Cover; Extreme Engineering; Exclusive Online Issues; by Staff Editor; 1 Page(s)

Table of Contents; Extreme Engineering; Exclusive Online Issues; by Staff Editor; 1 Page(s)

The Longest Suspension Bridge; Extreme Engineering; Exclusive Online Issues; by Satoshi Kashima and Makoto Kitagawa; 4 Page(s)

When it opens to traffic in April 1998, the Akashi Kaikyo Bridge will span almost four kilometers--3,910 meters, to be exact. The world's longest suspension bridge, it will help connect the island of Shikoku with the rest of Japan, while allowing free passage to ships in the international navigation channel below. Its central section will stretch 1,990 meters, its towers will soar 283 meters above the water, and its cables will carry tensile forces of 120,000 metric tons--far more than any other bridge.

The bridge will be the crowning glory of an elaborate system connecting Japan's four main islands: Honshu, Hokkaido, Kyushu and Shikoku. The smallest, Shikoku, has a population of about four million and is separated from the largest, Honshu, by the Seto Inland Sea. In the 1930s Chujiro Haraguchi, an engineer with Japan's Ministry of Interior who later became mayor of Kobe, proposed a bridge to link the two islands. He was inspired by American suspension bridges such as the Golden Gate Bridge in San Francisco, then under construction. But in those years Japan's economy and engineering skills were not up to such a feat.

Little Big Science; Extreme Engineering; Exclusive Online Issues; by Gary Stix; 5 Page(s)

Albert Einstein, as part of his doctoral dissertation, calculated the size of a single sugar molecule from experimental data on the diffusion of sugar in water. His work showed that each molecule measures about a nanometer in diameter. At a billionth of a meter, a nanometer is the essence of small. The width of 10 hydrogen atoms laid side by side, it is one thousandth the length of a typical bacterium, one millionth the size of a pinhead, one billionth the length of Michael Jordan's well-muscled legs. One nanometer is also precisely the dimension of a big windfall for research.

Almost 100 years after Einstein's insight, the nanometer scale looms large on the research agenda. If Einstein were a graduate student today probing for a career path, a doctoral adviser would enjoin him to think small: "Nanotech, Albert, nanotech" would be the message conveyed.

Growing New Organs; Extreme Engineering; Exclusive Online Issues; by David J. Mooney and Antonios G. Mikos; 6 Page(s)

Every day thousands of people of all ages are admitted to hospitals because of the malfunction of some vital organ. Because of a dearth of transplantable organs, many of these people will die. In perhaps the most dramatic example, the American Heart Association reports only 2,300 of the 40,000 Americans who needed a new heart in 1997 got one. Lifesaving livers and kidneys likewise are scarce, as is skin for burn victims and others with wounds that fail to heal. It can sometimes be easier to repair a damaged automobile than the vehicle's driver because the former may be rebuilt using spare parts, a luxury that human beings simply have not enjoyed.

An exciting new strategy, however, is poised to revolutionize the treatment of patients who need new vital structures: the creation of man-made tissues or organs, known as neo-organs. In one scenario, a tissue engineer injects or places a given molecule, such as a growth factor, into a wound or an organ that requires regeneration. These molecules cause the patient's own cells to migrate into the wound site, turn into the right type of cell and regenerate the tissue. In the second, and more ambitious, procedure, the patient receives cells-either his or her own or those of a donor-that have been harvested previously and incorporated into three-dimensional scaffolds of biodegradable polymers, such as those used to make dissolvable sutures. The entire structure of cells and scaffolding is transplanted into the wound site, where the cells replicate, reorganize and form new tissue. At the same time, the artificial polymers break down, leaving only a completely natural final product in the body-a neo-organ. The creation of neo-organs applies the basic knowledge gained in biology over the past few decades to the problems of tissue and organ reconstruction, just as advances in materials science make possible entirely new types of architectural design.

Synthetic Life; Extreme Engineering; Exclusive Online Issues; by W. Wayt Gibbs; 7 Page(s)

Evolution is a wellspring of creativity; 3.6 billion years of mutation and competition have endowed living things with an impressive range of useful skills. But there is still plenty of room for improvement. Certain microbes can digest the explosive and carcinogenic chemical TNT, for example - but wouldn't it be handy if they glowed as they did so, highlighting the location of buried land mines or contaminated soil? Wormwood shrubs generate a potent medicine against malaria but only in trace quantities that are expensive to extract. How many millions of lives could be saved if the compound, artemisinin, could instead be synthesized cheaply by vats of bacteria? And although many cancer researchers would trade their eyeteeth for a cell with a built-in, easy-to-read counter that ticks over reliably each time it divides, nature apparently has not deemed such a thing fit enough to survive in the wild.

