Aerogel: Cool Stuff!

aerogel sample in handAerogel is the world’s lightest solid — and also the most porous. I’ve got a story on Wired News this morning that explains all about this really cool material, how it was used in NASA/JPL’s recent Stardust mission, and how some companies are commercializing the stuff. This story was really fun to write, not least because of the nifty aerogel samples I got to handle.

Wired News: A Solid That’s Light as Air

[image courtesy NASA/JPL]

Aerogel: Cool Stuff!

A Solid That’s Light as Air

If you wanted to catch a few particles of comet dust speeding through the vacuum of space at 6 kilometers per second — without damaging or destroying those particles — how would you do it?

Faced with exactly this problem, scientists at the Jet Propulsion Laboratory focused on aerogel — an extremely lightweight, porous material that is chemically identical to glass, but weighs only a little more than air.

Aerogel is the lightest solid known to science. It’s also one of the most insulating materials on Earth, the most porous, and it’s nearly transparent. Those last two properties made it an ideal choice for catching flecks of comet and interstellar dust on the recently-returned Stardust mission launched by NASA and JPL.

Since the satellite returned to Earth on January 15, NASA scientists have been busy slicing open Stardust’s aerogel cells and carefully extracting the bits of dust it collected from Comet Wild 2.

“Aerogel is unique in having so many superlative properties, and a huge range of properties too,” said Donald Brownlee, a University of Washington astronomer and the principal investigator for Stardust.

Aerogel isn’t exactly space-age technology. It was invented in 1931 by Steven Kistler, in response to a bet made by a fellow scientist. Kistler found a way to remove the liquid from a silica gel without destroying the long silica molecule chains that gave the gel its structure.

Holding a piece of aerogel is an uncanny experience. It’s so light it feels nearly weightless, like a chunk of solidified fog or smoke. It feels a bit like Styrofoam, and it squeaks when you rub your finger on it. It’s strong enough to support many times its own weight if the load is distributed evenly. But bend it or squeeze it too hard, as one Wired News editor discovered, and a chunk of aerogel will shatter into tiny fragments.

Ordinary gels, like Jell-O, are comprised of tangled chains of molecules — polymers — surrounding empty pockets of a liquid, such as water. If you try to dry out a cube of Jell-O at room temperature, the surface tension of the liquid will cause the polymer structures to collapse as the liquid evaporates. The result is that the gel cracks, shrinks and eventually crumbles to dust.

Modern scientists make aerogel by pressurizing and heating an ordinary gel to its “supercritical” point, where the liquid’s fluid and gaseous phases are indistinguishable, and then draining off the supercritical liquid. Because there’s no gas-liquid interface, there is no surface tension and so the liquid can be removed without destroying the gel’s polymer structure. With the liquid gone, air fills up the spaces between the polymers, and the result is a meringue-like aerogel.

Scientists aren’t sure why aerogel works so well as a cosmic duster. One theory, says Brownlee, is that the porousness of the material gives particles a chance to slow down as they smash through the nanometer-scale silica structures. As they go, the particles pick up a “paint” of melted glass on their front edge, which protects them from further collisions with the structure until they come to rest.

The transparency of aerogel was also critical to the Stardust mission because it allowed scientists to find the particles by following their tracks through the material.

Back on Earth, that porousness (aerogel can be up to 99-percent air) makes aerogel an ideal thermal insulator. So it’s no surprise that companies are investigating commercial uses for this material, ranging from windows to home insulation to clothing.

Such a wealth of useful properties makes aerogel interesting not only to rocket scientists, but to entrepreneurs and venture capitalists, who sunk $50 million last year into Aspen Aerogels, a company devoted to commercializing aerogel.

“As an insulator, aerogel is two to four times more efficient than anything else out there,” said George Gould, the director of research for Aspen Aerogels.

Aspen Aerogels makes economical aerogel textiles by impregnating “blankets” of fabric with silica gel, then pressurizing the impregnated fabric and extracting the now-supercritical liquid. The result is a flexible fabric with aerogel integrated into its matrix.

