We approach the Cave of the Mounds, a landmark (so to speak) in Southwest Wisconsin, along a walkway painted with fossils and markings that start at the Ordovician era (450 million years ago), when the limestone beneath our feet was deposited as a rain of sea shells on an ocean floor. Finally, at the cave’s entry, the asphalt calendar enters the last million years, when the cave started to be excavated by flows of acidic water.

The geological markings under our feet are one indication that the cave-men and -women who operate this site are intent on linking past and present, above- and below-ground.

Cave of the Mounds was discovered in 1939 by workers blasting in a limestone quarry on one of the highest spots in southern Wisconsin. Today, it is a tourist destination with a message — a cool, underground mecca, strategically illuminated, where tour guides leave the nettlesome lectures above ground, and offer easy-to-digest science along the cave’s alleyways.

The above ground section of the site features resurrected prairies and oak savannas, but the main attraction is the stalactites hanging over stalagmites, flowstone, the fossils embedded in ancient limestone, and the rare opportunity to see geology at work as you observe the earth from the inside out.

Aftermath of a flood unparalleled

What caused the huge erosion features, ancient shorelines, and scoured potholes in the “channeled scablands” in Eastern Washington state? In 1923, J. Harlen Bretz coined that ominous moniker and proposed that the features had been created by a gigantic flood.

During this time, geology was ruled by a “uniformitarianism” dogma, which highlighted gradual processes like deposition and erosion, and discounted the power of sudden events like floods (and perhaps even earthquakes, tsunamis and volcanoes).

Skeptics demanded to know the source of all that water in an arid region, and Bretz had a reputation as a kook. Then, geologists gradually realized that the ice-age flood had originated to the east, in glacial Lake Missoula, which had been plugged by the lobe of a glacier emanating from Canada.

In the 1950s, the idea that this huge lake had eaten through an ice dam and then coursed downstream with phenomenal power started gaining acceptance, and in 1979, Bretz, age 96, received the highest award from Geological Society of American for solving this great Earth riddle. Today, scientists believe the floods may have recurred every few years or decades as the ice age was waning, around 14,000 years ago.

The evidence for the floods comes in all sizes. Alternating stacks of coarse gravel and fine sand show gravel left by flood currents under sand left by slower water when the floods receded. A dry river bed called the Grand Coulee, in Eastern Washington, was gouged by the astonishing flow of uncorked glacial melt water. The periodic cascades that shaped Dry Falls, now in Sun Lakes State Park are considered the largest known waterfalls in Earth’s history.

The unbearable whiteness of being

The world’s largest field of gypsum dunes, at White Sands National Monument in south-central New Mexico, could arouse anybody’s inner drywaller, as gypsum is the mineral basis for both drywall and plaster. But here, where 275 square miles of gypsum dunes have built a hot, severe and scorchingly beautiful landscape, there’s not a sheet of drywall in sight.

Set aside as a national monument by President Herbert Hoover in 1933, the dunes trace their origin to vast deposits of hydrated calcium sulfate — gypsum — that were laid down on an ancient lake a quarter-billion years ago. After a geological uplift, they were exposed roughly 10 million years ago, and eventually moved to the present site in a geologic eye-blink — the last 7,000 years.

Mammoth tracks have been seen in the dunes, but they could get buried with time: Some dunes are moving 30 feet a year, as the wind piles them up on the windward side and gravity avalanches them down the lee.

The gypsum dunes are said to be the largest in the world, but what’s most amazing is not the geology, but the evolutionary adaptations life has used to survive these harsh conditions. At least seven species of animals, including three lizards, that are closely related to darker varieties living in the surrounding desert have turned white for camouflage in this bleached world. (The drywalling lizard or the plastering mouse must be here somewhere!)

Visiting the Sands? Ponder a trip to Trinity, the site of the first test of the atomic bomb.

Science museums: Try the trifecta!

The Windy City boasts not just one, but three cool science destinations, all next door to each other on the Museum Campus along the shore of Lake Michigan.

To explore some of the world’s biological and cultural wonders, spend the day at the Field Museum of Natural History, a collision of anthropology, botany, geology, paleontology and zoology. The permanent exhibits include the DNA Discovery Center, a journey through four billion years of earthly life, and Sue, the largest (and most expensive?) complete skeleton of the ferocious T. rex. Among the temporary exhibits was a recent one on the horse and its deep relationship with humans (an exhibit that particularly excited one horse-crazy Why Filer).

If your palate is whetted for a wetter world, walk to the Shedd Aquarium to explore underwater life from the Amazon, the Caribbean and both poles. Green sea turtles, beluga whales, moray eels, piranhas and penguins will be among your hosts.

If otherworldly science is more your thing, visit the Adler Planetarium. Chat about the stars with real space scientists at their Space Visualization Laboratory, or just sit back and watch the star show. Adler’s centerpiece is the Doane Observatory, the largest publicly accessible telescope in the Chicago vicinity. While you can only peer through the lens after dark, this could make for a great conclusion to your trip.

Discover a life aquatic

An Australian freshwater crocodile grows in Baltimore. Seriously. The National Aquarium Baltimore boasts more than 660 species of fish, birds, amphibians, reptiles and mammals, totaling around 16,500 marine creatures.

In addition to its rich marine menagerie, the aquarium has a collection of special exhibits and interactive oceanic enjoyment. See the world through a dolphin’s eyes at Our Ocean Planet, a show that teaches visitors about dolphins and the connections between people and their seafaring friends. Or soak in ocean sensations with a movie at the 4-D Immersion Theater, where you can experience sea life in multiple dimensions, including the smell and feel of (simulated) mist and wind. Or take an expert-led tour, including behind-the-scenes peek of the sharks’ quarters.

The aquarium is also a center for conservation. For example, its Marine Animal Rescue Program tracks the progress of rescued animals after release. Other conservation projects include restoring wetlands and investigating the impacts of mercury on the marine food chain. After all, protecting the life that sustains the ocean ecosystem benefits everyone—not just aquarium visitors.

An excursion exotic to Melville

What’s more breathtaking than seeing the world’s largest animals in the wild? Whale watching puts you up close and personal with these magnificent marine mammals. Since the 1950s, in a 180° turnaround from Herman Melville’s day, people have been flocking by the boatloads to glimpse whales doing what they do rather than to kill them.

Both the U.S. east and west coasts have whales to watch, though you must catch them in the right season during their migration. There’s no guarantee, but on the western seaboard, you could spot orcas and gray whales. The east is home to the right, fin and sei whales. Humpbacks, minkes, and blue whales troll both coastlines.

Several cetaceans (a scientific category including whales, dolphins and porpoises) are endangered, including the North Atlantic right, blue, fin, sei and gray whales. In any case, marine mammals are heavily protected by law, so whale watching should be done with professionals who obey the rules.

Celebrating, protecting southern nature

With more than 500 full-time employees and an annual budget exceeding $30-million, Audubon Nature Institute sounds more like a business than a private, non-profit organization dedicated to explaining and preserving the wonders of nature with a Cajun flavor. The group operates a zoo, aquarium and assorted parks in and around New Orleans. The Aquarium of the Americas focuses on the Caribbean, Amazon, Gulf of Mexico (complete with oil-drilling replica) and Mississippi River.

