Chengde Mao / Purdue

DNA strands can be programmed to create the scaffolding for complex 3-D structures, as shown in this artwork. Click on the image for a larger version.

The DNA double-helix molecule serves not only as an excellent construction manual for life as we know it, but also as a pretty good construction material in its own right. Scientists can bend the twisty stuff into two-dimensional shapes, including a "happy face" design - but three-dimensional shapes are much trickier.

In this week's issue of the journal Nature, researchers describe how sticky bits of DNA can put themselves together like Lego blocks to build up hollow geometrical shapes - ranging from pyramids to soccer balls less than a micron wide.

These DNA structures aren't just for kicking around: In the future, they could be used to deliver drugs, build nano-machines ... or hold prize molecular catches.

One of the researchers behind the Nature study, Purdue chemist Chengde Mao, told me today that the first applications for such structures would likely be as nano-containers.

Scientists could use such containers as cages for interesting molecular-scale structures, Mao said. Let's say you want to study the machinery of cellular factories known as ribosomes: You want to keep the ribosome in a medium where it can process proteins, but you don't want it to float away. In the future, you could hold the ribosome - or other interesting molecular structures - inside a DNA buckyball, Mao said.

"Think of it as a porous fish basket," he explained. "If you catch a fish, you can hold the fish in this confined space, but water can move in and out. ... The fish will be pretty happy."

The beauty part is that the DNA baskets build themselves out of smaller Lego-like structures, which Mao and his colleagues call "stars."

"We bought this DNA from a commercial company," Mao said. The trick is to mix the DNA and other ingredients in the right proportions and concentrations, heat the solution up to near the boiling point, then cool it down slowly.

The simplest star is a short three-pointed tripod with chemically sticky ends. Under the right conditions, the ends of three stars connect with each other to form a tetrahedron. A slightly bigger star has two sticky ends pointing out from each side of a bar. Depending on the recipe, the stars come together to form either a 12-sided dodecahedron or a 32-sided buckyball (which looks like the outline of a soccer ball).

The tetrahedra measure about 10 nanometers wide, the dodecahedra are about 70 nanometers wide, and the buckyballs are about 110 nanometers wide. The smaller the nano-gadget, the easier it is to self-assemble: Mao and his colleagues found that their recipe for tetrahedra yielded a 90 percent success rate - but the yield was only 76 percent for dodecahedra, and 69 percent for the buckyballs. The rest of the time, the DNA bits built themselves into less useful shapes, such as two-dimensional crystals.

This means picking out the keepers from a batch of DNA might have to be a little bit like picking out the consonants from a bowl of Alpha-Bits cereal. But there might be ways to streamline the filtering process - and Mao's group is also looking for different kinds of stars that can build even more complex structures.

Theoretically, the DNA structures could be used as cogs or ball bearings for nano-machinery. Or they could serve as packages for drug molecules, meant for unwrapping inside cells. That was one of the goals behind earlier research into DNA buckyballs, conducted by Cornell University's Dan Luo and colleagues. But Mao as well as Luo cautioned that the drug-delivery application was still far off.

In an e-mail, Luo said he was "quite impressed by the design" described in the Nature paper:

"DNA is indeed becoming a true designer polymer, and this work further demonstrates the power of DNA."

"As for applications, I, along with many people in the field, firmly believe that real-world applications will be realized in the near future with DNA materials such as reported by Chengde's group. The challenges are how to design and control DNA materials (Chengde's work clearly is a progress toward that challenge), how to expand DNA materials to wider fields and ultimately to consumers, and how to interface DNA materials with biology. In particular for drug delivery, it is still a black box in terms of how our body will interact with and react to complicated DNA tiles and closed 3-D structures as reported in the article."

We've already discussed the promise and potential peril of nano-machinery this week, but feel free to comment on this fresh facet of DNA technology.

Mao's colleagues in the Nature research are Yu He, Tao Ye, Min Su, Chuan Zhang, Alexander Ribbe and Wen Jiang, all of Purdue University.

Update for 12:20 a.m. March 13: I revised the first reference to the DNA buckyballs in response to a comment arguing that a molecule of buckminsterfullerene had a better claim on the title of "world's smallest soccer ball."

NBC News

Click for video: How impossible is teleportation? Physicist Michio Kaku gives his perspective.

Just how impossible are such science-fiction concepts as teleportation and invisibility? They're not that impossible, physicist Michio Kaku says in a new book titled "Physics of the Impossible." In fact, they're considered mere Class I impossibilities - and someday soon they may be off the impossible list altogether.

Now, if you're looking for a Class III impossibility, there are only a few things in Kaku's book that rise to that level. See if you agree with his assessment.

"Many times, physicists say that certain things are impossible – like physicists said that airplanes were impossible at one point," Kaku told me. "That's because we didn't understand the laws of physics very well. Well, today we have a pretty good handle on Einstein's relativity theory and quantum theory. And now we have to expand our horizons as to what is really impossible."

To some extent, it depends on what your definition of the word "impossible" is. For decades, scientists (and science-fiction authors) have talked about Type I, Type II and Type III civilizations - that is, civilizations that can harness the power of an entire planet (Type I), a star (Type II) or a whole galaxy (Type III). On this scale, we rate as a Type 0 civilization.

Kaku picks up on this idea in his classification system for impossibilities:

• A Class I impossibility is something that doesn't violate the known laws of physics, and could conceivably become possible decades or a century from now. Back in 1800, airplanes might have been on that list, just as "Star Trek"-style cloaking devices are today.
• Class II is reserved for technologies that sit on the very edge of our understanding of physics, and might be realized thousands or millions of years in the future. Faster-than-light spaceships, wormholes and backward time travel are on Kaku's Class II list.
• Class III impossibilities are feats that clearly violate the known laws of physics. "If they do turn out to be possible, they would represent a fundamental shift in our understanding of physics," Kaku said. Buillding perpetual motion machines and predicting the future are the two broad topics that get a Class III rating in Kaku's book. (But if you can go back into the past, couldn't you in effect predict or change the future? Well, maybe not.)

