Shark behavior is one of the great mysteries of the ocean, and mediocre tags are primarily to blame. Scientists can't understand something they can't measure. Compared with other marine-animal tags, the HammerTag, now in prototype, is cheaper by hundreds of dollars, lasts years longer, and stores up to a thousand times more data. It can record a shark's entire life, and when the shark dies, it will detach-via explosive charge-and float to the surface to make a final data dump.

1) ATTACHMENT

Scientists attach the tag to the shark in two ways. On smaller sharks, they use a small lance. On larger ones, they drill three small holes in the dorsal fin and string a nylon cord through them.

2) NOSE CONE

The nose cone connects the tag to the shark. It remains attached to the shark even after the micro-charge blows.

3) EXPLOSIVE CHARGE

When the device senses that a shark has stopped moving, meaning it's dead, it triggers a micro-charge to fire. The charge separates the bulk of the tag from the nose cone, freeing it to float to the surface, where it can transmit data.

4) PAYLOAD

Constructed as a modular unit, the payload contains a backup battery, temperature sensor, and three-axis accelerometer that can determine whether the shark is resting or in pursuit.

5) SOLAR PANEL AND MAGNETOMETER

The tag's photovoltaic cells can collect energy at two times the distance of vertical visibility, so 100 feet at 50 feet of vertical visibility. Near the surface it can charge the battery in 20 minutes. A magnetometer determines a shark's north-south position depending on the strength of the magnetic field. GPS does not work underwater.

6) FLOAT BODY

A head made from syntactic foam will float a tag to the surface once it detaches from the shark.

7) DEPTH SENSOR

Nested in the foam head, a pressure sensor relays depth information to the central processor.

8) SATELLITE ANTENNA

Providing the shark is near the surface, the ARGOS satellite antenna can transmit up to 120 32-byte packets a day, enough to convey moment-by-moment details or a single-day summary.

This article originally appeared in the May 2013 issue of Popular Science. See the rest of the magazine here.

Changing swords into plowshares and spears into pruning-hooks is an ancient metaphor for turning away from violence and toward peaceful labor. Mike Izbicki, a former Navy midshipman who in 2011 was discharged from service as a conscientious objector, has created a modern-day, literal interpretation of the analogy. He recently transformed an AK-47 that had been used by the Romanian army during the Cold War into a (rather heavy) serving ladle. Here's how he did it:

1. Disassemble the gun: Assault rifles are filled with interlocking parts, many of which don't lend themselves particularly well to reforging. Izbicki took just the metal barrel assembly for his ladle.

2. Set up the anvil: When not busy falling on cartoon character's heads, an anvil serves a vital purpose in metalwork by providing a strong, hard surface against which metal can be shaped by hammer blows. Izbicki purchased an anvil and 5-lb hammer online for $80.

3. Make a forge: Izbicki stacked cinderblocks on top of a large propane stove burner to create his forge. Temperatures inside the cinderblock chamber rose above 2,000 degrees Fahreinheit.

4. Hammer time: Once the metal gun barrel was red-hot from the furnace, Izbicki hammered it against the anvil to change its shape from gun-like to mess-like.

5. Hammers, part two: After removing extra caked-on metal with pliers, the next step was shaping the flattened barrel into a rounded body that could hold liquid. Izbicki accomplished this by hammering the spatula-like shape at an angle.

6. Don't eat with it: Even if the barrel turns into a perfectly smooth and liquid-bearing spoon, this tool should not be used with real food. A gun that's been fired has gunpowder residue on it, which is full of lead and can cause adverse health effects when inhaled or ingested.

Of course, the point of this project was to render the gun useless, not to create a practical utensil. It isn't plowshares or prune hooks, but it is one less gun.

Consider it per-forge-mance art.

See more of Izbicki's project here.

The U.S. Navy's autonomous X-47B drone took off from an aircraft carrier today. This is a big deal in the military world--an airplane that takes off from and lands on an aircraft carrier has the highly valuable ability to fight both at sea and over land.

But this isn't the first time as unmanned aircraft has taken off from a naval ship. Pictured above, the RAE Larynx was hardly the first drone, but it was still in the first generation. World War I saw several attempts at unmanned flying machines, the most successful of which was the Kittering Bug, a bomb-carrying biplane designed to fly a set distance and then crash to the ground. The RAE Larynx was made later, in the interwar years. It had the body of a single-wing fighter, and a powerful engine gave it a top speed of 200 mph, making it faster than contemporary fighters. Carrying an explosive payload and flying toward a target, it was less like a modern warplane and more like a cruise missile.

The Royal Navy tested RAE Larynxs for nine years. The first unsuccessful attempt to launch one from a ship took place July 20, 1927, and the first successful launch occurred September 1 that same year, though the plane was never recovered; the Royal Air Force believes the plane flew about 100 miles, before it got lost.

The British military canceled further development in 1936. The aircraft was inaccurate, had limited range, depended on ideal weather conditions, and was expensive.