A primate exhibit in the Audubon Zoo shows dozens of our opposable-thumbed relatives. Its 360 species of animals include a jaguar shown in a replica Amazon jungle. The “Embraceable Zoo” is devoted to full-contact animal admiration, and you can also eyeball, if not pet, a prickly Indian crested porcupine. Audubon maintains two locations that focus on captive breeding and survival of endangered species; these are closed to the public, but we expect to see you at the new insectarium, located in the old Federal customs house, for the beetle races on Sept. 3.

North Carolina: decapitation capitol

Every summer, vacationers flock to North Carolina’s coast for a beach getaway. But beach vacations would have been a hard sell early in the 18th century, as the coast was the stomping grounds of the South’s most feared pirate, Edward Teach, otherwise known as Blackbeard.

Nowadays, the area is proud of its sordid past, attracting pirate-curious tourists and archaeologists alike. In 1996, Blackbeard’s biggest and final ship, Queen Anne’s Revenge, was found off the coast of Beaufort, where it had been hiding for more than 270 years. While the dives did not uncover much treasure, archaeologists estimate the wreckage holds up to 750,000 artifacts, some of which are displayed at Beaufort’s North Carolina Maritime Museum.

Blackbeard is a primary local industry. Ocracoke Island, a favored Blackbeard anchorage, was where he met his fate at the hands of what he mocked as a rabble of “cowardly puppies.” Bath has the legendary ball of light, presumed to be Blackbeard’s ghostly severed head.

So why watch Johnny Depp impersonate a pirate at the multiplex when you can check out the history of this famous scoundrel? Like we said, this old, dead, head-free pirate is a godsend for small business…

Tar is my name. Fossils are my fame

If you’re stuck for a scientific sojourn in Southern California, head for the pits. Since long before there was a Los Angeles, the La Brea Tar Pits have been an oozing, 3-D flypaper for animals, now with that all-too-trendy urban accent. Asphalt, we learn, is not just good for roads, but also for trapping live animals and preserving their fossils. Since their first description in a scientific publication in 1875, the pits have produced prodigious prizes for paleontology. The onsite Page Museum houses more than 650 species of plants and animals, all removed from the black goo, and dating back 11,000 to 50,000 years.

The tar pits were a graveyard for thousands of carnivores, including the dire wolf, coyote and saber-toothed cat, and a smaller number of herbivores, including mammoth and bison. In an effort to transcend the “heroic” era of paleontology and flesh out (if we can put it that way) a comprehensive picture of life in the era of ice, researchers have recently shifted their focus to fossils of plants and smaller animals, including millipedes, 31 species of mollusks, and 25 species of beetles.

Listen hard: Hear the galaxies?

Love big? Dig distant, mysterious and unfathomably old? At the Very Large Array, in western New Mexico, you can gawk at 27 giant antennas used by astronomers to “listen” to radio signals from the universe. When you’re done rubber-necking the hardware, check out exhibits at the visitor center.

Then climb an observation tower to get another view of the world’s premier radio telescope zoo. Notice how every single antenna has silently and inexorably changed its orientation, and is now pointing to another invisible spot in the heavens? You are looking at visual proof of our planet’s normally insensible rotation.

It takes a lot of work, and some hefty equipment, to pry loose the secrets of the universe, and here, the scale of the operation is written across the desert. Since 1980, the VLA has, alone or in tandem with other telescopes, been collecting the astrophysical evidence for the formation and destruction of stars and galaxies. The new “enhanced VLA” can “hear” three times as many radio bandwidths as the VLA and is 10 times more sensitive. How sensitive is that? They say it could hear a cellphone calling from Jupiter…

Go under cover in the capital city

Explore life under cover (and the technology that allows a spy to hide in plain sight) at the International Spy Museum, the only public museum of its kind in the United States. With the largest public collection of international espionage artifacts, the museum provides a unique global perspective of this covert profession — said to be the second oldest — and how it has shaped the past and present.

Before you start your mission, you are challenged to adopt a secret identity. As you snoop about, you’ll discover the Secret History of History, which highlights the influence of spies through the ages; gadgets and stories of espionage during the American Civil War, World War II, and Cold War; and a gallery of spy technology. You can even see if you have what it takes to be an agent in the Operation Spy interactive experience, in which you must find a missing nuclear trigger before it ends up in the wrong hands. Just don’t blow your cover!

Visit the “Boneyard”

Warplanes go to the desert to die, and there, for a fee, you can tour thousands of mothballed fighters, bombers and helicopters at the 309th Aerospace Maintenance and Regeneration Center. Bus tours run from the Pima Air and Space Museum, on the outskirts of Tucson, Ariz. With more than 4,200 planes, the “boneyard” is the ultimate in aerial combat nostalgia.

Some of these planes will be scrapped, others may be sold or salvaged for parts, or pressed back into service during future wars. Seldom celebrated, but perhaps more important from a technological point of view, the site also stores 350,000 tools used to make these machines, including, we presume, the one-of-a-kind tools and dies used to shape jet engines, wings and fuselages.

Ogling killing machines may seem macabre, but then, if you are a U.S. taxpayer, you’ve already paid for this stuff… might as well check it out, and witness how the technology of aerial warfare has changed over the decades!

Edison’s Garden of Invention

In 1887, after he had patented the first practical electric light bulb, mega-inventor Thomas Edison invented an inventor’s playground in West Orange, N.J., just outside Manhattan. Edison stocked the lab with every resource needed to crank out movie cameras and projectors, teletypes, recording and playback devices, batteries and countless other electric gadgets for the fast-modernizing nation.

With labs focusing on chemistry and physics, and with shops devoted to woodworking and metal-working, Edison could concentrate on his strong points: cranking out ideas and masterminding publicity stunts that helped ensure his commercial success. During World War I, 10,000 people cranked out electrical devices for the military at the factories clustered around the lab. Edison worked at the West Orange lab until his death in 1931.

Think of Edison as primarily an inventor? Then you have to wonder how his name wound up on the companies selling electricity to New York and Chicago. God may have made the Garden of Eden, but Thomas Edison made the garden of invention in north Jersey, and it awaits your visit.

– David J. Tenenbaum & Jenny Seifert

Wondrous weevils sport super screw!

In animal appendages, some joints resemble hinges. Others, like your hip, are unmistakably akin to the ball-and-socket joint, another mechanical mainstay.

Now, scientists have found a biological screw in a type of beetle called a weevil. Obliquely described as having “rotational movement combined with a single-axis translation,” the new screw-and-nut assembly was first seen in a weevil from New Guinea, says entomologist Alexander Riedel.

The discovery of the first biological screw-and-nut assembly emerged from an exploration of the weevil’s characteristic defense mechanism, says Riedel, an entomologist and curator who specializes in weevil classification at the State Museum of Natural History in Karlsruhe, Germany.

Two things weevils have in common are small size – the Trigonopterus oblongus under study was about 4 millimeters long – and legs that fold under the body. “We wanted to look at their particular defense mechanism,” says Riedel, “to know how it works.”