Kaku has always been one to give wide latitude to scientific possibilities, in a series of books including "Hyperspace" and "Visions." He told me he wrote this latest book because some of the things that were once thought to be purely science fiction are starting to look as if they're possible, at least in the realm of lab experiments if not practical applications.

"Things that a physicist would snicker at today could become possible in the coming decades," he said. "As we get a better grasp on quantum theory, we think that it may be possible to make objects invisible. It may be possible to teleport them like you see on 'Star Trek.'  So some of the things that we see in science fiction could very well become science fact in the coming years."

Turning the impossible into the possible usually comes with caveats:

• Scientists are working on ways to make whatever you put inside a specially shaped hunk of metamaterial invisible - but only in certain wavelengths.
• Quantum teleportation is indeed a reality already - but what's teleported is actually information rather than, say, "Star Trek" crew members or characters from the movie "Jumper."
• Even backward causality is the subject of serious research - but there's likely to be a yet-to-be-discovered clause in the laws of physics that will rule out time paradoxes.

The reality behind achieving the impossible may not always be worth the trouble. For example, take psychokinesis, the ability to move things with your mind. Kaku classifies this as a Class I impossibility - because soon scientists could conceivably set up a system that reads your thoughts using a brain-imaging device, processes your mental command using a computer, and then levitates objects magnetically using room-temperature superconductors.

All that sounds a lot clunkier than using Uri Geller's spoon-bending trick - or just walking over and picking up the darn spoon yourself.

Speaking of Uri Geller, Kaku notes in the book that scientists aren't always good at picking up on hoaxes that seem to achieve the impossible. "Scientists are trained to believe what they see in the lab. Magicians claiming psychic powers, however, are trained to deceive others by fooling their visual senses," Kaku writes.

On the other hand, scientists (and, by the way, journalists who write about scientists) aren't always good at picking up on what is truly possible. Kaku's reference to magicians brings science-fiction guru Arthur C. Clarke's three laws of impossibility to mind: 

• "When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong."
• "The only way of discovering the limits of the possible is to venture a little way past them into the impossible."
• "Any sufficiently advanced technology is indistinguishable from magic."  

At age 61, Kaku is hardly elderly. But is he right or wrong about scientific impossibilities? Take this quiz to find out whether you agree or disagree with Kaku's classifications, and feel free to weigh in with your own opinion below.

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For years, nanotechnology has held out the hope of molecular-scale contraptions that can manufacture custom-made drugs or revolutionize the way computer chips work.

Now researchers in Japan say they have taken a big step toward that nano goal by creating the first molecular machine that can do parallel processing.

"The discovery could provide a way to control many molecular machines simultaneously, increase computer processing power, and perhaps keep Moore's Law alive," according to the Proceedings of the National Academy of Sciences, which published the researchers' paper online today.

The multitasking machine was coaxed to assemble itself on a surface of gold from 17 molecules of an organic compound called duroquinone. Sixteen of the molecules form a weakly bonded ring around the central molecule, which serves as the control unit for the machine.

Anirban Bandyopadhyay / ICYS

Click for video: This graphic shows the structure for a parallel-processing molecular machine, Click on the image to watch a video about the machine; click here for a larger version of the graphic.

Using electrical pulses from the tip of a scanning tunneling microscope, the researchers could flip the control molecule to any one of four configurations, or states. Those flips, in turn, could change the states of the other 16 molecules - just as, say, knocking down one domino can simultaneously set off several chains of falling dominoes.

Researchers used the scanning tunneling microscope to make sure that the 16 molecules really did respond to the central control molecule as they hoped.

"We can use [the central molecule] like a space station to talk to spacecraft - or if you have seen the movie 'Fantastic Voyage,' it is similar to that," Anirban Bandyopadhyay of Japan's International Center for Young Scientists told me over the weekend. Bandyopadhyay and a colleague at the center, Somobrata Acharya, are the researchers behind the study unveiled today.

Bandyopadhyay said that the assembly was modeled on how glial cells work to pass along instructions among neurons in the nervous system. Such "one-to-many" communication is essential to the way the brain works, and computer scientists have said for decades that massively parallel processing could revolutionize the way machines think.

"The architecture looks almost like the neural network inside our brain," Bandyopadhyay told me. He said his findings showed that a single instruction given to the control unit was capable of generating more than 4 billion (4¹⁶) possible outcomes.

Molecules and medicine
But wait ... there's more: If scientists can create assembles that can pass along instructions from one molecule to 16, then to 256, then to 4,096, and so on - pretty soon you could have nanofactories capable of churning out mega amounts of custom-designed molecules. That could open the way for medical therapies that have long been the subject of dreams (and nightmares).

"In the future, there will be no surgery for brain tumors," Bandyopadhyay said. "The blood [containing molecular assemblies] will be injected into the body, and will go to the targeted place."

Once nanochips containing the molecular assemblies reached a place where they sensed that a tumor was active, they would gear up the machinery and start producing molecules custom-made for small-scale chemotherapy. When the tumor was taken care of, the machines would shut themselves off. At least that's the theory.

Mark Ratner, a chemist at Northwestern University who specializes in nanotechnology, said the newly published research represented a significant step toward molecular-scale computers as well as molecular-scale medicine.

"People have been talking about both these things for a long time," Ratner told me. "People have even thought about putting these two things together. ... But this is quite pretty because [the researchers] actually use all of the constituents, and that's really neat."

