Though the wing-flapping contraptions of early human flight haven’t quite caught on, researchers think birds may still have something to teach us about navigating the air: how to land. MIT researchers have made a system that can bring a modified glider to an elegant bird-like stop, causing it to set down on its tail.

Russ Tedrake of MIT’s Computer Science and Artificial Intelligence Laboratory and his student Rick Cory developed the computer model to bring a basic foam glider to a unique landing. The principle behind the plane’s stop is the same one used by stunt planes–stall. When its wings tilt back, the plane loses lift and falls from the sky. Traditional planes don’t use this method to land because the airflow is chaotic (see smoke visualization above) making it hard to predict how the plane will behave.

Birds come to a stop by tilting their wings back at sharp angles. This creates turbulence and large, unpredictable whirlwinds behind the wings. If an airplane pointed its wings up in this way, it would lose lift and fall out of the sky. But MIT researchers wanted to take advantage of stall–specifically, post-stall drag–to help a plane come to a controlled landing. [Popular Science]

Video after the break.

Tedrake and Cory developed a computer program to control the glider with a steering motor attached to its tail. The program predetermined the best flight paths to bring the glider to a safe landing, and also how to correct or switch courses if it veered too far off the path.

For a range of launch conditions, they used the model to calculate sequences of instructions intended to guide the glider to its perch. . . . Cory and Tedrake also developed a set of error-correction controls that could nudge the glider back onto its trajectory when location sensors determined that it had deviated from it. [MIT]

They launched the 90-gram craft from 12 feet away from its landing wire, in winds between 13 and 19 miles per hour. Though they don’t predict a passenger plane landing like this anytime soon, they think the technique might prove useful for flying robots that could perch and recharge their batteries on a power line. With more research, they might also make craft that use other bird strategies.

The researchers say they are continuing the research and will next be moving outside into real-world conditions. They also plan to explore the use of flapping wing vehicles as well as more typical propeller driven aircraft. [Wired]

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80beats: Flying the Sunny Skies: Solar-Powered Plane Completes 2-Hour Test Flight

Image: Courtesy of Jason Dorfman (MIT/CSAIL).
Video courtesy of Russ Tedrake and Rick Cory

As you read this, forceful explosions are rocking the planet, covering it in mushroom clouds. Thankfully, nuclear winter isn’t going to befall us quite yet. These explosions are caused by biological cannons rather than man-made bombs and the clouds they produce are mere millimetres high. They are the means by which peat mosses disperse their spores.

There are over 285 species of peat moss, all belonging to the genus Sphagnum. They are among the most common plants in the world, growing in the cold, moist parts of the Earth and covering about 1% of its land. They rely on the wind to disperse their spores and all of them face a similar problem. They grow in flat mats, which hug the ground at a level where the air is relatively still. Ideally, they need to get their spores into the ‘turbulent boundary layer’ – a zone up to 10cm off the ground, where swirls of air and sideways currents can carry the spores over long distances.

Most species place their spores at the end of stalks, but even these only stick out a centimetre off the ground. To get the spores even higher, the peat mosses shoot them out, using their stalks as mini-cannons. Each one has anywhere from 20,000 to 250,000 spores loaded into a round capsule at its tip. On sunny days, the capsule dehydrates and collapses inwards, transforming from a sphere into a cylinder and squashing the air inside it. Soon, the pressure becomes too great and the capsule literally blows its top, shooting out both spores and air.

The whole process takes less than a hundredth of a millisecond. The spores are ejected at around 30 miles per hour at around 32,000 times the force of gravity. And they reach a height of around 10 centimetres, more than enough to reach the turbulent layer of air above the moss.

But this isn’t the whole story. Despite its forceful launch, the spore shouldn’t be able to reach that height. Given its initial speed, it should get to a maximum height of no more than 7 millimetres in less than half a millisecond. In reality, it goes far higher for much longer. After 5 milliseconds, the average spore has already risen by 4 centimetres, with only vague signs of slowing down.

To solve this mossy mystery, Dwight Whitaker from Pomona College and Joan Edwards from Williams College filmed the firing of the spore cannons. The action is so quick that they had to use ultrahigh-speed cameras that shoot up to 100,000 frames every second. These videos revealed that each launch is accompanied by a tiny mushroom cloud. These clouds are rolling haloes of air called ‘vortex rings’. It’s these rings that give the spores the extra boost they need to rise above it all.

Vortex rings are produced when a ball of fluid (in this case, the air trapped in the capsule) moves through larger mass of fluid (in this case, the atmosphere). As the ball of capsule air explodes outwards, its leading edge pushes the molecules of the surrounding air apart. But remember that air has friction – because of this, the outer layer of the ball is pulled outwards only to roll back in on itself later. The result is a moving doughnut of air – a vortex ring. You can see this happening more clearly in the animations on this page.