Prices for the material vary, but a typical price is a few dollars per square foot for quarter-inch thick material. When Aspen Aerogel’s second factory is completed later this year, Gould said, the company will be able to produce 100 million square feet per year of its aerogel textiles, bringing costs even lower.

Aspen’s products have been used to to insulate the pipelines used in deep-sea oil drilling operations, in winter jackets by Burton Snowboards and even to make shoe inserts.

Other commercial producers of Aerogel include Aerogel Composite and a Swedish company, Airglass, which sells aerogel-based insulated windows.

The problem these companies face is that, while aerogel is a vastly superior insulator, the alternatives (like fiberglass or plain glass windows) are dirt-cheap.

The high pressure needed to create aerogel (around 800 pounds per square inch) means that producing even a tiny amount requires costly lab equipment. You can buy aerogel samples on eBay but they cost around $30 to $50 for small, nickel-sized chunks.

That means aerogel is unlikely to play a major role in construction or clothing unless its makers can bring the price down much further — or capitalize on its space-age reputation enough to make customers willing to pay extra for cachet.

“The costs are not necessarily prohibitive,” said Gould. “Relative to something like fiberglass, the costs are certainly greater but a lot of it has to do with capacity.”

Link: A Solid That’s Light as Air

Link broken? Try the Wayback Machine.

A Solid That’s Light as Air

Search two-fer.

I’ve got not one, but two stories about search engines appearing today.

Here Comes a Google for Coders, on Wired News, talks about a startup search engine called Krugle, which will let programmers find source code and documentation online. Krugle debuted last week at Demo. My story adds some details about how Krugle works and its business model that haven’t been covered in the press yet, as far as I can tell. (Krugle’s chief blogger Chris Locke blogged the story with some nice comments here. Chris’s comment: “And he actually interviewed people! (Wow, a wrinkle like that could really catch on.)”)

And over on Technology Review, my story Google’s Private Lives investigates the “Share Across Computers” feature of the new Google Desktop 3. This feature lets you search for files on more than one computer–but in the process, it stores files on Google’s servers, rendering them vulnerable to secrete government subpoenas.

Update 2/17/06: My Krugle story got Slashdotted. The Krugle folks say it boosted their site to the #1 search on Technorati today. Amazing. Now let’s see what they do with their newfound fame: They’ve promised a lot, and what they have to do next is deliver.

Search two-fer.

Google’s Private Lives

A new search technology from Google makes it possible for law enforcement officials to examine personal documents from your hard drive, without your knowing it, according to the digital-rights advocacy organization Electronic Frontier Foundation (EFF).

Released last week, Google Desktop 3, the latest version of the company’s desktop search utility, adds a “Search Across Computers” feature that automatically uploads files from a user’s computer onto Google’s servers. Then, when a search is performed on any computer owned by the user, Google Desktop will pull search results from both the Web and information stored on all the user’s computers.

Certainly, such a feature will be handy for anyone trying to coordinate a project from different locations. Yet the idea of turning over private files to a public company is worrisome to privacy advocates. In fact, in a press release, the EFF has urged consumers to avoid the Search Across Computers feature because it would make consumers’ files more vulnerable to subpoenas from government investigators as well as private litigants.

Of course, it’s headlines news that Google (as well as its competitors) has already given in to pressure from a national government, by excluding censored content from its Chinese portal (Google.cn). Although so far the company has resisted a U.S. Department of Justice subpoena asking it to turn over logs for millions of recent search terms, smaller subpoenas — such as those for the search history of a particular user’s IP address — don’t make the news, because they’re often sealed.

EFF staff attorney Kevin Bankston says that files on a service provider’s computers, such as those stored by Google, would be easier for law enforcement to access because a subpoena would be issued to the provider, rather than the user. In some circumstances, as with Patriot Act requests, Google would not even be required to notify the user that their files were being turned over. Because of the secrecy of such investigations, it’s impossible to know how many such subpoenas have actually been issued. However, says Bankston, “It’s fair to assume that Google — and all the other search engines — have received and complied with this kind of request in the past.”

“This is every text document on your computer that you’ve set Google to index,” says Bankston. “Unless you’ve individually marked all of your private files [not to be indexed], you are going to be putting your most private data on Google’s servers.”