Nano now? No ...
Ratner edited the paper for the Proceedings of the National Academy of Sciences, and he said the reviewers were particularly impressed to see how the molecules meshed themselves into a machine - as well as how an electrical input into one molecule could produce multiple responses. However, Ratner cautioned that the technology wasn't ready for practical application.

"Is it useful tomorrow? No," he said.

One of the biggest conceptual hurdles has to do with the input/output device: Although the assemblies themselves are at the molecular scale, the scanning tunneling microscope is a big piece of equipment. It wouldn't be practical to use those microscopes to read out the result of a nanocomputer, or harvest the chemicals produced by nanofactories.

Bandyopadhyay said other control methods would be developed for working devices - perhaps optical readers for the nanocomputers, or chemical triggers for the medical nanochips. Ratner said several companies, including an outfit called NanoInk, were working on technologies that might work.

In the meantime, Bandyopadhyay is working to ramp up his molecular machines from two-dimensional arrays to three-dimensional structures. "Within one and a half years we will have 1,024 machines connected," he told me.

Theoretically, the technology could allow for the development of a super-duper information processor contained in a sphere less than 2 inches in diameter, Bandyopadhyay said.

"That will contain the equal amount of components and connectivity that is required inside our brain," he told me.

Say that again?
After our initial talk, Bandyopadhyay sent me an e-mail going into more detail about the potential applications of his molecular machines. Here's the text, slightly edited to fine-tune the style and add Web links:

"The first application is mimicking the 1965 movie 'Fantastic Voyage.' Prior to our work, the prediction that in the future medical doctors will not have to go for surgery if a patient has brain tumor, or damaged lungs, heart or lever, was considered merely a dream. It was also predicted that, for any disease, the doctor would choose suitable molecular machines - but it was not known how they would be controlled after injection into the blood, though several machines already have been invented.

"Now our work provides a unique conceptual solution. What a doctor would have to do is attach a control program molecule at the center, similar to our kind of machine assembly. The specific molecular machines dedicated to do particular job would be attached around the ring. Then, finally, the complete assembly would have to be injected into the blood. The machine assembly would be capable of instructing the other machines docked with its ring members.

"The major query that arises is: Given that we study the system under a scanning tunneling microscope in an ultrahigh vacuum condition, what is the guarantee that it will work as a standalone system? Now, since to build a standalone system we require only a single contact to the central molecule that would be used to donate and extract electrons as required, we have already found suitable reversible redox active enzymes. Therefore, it could be programmed in such a way that a very particular environment would activate the central molecule in a remote environment.

"The second application is building a massively parallel supercomputer based on the working principle of our brain. The computer that we are going to build is based on the proposal of L. Chua and Roska's work on cellular neural networks (CNN) in 1989, which is a combination of cellular automation and the neural network of our brain. In this concept, highly interconnected arrays of cells communicate with all their neighbors at a time, following a particular equation. In principle, these unconventional processors are astronomically powerful compared to existing processors.

"Several such processors have been proposed; however, the key to the system's realization - 'one-to-many communication' at a time - has not been realized yet. Therefore, this is a significant advance compared to the realization of single CNN cells. Also, please note that these processors will not use any logic gate. It will be purely visual computing, where patterns will replace the differential equations that have been used to express physical phenomena for the last 300 years of science.

"Until now, all these concepts were seen in mathematical models and particular CMOS chips that have been constructed based on CNN principles. But true realization of 'one to many communication' would make an important paradigm shift, as it opens the door to bottom-up parallel processing."

Will we see molecular machines doing useful work in our lifetime? If so, will this lead to the "singularity" that futurist/inventor Ray Kurzweil is predicting for the year 2045? And could that in turn set the stage for a real-life replay of "Terminator 3: Rise of the Machines"? Feel free to weigh in with your comments below.

Update for 12:11 a.m. ET March 13: Based on the comments, I changed the date for Kurzweil's prediction of the singularity to 2045. The year 2029 is when Kurzweil believes artificial intelligence will basically match human intelligence, as described here.

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NASA / ESA / SSI

Click for slide show:  See Cassini's images  of Enceladus.

The Cassini orbiter is due to make its closest-ever approach to a celestial body next Wednesday, when it comes within 30 miles of the surface of Enceladus, one of Saturn's myriad moons. Enceladus isn't just any moon: It just happens to shoot up geysers of ice crystals, which may hint at the presence of liquid water (and perhaps even life) beneath the moon's frozen surface. Cassini will be "scraping" right through the heart of the plume, at an altitude high enough to escape damage - but low enough to take samples and find out whether life's building blocks lurk in that alien sleet.

"We should come away from this flyby with a better idea of the composition of the plume, in particular, a better measure than we've had up until now of the abundances of ammonia and some simple organic compounds, both of which are important to ascertaining the astrobiological potential of the source environment of the jets," the Space Science Institute's Carolyn Porco, leader of Cassini's imaging team, said in an e-mail.

Cassini has had close brushes with Enceladus before, but those flybys were nowhere near this close. In fact, at the precise moment when Cassini is closest to Enceladus, the bus-sized spacecraft will be zooming so fast that it can't really take any useful pictures.

The good news is that Cassini will be taking in data like crazy when it goes through Enceladus' south polar plume just a half-minute later, at an altitude of 120 miles (200 kilometers). John Spencer, a Southwest Research Institute planetary scientist on the Cassini team, said the previous flybys had at best a glancing encounter with the ice plume. "This time, we're really plunging into the plume," he said in a NASA video explaining the flyby.

That's why this year's series of Enceladus encounters are called "scraping flybys." It may sound scary to subject a $3.4 billion space probe to a sleet storm, but Cassini's mission managers say this sleet shouldn't pose a threat: At a height of 120 miles, the particles of ice are expected to be no more than a micron wide (that's 0.00004 inch).