Using a microscopic counterpart to CT scanning, German researchers snapped electron micrographs of the weevil’s trochanter (“screw”) and (ROLLOVER) coxa (“nut”).”

Image © Science/AAAS

It’s all in the scan, man!

Given the small size, the scientists relied on a kind of micro CT scan driven by X-rays from a synchrotron, “We realized there is a very nice screw joint,” Riedel says, “We’ve had this information for some time, but while talking with a herpetologist colleague, we realized there is no other case in the whole animal kingdom, in all of biology, with a similar screw joint.”

The nut-and-screw are located at one of three major joints in the beetle’s leg; when the leg is retracted, the screw tightens in the nut, which remains stationary, Riedel says. Overall, the screw and nut would be able to turn 345 ° although the leg itself does not move that much.

A (good) turn of the screw!

“The weevils, or snout beetles, have been known from ancient times,” says Riedel. “There are grain weevils and lots of other species, including the boll weevil [a cotton pest]. Many other species are not pests … and so are of no particular interest to humans, which is why nobody knows much about them.”

Why does every weevil species that that Riedel examined have such a mechanism? Weevils, which spend a lot of time climbing on vegetation, apparently evolved from beetles that usually walk on a flat surface or underneath bark, Riedel says. “If a weevil is sitting on the edge of a leaf and wants to walk on a small twig, it’s essential that it can grip under its body, and this motion goes very nicely with this screw joint. A ground [walking] beetle would have great difficulty walking in similar conditions.”

The screw joint now joins the hinge, ball-and-socket and saddle joint as fundamental technologies invented by evolution, Riedel says. Historians of technology have long wondered about the origin of the incredibly useful screw, and it turns out that screws and nuts were in their flour bins all along – but only visible to those who happened to have a handy synchrotron!

– David J. Tenenbaum

On March 11, a catastrophic earthquake — one of the four largest in the past century — struck in the ocean east of Japan, sending a colossal tsunami against the shore. By March 21, the toll of dead and missing, mainly from the tsunami, was estimated at 22,000.

As Japan confronted what Emperor Akihito called the worst crisis since World War II, we began to hear that the six-reactor complex at the Fukushima Daiichi plant, located directly in the tsunami’s path, had lost electrical power. The emergency generators also failed, apparently due to water damage to them or their fuel supply.

As we focus on the nuclear disaster at Fukushima, we emphasize that as of now, the tsunami itself is the far larger human tragedy. But like the tsunami itself, the nuclear disaster may portend further problems in other places, and is likely to affect a trend toward greater use of nuclear power around the world.

Not cool

Immediately, the arrow of trouble aimed at the most ominous type of nuclear accident: loss of cooling. Fission — splitting of radioactive elements that powers nuclear reactors — can stop when reactor operators flip a switch to insert control rods to absorb neutrons. This stops the chain reaction — the divison of uranium atoms that releases neutrons that split other atoms and generate heat — which is the whole point of building nuclear reactors to boil water and drive turbines.

But once the fission reactions cease, decay heat continues to be released from the unstable atoms that remain after fission, and it is this heat that must be removed by a cooling system after shutdown.

Past accidents have shown that decay heat can build up in seconds; and significant damage to the fuel and potentially reactor equipment can occur within minutes. The danger of such a “meltdown” is a major reason why nuclear designers and engineers focus so much effort on cooling the reactor core.

In the beginning, there was Three Mile Island

Japan, target of the only two atomic bombs used in war, is hardly the first nation to confront a “loss of coolant” emergency at a reactor. That happened on March 28, 1979, in the United States, where Pennsylvania’s Three Mile Island (TMI) reactor #2 began a partial melt-down.

Much later, the Nuclear Regulatory Commission concluded that the accident “was caused by a combination of personnel error, design deficiencies, and component failures.” As hundreds of alarms buzzed in the control room, operators, lacking a direct measurement of the water level inside the reactor, made a bad situation worse, the reactor went at least partly dry, and a large percentage of the fuel melted.

It’s safe to say the public reaction verged on panic as a bubble of explosive hydrogen built up inside the plant and evacuations were ordered.

The slow, dangerous removal of fuel revealed massive heating and damage inside the reactor. According to the book, “TMI 25 Years Later”¹: “A large portion of the core melted and flowed into the lower vessel. Most of the core experienced temperatures of at least 1727° C, with certain parts reaching 2527°C.”

At these temperatures, the essential containment vessel can weaken and fail.

TMI, the above book concluded, neared a complete a meltdown. “No one can say for sure, but some experts say that had the accident continued for another 20 to 45 minutes, the [reactor] vessel would have heated up and the metal would have lost its strength, leading to a rupture,” preventing further cooling and allowing superheated fuel to melt through the reactor vessel and enter – and likely exit — the reactor building.

From there, it’s impossible to speculate how widely the radiation would have spread, the authors wrote, but this is what is called the China Syndrome — a runaway load of reactor fuel melting its way down into the earth. Oddly, “China Syndrome” – the movie — was released 12 days before the TMI meltdown.

TMI #2 has since undergone a major cleanup. Intact and damaged fuel has been moved to storage at Idaho National Engineering Laboratory. Reactor #1 is operating normally, and final removal of the destroyed #2 awaits the decommissioning of its companion.

According to the Nuclear Regulatory Commission: “Estimates are that the average dose to about 2 million people in the area was only about 1 millirem. To put this into context, exposure from a chest X-ray is about 6 millirem.”

Nevertheless, the alarm over TMI sent the U.S. nuclear industry into a tailspin.

 

The meltdown of TMI was the death knell for growth in American nuclear industry — the spate of plants licensed during the 1980s had all been planned or under construction by 1979. Rollover to see a comparison of present dependence on nuclear energy.

Graph 1: U.S. Nuclear Regulatory Commission. Graph 2: International Atomic Energy Association

Chernobyl – the unmitigated disaster

The Lord Voldemort of nuclear accidents started on April 26, 1986, when Chernobyl reactor #4 exploded, burned and melted down in a spectacular fire that spewed an estimated 50 tons of radioactive fuel over a swath of Eastern Europe. Unlike TMI (and the imperiled Japanese reactors) Chernobyl had no vessel to contain its fuel, and a giant fire – consuming the estimated 800 tons of graphite used to slow neutrons in the reactor — burned for more than a week as brave crews tried to damp it with sand, boron and lead.

Chernobyl was located in a part of the Soviet Union that is now in Ukraine.

The meltdown produced some of the worst radiation injuries in history, and hundreds of thousands were force-evacuated from an “exclusion zone” — roughly 30 kilometers in radius — around the smoking, radioactive hulk of #4.

Within months, the cooling reactor was hastily wrapped in a giant concrete “sarcophagus” (stone coffin) to contain further radiation. But the sarcophagus is leaking, says Leon West, a professor of mechanical engineering at the University of Arkansas, who has 40 years of experience in nuclear physics, radiation protection and nuclear engineering. “Chernobyl is still open and is still a threat to the local environment.”
“Construction has already begun on the New Safe Confinement,” says photographer Michael Foster Rothbart, who lived 12 miles from the exclusion zone between 2007 and 2009, “and although it keeps falling behind schedule, target finish date is 2013.”