Squid and jellyfish commonly produce vortex rings behind them to push themselves along. Humans make them whenever we blow smoke rings. Dolphins produce them sometimes by blowing water rings. But this is the first time that anyone has found a plant that can create its own vortex rings. The fact that the low-lying peat mosses can shoot their spores to such a height is a crucial element of their success.

Reference: Science http://dx.doi.org/10.1126/science.1190179

Images by Clara Hard, Dwight Whitaker and Joan Edwards

More amazing plants:

• Tobacco plants foil very hungry caterpillars by switching pollinators to hummingbirds
• The 13,000-year old tree that survives by cloning itself
• Review: Royal Institution Christmas Lecture – the 300 million year war
• Ancient plants manipulate insects for hot, smelly sex
• Flowers change colour and back again to advertise their opening hours
• 2,000 year old “Phoenix” seed rises from the ashes
• Orchid lures in pollinating wasps with promise of fresh meat

If the citation link isn’t working, read why here

Darryl Cunningham, who took down homeopathy and Andrew Wakefield in comic form, has turned his attention to the Moon Hoax. His cartoon about it is very well done and worth checking out.

At TAM8 I was accosted by an honest-to-Armstrong Moon Hoax believer. I was surprised, as this particular species is very close to extinction, even in the wilds of places like YouTube. Perhaps I’ll tell that tale in detail sometime, as it was interesting, but suffice to say that while I was happy to be interviewed by him at first, his persistent and accusatory sideswipes at me (and My Close Personal Friend Adam Savage™) at the meeting quickly grew tiresome, and I told him to go away. I would’ve talked to him, but it was obvious that he couldn’t take "no" for an answer — he clearly had an arsenal of things he wanted to confront me with, and I knew if I engaged him I’d never get away from him. It was a matter of return on investment; spend an hour or more debunking his claims, or go have skeptical fun with friends I only get to see once per year during the short time we’re together at TAM. Hmmmm… but too bad. It would’ve been interesting to talk to him about all this, but he made it impossible.

Since I’ve moved to Discover Blogs I suspect my readership has changed a bit. I have the results of a previous survey from early in 2010, back when I was at ScienceBlogs, but haven’t posted on it in detail. I’ll try and do that in the next few days, but I also will put up a survey for this incarnation of the weblog to see if there are changes. I’ll ask the standard demographic questions (age, sex, race, income, education, etc.), but the comments are open if you are curious about something about the readership of this weblog and would like me to include a question regarding that issue. I can’t guarantee I’ll add it, but I might.

Additionally, I want to highlight that I have a personal delicious feed going. That’s where I usually get the stuff for “Daily Data Dumps.” If you want to subscribe, the RSS address for that is http://feeds.delicious.com/v2/rss/gnxp?count=15. I also contribute to two other blogs, Gene Expression Classic and Secular Right. If you subscribe to my total feed you can get all the content of this weblog, as well all the posts for those two blogs, as well as my periodic contributions to Comment is Free at The Guardian.

Finally, some blogs which you might not know about, but perhaps should. A Replicated Typo, on the evolution of culture (with a focus on language). And I can’t recommend Genomes Unzipped enough. What blogs are you reading out of curiosity? I “circulate” my RSS feed subscriptions a fair amount outside of a core set.

David Dobbs has a long measured response up to David Appell’s strange argument that Pepsi’s “free speech” rights were violated during the recent ScienceBlogs kerfuffle, by way of which he casts some aspersions on the character and agenda of specific bloggers. Here’s the thing about Appell, he has a long history of confused and surly criticisms and interrogations of others and himself. I know that history because I first became familiar with Dave Appell in May of 2002. In between pointers and commentary on physical science, his primary beat as a science journalist, he would offer some personal reflections, frustrations, and worries. I’m not big into bloggers who “overshare,” especially science bloggers, so I tried to ignore that as I focused on the substance of Appell’s posts.

But he popped up again in subsequent years with what I felt to be peculiar and emotionally driven behavior. First, in early 2007 I heard Rod Dreher offer a long explanation and apology on NPR for his support and subsequent opposition to the Iraq War. Dreher was heartfelt from what I recall, and didn’t soft pedal his faults which led him to his initial opinions. Well, that wasn’t enough for Dave Appell, he sent Dreher a nasty note where he stated that hoped that Dreher would burn in hell for the suffering that he caused. For someone who believes in free speech Appell certainly does not incentivize public candor about error. If you do something stupid, and perhaps even foul, keep your mouth shut! Then in 2008 he had a relatively widely linked post up criticizing the whole enterprise of blogging and the blogosphere. He concludes:

So more and more I am focusing on real writing, detailed reporting for magazines where you can do some real investigation and reporting and your audience isn’t just people reading over their calzone at lunch. I don’t want to end up some vapid blogger who tries to say everything and so who says nothing whatsoever. Life is too short. I’m really not sure what the solution is.

