Oct. 9, 2002
NASA Ames Research Center, Moffett Field, Calif.
Phone: 650/604-5026 or 604-9000
NASA SCIENTIST SIMULATES SUB-MICROSCOPIC PARTS AND WINS BIG AWARD
Growing atomic-scale 3-D computer circuits that may lead to human-like sensory systems is the latest simulation effort of a NASA scientist who recently won a scientific medal for years of work.
Using a computer to simulate molecular carbonnanotubes, so small they cannot be seen with a conventional microscope, is the work of NASA scientist Deepak Srivastava for which he earned the prestigious Eric Reissner Medal. Carbon nanotubes are only a few atoms wide, but these extremely strong tiny carbon pipes someday could be the major pieces from which scientists make future artificial brains as well as tiny machines that may help with tasks as diverse as planetary exploration and the curing of disease.
"We have proposed a system of three-dimensional carbon nanotube networks that could function similarly to a biological nerve system," said Srivastava, a senior scientist at NASA Ames Research Center in Californias Silicon Valley. "The biologically inspired computer structure will have sensing and learning capabilities similar to a human sensory system."
The International Conference on Computational Engineering & Sciences recently presented the medal to Srivastava during a meeting in Reno, Nevada, for his distinguished contributions to nanoscience, "with particular relevance to carbon nanotubes."
"I am pleased NASA Ames contributions in computational nanotechnology have been recognized through this award," said Meyya Meyyappan, the director of the Center for Nanotechnology at NASA Ames. "Computational nanotechnology has been the trail blazer, uncovering the properties and potential of nanomaterials."
"We are simulating nanotubes for use in three general areas: the next generation of molecular computers, synthetic composite materials and molecular machines," Srivastava said. The carbon nanotube is a new form of carbon. Using several laboratory techniques, scientists grow the tiny carbon pipes that are just a few nanometers in diameter, and a few microns long. A micron is one-millionth of a meter. The tubes are stiff and as strong as diamond.
Scientists want to use carbon nanotubes to build tiny electronic circuits in 3-D arrays, unlike the two-dimensional circuits that are the standard of todays microelectronics industry.
"We recently showed that three nanotubes connected at one place can serve as switches and can process information," he said. "These properties inspired us to consider the concept of a system architecture similar to the biological neural system, but made of synthetic material such as nanotubes or nanowires."
An artificial brain or computing system, if fully developed, could be used to power robotic probes on spacecraft, planets and moons. The computing power of these nano-carbon circuits could be many, many times as great as todays most powerful supercomputer, but housed in a package the size of a small teakettle, according to Srivastava.
Five years ago, Srivastava and his collaborator, Madhu Menon of the University of Kentucky, first proposed and simulated a simple, biological-like, carbon-nanotube branched structure. Srivastava used a powerful NASA computer to simulate and see what the architecture of the nanotube structure would look like. As recently as August, university scientists at Rensselaer Polytechnic Institute (RPI), Troy, N.Y., created the branched nanotube structure that Srivastava had predicted.
"That scientists can make these simple, branched 3-D nanotube structures is a really exciting development," he said. "Using our NASA supercomputers, we now are starting to simulate complex, tree-like carbon-nanotube networks, and how these networks can be used for sensing and computing."
"In addition to making computer parts with nanotubes, we envision simulating new materials out of a combination of tiny amounts of carbon nanotubes and traditionally manufactured materials. These composite materials are expected to be much stronger and lighter weight than todays best-known materials used to build airplanes, cars and even spacecraft," he said. "If these materials can be made in large quantities, they could be used to make spacecraft that could be much less massive with the same or better capabilities of todays aerospace systems."
Srivastava is working with a team including scientists from NASA; Stanford University; the University of Kentucky; University of Crete, Greece; and St. Petersburg University, Russia. The NASA Computing, Information and Communications Technology (CICT) Program funds Srivastavas work.
One of the major reasons Srivastava received the award for his work is that he accurately predicted the stiffness, the strength and breaking point properties of carbon-nanotubes and composite materials that contain carbon nanotubes.
"Previously, it was predicted that carbon nanotubes could be stretched as much as 30 percent to 40 percent before they would break, but we recently simulated the more realistic breaking point value to be about 10 percent. This agrees very well with recent experimental observations," he said.
Additional technical information about Srivastavas carbon-nano-tube work is on the Internet at
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