Japan: Facing Three Mile Island or Chernobyl?

By March 21, 10 days after the tsunami, the owners of the Fukushima power plant reported that it had reconnected electric power to all six reactors. The disaster seems headed toward resolution, says Jeff Geuther, who manages a research reactor at Kansas State University. “My understanding is that the fuel [in the three recently operating reactors and the three spent-fuel pools at other reactors] is all under water. The radiation dose has been falling at the plant, an indication that water level has increased in the spent fuel pools.”

Although it’s not clear how much fuel has melted, Geuther says, “It’s fairly clear that the cladding [a thin sheathing on the fuel rods], at a minimum, had some damage. Iodine and cesium have been detected offsite; these are fission products that would be typically be trapped inside the cladding.”

By March 23, the utility reported that the lights were on in the control room of reactor #3, but work had not yet begun on monitoring equipment and reactor cooling pumps in the three reactors that were operating before the quake. By March 24, smoke was rising from several reactors, three plant employees were being treated for radiation exposure, and the zone of concern about radiation in drinking water had been expanded. The local populace remains under evacuation.

Near-term progress in stabilizing the Fukushima plant will be measured by

A near miss?

Two positive factors helped what looks like a near-miss at Fukushima. First, those reactors (unlike Chernobyl) had thick steel containment vessels, which, despite some reports of damage, seemed to hold up reasonably well.

Second, also unlike Chernobyl, Fukushima used water, not combustible graphite, to slow neutrons.

On the other hand, Fukushima faced systemic difficulties due to the precipitating natural disasters: After the epochal earthquake-towering tsunami sequence shut the reactors down, the electric grid died, killing the emergency cooling pumps.

Then the emergency diesel generators failed, and without cooling, the reactors quickly overheated. But with roads out and the nation tending to survivors and victims of the tsunami, the nuclear emergency festered for days, through a series of explosions, fires, bursts of radiation, and evacuations of plant workers.

At one point, just 50 workers were on hand to deal with multiple emergencies at several reactors and pools of spent fuel. The desperation was on display when helicopters tried to dump buckets of water into the fuel pools and fire trucks sprayed cooling water through explosion-blasted walls.

How many broken reactors?

Despite early fears that Fukushima was mimicking Chernobyl, it seems rather to be headed toward the less malignant TMI precedent, says West. “A big leak [like Fukushima] is not like the open-air nuclear bonfire of Chernobyl that spewed radioactive materials into the upper atmosphere. The extent of the release of radiation and the continuing difficulties with cooling of reactors and spent fuel has clearly put the Daiichi site at the TMI stage.”

As radioactive particles cross the Pacific on the jet streams, “California, Oregon, and Washington should start reporting measurable traces of radioactive materials in air samples,” says West, “but for the United States, this should be more like a Chinese test of a nuclear weapon and of no health consequence.”

Radiation has already been detected on milk and green vegetables near the reactor, and now in drinking water in Tokyo. “The Japanese will need to monitor and control agriculture products to minimize the risk to public health,” says West. “This will be similar to efforts in the United States during the 1950′s, when the U.S. was detonating nuclear weapons in Nevada,” and farmers were prohibited from selling milk for four days afterwards.

Japanese meltdowns, American reverbs

As Japan evacuated neighbors from the Fukushima plant, the U.S. Nuclear Regulatory Commission (NRC) advised American citizens in Japan to move at least 50 miles away. That’s much further than specified American evacuation plans, notes Vicki Bier, a professor of industrial engineering at the University of Wisconsin-Madison. “If the NRC is concerned up to 50 miles in Japan, that certainly calls into question emergency planning here, which is limited to 10 miles.”

On March 16, California Senators Barbara Boxer and Dianne Feinstein asked the NRC to review safety at two California plants located near earthquake faults. “Roughly 424,000 live within 50 miles of the Diablo Canyon and 7.4 million live within 50 miles of San Onofre Nuclear Generating Station,” the senators wrote.

And on Mar. 22, the Nuclear Regulatory Commission agreed to accelerate a safety review at Indian Point, a pair of reactors 30 miles from Manhattan.

Japan: How prepared, in reality?

How did such severe nuclear troubles arise in Japan, where “tsunami” was coined, and which is the world’s leader in earthquake engineering and disaster preparedness?

For starters, the tsunami was much bigger than expected. But we’ve also learned from the Associated Press (on March 24) that Japanese preparations focused on natural disasters.

Was the nuclear emergency made worse because six reactors were at one location? As we saw, radiation vented from one reactor caused the flight of workers trying to tame other reactors. But multiple siting had “always been considered to be a really good idea,” says West. “You have a collection of focused professionals with lots of resources [for example, to fight fires], so if one reactor has difficulties, you could take those excess resources and focus on that situation. … This is the first situation, where [multiple sitings] appears to need to be reexamined.”

Early reports point to a critical design failure at Fukushima, says Bier, an expert on risk assessment at nuclear plants. “They were designing for earthquake and tsunami, but not for this level of damage; you’ve got to give engineers some criteria; they can’t design for anything. They could have designed for what did happen, but they apparently decided it was too unlikely.”

Design: Where are the goalposts?

A specific weakness concerned the emergency diesel generators needed to run the pumps, which apparently were swamped by the tsunami, says Bier. “There is a lot we won’t know for months, but there is reasonable speculation about things that could be done differently at modest cost. You can’t prepare for every eventuality, but probably it would have been possible to get better protection for the diesels in a bunker or on higher ground.”

The systematic disruption and near chaos interfered with tasks like avoiding melt-downs in the pools holding spent fuel, which lack the containment usually found on reactors. As Fukushima proved, accidents can be made worse as effects are compounded: the real-life scenario included a combination of a Japan-record earthquake, massive tsunami damage, regional blackouts and radiation releases.

“The surrounding area was so damaged by earthquake and tsunami that it impeded the emergency response,” says Bier. “We have seen stories about people within the evacuation zone who could not evacuate because the roads are impassable or buildings have collapsed, and they were not sending in rescue teams because the radiation was too high. Certainly it was not anticipated that the damage would be this severe, or the radiation would be too severe to evacuate.”

 

Photo: Japan Red Cross Society

Thousands of Japanese have been evacuated from around the Fukushima Daiichi reactors; masks retard the spread of disease in close quarters. Few experts expect the need for a permanent exclusion zone, like the one in Chernobyl, around Fukushima.

Fukushima: End game

Will the six reactors at Fukushima Daiichi be dismantled, like TMI #2, or wind up inside a Chernobyl-style concrete coffin?

The three reactors that got emergency cooling with sea water are likely finished due to corrosion, not to mention possible explosion damage. “Salt water is a killer,” says Robert Rosner, professor of astronomy, astrophysics and physics at the University of Chicago. Rosner expects these reactors to be taken apart and trucked to long-term storage.

Although the age of the reactors – about 40 years – militates against spending large sums on refurbishment and updating, Japan now faces an electricity shortage, so Rosner expects one or two of the plants to return to service, at least for a while.

West, however, suggests that at least one reactor may wind up encased in concrete. “If I were an engineering manager, I would be looking at the possibility of stabilizing it to deal with all the issues” and then build an outer containment to isolate the reactor but allow service visits.