None of these problems is expected to plague the X-47B--well except for the costliness (an estimated $813 million). Given that the X-47B has already successfully landed on aircraft carriers, it's unlikely it will suffer the Larynx's problem of getting lost after launch.

Amazing how much better technology gets in a century.

During NASA's 2007 Astronaut Glove Challenge, costume fabricator Ted Southern met fellow competitor Nikolay Moiseev, a Russian space-suit builder. Although each walked away from the competition empty-handed, they formed a productive friendship. Two years later, they entered a glove they built together and won $100,000.

Southern and Moiseev are now building the third generation of a complete space suit, called 3G, in hopes of capturing a piece of the suborbital spaceflight industry-valued at $1.6 billion over the next decade. As companies such as Virgin Galactic, SpaceX, XCOR, and Blue Origin prepare to launch tourists toward the edge of space, Southern says the dangers of the environment have opened up a new market. "It's almost a full vacuum up there," he says.

At about $200,000 each, modern space suits can cost more than the suborbital ticket itself. And most use an inflatable inner bladder and a durable outer restraint layer-a two-layer design that makes them heavy, bulky, and inflexible. Yet "comfort is a big requirement for suborbital flights. These are people paying a lot of money out of pocket," says Jonathan Clark, a space medicine consultant at Baylor College of Medicine.

In 2009, Southern and Moiseev began developing a single-layer space suit that they hope to sell for about $50,000. The designers build it by fusing together pieces of urethane-coated nylon-a durable, airtight, and pliable material. When inflated, carefully positioned seams and metal braces help a wearer maintain flexibility, and internal tubing circulates air for cooling. Ports on the front allow for custom life-support attachments.

The NASA certification process, crucial for any new suit, isn't cheap, so last year Southern and Moiseev sought crowdfunding. The $27,000 they earned has them 90 percent of the way to a finished prototype, and the duo has already begun testing key components for flight certification. The industry has taken note. "We recently had a visit from former astronaut Garrett Reisman," a crew safety specialist for SpaceX, says Southern. "He saw a pressurized [second-generation] suit and was pretty impressed."

INVENTORS
Ted Southern, Nikolay Moiseev

COMPANY
Final Frontier Design

INVENTION
Third Generation (3G) Suit

COST TO DEVELOP
$300,000

MATURITY
6/10

See the rest of the articles from our 2013 Invention Awards section here, and see all of our May issue here.

Semitruck drivers idle their engines to heat or cool their vehicles' cabs-a practice that burns a billion gallons of fuel each year. Small engines on the back of a cab, called auxiliary power units (APUs), get the job done with less fuel, but they're loud and smelly. A team of five Ontario-based engineers and mechanics has devised what may be a better solution: an APU called HYPER that runs on waste heat.

The group originally formed to build a 100mpg car for the 2008 X Prize competition. During one brainstorming session, someone wondered aloud: Why not use energy from a vehicle's exhaust to run an HVAC system? "We did a lot of modeling and realized that the energy numbers made sense," says team member Jack MacDonnell. He and two others decided to work full-time to develop a new kind of APU.

Like a household refrigerator yet a third the size, HYPER chills air by depressurizing a liquid refrigerant under high pressure into a gas-a process that absorbs energy. The gas then condenses to start the cycle anew. But instead of using electricity to drive the process, HYPER does it with a semitruck's 660°F exhaust heat. MacDonnell says the APU stores between six and 10 hours of heating or cooling capacity after an hour of driving. Based on early tests, he thinks the device could cut a trucker's yearly fuel consumption by 9 percent and carbon emissions by about 20 tons.

The team is testing HYPER on a retrofitted semi in hopes of selling road-ready devices in 2014. With 2.5 million trucks on U.S. roads, HYPER could make a significant impact-but the team also hopes to retrofit buses, RVs, passenger vehicles, and more. "We would drastically cut emissions, fuel consumption, and be less dependent on foreign oil," MacDonnell says.

HOW IT WORKS

1) 660°F semitruck exhaust heats a refrigerant mixture [red] flowing through an exchanger. The refrigerant's solvent boils from its solute, pressurizing the HYPER system.
2) A second exchanger uses a fan to help cool and condense the refrigerant into a high-pressure liquid.
3) The refrigerant [yellow] passes through a nozzle, flashing it into a gas [blue]. This draws heat from an adjacent fluid loop, cooling it to about 23°F [green].
4) A reservoir stores the chilled fluid.
5) Air blown across an evaporator (fed by chilled reservoir fluid) cools the truck cab.
6) A final exchanger condenses the refrigerant into a liquid to restart the cycle.

INVENTORS
Jack MacDonnell, Dave Gibbs, John Stannard

COMPANY
EnerMotion

INVENTION
HYPER APU

COST TO DEVELOP
$800,000

MATURITY
6/10

Update, April 19, 2013: The article's illustration was clarified to show more detail about how the HYPER APU system works. An error in caption 2) was also corrected.

See the rest of the articles from our 2013 Invention Awards section here, and see all of our May issue here.