The entire time line for Wednesday's flyby is outlined on the Cassini imaging team's Web site, and to celebrate Cassini's first scrape, NASA's Jet Propulsion Laboratory has put together a goodie bag of Enceladus-flavored treats:

• You'll find this interactive look at the moon (complete with plume!), courtesy of NASA's Saturn Moons Explorer.
• There's also a mini-guide to Enceladus as well as a short feature that summarizes the key issues for Enceladus.
• To get a Cassini's-eye view of the deep-space trip, you can consult NASA's CASSIE Web site.

While you're at it, check out everything we have to offer on Enceladus, including this slide show highlighting the moon's plume and "tiger stripes." And stay tuned for updates: After Wednesday's scrape with Enceladus, Cassini is due to dig in again in August, and then at least twice more during the probe's extended mission.

If the results are interesting, that would bolster the case for making an even more ambitious trip to Enceladus. Later this month, European scientists are due to discuss a future space mission called TANDEM, which could send probes to the surface of Enceladus as well as Titan, another one of Saturn's most mysterious moons. NASA has a similar concept for a follow-up mission to Saturn's moons, called the Titan Explorer, which would be launched sometime after 2020.

There are lots of places to look for traces of life in our solar system - ranging from Enceladus to Mars to Jupiter's ice-covered moons. What do you think we'll find? Feel free to leave your comments below.

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CWRU

Click for video: Watch a demonstration of the hard-to-soft material.

A sea cucumber can activate its body armor in a matter of seconds, by secreting chemicals that stiffen its soft skin. Now researchers are adapting that trick to create plastics beefed up with nanomaterials that can switch from hard to soft, or vice versa, with the flick of a signal.

Writing in Friday's issue of the journal Science, the researchers say such plastics could eventually be used for future biomedical implants, such as brain electrodes or … well … whatever.

"Where would you want to have materials that can electrically switch between floppy and rigid? I'd just encourage you to use your imagination," said Christoph Weder, a materials scientist at Case Western Reserve University and one of the senior authors behind the research paper.

Building on previous research published last year in Nature Nanotechnology, Weder and his colleagues took a page from the sea cucumber's cookbook - and changed the ingredients to suit their own purposes. The sea cucumber's skin has rigid collagen nanofibers embedded in soft connective tissue. When the creature senses a threat, it secretes chemicals that cause the nanofibers to bind together, hardening the skin into more of a shell.

"We've taken that architecture - not the chemistry and the materials that nature is using - but we've taken the architecture to produce an artificial material that does a similar trick," Weder told me.

Fred Carpenter

Sea cucumbers, like the one shown at the center of this image, inspired the design of nanocomposite plastics that go squishy when a solvent is added.

To mimic the sea cucumber's skin, the researchers substituted cellulose nanofibers for the collagen, and embedded them in a rubbery, porous polymer. The nanofibers were specially treated so that they would stick together in a matrix when dry, but would separate when exposed to a hydrogen-bond-forming solvent - like water, for example.

The resulting material is as hard as the plastic in a CD case when it's dry - but goes limp and floppy like soft rubber when it's immersed in water. When the material dries out, it gets hard again.

"The current application that we're interested in is to make materials for biomedical applications that are originally rigid, but when you implant them in a biological material, they soften in a very controlled way," Weder said.

Going soft in the brain
For now, the technology is being developed primarily for microelectrodes that can be implanted in the brain. Such devices are being used experimentally in "artificial nervous systems" to treat medical conditions ranging from strokes and spinal cord injuries to Parkinson's disease.

Some experiments have shown that the brain signals degrade within a few months after implantation, and researchers suspect that this occurs because the stiff microelectrodes do damage to the surrounding brain tissue over time. Electrodes that go soft "could alleviate this problem," Dustin Tyler, another member of the research team, said in a Case Western news release.

"That's why we designed our first materials to respond to water," Weder said. "This allows the rigid electrodes to become soft when implanted into the water-rich brain."

You might wonder whether there are similar ways to achieve the same result. For example, even a dry sponge can get all floppy when it's thrown into a bucket of water. But Weder said it was important to come up with a hard-to-soft technology that didn't depend merely on soaking up a liquid. If their material swelled up like a sponge in the brain ... well, you can imagine how bad that could be.

To make sure that their material worked instead by responding a chemical switch, they dipped the stuff in a different liquid, isopropyl alcohol, and found that the plastic retained its stiffness. That demonstrated that the stiff-to-floppy transition could be chemically controlled.

Weder said the hard-to-soft plastic is currently being tested in animal studies - but he acknowledged that "it's very difficult to say how long this is going to take," due to the protracted period required to certify such materials for medical purposes.

Dr. Rodolfo Llinas, a neuroscientist at New York University, is working on a different kind of microelectrode technology and was not involved in Weder's work. Nevertheless, after reviewing the Science paper, he told me in an e-mail that the soft-polymer technology looked promising: 

"The use of polymer-based electrical stimulating/recording probes is clearly the next step in direct interface with the central nervous system. I suspect that as we learn more about such materials, their optimal utilization in neuroscience will afford stunning new experimental designs. Indeed, the 'Holy Grail' in central nervous system research, to record/stimulate in freely moving animals with hundreds of probes, over a protracted time, might become a reality."

Beyond the brain
Weder told me he doesn't intend to stop with microelectrodes. On the biomedical side of things, you could make implantable stents from plastic instead of wire. You could also create "smart casts" for injured limbs, Weder said.

"There are conditions where, every now and then, it is desirable for the system to soften up so you can stretch your arm, and then the cast can harden back up," he explained.

All sorts of other gee-whiz devices become marketable if researchers can figure out a way to control the stiff-vs.-floppy switch with an electrical signal rather than a chemical signal. (I can imagine the erectile-dysfunction ads already!) Weder took the high road in his own example, saying the technology could lead to "smart bulletproof vests that you can switch from soft to rigid."