Credibility at stake

Assessing the long-term impact of Fukushima requires us to look at the technology’s unique place in the popular eye. Whether the nuclear industry likes it or not, nuclear carries plenty of emotional baggage. Nuclear physics produced the mushroom clouds over Hiroshima and Nagasaki long before it was used to make electricity. And because ionizing radiation is invisible, it’s a case where what you don’t know can hurt you.

Nuclear energy also arouses fear because power-plant neighbors cannot control it, says Nathan Hultman, an assistant professor of public policy at the University of Maryland. “A lot of research has looked at why people view risks differently, and both dread and the degree of control in nuclear are nerves that are touched very strongly. We feel safer driving cars than in an airplane, even though statistically, airplanes are much safer, because we feel in control in a car.”

 

Photos: TMI, Cherobyl:Wanrouter.

While TMI today shows the scars of its accident (reactor #2 on left melted down in 1979), Chernobyl’s gravesite (rollover) evokes a much bleaker history and deeper wounds. The thrown-together concrete enclosure may need to be replaced – a hazardous, expensive task.

The Japanese nuclear industry also faces credibility problems, Hultman notes.

“Small nuclear accidents were covered up,” says Hultman. “Often the initial reaction was ‘Everything is just fine, the situation is normal,’ then it came out there was a deeper problem. Now we are in a situation where very bad things are happening, and people are not sure what to believe.”

Hultman adds that these issues are a likely fixture in the coming debate over nuclear power. “Nuclear is not the only way to boil water to generate electricity,” he says, and the discussion of energy sources must be broader than that. “Rather than say, ‘We must have nuclear,’ we need to talk about alternatives as well.”

The Fukushima debacle could further polarize a nuclear debate that was altered by both TMI and Chernobyl, says Hultman. “There is almost a religious division. People who believe it’s good think it will be the answer to all our problems, and people who don’t like it, really really don’t like it.”

An omen for the future?

The Fukushima disaster carries striking ironies. Japan was the only country at the receiving end of atomic bombs, and studies of survivors at Hiroshima and Nagasaki have been the basis for understanding the health effects of low-level radiation.

Historically, the Fukushima disaster occurred as nuclear was gaining so much traction as a low-carbon solution to global warming that some prominent environmentalists had begun to talk nuclear. “This is going to have a big effect on the rebound toward nuclear,” says West, who adds, “We just can’t burn our forests — and coal is an old forest — forever,” due to global warming.

Even technological disasters that loom large in the short run may eventually be seen as lessons, West says. “The crash of a major aircraft … does not mean that air travel should end, it means we need to tighten up our design.”

Rosner, however, suggests that nuclear, with its potential for widespread, long-term contamination, needs to live by different rules. “When you are engineering something where the consequences, if something goes wrong, are devastating, even though the probability is very small, you need to engineer to avoid the devastation. We’ve known how to do that for 50 years, but it was always just a bit too expensive on the front end, so the decision was made: The probability is so low, we are not going to worry about it.”

As deadly American drones work the skies over Afghanistan and Pakistan, we got to wondering how similar remote-control approaches are contributing to science. In science, as in war, leaving the staff behind can slash costs and allow sustained exploration of no-go zones.

Part of the story is propulsion: New science vehicles can travel long distances through the ocean and atmosphere with minimum energy. Brains-on-board also matter: Computers enable these super-sensors to make decisions and work long stretches with little or no back-seat driving.

The result is a lot of science per gallon.

Although the vehicles we’ll look at have scientific purposes, they get major financial and technical support from the Department of Defense, proving that military and peaceful pursuits are inextricably linked in extreme environments.

If you dig the deep ocean, WHOI — the Woods Hole Oceanographic Institution on Cape Cod — is a good place to be. The renowned saltwater scientific outfit has a new, deep-water explorer that works without a lifeline.

Meet Sentry, which can take photos and make chemical and geophysical measurements down to 4,500 meters depth, and has worked two high-profile environmental issues: global warming through methane release, and BP’s Deepwater disaster.

Sentry has been used to look for “cold seeps,” regions of the seafloor that release large amounts of methane, says Chris German, WHOI’s chief scientist for deep submergence. “Cold seeps are like the overlooked younger sisters of hydrothermal vents,” the “black smokers” that release superheated fluids and anchor unique ecosystems at the sea floor, usually in mid-ocean.

Cold seeps are located closer to the continents, and “are not as spectacular thermally or geologically, but they do have some of the same chemistry,” says German, “and a lot of the same kinds of animals, even the exact same species.” Cold seeps may explain the distribution of deep-sea organisms around the ocean, he adds. “We want to understand … whether animals are using these locations as stepping stones.”

Most cold seeps were found by accident, but German thought Sentry could detect subtle chemical clues, and last October, he got to test that idea at an underwater landslide off the coast of Norway. The landslide had released pressure on a material called methane hydrate, and a large amount of methane was bubbling from the seafloor mud, creating a “mud volcano.”

Methane is a much more powerful greenhouse gas than carbon dioxide, and given the staggering amount of methane held in methane hydrates, such releases could create a nightmare feedback: warming releases methane, which traps more heat, causing more warming that releases more methane.

Getting engulfed

By prowling around the known cold seep near Norway, German confirmed the detection hypothesis.

Then, the day after Sentry returned to Woods Hole, a real-world opportunity appeared for the new technique.

Biologist Charles Fisher at Penn State was about to embark on a mission into the aftermath of BP’s blowout in the Gulf of Mexico, and he wanted help locating a coral patch to compare to another he’d already located 1,200 meters deep, 11 kilometers southwest of the blowout.

That coral was coated with a brown goop that looked suspiciously like crude oil. Could Sentry locate, for long-term comparison purposes, a similar coral outside the oil plume?

Fisher was part of a National Science Foundation-sponsored “rapid response” cruise to the Gulf, but German was still unpacking. “We’d have two weeks to turn around and get going, and I went to our guys Monday morning and asked, ‘Can you do this?’”

The maintenance crew figured out who would miss what weekend, and they agreed to do it, German says.

Cold seeps and deepwater coral in the Gulf of Mexico are linked, German explains, because the coral live on bare rock, which is often carbonate, and carbonate rock forms at cold seeps when methane is oxidized into carbon dioxide. “So beneath every healthy deep coral, is an active or historic cold seep.”

Suddenly, a theoretically interesting search technique became relevant to the biggest American oil spill in a century.

“Flying” with a map

Based on oil-industry data about the sea bottom, Sentry visited one location southeast of the Macondo well and found no coral. But at the second location, German says, “We hit pay dirt. We flew backward and forward, and found an active cold seep and evidence for tube worms, mussels and coral.”

Ocean-floor research seldom moves so fast, German says, and within hours, he was one of three people to visit the spot in Alvin. “In 36 hours, we went from nothing other than a hunch, to having a topographic map and photos,” German says. “We dove to the sea floor, and there was no mysterious driving around in the dark. Within 15 minutes, we drove to the site because we had a perfect map of where to go.”

In fact, German was holding a fresh, glossy photo of the target, taken less than two days previously.