Gold, precious forever but especially lately, is a tricky metal. Bound up in consumer electronics, jewelry and the ores that it comes from, gold is difficult to extract, and most modern processes do it with a highly toxic combination of cyanide salts. The cyanide leaches the gold out, but the cyanide can seep into the ground, causing environmental problems and posing threats to human health.

Researchers at Northwestern University recently stumbled upon a solution that uses cornstarch instead. It involves some complex chemistry, but it's cheap, biologically friendly and nasty-ingredient-free.

Led by Sir Fraser Stoddart, a chemistry professor at Northwestern, the team discovered this method by accident when looking for something else. A postdoc named Zhichang Liu was trying to make three-dimensional cubes out of gold and starch, aiming to use them as storage containers for gases and small molecules. But a liquid mixture of dissolved gold-bromide salts and a starch-derived sugar didn't form cubes, it formed needles. This was strange, so the team decided to try to replicate it and tested different forms of sugars.

Alpha-cyclodextrin, a cyclic starch fragment with six glucose molecules, is the best way to isolate gold, they found. "Zhichang stumbled on a piece of magic for isolating gold from anything in a green way," Stoddart says in a statement. The spontaneous bundle of needles is made of thousands of nanowires, each 1.3 nanometers in diameter, which contain a charged gold atom inside four bromine atoms.

The interaction between the starch fragment and the gold allows the precious metal to be selectively recovered from other materials, including platinum, palladium and others. The researchers already developed a process to isolate gold from scraps, and they hope this will lead to an environmentally friendly, cheap way to recover gold from anything. The research is published in Nature Communications.

The humped bladderwort is a flower that's as strange as its name. It grows in mats in shallow water, it doesn't have true roots, and it bears small, inflated, hair-triggered bladders that it keeps underwater. Any time a tiny swimming animal brushes past one of these bladders, the bladder expands, opens its mouth, and then sucks the animal up and digests it. It's like a Venus flytrap and vacuum in one.

Now, an international team of biologists has found yet another weird characteristic of the Utricularia gibba. It has a remarkably efficient genome. Many life forms have lots of DNA that isn't contained in genes, which are defined as stretches of DNA that contain the code for making proteins. About 98 percent of human DNA doesn't code for proteins. For the humped bladderwort, on the other hand, the numbers are practically reversed. Only 3 percent of the humped bladderwort's DNA doesn't either code for a protein or for genetic material that controls the genes that make proteins.

The bladderwort findings come at a time when scientists are still debating the importance of non-protein-coding DNA. Last year, a major U.S. science project named ENCODE tested much of the human non-protein-coding DNA. Biologists are still debating ENCODE's results. Is non-protein-coding DNA important to human health? Or not?

Those aren't questions that a freaky freshwater plant can answer. But the bladderwort's genome does suggest that at least some organisms get by with very little non-protein-coding DNA. The humped bladderwort still has a comparable number of protein-coding genes to other plants, although most other plants have much more non-protein-coding DNA. With about 28,500 genes, Utricularia gibba has more genes than papaya plants, grapevines and a small flowering mustard relative called Arabidopsis thaliana. (But fewer genes than a tomato.)

More importantly, the humped bladderwort still does normal plant stuff, including photosynthesizing, bearing flowers, reproducing and that whole vacuum bladder thing.

Because some plants have a lot of non-protein-coding DNA while others have trimmer genomes, more like Utricularia gibba's, the study authors hypothesized that some species intrinsically tend to destroy non-essential DNA, while some species don't. Neither keeping nor destroying non-essential DNA is better, evolutionarily, the researchers wrote in a paper they published about their findings. It's a neutral process that's helped give rise to the diversity in genome sizes in plants.

That's not to say animals would do fine if they cleared out their non-protein-coding DNA. In plants, there's another common genetic process that may help those that tend to get rid of their non-protein-coding DNA. Many plants have several duplicates of their entire genome-in some plants, it helps make really big fruit-which may protect the essential parts of the genome from deadly mutations. In its evolution, the humped bladderwort has duplicated its genome at least three times, the study authors found.

The researchers published their findings May 12 in the journal Nature.

A molecular imaging study has pinpointed a set of biological markers that could help diagnose post-traumatic stress disorder more accurately, and might even lead to a pharmacological treatment in the future.

The research, published online today in Molecular Psychiatry found that people with PTSD have a greater number of CB1 receptors, cannabinoid protein receptors, and a lower concentration of one of the neurotransmitters that binds to them, anandamide. This provides empirical evidence for the theory that marijuana, which also binds to the cannabinoid system, can help alleviate some of the symptoms of PTSD, although the paper doesn't recommend it as a treatment option.

Animals studies have found that chronic stress decreases the concentration of anandamide, an endocannabinoid neurotransmitter nicknamed "the bliss molecule" that has a very similar chemical structure to THC. Recentresearch has suggested that the endocannabinoid system might play a part in working through traumatic memories.

Endocannabinoids bind to two types of receptors throughout the central nervous system. Cannabinoid type 1 receptors, or CB1 receptors, help mediate various processes including mood, appetite and memory. People with PTSD had significantly more of these receptors in their brain compared to the study's control group, including those who had been exposed to trauma but didn't develop PTSD.