That would bring the concept around full circle: What started out as body armor for the sea cucumber could someday lead to next-generation body armor for humans.

In addition to Weder and Tyler, the authors of the Science paper include Jeffrey Capadona, Kadhiravan Shanmuganathan and Stuart Rowan of Case Western. Capadona, Tyler, Rowan and Weder also are affiliated with Cleveland DVA Medical Center.

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Reuters file

Will Barack Obama and Hillary Clinton face off on science in April? We'll see.

Prospects for a presidential debate focusing on science and technology next month are on the upswing, thanks in large part to the fact that the Democratic nomination is still in play. Debate organizers say all three major candidates – Hillary Clinton and Barack Obama for the Democrats as well as the GOP's presumptive nominee, John McCain – are thinking about attending the tentatively scheduled April 18 event.

Science Debate 2008 would be presented at Philadelphia's Franklin Institute at a key time, four days before the Pennsylvania primary. But will it actually take place? That depends on political calculations so complex they'd leave mathematicians scratching their heads.

If Clinton had done poorly in the Texas and Ohio primaries, Pennsylvania would have become irrelevant in the Democratic campaign. Science Debate 2008 would probably have put its months-long effort to drum up a debate on science and technology issues - ranging from global climate change and stem cell research to energy policy and technological innovation - on hold until after this summer's nominating conventions.

However, with Clinton resurgent, it's almost certain there will be a debate in Pennsylvania - so why not make it the Science Debate? For the Franklin Institute, the event would cap a week devoted to celebrating the top achievements in science. Lynda Bramble, the institute's director of public relations and communications, told me that the auditorium already has been set aside for an April 18 presidential debate.

"I want the Science Debate here," she said. "I don't want anything to get in the way of that."

At a surrogate science debate presented in Boston a couple of weeks ago, physicist Lawrence Krauss theorized that there was a 20 percent chance of the candidates actually showing up for April's debate. Today, he quipped that the chances were at "80 percent ... or 1 percent."

Clinton is the most likely to go for a Science Debate: "I think her campaign views it as having the greatest value for them," said Krauss, a professor at Case Western Reserve University who helped kick off the Science Debate campaign with an op-ed piece in the Los Angeles Times.

Clinton not only needs to play a serious game of catch-up in the delegate race, but she also has given science and technology issues more visibility than the other candidates have.

To be sure, Obama's campaign has drawn up detailed policy statements on science and technology - and as ranking GOP member of the Senate's Commerce, Science and Transportation Committee, McCain also knows the territory. But the conventional wisdom is that Obama would see less of a need to join a debate on a niche topic, while McCain would likely wait at least until he knows who he's running against.

Shawn Lawrence Otto, one of the lead organizers behind Science Debate 2008, gave me some unconventional reasons why Obama and McCain might want to attend.

"From the Democrats' point of view, it is going to be particularly important for the candidates to find new ways to differentiate themselves from each other," Otto told me. "These are issues that all voters are really concerned about. This debate gives each of the candidates an opportunity to paint a big vision for the future of America and the world."

Even though a multiparty debate before the conventions would be unorthodox, Otto argued that the Republicans might want to get a piece of the action as well. "Really, from McCain's point of view, he's in a general-election race now, and he needs to appeal to the vast majority of moderate swing voters who care about these issues," Otto said.

Otto and his colleagues at Science Debate 2008 say they are currently in the midst of a delicate dance with network executives and campaign representatives. To my mind, the best they can hope for is a Democratic debate at the Franklin Institute that may include a brief nod to science and technology (as a courtesy to the hosts) while putting more weight on less geeky issues - such as Iraq, the economy and negative campaigning.

Complicating the matter is the fact that the Franklin Institute is facing some stiff competition from another potential debate venue. The National Constitution Center, just a couple of blocks away from the Liberty Bell, is reportedly making its own pitch for a campaign face-off in Philly.

But who knows? If scientists can put a man on the moon, why shouldn't they be able to get a woman and two men to talk about science for a couple of hours?

While we're on the subject...
What happens when politics and space policy mix on the Internet? You can find out by checking these Web sites:

• Space Democrats is a recently created discussion forum with the stated mission of "defining, advocating and enacting a progressive U.S. space policy."
• Space Advocates for Obama has just been set up to focus attention on Obama's policies on space exploration (and perhaps to get the Obama campaign to focus its attention on space as well). The site is linked to the Space Policy Advisory Group, and there's talk that a similar space-advocacy Web site might be created for Clinton supporters as well.
• John McCain says on his Web site that he's a "strong supporter of NASA and the space program." If anyone has Internet links for Republican-leaning space advocates, pass them along as comments below and I'll make sure they're added here.
• Space Politics provides straight talk on space policy no matter what your political persuasion may be, courtesy of blogmaster Jeff Foust.

And on the engineering frontier...
Technological innovation may not get voters as fired up as other issues in the campaign, but we did receive some fiery comments in the wake of our story about the 21st century's Grand Challenges for Engineering. Here's a selection:

Ray Hull, Prescott, Ariz.: "The greatest challenge at present is to overcome the misinformation with respect to global warming.  A good look at the science will make it clear that Al Gore and others are doing a great injustice to the poor people of the world.  At the present course we will waste trillions of dollars on an effort that will not change signficantly over the 1,500-year cycle of global warming and cooling that has been going on for millions of years. Green is needed, but trying to influence the global climate will harm the human race by diverting resources that otherwise could be used to help the disadvantaged and to develop a way to feed the 8 billion people the world will have soon.  A great index to the data is located at CO2science.org."

CO2Science.org definitely has a particular slant on the issue, Ray. I can't really let that go without at least mentioning the award-winning RealClimate Web site as well.

