NASA Explains How
Gears Might Work

Don Nolan-Proxmire Headquarters, Washington, DC April 21, 1997 (Phone: 202/358-1983) John Bluck Ames Research Center, Mountain View, CA (Phone: 415/604-5026) RELEASE: 97-75 NASA EXPLAINS HOW MOLECULAR-SIZED GEARS MIGHT WORK

A technical paper sponsored by NASA and recently accepted by the journal "Nanotechnology" explains how molecular-sized gears might work.

"Thanks to simulation of molecular-sized gears by a NASA supercomputer, hope is growing that products made of thousands of tiny machines that could self-repair or adapt to the environment can ultimately be constructed," said Al Globus, a co-author of the paper.

Authors are Jie Han, Al Globus, Richard Jaffe and Glenn Deardorff of NASA's Ames Research Center, Mountain View, CA.

Researchers have simulated attaching benzyne molecules to the outside of a nanotube to form gear teeth, explained Globus. Nanotubes are molecular-sized pipes made of carbon atoms. "You also need a cooling system for gears. We used a supercomputer to simulate successful cooling of molecular-sized gears with helium and neon gases," he explained.

To "drive" the gears, the computer simulated a laser that served as a motor. "The laser creates an electric field around the nanotube. We put a positively charged atom on one side of the nanotube, and a negatively charged atom on the other side. The electric field drags the nanotube around like a shaft turning," he said.

"These gears would rotate best at about 100 billion turns per second or six trillion rotations per minute (rpm)," he added. The gears that Globus and others have simulated with computers would be about a nanometer across. A nanometer is one-billionth of a meter.

One practical use of nanotechnology would be to build a "matter compiler," said Creon Levit, a Globus colleague at Ames. "We would give this machine, made of nano parts, some raw materials, like natural gas, for example. A computer program would specify an arrangement of atoms, and the matter compiler would arrange the atoms from the raw materials to make a macro- scale machine or parts," Levit added.

"A matter compiler is not just science fiction. In the biotechnology industry, there are already 'peptide synthesizers' in use. You give them a sequence of amino acids you want produced, and the machine will create those peptides. But you can't make rockets out of peptides," he said. A peptide is a sequence of amino acids.

"A step along the way to make an aerospace matter compiler is an even smaller hypothetical machine, the 'assembler/replicator,'" said Globus. "The replicator can make a copy of itself, just as a living cell can duplicate itself.

"We would like to write computer programs that would enable assembler/replicators to make aerospace materials, parts and machines in atomic detail," he said. "Such materials should have tremendous strength and thermal properties." Further information on these materials can be obtained on the researchers' Internet page at URL:

An image of the nanogear from a computer simulation is available at the following URL:

A long range goal, according to Globus, is to make materials that have radically superior strength-to-weight ratio. Diamond, for example, has 69 times the strength-to-weight ratio of titanium. A second goal is to make "active" or "smart" materials.

"There is absolutely no question that active materials can be made," Globus explained. "Look at your skin. It repairs itself. It sweats to cool itself. It stretches as it grows. It's an active material," he said.

Globus strongly emphasized that making real nanomachines may be decades away, but he said that computer simulations suggest the tiny machines are possible after engineers learn to build nanoparts and to assemble nanomachines.

The nanogear and other related Ames research is a collaboration between the Ames Numerical Aerospace Simulation Systems Division and the Ames Computational Chemistry Branch.


Note to Editors: A black & white image of the molecular-sized gears is available by calling the Broadcast & Imaging Branch at 202/358-1900. The photo number is 97-H-220.