When the brain identifies too-low levels of anandamide, it increases the number of CB1 receptors in response to ensure that it can grab them all. It's unclear whether a greater availability of CB1 receptors puts people at risk for PTSD, or if it's a result of the condition, according to lead author Alexander Neumeister, a professor of psychiatry and radiology at the New York University School of Medicine.

Using brain scans that illuminated CB1 receptors, the study looked at the brains of 60 volunteers, some with PTSD, some with a history of trauma and some with neither. Women had higher levels of CB1 receptors in brain regions associated with fear and anxiety, consistent with the fact that women are much more likely to develop PTSD than men. According to the U.S. Department of Veterans Affairs' National Center for PTSD, 10 percent of women develop PTSD, compared to 5 percent of men. Scientists can't really explain why yet. Neumeister says it could be a biological phenomenon that women have higher levels of CB1 receptors and are therefore at greater risk, but it's most likely a consequence of trauma.

In general, scientists aren't sure why some people develop PTSD in response to traumatic events, while others do not, and so it remains a difficult condition to diagnose. "In most cases [experiencing trauma] does not change the life of people in a fundamental way, but there's an important sub-group out there that when they experience trauma, it changes their life," Neumeister explains.

Ideally, treatment should begin as soon as possible after a traumatic event. With an objective biological marker, the condition could be more rapidly diagnosed, so that patients could begin receiving treatment sooner. By looking at CB1 receptors, anandamide and cortisol levels, Neumeister and his team were able to correctly classify 85 percent of PTSD cases.

This could also lead to a pharmaceutical treatment for PTSD. "What we have currently doesn't work. That's the sad truth," Neumeister says.

"There's a consensus among clinicians that existing pharmaceutical treatments such as antidepressant simple do not work," he said in a press statement. "In fact, we know very well that people with PTSD who use marijuana -- a potent cannabinoid -- often experience more relief from their symptoms than they do from antidepressants and other psychiatric medications."

Neumeister isn't pushing for smoking pot to combat the symptoms, though. "I'm very much an advocate against smoking pot as a treatment for PTSD," he says. That's partially because chronic marijuana usage has been found to a decrease the amount of CB1 receptors in the brain, in effect mimicking PTSD, increasing anxiety and irritability.

Instead, he's focusing on developing a medication that could block the degradation of anandamide, balancing the endocannabinoid abnormality in the brains of people with PTSD. He's still waiting on funding to start clinical trials, although he has completed several animal studies. He says this study shows that the animal models can easily be extended to humans, which isn't always the case. "The beauty of these results is we could replicate something in living people with PTSD."

His research has piqued the interest of the Department of Defense, a potential funder with a huge stake in finding effective treatments for post-traumatic stress disorder. According to the U.S. Department of Veterans Affairs, between 7 and 8 percent of the U.S. population will have PTSD at some point in their lives, and as many of 20 percent of veterans of the wars in Iraq and Afghanistan deal with it.

[Science Daily]

Noticed any outages on your bank's website over the past year? They could have been the work of Iranian hackers. Hackers that intelligence officials identified as Iranian have affected some of the biggest U.S. banks, including JP Morgan Chase, Bank of America, Wells Fargo, Citigroup and others, Reuters reported.

The U.S. Federal Bureau of Investigation plans to arrest some of the bank attackers, bureau executive assistant director Richard McFeely told Reuters. Such online criminals often don't get caught, but the bureau is hoping arrests will help convince more companies to cooperate in FBI investigations. Banks are sometimes reluctant to cooperate because they don't want to reveal how much they've lost to online theft.

The FBI recently briefed bank officials about the attacks, Reuters found. Federal agencies have been more open with private companies about cyberattacks lately. The Washington Post reported last week that Homeland Security warned American power companies about evidence it found of online attacks from Middle Eastern hackers.

This bank briefing and the power company warning both came out of an executive order President Barack Obama signed in February meant to give business execs the clearance they need to learn about cyberattacks the government detects.

[Reuters]

In February, the winner of the prestigious World Press Photo of the Year award came under fire after allegations surfaced that it had been significantly altered. The organization has stood by the photo, but a forensic image analyst, Neal Krawetz, now claims his analysis proves that it is a composite of multiple photos.

The photo in question, an image by Swedish photographer Paul Hansen called "Gaza Burial," shows a group of men carrying the bodies of two children killed in an airstrike through Gaza City. According to the results of a forensic analysis published by ExtremeTech yesterday, it might be a composite of three different photos spliced together and then altered to illuminate the faces of the subjects. The photographer has denied the allegations.

Krawetz, a computer scientist and author who specializes in "non-classical computer forensics," blogged about his reservations with the photo, which he saw after a friend sent him an article on the controversy. By looking at the file's Photoshop save history, the shadow placement in the image and an error-level analysis of the pixels in the photo, Krawetz says he found that Hansen's image was significantly manipulated--a controversial topic in documentary photography.

