"NASA certainly has an interest in making energy storage devices from newmaterials such as carbon nanotubes.  This could be in the form of batteries, ultracapacitors, or fuel cells.  There is some work going on in this area, including work in our group through two small businesses," wrote Dr. Bradley S. Files of NASA's Materials Branch, and former group leader on nanotubes. The two businesses are Inorganic Specialists of Miamisburg, OH and ReyTech of Bend, OR.

Carbon nanotubes could mean a lot more to keeping astronauts alive than being the material with which lighter and stronger oxygen tanks are made. They have an extremely high surface area, and their pores can be designed to pull dangerous gases into themselves for detection and removal from the environment.

"Here at Ames, we are actively exploring the use of CNTs for gas adsorption," explained Dr. Leonard Yowell, the current NASA lead on nanotubes, in a separate email interview. "Toxic gases such as NO2, NO, etc. can accumulate over time due to a number of factors, and CNTs are particularly well-suited for study since they possess extremely high surface area, can be tailored for certain gas selectivity (nanopore size tuning), are good support materials for catalytic conversion of NOx into non-toxic products such as N2 and O2, and they can also be used as a sensor material for detection of these species.  Combining all of these properties, we believe that CNTs are great materials for this life support applications," Cassell wrote.

Smalley readily concedes, "for all of the wonders of carbon a nanotube, it does have an Achilles Heel. It burns."

But that's only in comparison with their famed tension strength. Space vessels designers have avoided flammable materials ever since the Apollo 1 disaster that claimed the lives of three astronauts. But carbon nanotubes aren't particularly prone to flame - they burn at 900 degrees Celsius. And they conduct heat largely into one direction, a quality called anisotropism, so carbon nanotubes could conduct heat away from a wing's leading edge, rocket's nozzle, or from electronic components.

But for extremely high temperatures, Smalley notes that carbon nanotubes have an unsung cousin, boron-nitride nanotubes. These two elements can combine to mimic the carbon nanotube form, and can withstand much greater heat. It may prove our only fallback in this field. "After you've finished with carbon and boron-nitride, there's nothing else," Smalley said. Other shapes, patterns of atomic bonding, aren't as ideal. "A pentagon would provide curvature, but it would be an odd number," meaning that vulnerable edges would remain, he noted.

Yowell shares Smalley's assessment. "A molecular tube of pure carbon offers some really wonderful and unique advantages, but for certain applications - at very high temperature for example - we want to consider other materials (such as Boron-Nitride nanotubes). The benefits really come from the unique properties of structures at the nano-scale. Regardless of the constituent elements, it makes sense to design and manufacture materials from the atom up."

In additional to the surfaces of nanotubes being conductors, they offer the strange prospect of ballistic conductions - firing electrons down the barrels of sawed off nanotubes. Rather than scattering chaotically - zigzagging in one vague current direction - as happens in conventional wire, electrons are forced down a nanotube's single, perfect, narrow passage. That will make ultra-small and fast quantum level computing much easier, allowing electrons to be send through wires as precisely as photons are sent down an optic fiber. This property could also revolutionize flat, bright panels as individual electrons are fired at precise points on a display.

This relates to the electrical conductivity of the single wall carbon nanotubes.  They allow a plastic to dissipate a static charge with very low amounts of nanotube filler, Files explained.

Smalley noted that windows and computer screens might have invisible sprinklings of carbon nanotubes embedded within them to eliminate static and thus the dust that's attracted to the energy field.

BIOMEDICAL APPLICATIONS

NASA is working toward providing an environment for the astronauts where they can monitor their own bodies and not rely on communication from the ground.  This will be important as we work toward longer duration missions and the crews must become more self-sufficient," noted Files. Carbon nanotubes, which are hollow, could even deliver drugs into individual diseased cells, but Yowell cautioned that this field isn't yet focused on that application.

Carbon nanotube snippets will be mixed with polymers to form mechanically strong composites at a much earlier stage than applications that require long threads. NASA has already made such composites, molding epoxy and nanotubes into the shape of..."small dogbones," according to a report written by Files.

And even after production has reached levels where carbon nanotubes could be as common as steel, the material has limitations. Smalley remarked in the context of skyscraper building that while the tension of carbon nanotubes is great, their compression strength isn't as impressive. Einstein demonstrated that we experience acceleration much as we do gravity (that's why we measure movement in terms of "Gs") it's clear that failures due to compression in heavy skyscrapers would be matched in spacecraft rapidly accelerating away after liftoff.