When it comes to taking the next "giant leap" in space exploration, NASA is thinking small -- really small.
In laboratories around the country, NASA is supporting theburgeoning science of nanotechnology. The basic idea is to learn todeal with matter at the atomic scale -- to be able to controlindividual atoms and molecules well enough to design molecule-sizemachines, advanced electronics and "smart" materials.
If visionaries are right, nanotechnology could lead to robots youcan hold on your fingertip, self-healing spacesuits, space elevatorsand other fantastic devices. Some of these things may take 20+ years tofully develop; others are taking shape in the laboratory today.
Simply making things smaller has its advantages. Imagine, forexample, if the Mars rovers Spirit and Opportunity could have been madeas small as a beetle, and could scurry over rocks and gravel as abeetle can, sampling minerals and searching for clues to the history ofwater on Mars. Hundreds or thousands of these diminutive robots couldhave been sent in the same capsules that carried the two desk-sizerovers, enabling scientists to explore much more of the planet'ssurface -- and increasing the odds of stumbling across a fossilizedMartian bacterium!
But nanotech is about more than just shrinking things. Whenscientists can deliberately order and structure matter at the molecularlevel, amazing new properties sometimes emerge.
An excellent example is that darling of the nanotech world, thecarbon nanotube. Carbon occurs naturally as graphite -- the soft, blackmaterial often used in pencil leads -- and as diamond. The onlydifference between the two is the arrangement of the carbon atoms. Whenscientists arrange the same carbon atoms into a "chicken wire" patternand roll them up into miniscule tubes only 10 atoms across, theresulting "nanotubes" acquire some rather extraordinary traits.Nanotubes:
* have 100 times the tensile strength of steel, but only 1/6 the weight;
* are 40 times stronger than graphite fibers;
* conduct electricity better than copper;
* can be either conductors or semiconductors (like computer chips), depending on the arrangement of atoms;
* and are excellent conductors of heat.
Much of current nanotechnology research worldwide focuses on thesenanotubes. Scientists have proposed using them for a wide range ofapplications: in the high-strength, low-weight cable needed for a spaceelevator; as molecular wires for nano-scale electronics; embedded inmicroprocessors to help siphon off heat; and as tiny rods and gears innano-scale machines, just to name a few.
Nanotubes figure prominently in research being done at the NASA AmesCenter for Nanotechnology (CNT). The center was established in 1997 andnow employs about 50 full-time researchers.
"[We] try to focus on technologies that could yield useable productswithin a few years to a decade," says CNT director Meyya Meyyappan."For example, we're looking at how nano-materials could be used foradvanced life support, DNA sequencers, ultra-powerful computers, andtiny sensors for chemicals or even sensors for cancer."
A chemical sensor they developed using nanotubes is scheduled to flya demonstration mission into space aboard a Navy rocket next year. Thistiny sensor can detect as little as a few parts per billion of specificchemicals--like toxic gases--making it useful for both spaceexploration and homeland defense. CNT has also developed a way to usenanotubes to cool the microprocessors in personal computers, a majorchallenge as CPUs get more and more powerful. This cooling technologyhas been licensed to a Santa Clara, California, start-up calledNanoconduction, and Intel has even expressed interest, Meyyappan says.
Designing the future
If these near-term uses of nanotechnology seem impressive, the long-term possibilities are truly mind-boggling.
The NASA Institute for Advanced Concepts (NIAC), an independent,NASA-funded organization located in Atlanta, Georgia, was created topromote forward-looking research on radical space technologies thatwill take 10 to 40 years to come to fruition.
For example, one recent NIAC grant funded a feasibility study ofnanoscale manufacturing--in other words, using vast numbers ofmicroscopic molecular machines to produce any desired object byassembling it atom by atom!
That NIAC grant was awarded to Chris Phoenix of the Center for Responsible Nanotechnology.
In his 112 page report, Phoenix explains that such a "nanofactory"could produce, say, spacecraft parts with atomic precision, meaningthat every atom within the object is placed exactly where it belongs.The resulting part would be extremely strong, and its shape could bewithin a single atom's width of the ideal design. Ultra-smooth surfaceswould need no polishing or lubrication, and would suffer virtually no"wear and tear" over time. Such high precision and reliability ofspacecraft parts are paramount when the lives of astronauts are atstake.
Although Phoenix sketched out some design ideas for a desktopnanofactory in his report, he acknowledges that -- short of abig-budget "Nanhatten Project," as he calls it -- a working nanofactoryis at least a decade away, and possibly much longer.
Taking a cue from biology, Constantinos Mavroidis, director of theComputational Bionanorobotics Laboratory at Northeastern University inBoston, is exploring an alternative approach to nanotech: Rather thanstarting from scratch, the concepts in Mavroidis's NIAC-funded studyemploy pre-existing, functional molecular "machines" that can be foundin all living cells: DNA molecules, proteins, enzymes, etc.
Shaped by evolution over millions of years, these biologicalmolecules are already very adept at manipulating matter at themolecular scale -- which is why a plant can combine air, water, anddirt and produce a juicy red strawberry, and a person's body canconvert last night's potato dinner into today's new red blood cells.The rearranging of atoms that makes these feats possible is performedby hundreds of specialized enzymes and proteins, and DNA stores thecode for making them.
Making use of these "pre-made" molecular machines -- or using themas starting points for new designs -- is a popular approach tonanotechnology called "bio-nanotech."
"Why reinvent the wheel?" Mavroidis says. "Nature has given us allthis great, highly refined nanotechnology inside of living things, sowhy not use it -- and try to learn something from it?"
The specific uses of bio-nanotech that Mavroidis proposes in hisstudy are very futuristic. One idea involves draping a kind of"spider's web" of hair-thin tubes packed with bio-nanotech sensorsacross dozens of miles of terrain, as a way to map the environment ofsome alien planet in great detail. Another concept he proposes is a"second skin" for astronauts to wear under their spacesuits that woulduse bio-nanotech to sense and respond to radiation penetrating thesuit, and to quickly seal over any cuts or punctures.
Futuristic? Certainly. Possible? Maybe. Mavroidis admits that suchtechnologies are probably decades away, and that technology so far inthe future will probably be very different from what we imagine now.Still, he says he believes it's important to start thinking now aboutwhat nanotechnology might make possible many years down the road.
Considering that life itself is, in a sense, the ultimate example of nanotech, the possibilities are exciting indeed.
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