ExtremeTech wrote:

Hansen responded today in an interview with news.au.com, denying that the image was a composite or in any way fraudulent. He explained his process like this:

World Press Photo has previously defended Hansen's work. Santiago Lyon, the director of photography at the Associated Press and chairman of the 2013 contest jury, said in a press conference earlier this year that "we are confident that the images conform to the accepted practices of the profession" and that some images had been disqualified from the competition based on alteration.

"Paul Hansen has previously explained in detail how he processed the image. World Press Photo has no reason to doubt his explanation," the organization stated to the Huffington Post UK today. But they will be doing some forensic sleuthing of their own in response. "However, in order to curtail further speculation - and with full cooperation by Paul Hansen - we have asked two independent experts to carry out a forensic investigation of the image file. The results will be announced as soon as they become available."

Biology's equivalent of an office copier is a PCR machine. PCR, short for polymerase chain reaction, is now a staple in crime-scene forensics, heredity tests, and organism hijacking. It's a mind-boggling feat. Among billions of base pairs that make up DNA's genetic code, PCR finds exact sequences and, in a couple of hours, makes billions of copies-enough to decode or splice together useful combinations of genes. Professional machines cost about $10,000 dollars each, but Russell Durrett has devised one from PVC pipes, a 150-watt lightbulb, a computer fan, a cheap microcontroller, and a few reagents he ordered online.

1) PILE UP

Stack five pieces of PVC piping to form a silo [right] that holds vials of DNA, heats them with a lightbulb, and cools them with a computer fan.

Top: Drill a dozen or so ¼-inch holes into the top of a slanted adapter (to hold the vials), fit a pipe inside the adapter's base, and cut a square hole in the exposed pipe to match a computer fan's exhaust port.

Middle: Cut the same square port in the top of a straight PVC coupling and hot-glue the fan in place. Drill a hole into the coupling's side, just above the center, and bolt on a clamped lightbulb socket.

Bottom: Drill a hole in a second coupling for a bundle of wires leading to an Arduino Uno microcontroller.

2) WIRE UP

Connect the socket and computer fan to 5-volt relays, and link them to the Arduino. Lead one socket wire to a 110-volt AC power source, and wire a thermistor to the Arduino. Insert the thermistor into a vial containing mineral oil and water, and place it in a vial hole. This gives the Arduino temperature data, allowing it to turn the lightbulb-and heat-on and off.

3) PICK A GENE

Whether you're testing breakfast cereal for genetically modified grains or screening yourself for HIV resistance, pick a gene to copy. You'll need to order from the Internet reagents that can hijack DNA-copying molecules [see "How It Works," on the next page.]

HOW IT WORKS

PCR machines cycle temperature to enable DNA-copying reagents, including primers, nucleotides, and the enzyme Taq polymerase.

201ºF

DNA temporarily unzips into two strands.

131°F

Primers-small pieces of DNA that "prime" replication-attach to the ends of a gene.

162°F

Taq polymerase recognizes the primers, latches on, and copies DNA between them.

. . . And Repeat

In the first five minutes, PCR makes two copies of a gene. Subsequent 30-second cycles continue the doubling. By the eighth cycle, 256 genetic copies exist, and by the 30th-
a couple of hours later-there are more than a billion.

Time: 5 hours
Cost: $50
Difficulty: 3/5

For Durrett's complete build instructions, download this PDF. Arduino code is available here.

This article originally appeared in the May 2013 issue of Popular Science. See the rest of the magazine here.

ABOARD THE USS GEORGE H.W. BUSH, ATLANTIC OCEAN--All that was left on the carrier deck was a cloud of white steam wafting over a flight crew that was visibly bursting with excitement even with faces concealed behind bulky protective headgear, noise suppressing headsets, and darkly tinted goggles. Much of this whooping, backslapping, and enthusiastic embracing took place square in the middle of the flight deck where the Navy's experimental X-47B unmanned, autonomous combat jet had stood just moments before, Pratt and Whitney F100 jet engine screaming--before the robot gave its go-ahead salute--indicated by the a flash of its wingtip lights--and the catapult officer responded with the signal to launch, sending the X-47B catapulting off the carrier deck and into aviation history.

This morning at 11:18 a.m. eastern time, the X-47B became the first unmanned aircraft to ever complete a catapult launch from a carrier deck, an achievement just as momentous as the first launch of an aircraft from a naval vessel more than a century ago. And that's simply where the list of the X-47B's firsts begins.

The X-47B is also the first tail-less aircraft to operate from a carrier deck, which also makes it the first jet, manned or unmanned, with a low observable "stealth" profile to operate from a carrier. It's the first self-piloting, autonomous unmanned jet to fly in any branch of the military. In this writer's experience, it's the first unmanned aircraft that's this ridiculously cool.

Which explains the enthusiasm of the Navy/Northrop Grumman program crew that finally launched their Unmanned Combat Aerial System (UCAS) after years of development (though "combat" is part of the title, the two existing X-47Bs are only technology demonstrator meant to prove technological capability; Navy brass emphasize that it is not intended for active service, nor for weaponization). The team has been hard at work for the past year at Naval Air Station Patuxent River putting its X-47Bs through their paces on a terrestrial carrier simulator.