Two years on he’s obviously still reading blogs, still blogging (posting YouTube clips and updates on his kittens even!), and commenting on the situation of the blogosphere. He even wants to broaden the discussion and let a thousand flowers bloom.

Sometimes when the message seems a bit muddy, it’s not because you lack powers of perception. If you see the byline “Dave Appell,” and it doesn’t have to do with atmospheric physics or such, update your priors! (or better yet, click away)

A depression near the Bahamas is now on the verge of being upgraded to tropical storm status, which would make it TS Bonnie. What is troubling about this one is the forecast track–possibly toward land across the slick. Fortunately, the system is not currently forecast to become a hurricane due to its surrounding conditions, but even a tropical storm is trouble for the ongoing disaster in the Gulf:

Jeff Masters has a lot more on the storm that may soon be Bonnie.

I’ve said many times already that I have a lot of fears about this hurricane season. Now, it seems the tropics are starting their firing. Let’s hope I’m not right in my concerns.

We know that the Search for Extraterrestrial Intelligence (SETI) is often strapped for cash. But what if the aliens out there trying to reach us, rather than being far superior technologically and beaming signals in all directions, are actually starving scientists, too?

In a pair of papers in Astrobiology, three members of the Benford family—Gregory, an astrophysicist and sci-fi author; James, president of Microwave Sciences; and James’ son Dominic, of NASA—ponder the possibility of E.T. trying to reach us on a budget, and say that we might have to revise the way we hitherto have watched.

Aliens wishing to communicate would probably broadcast at frequencies between 1 and 10 gigahertz, where there is less astronomical background noise than in other wavebands. Most SETI projects tune in to the “cosmic water hole” waveband between 1.42 and 1.72 gigahertz. The reasoning goes that alien astronomers might expect earthly scientists to be looking there anyway as this is the frequency of radiation emitted by interstellar hydrogen and hydroxyl clouds [New Scientist].

But, the Benfords say, it would be more cost-effective from the aliens’ perspective to transmit closer to 10 GHz. Given the energy needed to continuously broadcast in all directions, the authors say that aliens probably wouldn’t do that either. Instead, it’s more likely they send short pulses, and that they do it across the plane of the galaxy toward as many stars as possible.

“This approach is more like Twitter and less like ‘War and Peace,’” said James Benford [Space.com].

The problem, then, becomes picking out a tweet from the noise in space. The best candidates, the Benfords say, would be brief flashes that shone for a few seconds and then vanished. Because those kinds of signals have been spotted before, they’re trying to get scientists to comb the records for possibilities. But, there are other possible explanations for this kind of phenomena, like flare stars and pulsars.

We don’t have to just sit and watch, either. The Benfords propose a way for humans to create the kind of signals they say aliens are likely to make, and might therefore expect. However, for astronomers focused on cost-cutting, they’re talking about an awful lot of money.

They calculated that a galactic-scale beacon, with an antenna roughly a half-mile (0.9 km) wide with a range of a little more than 1,000 light-years, could be built for $1.3 billion. It would cost $200 million annually to operate. To work economically, it would use only narrow, high-power microwave beams and 35-second bursts aimed at each target star. “Of course, if you want to send a message, first you have to find a billionaire for this,” Gregory Benford [says] [Space.com].

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DISCOVER: Who’s Out There?
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DISCOVER: Is Anyone Out There?

Image: flickr / Tama Leaver

Researchers at Antarctica’s McMurdo Station may face annual average temperatures of minus .4 degrees Fahrenheit and drifting snow of depths around five feet–but at least they have easy access to cash. Since around 1998, Antarctica has had an operating ATM.

The blog NeedCoffeeDotCom interviewed a Wells Fargo representative about the challenges of keeping an Antarctic ATM working. According to a vice president in the ATM banking division, David Parker, there are actually two of the machines in the remote McMurdo Station, but one serves exclusively as a back-up that can be “cannibalized” for parts in case the other fails. The machine recycles the station’s limited cash supply, since–beyond chucking dollar bills at penguins–there aren’t many things to do with cash outside the snug walls of McMurdo.

Parker says that the machines were a hard sell at first (the bank wondered “Why would we need an ATM in Antarctica?”), but researchers and workers employed by Raytheon Company have been putting the cash machine to good use for over a decade.

Station workers are trained to perform basic repairs, but Wells Fargo sends a technician every other year for complete machine tune-ups. Parker says that “mission: Antarctica ATM” requires a ten-month preparation process, and notes that the technician must wait in line to get a flight, since all flights are prioritized according to the station’s needs. Trash removal, for example, is ahead of ATM-repair.

The machines themselves are similar to Wells Fargo ATMs in more traditional locales except McMurdo researchers have one perk: no surcharge.