Carol Kelso, Birmingham, Ala., on carbon sequestration: "Why is this a good option? We live on a planet that has a surface with a tendency to shift and move.  Could earthquakes and other seismic disturbances cause carbon dioxide stored underground to be released?  What if we had a lot of it stored and then a catastrophic earthquake sent all of it into the atmosphere?  Is there a way to stream carbon dioxide into space?  If so, would this be harmful to anything or anyone in the future?"

I'm pretty sure expelling carbon dioxide into space would be an engineering challenge beyond our current capability - but check out this report if you want to learn more about carbon sequestration.

Mark Flahaut: "I read your article on the top engineering challenges.  I was a little upset by several of the challenges being characterized as engineering tasks as opposed to medical science tasks.

"Often, you will hear of a successful quarterback as having 'engineered a winning drive.'  I grow weary of hearing the term not used properly, at least in my view.

"Four of the items on the list were not engineering tasks in my view. They are
a) advanced health informatics
b) engineering better medicines
c) reverse-engineering the brain
d) advancing personal learning

"My definition of engineering is using math, science, physics, as well as important testing and research where the math has not been figured out yet to develop and improve devices, structures, electronic gizmos, etc.  I know that was a little vague. My point is this: The above list is in the areas of medical research and behavior research.  I have been an engineer for nearly 20 years. Perhaps my idea of a typical engineer is limited as compared to the average person out there in America.

"Please understand that I'm not attacking you but rather the list. I like the challenge of coming up with a practical and cheap way of using solar power.  I believe we need to put more true thought into saving power. The compact fluorescent bulbs have cut quite a bit off my electrical use.  But reducing consumption is only part of the long term solution. Alternative power is the other part as only so many fossil-fuel sources are left before we suck them up. We need to really turn up the wind power development sector.

"I would say the list of the non-engineering problems needing solutions are needed but 'aimed' at the wrong academic sector. It is very important for our society to develop and equip our nations teachers with the best tools money can buy. We are a very rich country but intellectually poor as compared to many other nations. It is a matter of time before we decline if we don't wake up and catch our kids up in math and science when compared to other industrialized nations.

"If we can't teach our children well, how can we solve the list's problems? My 2 cents."

Great comments, Mark. To paraphrase Bill Clinton, it all depends on what your definition of "engineering" is.

David Boyle (no relation, by the way): "I find it extremely disappointing that none of the fixes mentioned in Greatest Challenge addressed the root problem - that there are way too many of us.

"This used to be a nice place to live and grow up in, no matter what species you happened to be. Now, if you're not a member of the human race, you are expendable, with the only thing slowing your demise being how useful a creature / plant you happen to be. The human race is no smarter than it was 40,000 years ago, but unfortunately for the earth's biosphere we now also have technologies to ravage the planet (and once we perfect robots, that ravaging can be done from the comfort of our air-conditioned control rooms!). What's even worse is the budding world populace that wants to be like the people of the U.S. of A., who are without a doubt most wasteful populace on the planet. Considering the ridiculously high proportion of people in this country who think like King George, the engineers and scientists who made the list don't need to worry about making inroads on global warming.  'We the People' aren't interested in things best left to our grandchildren. I have a feeling that a lot of those grandchildren would spit on our graves if they knew how great a place this used to be, and that we were partially responsible for the latest Great Extinction.

"If I remember right, the world's most populous animals are ants, spiders and termites.  I have no doubt whatever that the most damaging, most globally detrimental one is us.  Unless and until we recognize that we are but one of tens of millions of species that have evolved over earth's history, and recognize that what we are doing to the planet is bad, is disgraceful, and is in fact, as King George would say, evil, the long-term future of this planet is doomed.

"I worried about The Bomb when I was a kid, and used to think that World War III would be a very bad thing.  Now I'm not so sure.  WWIII would most definitely have been grotesque and likely would have killed tens and maybe hundreds of millions of people.  The downside to not having a WWIII is that without it, the human race will continue expanding until something really, really bad finally levels the playing field.  If history teaches anything, it's that population expansions cannot continue indefinitely (unless we find another planet to wreck).  So we can either try to do something about our planetary infestation - though I haven't a clue how - or sit back and smother in our own filth. (Personally I find the thought of New York, Chicago and all our other great cities becoming like Calcutta sickening...though that's exactly the direction we are going, and going there world wide.)

"I wish population control - city, state, and/or global - would at least have made honorable mention. Then again, it's maybe too hard a problem for even the smartest of guys to think about.  Too bad, too. Up until we got here, planet Earth was a really swell place.

"Oh, and I do realize you're the messenger here.  Normally I like what you've got to say."

Thanks for not shooting the messenger, Dave ... even though that would free up a bit of extra space.  ;-)

Hugh O. Coleman, Kelso, Wash., on the Grand Challenges: "They left out the most important facet. We must actually do on the required scale, in many cases, things we already know how to do. We must actually act, not just talk."

I'll vote for that.

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Microsoft via AFP - Getty Images

Microsoft's LucidTouch displays "pseudo-transparent"  fingers on a handheld computer screen. Sensors  keep track of your fingers on the back of the device.

Once a year, Microsoft Research gives outsiders a glimpse of its high-tech frontiers: gizmos that transform your fingers into ghostly digits on the screen, or make you look like a Webcam celebrity ... viewers that let you unravel the inner workings of the cell, or explore the outer depths of the cosmos ... sensor networks that monitor how climate change affects glaciers in the Swiss Alps, or how the chemistry of life works at the bottom of the Pacific Ocean.

Even though I work right on Microsoft's main campus, I'm usually counted as one of those outsiders - but today, I finally got my first glimpse at TechFest, a science fair geared for grown-ups.

Microsoft Research TechFest has been around for seven years, but until last year it was meant exclusively for the software company's employees. It's actually a cross between a science fair and a trade fair, with researchers showing their innovations to product developers who might actually use them.

Last year, the company opened up the TechFest displays for one day to potential customers and partners, as well as journalists and dignitaries. The same system was in effect this year.