Noticeably absent from today's demonstration, however, was an arrested landing aboard the carrier. After launching from the USS Bush the air vehicle designated "Salty Dog 502" for the purposes of this demonstration flight made two approaches to the carrier, one at roughly 1,000 feet altitude and another just 50 feet above the flight deck. Both were simulated "wave-offs," where the Landing Signal Officer on deck or the aircraft decides that a landing is not safe and the aircraft aborts touchdown. Instead of eventually landing, Salty Dog 502 turned west and made a 65-minute flight back to Pax River in Maryland, where it landed on a terrestrial runway.

Navy brass on hand explained that while X-47B has already made several arrested carrier-style landings on the terrestrial simulator, it had not yet gathered enough of them to certify it for carrier operations and therefore could not, by Navy rule, return to the Bush. The X-47B's first carrier landings are slated for later this summer (probably July or August), said UCAS deputy program manager Don Blottenberger. And the lack of an arrested landing to cap off the day didn't seem to put a damper on the Navy UCAS team's spirits as the X-47B made passes over the carrier deck before autonomously banking into a flight path toward its home base at Pax River.

"This was one small step for man," Rear Adm. Mat Winter quipped shortly after the flight. "And one giant leap for unmanned kind."

Yesterday the Associated Press reported that the U.S. Department of Justice used subpoenas to collect telephone calling records for many of their journalists and editors. In doing so, the AP brought light to an interesting crisis at the nexus between secrecy, privacy, constitutional boundaries, and modern technology.

The relevant law for wiretapping phone communications dates back to a 1979 Supreme Court decision, which said there is a distinction in privacy between dialing a number and listening to a call; the Supreme Court narrowly limited protection to the latter.

The backstory: Last year, the AP ran an article about an al-Qaeda underwear bomb plot that relied on sensitive information given to the news service by an undisclosed source. The Department of Justice considers leaking classified information to be a national security risk. When someone leaks to the press, the department's policy is to pursue the leak, not the journalists who extracted it.

Which is why the Justice Department went after the AP's phone records. A list of numbers dialed by editors and journalists is in theory a good place to start looking. Under current wiretap law, dialed numbers are not afforded the same protection as calls, and can be obtained without a warrant.

Here's the problem. When the Supreme Court set the legal precedent back in 1979, phone records contained much less information. Nowadays, a phone record's metadata includes not just the phone number, but the time the call took place, the call origin, the call duration, and the carrier.

The Electronic Frontier Foundation, a non-profit dedicated to the protection of digital rights, said in a statement released yesterday that it "no longer makes sense to treat calling records and other metadata related to our communications as if they aren't fully protected by the Constitution."

Electronic communications have improved drastically since the legal precedent was set, and the amount of revealing data now transferred with a phone call is far greater than just a telephone number. But the law has yet to catch up with technology-which means the Justice Department has access to a lot more than just the numbers dialed by the AP's journalists.

After the discovery of the Higgs boson last summer, particle physicists are exploring new avenues to help shed light on how the universe works. But the most intricate physics experiments need ginormous machinery, which is expensive and difficult to build. Rather than construct something from scratch, two of the nation's premier physics labs are repurposing some old equipment. Transferring it to a new home will be a huge undertaking of its own.

In the suburbs outside Chicago, the Fermi National Accelerator Laboratory was once home to the world's most powerful particle accelerator. After its storied Tevatron shut down, Fermilab scientists started looking to muons for the future. Muons are negatively charged subatomic particles, much heavier than electrons, and they're interesting for several reasons, like their incredibly short lifespan: They last only 2.2 millionths of a second.

Muons wobble like a spinning top, and when they're in a magnetic field, they start to rotate. The way they move, called gyromagnetic procession, can tell physicists very interesting things. At Brookhaven National Laboratory, physicists already have a device for measuring muons, so Fermilab scientists are in luck. Except the device is a 600-ton, 50-foot-diameter ring with cryogenically cooled magnets--not exactly easy to ship.

During a visit to Fermilab last fall, I learned about this device from Chris Polly, the project manager for a new muon experiment called Muon g-2. He didn't seem fazed at all by the prospect of getting the huge muon ring from New York to northern Illinois. We have the Great Lakes and the Mississippi, after all.

This week, Brookhaven and Fermilab announced their plans to move the ring on an epic barge journey. The trip will be tense, because the ring's massive electromagnet cannot tilt or twist more than a few degrees, or the wiring inside will be irreparably damaged. It will float from New York Harbor in June, down the East Coast, around Florida, up the Gulf Coast and up the Mississippi River by July.

Once it arrives in Illinois, the ring will be placed on a special truck built for this purpose. Last fall, Fermilab scientists measured the state's highway toll booths to make sure it would fit. It will--with just four inches of clearance, as Polly told me at the time. It will drive at night, to minimize traffic delays.

When it arrives, scientists will re-assemble all the pieces and start using particle accelerators to produce muons, which will whip around inside it. "It's like a holding pen for them; they are going at the speed of light," Polly said.