Google spokesperson Sonya Boralv counters that the company is taking measures to protect the security and privacy of individuals. For one thing, the Search Across Computer feature gives users control over what they upload to the Google servers, allowing people to exclude specific files or types of files. Furthermore, Google Desktop encrypts files before transmitting them to and from Google, and they’re stored in encrypted form on Google’s servers. In other words, they can’t be easily snooped in transit. Finally, Google deletes personal files from its servers as soon as they’re downloaded to a user’s computer; and if the files aren’t downloaded, Google deletes them after 30 days.

However, Bankston points out that, since Google Desktop uploads files whenever they’re accessed, frequent users will be continually refreshing Google’s servers with the latest copies of their personal files. Google provides a button for clearing all one’s personal files stored on its servers, but deleted files may reside there for as long as 30 days, according to Google’s Boralv.

To be fair, since Google Desktop is intended for power users, its Search Across Computers feature is not turned on until a user indicates his or her acceptance of the company’s privacy policy. “We’ve tried to take really proactive steps to make sure that people know where their data is going, and how it’s going to be handled,” says Boralv. “Our role as a service provider is to make it really easy for them to make an informed decision.”

Despite these controls, though, privacy advocates are concerned that most people won’t understand the implications of uploading their files to a public server. Boralv says that Google has a key to unlock the encrypted files stored on its servers. And, as its privacy policy states, the company will turn over personal information, including users’ stored files, to comply with law enforcement requests. And the ongoing controversy over the federal government’s secret surveillance of U.S. citizens makes such a possibility more than just theoretical.

“There’s a parade of horrible things that could happen” when files are stored on a service provider’s servers, says Jonathan Rosenoer, an attorney and author of Cyberlaw. “You’ll never know if you’re spuriously a target of investigation, and the government has gone fishing through your files.”

To its credit, in its privacy policy, Google informs users of its obligations to law enforcement and discloses how the Search Across Computers feature works — at least it explains it for those who understand it.

“We’re not blaming Google for the state of the law,” says Bankston. “[But] if they want to ‘not be evil,’ they should be mobilizing resources towards reforming the law and educating the public about its risks. And, until then, they should be designing around the law,” for example, by using peer-to-peer file-sharing technologies instead of storing files on Google’s own servers.

Google spokesperson Sonya Boralv counters that the company is taking measures to protect the security and privacy of individuals. For one thing, the Search Across Computer feature gives users control over what they upload to the Google servers, allowing people to exclude specific files or types of files. Furthermore, Google Desktop encrypts files before transmitting them to and from Google, and they’re stored in encrypted form on Google’s servers. In other words, they can’t be easily snooped in transit. Finally, Google deletes personal files from its servers as soon as they’re downloaded to a user’s computer; and if the files aren’t downloaded, Google deletes them after 30 days.

However, Bankston points out that, since Google Desktop uploads files whenever they’re accessed, frequent users will be continually refreshing Google’s servers with the latest copies of their personal files. Google provides a button for clearing all one’s personal files stored on its servers, but deleted files may reside there for as long as 30 days, according to Google’s Boralv.

To be fair, since Google Desktop is intended for power users, its Search Across Computers feature is not turned on until a user indicates his or her acceptance of the company’s privacy policy. “We’ve tried to take really proactive steps to make sure that people know where their data is going, and how it’s going to be handled,” says Boralv. “Our role as a service provider is to make it really easy for them to make an informed decision.”

Despite these controls, though, privacy advocates are concerned that most people won’t understand the implications of uploading their files to a public server. Boralv says that Google has a key to unlock the encrypted files stored on its servers. And, as its privacy policy states, the company will turn over personal information, including users’ stored files, to comply with law enforcement requests. And the ongoing controversy over the federal government’s secret surveillance of U.S. citizens makes such a possibility more than just theoretical.

“There’s a parade of horrible things that could happen” when files are stored on a service provider’s servers, says Jonathan Rosenoer, an attorney and author of Cyberlaw. “You’ll never know if you’re spuriously a target of investigation, and the government has gone fishing through your files.”