Sub-terra cognita? Not!

And so is the ocean bottom, as people often say, still less familiar than the far side of the moon? German insists that it still is, despite years of research and an increasingly capable flotilla of deep-sea ships. “In December, in the Gulf, I could see at least 10 to 20 oil rigs… but I’m pretty sure, driving across that seafloor a couple of hours offshore from the United States, that nobody ever laid eyes on it before.”

A recent survey of marine biodiversity shows a chain of ignorance stretching across the Pacific, located near regions of extremely high biodiversity near the Philippines and Australia, German says. “In many of those locations, they’re 300 miles square, there have been fewer than 50 biological measurements in the history of the ocean. This is a chain across the South Pacific ocean, the single biggest contiguous ecosystem on the planet, and it has not been studied.”

And that’s the rule, not the exception, German says. “Close to one-half of the planet is at least 3,000 meters deep, and it’s much further away [and deeper] than the Gulf. From satellite altimetry we have an idea where the bumps are on the seabed, but we don’t know what’s going on; we have a vanishingly small idea.”

Deep water may be the sexiest place in oceanography, but long-term studies are also difficult and expensive in shallow waters, especially if they are remote, icy, stormy, or all three. Propellers, the standard way of moving through water, require a lot of energy and quickly drain batteries on artificial fish.

Gliding — think of soaring like a hawk as opposed to flapping like a sparrow — is a much more conservative approach.

And gliding is the MO of Seaglider, a project built by the University of Washington with money from the Office of Naval Research and the National Science Foundation. Using battery power, the glider alters its buoyancy, causing it to rise or fall through the water. By altering its center of gravity and adjusting its fins, the metal fish moves horizontally with minimal amounts of electric current.

How minimal? In 2009, a Seaglider traveled a record 3,050 miles through the North Pacific during a 9-month journey, without the caress of a human hand or an electric transfusion.

Costing “only” about $100,000 apiece, about 60 gliders are working around the globe, says Craig Lee, a principal oceanographer at UW’s Applied Physics Laboratory, recording basics like temperature, salinity, dissolved oxygen and optical characteristics of its surroundings.

In 2008, south of Iceland, gliders and floats studied carbon uptake by phytoplankton — floating plants that bloom in spring and play a major role in the global carbon cycle. The goal was to follow “parcels” of water during the entire bloom — which ends after some weeks when plankton are eaten or sink in the water. Both processes can remove carbon dioxide from the atmosphere for long-term storage, and therefore have implications for global warming.

“We were trying to learn what drives the carbon flow,” says Lee. “Nobody had done this before: the Seagliders and the buoys had the persistence, the ability to be there for the entire duration of the bloom. You would have to schedule a ship one year ahead, and … if you got there on time, it would be too expensive to keep the ship out there for the whole bloom.”

If ice is nice, under ice is nicer!

In 2009, a Seaglider spent 51 days in Davis Strait, the frigid water separating Greenland and Baffin Island, traveling more than 450 miles under the ice. The Strait is a chief source of melt-water from the frozen Arctic Ocean.

Climatologists worry that a rush of cold, fresh water through the Strait could alter the warm Gulf Stream and freeze Northern Europe.

Getting measurements from Davis Strait is expensive and dangerous, especially considering how much of it is under ice. But the Seaglider did just fine, says Lee. “This was very exciting, that ability to stay out there for a long time, and the ability to get to places that otherwise would be difficult. In winter in the North Atlantic, nobody wants to be there…”

The fish navigated under the ice using five anchored sonar beacons that created an undersea version of GPS, Lee says. Ten times, using its software, the glider found holes in the ice, poked its nose through them, and phoned home via satellite telephone. “It tries to sense ice by looking at the temperature of the water,” says Lee. “It emits a ping and tries determine whether ice is overhead, and it has a climate map that tells it, for a given position at a given time, is ice likely to be overhead? Using all that information, it decides whether to surface.”

During those famous North Atlantic storms, “It just keeps working, it does just fine, continues to navigate, continues to report. We’ve been in 40-foot seas, with 60- to 80-knot winds, and everybody’s happy, although it takes a little longer to get a phone call through.”

The glider carries a quarter for the phone call, but no Dramamine…

A fruit of the military’s desire to see everything from a safe vantage, Global Hawk is a secretive, high-flying, pilot-free jet that can fly at 60,000 feet for 30 hours, non-stop.

For its occasional forays into peaceful work, Global Hawk carries a large cargo of scientific instruments that can monitor light, pollution, ozone, water vapor, weather, clouds, incoming and outgoing radiation, even particles smaller than 1 millionth of a meter across.

The Hawk, which flew scientific missions from NASA’s Dryden Flight Research Center in California in April, 2010, can also be used for earth observation, such as tracking algal blooms in the ocean, vegetation on land, and various resource issues.

Hawk has tracked pollution from Asia above the North Pacific as it moves toward North America and looked at large-scale atmospheric circulation, which influences weather and the distribution of radiation-blocking high-altitude ozone.

We could not get through to a source at the National Oceanic and Atmospheric Administration, which plays a role in Hawk’s science, but we grabbed a press release issued after Hawk’s first environmental flight.

According to Paul Newman, an atmospheric scientist from NASA, “The Global Hawk is a revolutionary aircraft for science because of its enormous range and endurance. No other science platform provides this much range and time to sample rapidly evolving atmospheric phenomena. This mission is our first opportunity to demonstrate the unique capabilities of this plane, while gathering atmospheric data in a region that is poorly sampled.”

In their quest for data on the deep, scientists have gotten a trickle of info from sensors attached to deep-diving marine mammals. In November, 2009, the Scripps Institution of Oceanography launched SOLO TREC (Sounding Oceanographic Lagrangrian Observer Thermal RECharging vehicles; glad you asked?), a bobber that can sink 500 meters into the ocean, then return to the surface to report via satellite to scientists who may prefer sipping lattes at a Java Joint to crowding the rail on a topsy-turvy research ship.

Let’s call this Solo, and let’s agree that it’s a strange vessel. Solo can adjust its buoyancy, but lacks propellers and cannot drive laterally, so its location is at the mercy of the currents.

Solo records basic ocean conditions, but the real accomplishment is proving that its power system needs no recharging and could, theoretically, operate more or less forever – or at least until it breaks or barnacles or plants foul the fish up and slow it down.

Solo had already completed 300 dives by March, 2010, and although it sounds like a perpetual motion machine, it actually sucks its energy from the ocean as it rises toward the surface:

According to Yi Chao of the Jet Propulsion Lab, a Solo principal investigator, “This technology to harvest energy from the ocean will have huge implications for how we can measure and monitor the ocean and its influence on climate.”

Funded by NASA and the U.S. Navy, Solo’s technology is also obviously useful for monitoring animals and the movement of ships and submarines.

When plywood came into industrial use a century ago, the criss-crossing layers of wood were glued with a soybean derivative. Then, in the 1930s (long before tofu sprouted in the American diet), strong, synthetic glues, derived from natural gas or oil, started to shoulder aside the soy stuff.

Cheap and water-resistant, these urea formaldehyde glues helped plywood, particle board and similar composite wood products dominate the furniture and building industries.