Muon g-2 will look at some unusual quantum effects that take place on the subatomic scale, which Polly calls a "very strange world." Particles pop in and out of existence, and heavy muons can coax them out. A new muon campus at Fermilab will enable new beams of muons that will end up in the Brookhaven storage ring. The ring produces an incredibly uniform magnetic field, which will allow physicists like Polly to see the particles' weird gyrations and possibly new physics.

Like electrons, muons are in the lepton family. That means they're not composed of other pieces--unlike protons and other hadrons. When hadrons collide, they break up into their constituent bits; when leptons collide, more energy goes into the collision, resulting in strange states of matter. Tiny muons are a big part of Fermilab's future.

Muon 2-g is scheduled to begin taking data in 2016. 

One summer, a young engineer walked into Austin's Park, an amusement center outside the Texas capital, and introduced himself to the manager as an intern from Waterloo Labs-a hacking collaborative sponsored by the engineering juggernaut National Instruments. He and his colleagues wanted to convert the go-kart track into a real-life, crash-happy version of the classic videogame series Mario Kart. The manager didn't just agree. He lent him a kart.

In Super Mario Kart, cartoon drivers zoom around a track littered with interactive objects. Some boost a player's speed, others hijack steering, and many can be launched at competitors. Four interns at Waterloo Labs grew up playing the game, so when someone suggested making a real-world version, they couldn't resist. "We weren't entirely sure how we were going to do it," says intern Tim Lynch, "but we said, ‘Okay, we need to do this.' "

Re-creating the game's interactivity meant that objects on the track had to communicate with speeding go-karts. At first, the team thought of using passive, close-range radio-frequency identification (RFID) tags. The interns tested that idea by tossing their ID cards at a security scanner to see whether the embedded chips transmitted a signal fast enough. "That didn't work," says Humphrey Huang. Next, they tried an active, self-powered RFID system. It cost an extra $500 but could transmit signals as far as 30 feet away, allowing each kart to interact with objects via its own RFID reader.

The interns' biggest hurdle: overriding the kart's controls. "We needed to be able to fight against someone trying to turn the wheel," says Lynch. They eventually selected powerful pneumatic pistons, which they attached to the chassis using zip ties, duct tape, and braces. When a driver captured or collided with an item, a reader would send that item's unique ID to the computer, which, in turn, ordered pistons, valves, or servomotors to swerve, stop, or speed up the kart [see "How It Works," next page].

They tested the hacked kart in the park's garage, tossing plush toys embedded with RFID tags at the vehicle and watching it respond like a living creature. Then-with the track manager's approval-they modified three other racers and added pneumatic cannons so that drivers could fire kart-crippling toys at competitors.

On game day, Huang, Lynch, Dylan Caswell, and Peter Gaylor raced, crashed, and futilely tried to prevent their carts from careening into the railing when RFID-tagged toys took over the controls. Lynch learned to steer with his knees while grabbing objects from the track and loading them into his cannon. Huang shot a plush turtle shell across the track at Caswell, triggering the RFID system in his kart and jamming the brakes. "We were doing lap after lap and thinking, ‘It's actually working,' " says Lynch. " ‘We're actually playing Mario Kart.' "

"LET'S-A-GO!"

The red shell slows down a driver and jams steering. Air pistons attached to the front wheel's tie rods lock it in place, while another piston depresses the brake pedal.

A driver who captures a green shell can stuff it into an air cannon and then launch it toward an opponent to fully stop his kart.

Plastic bananas cause one tie-rod piston to contract and another to expand, forcing the front wheels to the right on the left-aiming track. "We figured that would be most perilous," says Hunter Smith, Waterloo Labs' internship coordinator.

Normally, a spring prevents the throttle lever from opening more than 85 percent. The RFID tag in the plush mushroom, however, triggers a servomotor to pull on the lever-enabling the driver to reach speeds nearing 35 mph.

The lucky driver who grabs a plush star temporarily earns a fully opened throttle, while his Wi-Fi-equipped controller orders all other karts to brake.

(Get the specifics of the project on the next page)

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HOW IT WORKS

Hacking go-karts into the racecars of the Mario Kart videogame series was no simple feat. Four interns from Waterloo Labs began with standard four-stroke-engine vehicles and added components such as ruggedized cRIO computer controllers, Wi-Fi routers, and RFID readers.

1) TOY CANNON
Compressed air fed into a PVC pipe can blast a plush toy at competitors as far as 30 feet away.

2) FASTENERS
Zip ties, brackets, and other removable hardware made all modifications reversible.

3) AIR TANKS
A 3,000psi paintball tank stores 48 cubic inches of air to charge add-on pistons.

4) ELECTRONICS
A suite of gadgets can detect the RFID codes of objects on the track and then control the kart.

5) STEERING
A 130psi air piston attached to each tie rod can steer a kart off-course.

6) BRAKE OVERRIDE
A valve can depress the brake pedal by directing high-pressure air into a piston.