Microsoft may be a partner (along with NBC Universal) in the msnbc.com joint venture, but we're treated pretty much like other journalists when it comes to press access. So, armed with my press pass, I walked over to Building 33 on the Redmond campus this morning, waltzed in the door and blended in with the crowd - which included representatives from NASA, the Pentagon's Defense Advanced Research Projects Agency and a host of universities.

Clearer view of virtual telescope
The headliner at the event was the WorldWide Telescope, an astronomy program that we first wrote about last week (when it was demonstrated at the TED conference). Today, researchers at Microsoft and beyond were more willing to talk up-front about the virtual telescope, which is expected to go into free public release late this spring.

Like Google Sky, Stellarium and other such programs, WorldWide Telescope blends astronomical imagery from multiple sources using a clickable, zoomable interface that simulates the night sky on your desktop. Microsoft Research's Curtis Wong said he hoped the program would make its mark by letting astronomers and the general public create their own virtual tours of cosmic wonders.

"If you can create a PowerPoint presentation, you can create a guided tour of the sky," Wong told me.

One of the presentations demonstrated today was created by a 6-year-old Toronto boy named Benjamin, who gave a charming tour of the Ring Nebula. "My dream for this is to have more and more of these stories," Wong said.

But the WorldWide Telescope is more than a child's plaything: Professional astronomers are already planning to use it to archive data, present their observations in an academic setting, and even open the way for analysis and discovery.

"The astronomy community is really excited about it, mainly because we paid attention to a lot of details they care about," Wong said.

One of the early adopters is Alyssa Goodman of the Harvard-Smithsonian Center for Astrophysics.

"What we're doing is adding the functionality that only professionals would care about," she told me in a phone interview. "Making tours of papers, for example, or being able to do things with the coordinate system. ... The important thing is that it will become probably the premier interface for the professional virtual observatory."

The other sky software packages have their pluses as well, she said - and competition is usually a good thing for everyone involved.

"The way I see this is, it's almost like the browser wars," Goodman said. "The content is already out there, and right now I see this as a browser for the sky. ... The dream of the whole virtual observatory community is that all of these tools will interoperate as well as the Web does."

The technology behind the WorldWide Telescope could spawn other products as well.

"Some of the things we're able to do there may be brought into the medical sphere,"  Craig Mundie, Microsoft's chief research and strategy officer, said at TechFest. He pointed out that once you have the mechanism for blending terabytes of data from multiple sources, you could use that mechanism to present astronomical imagery from radar scans and X-ray telescopes ... or medical imagery from PET scans and hospital X-rays.

The WorldWide Telescope wasn't the only virtual realm on display. Here's a quick rundown on some of TechFest's other wares:

Virtual fingers
The coolest gizmo I saw was a handheld mobile device tricked out with a technology called LucidTouch, which allows you to work a touchscreen by moving your fingers on the back of the device. A ghostly, semitransparent projection of your fingers appears on the screen itself, thanks to a Webcam and a touch-sensitive surface on the back side.

Alan Boyle / msnbc.com

Microsoft Research's Patrick Baudisch demonstrates the LucidTouch device at TechFest.

Microsoft Research's Patrick Baudisch developed the technology to do away with the frustration of having to put your big fat fingers on a small touchscreen. The "pseudo-transparent" fingers are overlaid on touchscreen controls and give you an eerily effective sense of feedback as you twiddle your phantom digits.

Eventually, Baudisch hopes to do away with the clunky Webcam sticking out from the back of the device and get the technology built into a wide range of small-screen devices, ranging from smartphone-style wristwatches to handheld game consoles.

"Using the same surface twice isn't a great idea," Baudisch explained. "So why don't we use the surface that hasn't been used: the back."

Virtual cells
Andrew Phillips and his colleagues at Microsoft Research's British facility have developed a visual programming language, known as the Stochastic Pi Machine or SPiM, to help biology researchers analyze how cells do their work. The program can take a tangled chemical pathway and figure out what quantities of which proteins should be produced by that pathway.

Microsoft Research / msnbc.com

Click for video: Msnbc.com's Alan Boyle narrates animations from Microsoft Research that represent cellular signaling pathways at work.

"We want to build a model of a biological system on a computer," Phillips said. "We take a very complicated network and break it up into more manageable parts."

Graphic representations of chemical reactions in the cell show proteins as colored balls of various sizes, growing and shrinking as they are built up and broken down. The green connecting lines represent signaling pathways.

Researchers can compare the predicted outcome of a biological process with the actual results of their experiment, to find out if their model for the process is correct. Someday, the simulations might even suggest new strategies for countering cancer or developing new drugs.

Sensors on the ocean floor
Microsoft is participating along with the University of Washington and the Monterey Bay Aquarium in a program called Trident, which is developing a sensor system for studying the Pacific Ocean's active seafloor. Trident meshes with wider efforts known as Project Neptune and the Ocean Observatories Initiative.

Eventually, scientists could be watching the ocean floor remotely with HDTV cameras, seismometers, sonar and other scientific instruments - with all the data flowing back to land via a fiber-optic network.

"Once you have thousands of sensors, how do you process all that data?" said University of Washington oceanographer Deborah Kelley, a member of the Neptune team.

That's where Microsoft is helping out, by devising the data flow management system that will let researchers hundreds of miles from shore interact in real time with their experiments. "It democratizes science," Microsoft Research's Roger Barga explained.

Sensors on mountaintops
Another sensor-based scientific project is called SenseWeb. Swiss researchers are using SenseWeb to knit together data from weather monitoring stations planted in Switzerland's Genepi rocky glacier. A software program called SensorMap can extrapolate from the individual wind and temperature readings to develop time-lapse maps of the entire area. SensorMap also could be used to keep track of Seattle-area traffic or San Francisco airport parking, as shown on the project Web site.

