrared astronomy, making it less efficient. At longer wavelengths the inefficiencies of black paint requires the use of epoxies loaded with conductive metals, which adds weight to the instrument that is obviously undesirable for a space-based observatory.
Multiwalled Carbon Nanotubes have been found to offer an order-of-magnitude improvement in surface treatments by NASA’s Goddard Space Flight Center researchers, resulting in a stray light reduction by a factor of 10,000. Goddard researchers John Hagopian and Stephanie Getty and co-worked used carbon nanotube technology to create a material that absorbs 99 percent of ultraviolet, visible, infrared, and far-infrared light that hits it. The material is also less dense and remains black without the need for additives, making it very attractive for space flight instruments.
Hagopian et al. suggest that this new technology will be perfect for LISA, the Laser Interferometer Space Array. LISA’s main objective is to detect gravitational waves by utilising three identical spacecrafts in an equilateral triangular separated 5 million kilometres. The engineering challenge of LISA is the high precision of femtometer (10-15 meters) accuracies required to detect gravitational waves. To obtain this high precision extraordinary stray light control is needed, which the new carbon nanotube technology might be able to provide. For more information, see
- NASA Develops Super-Black Material That Absorbs Light Across Multiple Wavelength Bands, NASA Technologies News
- Multiwalled carbon nanotubes for stray light suppression in space flight instruments, Hagopian et al. (2010), Proc. SPIE 7761, 77610F [Swinburne login]
- LISA website
[Posting by Catarina Ubach, Guido Moyano Loyola and Sarah Maddison]