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Image: flickr / TheTruthAbout…

More adorable, breathtaking, and wondrous photos from deep in the North Atlantic at CNN…

When Ikaros unfurled, it unfurled like a spinning top blossoming into a pinwheel. Out in space earlier this month, the center piece of Japan’s solar sail was rotating quickly when it began to extend the arms that had been wrapped up inside. As they stretched out into a stiff X shape, like the stakes that hold a kite taut, the craft slowed to a gentler rotation (a consequence of conservation of angular momentum, like the way a figure skater’s spin slows down when she extends her arms). The JAXA scientists then could let Ikaros stretch the shining sail into a square that spanned 66 feet diagonally.

When Ikaros unfurled, it also breathed new life into a technology that has been dreamed for decades—using the the pressure of sunlight itself to cruise the solar system, and perhaps beyond.

In Brooklyn this week, solar sail enthusiasts gathered for an international symposium. Last night Osamu Mori of the Ikaros team (seen above with a mock-up) was the toast of the party, and a group of experts joined him to celebrate and look forward to a bevy of new explorations. The roster included Planetary Society current director Louis Friedman and director-to-be Bill Nye, NASA’s Les Johnson, Malcolm McDowell of the University of Strathclyde in Scotland, and Roman Kezerashvili of the host New York City College of Technology.

“I feel like they deserve a ticker-tape parade here in New York City,” Friedman said, “rather than just showing up for a scientific conference.”

So far, Mori said, Ikaros has succeeded in stretching out its sail, confirming that it is accelerating under pressure from the sun’s photons, and demonstrating its clever way of steering. Solar cells cover the surface of Ikaros’ sail, which is only microns thick, allowing the craft to create photovoltaic electricity. But the sail also carries small sets of LEDs. When the Ikaros team changes the color of particular lights, they change how much light that side of the sail absorbs, which can turn it. “It creates differential torque,” Friedman told me. “That’s very creative.”

While Ikaros prepares to cruise on a flyby of Venus in the months to come, the Planetary Society’s own project nears a launch. Friedman has long been an enthusiast of solar sailing, and the society previously built a craft that was lost during a launch accident—the price of not having hundreds of millions of dollars to launch your own rocket. But now its new LightSail-1 has passed its design review, and Friedman is angling to send the craft, which weighs just about 10 pounds, as a piggyback on a NASA launch next year.

NASA, too, is back in the game. Johnson, of the Marshall Spaceflight Center, said NASA investigated solar sails in the early 2000s, but the work mostly faded into the background. Now, with JAXA having shown that a solar sail can be achieved, NASA’s solar sail scientists are regrouping. In the hopper, Johnson said, are square sail ideas that look very much like Ikaros and LightSail-1. But NASA also has a much wilder design, a ribbon hundreds of meters long but less than one meter across. Surface area is what matters for solar sails, and different engineers will try any number of designs to find the most efficient.

Nye and the other panelists all praised this nascent solar sailing success as a open door to exploration. These missions, Johnson said, are by far the best way to make round-trips in space. “Most other missions run out of gas,” he says. But here, “as long as the sun is shining, you’ve got thrust.”

Dreamers like Friedman and Nye even imagine solar sails as the propulsion mechanism of choice to visit other stars. However, once you get too far from the sun you’d need a new way to push your vessel along: Like, maybe, ultra-powerful lasers in Earth orbit beaming a stream of photons across the expanse of space. As you might imagine, we don’t have ultra-powerful lasers in Earth orbit. Someday, though, we might. “You could be driven all over the universe by the momentum of photons,” Nye said.

We may all be long gone by the time that happens. But after so many years of yearning for this to work, Friedman finally has the chance to soak it in. “Of course,” he told DISCOVER, “I’m tremendously gratified to beat the naysayers.”

Related Content:
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DISCOVER: Japan Stakes Its Claim in Space, on the Hayabusa mission

Add one more job to the list–along with vacuuming floors and assisting in surgeries, now robots can try on clothes for you. The company Fits.me is developing a robotic torso for online shoppers that can morph to match shoppers’ body dimensions, creating virtual fitting rooms on clothing websites.

Men can try a demo version of the product on the company’s site. After entering measurements such as neck and waste size, and selecting from three torso types, the site displays what you might look like in a particular shirt. The torso doesn’t morph in real time; instead, the site pulls from a database of pictures–2,000 body size combinations, the company reports, systematically showing users if pinstripes in small, medium, or large will make them look fat. Shirt sellers Hawes and Curtis is already testing a version of the system on their site.

As reported by the BBC, the company next hopes to develop a version of the torso for women. Maarja Kruusma a professor of biorobotics at the University of Tallinn who helped the company develop the system, told the BBC that it’s a difficult task. Women’s clothing comes in more intricate styles, and their torsos are more complicated to model, she says:

“You can’t just take a male mannequin and put breasts on it. That doesn’t work.”

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