Lights, Webcam, action!
One of the not-yet-ready-for-prime-time technologies we saw demonstrated was a little something called "Active Lighting." It's basically two low-power LED arrays that are set up on each side of a Webcam-equipped computer monitor. When you turn on the video, a computer program checks your image and starts switching different-colored lights on and off.

"It analyzes the video and adjusts the lighting so it looks nice," Microsoft Research's Zhengyou Zhang explained.

How does the computer know when your image looks the nicest? Zhang said the software compares the lighting on your face against a database of celebrity photos. The more you look like a celebrity, the better the lighting must be. And who can argue with that?

For more about TechFest, check out these reports from CNet, Computerworld, Gizmodo, InfoWorld, Wired and Microsoft's TechFest Live blog.

Are you more likely to spend a tax rebate ... or a tax bonus? If you were automatically signed up for a retirement plan, would you stick with it ... or opt out? If the government sent you a filled-in tax return, would you go with Uncle Sam's figures ... or insist on doing the calculations yourself? Such are the questions that arise when economic policy intersects with the rising trend of neuromarketing, the science of selling to your brain.

Researchers are increasingly relying on neuromarketing to explain seemingly unexplainable facets of our buying behavior - for example, why the exact same wine really does taste better if it costs more, or why kids prefer even common foods that come wrapped in McDonald's packaging.

The technique also has been applied to politics, looking into how the average Republican's brain differs from a Democrat's, how this year's presidential candidates are perceived, and even who has the most effective viral videos.

Now neuromarketing may help shape economic policies as well, or at least shape the way those policies are framed.

Rebate vs. bonus
For example, take the "rebate vs. bonus" study, which was conducted by the University of Chicago's Nicholas Epley and colleagues. Their study appeared a couple of years ago in the Journal of Behavioral Decision Making, but it has come to the fore again because of the tax stimulus package that the White House and Congress recently pushed through.

Uncle Sam will be sending out billions of dollars in checks to taxpayers starting in May. For those economists who think a boost in spending is just what the nation's flagging economy needs, that's the good news. The bad news, at least based on Epley's research, is that the checks will be called "rebates."

"If the goal is to increase consumer spending, the checks should have been pitched as 'tax bonuses' instead of 'tax rebates,'" Epley said in a news release from the National Science Foundation, which funded his research. 

Epley and his colleagues - Lorraine Chen Idson and Dennis Mak - conducted experiments in which participants were given money characterized either as tuition rebates or bonuses. In one experiment, the people who were given a $25 rebate spent $2.43 on items sold to them in the lab. In contrast, the ones who were given a $25 bonus spent $11.16.

The idea is that people are more likely to spend what they see as extra money or an unexpected windfall (a bonus) rather than what they regard merely as regular income that's being returned to them (a rebate).

Now, most taxpayers already understand that they're simply getting more of their money back - and so the "rebate vs. bonus" issue may not make much difference when it comes to money from the Internal Revenue Service.

Experts have long debated whether tax rebates are the most efficient way to stimulate the economy. Many say that most of the rebate goes toward debt reduction or savings, which doesn't give the economy as much of a boost as new spending. My colleague on msnbc.com's business desk, John Schoen, has pointed to research showing that the stimulus effect is significantly stronger if the money is put toward, say, extending unemployment benefits and expanding food-stamp programs.

But Epley's larger point is that the government should act more like a business, and try test-marketing its economic packages. When lawmakers consider how to design and implement major public policies, they might want to have researchers "run some small-scale pilot studies to identify which designs or descriptions might be the most effective," he said.

"Market researchers do a great deal of this, but it's not so clear that this is done as much as it could be in public policy circles," he said.

Political neuromarketing
Test marketing is likely to play a bigger role in policymaking (or at least policyselling), no matter who goes to the White House next year.

Among the Republicans, John McCain favors state-by-state experiments in health-care programs, Mike Huckabee touts Arkansas' wellness program as a pilot worth expanding, and Ron Paul is ready to open a virtual laboratory of tax policies.

On the Democratic side, Hillary Clinton has long been a supporter of small-scale pilot projects in the food-stamp program as well as global warming policy. And Barack Obama's economic advisers have a lot of neuroeconomic strategies up their sleeve, as outlined in a New Republic report titled "The Audacity of Data." 

For example, one policy proposal would automatically enroll workers in their 401(k) retirement plans while allowing them to opt out. Studies show that most folks would stick with the status quo, which would significantly boost retirement savings.

In a similar vein, the University of Chicago's Austan Goolsbee - Obama's top economic adviser - has suggested drawing up an "automatic tax return." If you have no tax deductions or out-of-the-ordinary income, the Internal Revenue Service would send you a tax return that's already been filled out.

"As long as you accepted the government's accounting, you could just sign it and mail it back," The New Republic's Noam Scheiber reported. "Goolsbee estimates this small innovation could save hundreds of man-hours spent filling out tax forms, and billions of dollars in tax-preparation fees."

'Gotcha Neuroscience'?
That kind of economic shortcut often comes into play in the business world, taking advantage of the fact that our brains are basically lazy. It could be a timesaver, as Goolsbee suggests - or it could lead to the economic sleight of hand already practiced by phone companies, cable TV providers and credit-card companies (which is documented so well in my colleague Bob Sullivan's book, "Gotcha Capitalism").

Goolsbee has already stirred up a controversy, by seeming to contribute to mixed messages on Obama's trade policy. Will neuromarketing generate better economic policies or the same old marketing flimflam? Feel free to weigh in with your comments below.

If you want to keep up with the brave new world of behavioral economics, add Roger Dooley's Neuromarketing blog to your checklist. And while you're at it, check in with msnbc.com's Behavior section, where you'll learn why celebrities flock together and how shopaholics are made.

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