To its credit, in its privacy policy, Google informs users of its obligations to law enforcement and discloses how the Search Across Computers feature works — at least it explains it for those who understand it.

“We’re not blaming Google for the state of the law,” says Bankston. “[But] if they want to ‘not be evil,’ they should be mobilizing resources towards reforming the law and educating the public about its risks. And, until then, they should be designing around the law,” for example, by using peer-to-peer file-sharing technologies instead of storing files on Google’s own servers.

Link: Google’s Private Lives

Link broken? Try the Wayback Machine.

Google’s Private Lives

Here Comes a Google for Coders

For most people, open source is a synonym for free software. But for programmers, open source is about sharing code, building on the work of others and not having to reinvent the wheel — at least, that’s the ideal. In practice, code reuse remains very low, because it’s often too hard for programmers to find relevant bits of code for their applications.

A new search engine for programmers promises to alleviate that problem by making it easier to find and share code. That in turn could increase programmers’ productivity and give a fresh boost to the open-source movement.

Krugle, which launches officially next month, indexes programming code and documentation from open-source repositories like SourceForge and includes corporate sites for programmers like the Sun Developer Network. The index will cover around 100 million pages of what company founder Ken Krugler terms the “technical web” — high-quality technical pages for professional programmers. (By contrast, Google’s index covers about 11 billion pages.)

“This winds up being a window on all the open-source code in the world,” said Krugler, who estimates the Krugle index will contain between 3 and 5 terabytes of code by the time the engine launches in March.

The new service joins other source-code search engines like Koders and Codefetch, but Krugle intends to differentiate itself by allowing developers to annotate code and documentation, create bookmarks and save collections of search results in a tabbed workspace. Saved workspaces have unique URLs, so developers can send an entire collection of annotated code to a co-worker just by e-mailing a link.

Krugle also contains intelligence to help it parse code and to differentiate programming languages, so a PHP developer could search for a website-registration system written in PHP simply by typing “PHP registration system.”

Greg Olson, a co-founder of early open-source success story Sendmail and a consultant with the Olliance Group said Krugle will make it easier to reuse program components — something that the open-source movement has long promised, but never effectively delivered on. (Olson advised Krugle on the startup’s open-source usage.)

“It’s so cumbersome now to use tools like Google to search for code that the majority of programmers just write their own code,” said Olson — even if they know that an open-source component is probably available that would meet their needs. “If you can’t find the pieces, it’s too frustrating to try to reuse components. But if you can reuse components, you can get a factor-of-10 improvement in productivity.”

Simon Phipps, the chief open-source officer for Sun Microsystems, said Krugle could be useful as a learning tool, but the many different licenses that apply to open-source code are a potential stumbling block. In addition to the widely used Gnu Public License, Mozilla Foundation projects have their own licensing terms — and copyright holders may retain some rights even in otherwise publicly available open-source code, said Phipps.

“Let’s say you turn up a bit of code that’s licensed under the GPL … if you use it, that means your whole project needs to be licensed under the GPL. I hope that people are aware of these issues, because the licensing situation could get pretty hairy.”

Krugle will make money from advertising on its free, public search engine. The company is also planning to create an enterprise edition, due in 2007, to facilitate code-sharing within companies.

Link: Here Comes a Google for Coders

Link broken? Try the Wayback Machine.

Here Comes a Google for Coders

Another iPod request.

Dear Steve Jobs:

Next time you update the iPod and iTunes, can you please make the music styles listed in the equalization settings the same as the default music styles listed in the “Genre” field for each song? That way my iPod could automatically adjust the EQ based on the genre of each song. It would be a lot easier than going all the way up through the menus, then back down into the EQ section, then finding the appropriate setting and selecting it. By the time I finish doing all that the song is half over already. Honestly, Steve, the whole process reflects badly on your legendary obsession with good user experience. It’s as if two completely separate teams were designing those two parts of the iPod. What, your engineers don’t talk to each other? Anyway, you know how terrible AC/DC sounds on the “Jazz” EQ setting. Thanks.

Sincerely,

Dylan Tweney

Another iPod request.