10 November 2011

NASA Develops Material That Is Blacker Than Black

Engineers at the National Aeronautics and Space Administration (NASA) have produced a material that absorbs more than 99% of ultraviolet, visible, infrared, and far-infrared light that strikes it. They reported their discovery at the SPIE Optics and Photonics conference. John Hagopian is the lead engineer for the team who are based on NASA's Goddard Space Flight Center in Greenbelt, Md.

Hagopian has reconfirmed the material's absorption capabilities in additional testing. He adds, "The reflectance tests showed that our team had extended by 50 times the range of the material's absorption capabilities. Though other researchers are reporting near-perfect absorption levels mainly in the ultraviolet and visible, our material is darn near perfect across multiple wavelength bands, from the ultraviolet to the far infrared. No one else has achieved this milestone yet."

The technology involves nanotech based coating based on multi walled carbon nanotubes. These tiny hollow tubes are made of pure carbon and about 1 million times smaller than a dot or period printed on a page. In the project, These are positioned vertically on various substrate materials much like a shag rug. The NASA team grew the nanotubes on silicon, silicon nitride, titanium, and stainless steel, as these materials are commonly used in space-based scientific instruments.

Video: John Hagopian and his team at NASA explains their project

When used in instruments, the material will be able to allow scientists to collect data and measurements of objects far away in the universe that astronomers no longer can see them in visible light or those in high-contrast areas, including planets in orbit around other stars. Hagopian also adds that even Earth scientists can use the technology in studying the oceans and atmosphere since more than 90% of the light that their monitoring systems gather comes from the atmosphere which overwhelms the signal that they are trying to study and retrieve.

At the present, black paint is applied to baffles and other components to help prevent stray light from bouncing off surfaces. However, these absorb only 90% of the light that strikes it. Also, black paints do not remain black when exposed to below freezing temperatures. They turn into a shiny, slightly silver quality.

Since the new material absorbs more than 99%, the effect of multiple bounces of unabsorbed light makes the coating's overall advantage even larger, resulting in hundreds of times less stray light. Goddard engineer Jim Tuttle adds that the blacker the material used, the more heat it can radiate away.Super-black materials like the carbon nanotube coating, can be used on devices that take away heat from the instruments and radiate it away to deep space. This cools the instruments to lower temperatures, where they are more sensitive to faint signals.

Goddard scientist Ed Wollack is a scientist who is part of the Goddard team and is evaluating the carbon-nanotube material for use as a calibrator on far-infrared-sensing instruments that must operate in super-cold conditions to gather faint far-infrared signals emanating from objects in the very distant universe.

"This is a very promising material," Wollack said. "It's robust, lightweight, and extremely black. It is better than black paint by a long shot."

Video: nanotechnology and carbon nanotubes