Formaldehyde was also used in clothing, paint, paper, wall covering and roll insulation.

Many of these products released formaldehyde (CHOH) but inside the average house, the bulk of the exposure came from plywood and its plural planar progeny.

In 1991, the U.S. Environmental Protection Agency branded formaldehyde a probable human carcinogen. The compound quickly dissolves in mucus membranes in the nose, throat and lungs, causing irritation and triggering asthma attacks.

Inside the home, formaldehyde can be released from composite wood in furniture, cabinets, sub-floors and wall panels. The notorious FEMA trailers that sparked so many health complaints after Hurricane Katrina were chock-a-block with cheap, formaldehyde-glued structures.

Photo: FEMA

After Hurricane Katrina, “FEMA trailer” residents blamed health problems on formaldehyde released from composite wood products in the trailers. A new soybean-based glue could eliminate these problems after it is adopted more widely by manufacturers of particle board.

Legumes to the rescue!

Although manufacturers have taken steps to reduce formaldehyde releases, a more comprehensive solution could reside in the plant that was originally used to glue plywood — the soybean.

Charles Frihart, a chemist at the U.S. Department of Agriculture Forest Products Laboratory, described the evolution of a soy super glue to the American Chemical Society meeting in Boston yesterday. “Biological materials were used as adhesives until petroleum became very cheap after World War II,” he told us, “and the synthetics displaced agricultural, natural material.”

The soy-story is developing into a key advance for “green chemistry,” the quest to reduce toxic burdens from the factory to the disposal site. Until a few years ago, soy glue was less water-resistant than synthetics, Frihart says. Then, Kaiching Li of Oregon State University discovered how to increase water resistance by “cross-linking” the strands in soy-based adhesive.

More links = more power!

Long ago, cross-linking became the key to converting soft, sticky natural rubber into a useful product. “Rubber was never very useful because it would soften in the heat, until they developed a way to crosslink it,” says Frihart. Charles Goodyear invented vulcanizing, a process for cross-linking rubber, in about 1840, laying the groundwork for the bicycle and then the automobile.

Invention is usually a group activity these days, and Frihart points to cooperation between scientists at the Forest Products Lab and Columbia Forest Products, Inc., which is already making products with soy-based glues.

A key driver for the new glue came from California, which deemed formaldehyde-based glues an indoor health hazard. Before it banned the use of formaldehyde in indoor products, however, California needed to know that an alternative technology was available. Once the cross-linked soy glue was proven to work, the state enacted a low-formaldehyde standard that, in effect, went national. “California is the largest market and people are not going make a separate product for California,” Frihart says.

The cross-linking invention is already reducing indoor formaldehyde at the top of the furniture market, where plywood is used instead of particle board, Frihart says. “More than 50 percent of interior plywood used for cabinets and furniture is now being made with the improved soy-based adhesive.”

Researchers at Forest Products Laboratory in Madison, Wis. test the strength of soy glues: Two rams compress and heat the joint, then clamps at each end of the wooden strips pull until the joint breaks.

Practical for particle board?

Particle board remains the basis for most cheaper furniture, and while some particle board already uses formaldehyde-free glue, “We want to make it better, with higher strength, especially in wet conditions,” Frihart says.

Charles Goodyear did not have to integrate vulcanization into a rubber industry – which barely existed — but today, a new adhesive “has to fit into the way the product is being made commercially,” Frihart says, “and we continue to work on modifying the adhesive to fit better individual plants.”

Frihart says the soy story echoes a larger, but behind-the-scenes evolution in materials. “Because we better understand materials, and how to manipulate them, we keep figuring out ways to make them work better, even if they are not labeled new-and-improved.”

– David J. Tenenbaum

Cells are the basic unit of biology: the site where energy is transformed. It is the locale where DNA, RNA and proteins perform the timeless dance of cellular reproduction.

But cells are small (a mammalian cell is about 10,000 nanometers in diameter, which sounds large until you remember that one million nanometers equals one millimeter).

Photo: © Science/AAAS

That angled piece of ultra-slender wire at the end carries a transistor, and is about to slip inside one of the cells just above it. The two legs allow current to flow through the transistor.

Tracking events inside individual cells may get a lot easier, courtesy of a new transistor that is engineered to slip easily inside a cell and is just 50 nanometers wide.

This transistor, mounted on a much-thinner-than-a-hair wire, can detect and amplify faint electrical signals inside cells.

Several innovations from chemistry and material science were needed to construct ultra-mini transistors on a hairpin-shaped piece of wire, says Charles Lieber, a professor of chemical biology at Harvard University.

The nanowire itself is silicon, the basic material of solid-state electronics. To give the wire its hairpin shape, the researchers created two 120-degree bends, which had never been done before with nanowire, says Lieber.

To form a tiny transistor at the bend, Lieber, Bozhi Tian, who’s now a post-doctoral fellow at MIT, and colleagues “doped” the silicon wire with precise dollops of elements.

Small is indeed beautiful

The invention has advantages over the “patch clamp,” which was developed more than 25 years ago to measure voltage at ion channels on the cell surface, says Lieber.

Photo: The Athlete’s Heart Blog

Because the transistor “is an active device that amplifies the signal,” it can be much smaller than the patch clamp, Lieber says. The new probe is so small, he adds, that “you could envision putting several of these into the same cell to measure things on a scale that’s never been measured.”

The fabrication techniques impressed Xudong Wang, an expert in nanowire at the University of Wisconsin-Madison. “In making nanowires, it’s most difficult to grow a certain shape, and to put a specific function at a specific location.”

Although most early nanoelectronics are planar, Wang adds, “They made this part that is three-dimensional, so you can study something in 3D space.”

A matter of the heart

Because heart muscle cells exhibit an electrical rhythm that causes spontaneous contractions, Lieber’s research group used the probe to examine chicken heart cells in the lab. Inserting the nanowire did not seem to affect the cells, Lieber says. “The cell is beating, and as the device goes in, there is no change in the beat frequency or in the electrical potential.”

In contrast, harpooning a cell with a pipette — the slender glass tube used in the patch clamp — often disturbs it, Lieber says. And because that pipette also contains a liquid, “You will always have an exchange of medium from the measurement tool and the cell.” The new probe uses no fluids.

Photo: © Science/AAAS

Inside a single cell, this nanowire probe can measure electricity and may eventually be able to detect proteins and RNA.

King of nano-camo?

Photo: © Science/AAAS

To help the ultra-small probe enter cells, the researchers coated it with a layer that resembles a cell membrane, which causes the probe to be pulled into the cell. Cells use a similar process to devour viruses and bacteria.

Beyond measuring voltage inside a cell, Lieber suggests that the transistor could carry receptors for proteins or RNA, enabling it to measure chemistry in real time inside cells. That, in turn, would open a window on many basic biological mechanisms.

“It’s almost like a dream to be able to wire up a transistor, which is the fundamental unit in digital electronics, with a cell, which is the basic unit of information processing in biology,” says Lieber. “It does not take a lot of imagination to think there will be a lot of wild things that one can do with this technology.”