It may seem a simple matter of genetic engineering to rewire cells to glow in the presence of a particular toxin, to manufacture an intricate drug, or to keep track of the cells' age. But creating such biological devices is far from easy. Biologists have been transplanting genes from one species to another for 30 years, yet genetic engineering is still more of a craft than a mature engineering discipline.

Electrodynamic Tethers in Space; Extreme Engineering; Exclusive Online Issues; by Enrico Lorenzini and Juan Sanmart¿n; 8 Page(s)

There are no filling stations in space. Every spacecraft on every mission has to carry all the energy sources required to get its job done, typically in the form of chemical propellants, photovoltaic arrays or nuclear reactors.

The sole alternative--delivery service--can be formidably expensive. The International Space Station, for example, will need an estimated 77 metric tons of booster propellant over its anticipated 10-year life span just to keep itself from gradually falling out of orbit. Even assuming a minimal price of $7,000 a pound (dirt cheap by current standards) to get fuel up to the station's 360-kilometer altitude, that is $1.2 billion simply to maintain the orbital status quo. The problems are compounded for exploration of outer planets such as Jupiter, where distance from the sun makes photovoltaic generation less effective and where every gram of fuel has to be transported hundreds of millions of kilometers.

Flying on Flexible Wings; Extreme Engineering; Exclusive Online Issues; by Steven Ashley; 7 Page(s)

Airplanes typically look the same whether they are in the air or on the ground. Most wings extend from the fuselage at a fixed angle, and they are sufficiently rigid that they do not move or twist much in flight-certainly a reassuring feature for pilots and passengers alike.

In years to come, however, radical wing designs for advanced aircraft may change that. So-called morphing wings will be sophisticated structures that automatically reconfigure their shapes and surface textures to adapt to monitored changes in flying conditions. Such capabilities will in some ways mimic the subtle, nearly instantaneous adjustments that birds make instinctively to their wings, tails and feathers when aloft.

Building a Brainier Mouse; Extreme Engineering; Exclusive Online Issues; by Joe Z. Tsien; 7 Page(s)

When I decided to become a scientist, never in my wildest dreams did I imagine that my work would provide fodder for CBS's Late Show with David Letterman. But last September, after my colleagues and I announced that we had doctored the genes of some mice to enhance their learning and memory skills, I turned on my television to find that my creations were the topic of one of Letterman's infamous Top Ten Lists. As I watched, the comedian counted down his roster of the Top Ten Term Paper Topics Written by Genius Mice. (My personal favorites are "Our Pearl Harbor: The Day Glue Traps Were Invented" and "Outsmarting the Mousetrap: Just Take the Cheese Off Really, Really Fast.")

My furry research subjects had become overnight celebrities. I received mail by the bagful and was forwarded dozens of jokes in which "smart" mice outwitted duller humans and their feeble traps. It seemed that the idea of a more intelligent mouse was something that everyone could identify with and find humorous.

The Spirit of Exploration; Extreme Engineering; Exclusive Online Issues; by George Musser; 6 Page(s)

At 8:15 p.m. Pacific time on January 3, the Spirit rover, tucked inside its protective capsule, separated from its interplanetary mother ship and prepared to enter the atmosphere of Mars. For weeks, mission engineers and scientists had been listing in grim detail everything that could go wrong. Explosive bolts might not blow on time; strong winds might slam the capsule against the ground; the lander might settle with its nose down, wedged helplessly between rocks; radio links might fail. As the final days ticked by, a dust storm on the planet erupted, reducing the density of the upper atmosphere. To compensate, controllers reprogrammed the parachute to deploy earlier. Eight hours before the capsule's entry, deputy mission manager Mark Adler said, "We're sending a complicated system into an unknown environment at very high speed. I feel calm. I feel ready. I can only conclude it's because I don't have a full grasp of the situation."

This candid doom-mongering was reassuring. If the team had said there was nothing to worry about, it would have been time to start worrying. Between 1960 and 2002 the U.S., Russia and Japan sent 33 missions to the Red Planet. Nine made it. By the standards of planetary exploration, the failure rate is not unusually high: of the first 33 missions to the moon, only 14 succeeded. But the blunders that damned the Mars Climate Orbiter in 1999 - neglecting to convert imperial to metric units, then failing to diagnose the error when the spacecraft kept drifting off course - are hard to live down. And just a week before Spirit reached Mars, the British Beagle 2 lander bounded into the Martian atmosphere never to be heard from again.