Time: 8 weeks
Cost: $1,200

WARNING: We review all our projects before publishing them, but ultimately your safety is your responsibility. Always wear protective gear, take proper safety precautions, and follow all laws and regulations.

This article originally appeared in the May 2013 issue of Popular Science. See the rest of the magazine here.

Once your adult teeth come in, that's all you've got to work with. Knock one out, or lose a few to decay, and you'll have to get dentures. It's a pain, but at least one team of dental researchers is now studying how to regrow human teeth-by looking at alligator teeth first.

American alligators have 80 teeth, each of which they replace about once a year. Over their long lives, an alligator may regenerate something on the order of 4,000 teeth. So a team of researchers from the U.S., China and Taiwan performed a detailed study of alligator teeth to learn their secret.

Of course, a study of alligator teeth is a long way from being able to grow new human teeth, but that's the eventual goal of research like this. Understanding how alligators regrow their teeth may also help scientists better understand rare geneticdiseases in which people grow extra teeth or tumors from the tooth bed.

To perform their study, the researchers took snapshots of alligator teeth as the teeth cycled through stages of growth. They injected living juvenile alligators with a chemical that helped them visualize cells in the alligators' tissues that were growing and multiplying. They already knew that alligators have small replacement teeth waiting just underneath all their mature teeth, but these new experiments allowed the researchers to watch exactly what happens to the mature tooth, the replacement tooth and the bed the replacement tooth grows from, called the dental lamina, at different stages.

They even pulled teeth from alligators sooner than they would naturally shed, to see how the replacement tooth and dental lamina reacted.

The researchers concluded that the dental lamina likely has stem cells that help it regrow teeth. They also performed experiments to find what genes likely govern 'gator tooth growth.

They published their work in the Proceedings of the National Academy of Sciences.

In the early 1960s, a Soviet astrophysicist, Nikolai Kardashev, was contemplating mysterious radio signals coming from a recently discovered quasar and theorized that they might be evidence of extraterrestrial beings. In 1964, Kardashev debuted a system for categorizing alien civilizations.

Kardashev didn't make it a question of weaponry or space travel. Instead, he measured these hypothetical civilizations by their command of energy. His scale has three categories.

A Type 1 civilization uses merely all the energy on its planet.

A Type 2 civilization uses all the energy in its star.

A Type 3 civilization, the most advanced, uses as much energy as is in its own galaxy.

Never mind whether judging aliens means one is nuts. (And in his defense, Kardashev is head of the Astro Space Center at the Lebedev Physical Institute of the Russian Academy of Sciences.) The Kardashev Scale is an elegant way of describing our dreams, and others have seized on it. Carl Sagan went so far as to devise equations that subdivide the categories into a score, presumably to make the scale more useful, or perhaps less depressing. By his math, if a Type 1 civilization commands a planet's worth of energy, in 1973 we humans rated only a 0.7. The difference between 1 and 2 is a factor of 10 billion.

The scale puts things in perspective. The International Energy Agency's 2012 World Energy Outlook concluded that by 2035 the shift in oil supply and demand could make the United States a self-sufficient oil economy. This year, Citigroup's global head of commodities research suggested that in five years we may need to buy oil from only Canada. Happy news!

We decided, as Kardashev might have, that these are only half measures. So for this issue we went about assembling ideas that could truly revolutionize American energy. And I hope the undersea turbines, conical solar installations, and waste-to-energy systems in this issue inspire you. But I also picture Nikolai Kardashev, arms crossed, shaking his head. Because as he articulated so well, we have a long way to go.

--Jacob Ward

jacob.ward@popsci.com | @_jacobward_

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Focusing on drones as devices of scary military surveillance and execution ignores the entire field of consumer drones--which are, basically, next-generation remote-controlled helicopters. One of the fields that's seeing the most benefit from the new world of drones is photography--suddenly, combined with tiny, amazingly capable cameras, drones can accomplish what in years past you'd need tens of thousands of dollars of crane setups and cameras to do--for only a few hundred bucks. Our friends over at Popular Photography took a look at how this new technology is revolutionizing photography and videography. Check it out here.

Inside the European Southern Observatory's Atacama Pathfinder Experiment (APEX) telescope in Chile, there's a submillimeter-wavelength camera perfectly tuned to peer through the clouds of interstellar dust and gas that obscure our view of what's going on elsewhere in the universe. Fortunately for us, the camera is also good at picking up the faint glow given off by those very same grains of dust, at wavelengths too long for human eyes to see. The result: images like this one a "fiery ribbon" (that's how astronomers are describing it) stretching across a segment of the Orion Nebula some 1,350 light-years away.

But fiery though they may appear, these grains of interstellar dust are actually quite cold. In fact, the coldest objects captured by the APEX telescope have an orange tint, while the hottest objects appear blue.

The ribbon is part of a larger star-forming region within Orion's belt called the Orion Molecular Cloud. The bright cloud at the upper right of the image is the object known as Messier 42, or more commonly the Orion Nebula. It is the brightest part of this massive star-forming region and the closest site of massive star-birthing to Earth.