– David J. Tenenbaum

Photo: Fiorenzo Omenetto

But you sure can copy her. That’s an engineering approach called biomimetics – the quest to exploit the three billion-year evolutionary process that has perfected structures and materials as strong, spare and sophisticated as the hawk’s eye and mother-of-pearl.

Now we read about progress in the effort to make artificial silk – the light, ultra-tough fiber produced by spiders and silkworms. Like plastic, silk is a polymer – a series of repeated structures that can be altered to produce different results.

But unlike plastic, the sub-units in silk are proteins. And silk can’t be made in the lab – yet.

In fact, it’s not yet clear how silk is made inside silkworms and spiders. As silk is forming, its proteins are so dense that they should glom together before the animal can spin the silk fiber.

Because a glance at a spider’s web proves that silk is possible, biologists and engineers are exploring the chemistry and physics of silk production.

By controlling the acidity and flow of the liquid pre-silk, and using mechanisms that are presently mysterious, spiders and silkworms create a fiber that shames even Kevlar, the fiber that is blended with polymer for lightweight canoes and bullet-proof vests.

Strong, ‘n silky?

In terms of tensile (pulling) strength, silk approaches high-tensile steel, and is one-quarter as strong as Kevlar. But if you bend Kevlar, it “will fail immediately,” says David Kaplan, a professor of biomedical engineering at Tufts University.

In contrast, silk excels in a quality called toughness – the Rambo factor, which combines tensile strength and flexibility. “Silk is really good at tensile strength and toughness, and you can’t emulate that with a synthetic material,” Kaplan says.

Silk has many other desirable properties, adds Kaplan, co-author of a review on silk technology being published in tomorrow’s Science. The silkworm’s silk cocoon must protect the developing moth against rain and other environmental perils, yet the moth must digest the cocoon as it emerges.

Silk can also be highly elastic. “To catch prey, the spider can throw the silk like a lasso, and it sticks so the spider can reel the prey back in.”

Courtesy of what Kaplan calls “a glue-like feature that holds the fibers together through a protein-protein interaction,” spider-web silk can also adhere to itself, and to vegetation.

Because spiders and silkworms are only distantly related, the genes for silk must have evolved several times, Kaplan says. “That’s a vote for the simplicity and utility of the system, which clearly provides an important survival function.”

Finally, these remarkable materials are made with the ultimate green chemistry, with neither heat nor toxic byproducts, and using only water as the solvent.

Medical miracle?

Silk has been used for surgical suturing since Egyptian times. But Kaplan and others envision using this ultra-tough, biodegradable material as a

* scaffold to hold stem cells to regenerate diseased tissues, such as bone, kidney and cartilage;

* container to introduce cells, drugs or growth factors; and

Photos: University of Akron

For sheer toughness, spider silk trumps such synthetic fibers as carbon fiber and Kevlar.

* an injectable goop of silk precursors and the appropriate drugs or cells which would transform into a gel state and deliver its cargo before slowly degrading.

In 2009, Serica Technologies, Inc., got Food and Drug Administration approval for a silk-based material to be used as a supportive mesh in soft-tissue repairs. (Serica has since been acquired by Allergan, Inc.)

If silk is so slick, can it be made in larger quantities with traditional, in-glass chemistry? Perhaps, but Kaplan is more excited about moving the silk genes into plants or animals, so biology can make the precursors, or possibly a finished silk fiber.

As mentioned, the study of silk illustrates how engineers can be inspired by biology. Seventy-five percent of silk is composed of just two amino acids, Kaplan says, yet “this material is unique. It can make incredibly strong, tough, interesting materials, and do it through a green process. I can’t imagine where you can get more interesting properties from a simpler system.”

David J. Tenenbaum

Historians tell us the Spanish introduced pressurized water systems to the New World. But a new study indicates that the Maya were building pressurized pipes between about 450 and 750 AD, in Palenque, a major Mayan city in modern-day Mexico.

The Maya built a large number of cities in the Yucatan, Guatemala and Belize, before their cities were suddenly and mysteriously abandoned around 800. The Maya, whose descendants still live in the region, wrote with hieroglyphs, had extensive knowledge of astronomy, and their economy was strong enough to support cities such as Palenque, Chichen Itza and Cobal.

Until now, nobody had found evidence for pre-Spanish pressurized water in the New World, say the two authors of the new study.

The evidence takes the form of a narrow constriction in the underground Piedras Bolas aqueduct that routed water from a spring into Palenque. Unlike many Mayan cities, Palenque was built in low mountains, with only about 2,200 hectares of reasonably flat land. Untamed streams would gobble valuable real estate, so the Maya built limestone conduits to rout water through the city.

In some cases, the Maya plastered the inside of conduits with stucco to prevent leaks. And like modern builders, they Maya covered the conduits with stones that paved city streets and plazas.

Streaming, but not video

The suggestive constriction was six meters below the spring that supplied the stone pipe, and that height differential put the water under pressure, says co-author Christopher Duffy, a professor of civil and environmental engineering at Penn State University. The system is “analogous to a modern water distribution system. The water tower produces a ‘hydraulic head,’ or water pressure. The pipes go underground, and back up into the home, where water flows under pressure.”

The small opening at the bottom allowed the Maya to close off the conduit, so it would stay full of water. Air in the system will neutralize the hydraulic head, Duffy says.

Unfortunately, the Palenque site has been disturbed, and tantalizing questions remain, Duffy says. “We don’t know how they distributed the water from this point, but we can’t see any other purpose, other than as a control point in the buried conduit.”

Paving paradise to put up a … fountain — or a toilet?

Archaeologists already know that the Maya had an extensive irrigation system, fed by nine streams that ran through Palenque to the fields below.

The constricted conduit, one of nine, had a capacity of about 68,000 liters, and it alone could have stored enough water to supply scanty rations for several thousand people for a week during the dry season.

The pressurized pipe could have supplied a fountain where people could dip jars to collect drinking water. But the putative fountain was “probably beautiful,” says co-author Kirk French, a lecturer in anthropology at Penn State. “Everything the Maya did at Palenque was over the top, grandiose, in art and architecture.”

Fountains also serve a social purpose, says French. “They are in a central part of the city, where people can fill jugs and socialize. It’s funny, we refer to ‘water-cooler conversations,’ but it seems this has been going on for a very long time.”

Did the Maya’s pressurized plumbing have a more, er, “sanitary” function? “We don’t know the exact application,” admits Duffy, who specializes in hydrology, “although we were recently told, after the paper came out, that there are sweat baths, and perhaps toilets, in the palace at Palenque.”

In fact, the palace has “four toilet-like features,” French says, “They are in a line, at the right height, and share the same drain, but it’s hard to prove that they are toilets.”

The sanity of sanitation

Toilets or not, the newly discovered plumbing shows that the Maya “are better engineers than they ever got credit for,” Duffy says. Although the Maya may have never seen pressurized water flow in nature, people are inventive, especially when it comes to something as important as water.

“We think this is the first example in the New World, but a lot more will probably be discovered,” says Duffy. “The Maya built like the Romans. They were practical. They would build, if it failed, they would build again. It’s a standard engineering strategy. Do something, fail, learn, and do it again.”

– David J. Tenenbaum