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Random Walk G ENESIS B OUNCES B ACK JPL’s Genesis mission to and whose chemical com- bring back atoms from the position mirrors that of the solar wind deviated from the material from which the solar script when it delivered its system formed. cargo to the empty expanse But this cliffhanger has a of the Utah Test and Training happy ending. The top scien- Range on September 8. As tific priority, the concentrator written, one of a pair of heli- that collected oxygen atoms to copters piloted by Hollywood measure their isotopic ratio, stuntmen was to snatch the was in pretty good shape. The parachuting capsule out of second priority, a sheet of gold the sky to avoid jarring the foil to collect nitrogen atoms delicate contents. But the for the same purpose, was chute missed its cue and the undamaged. And although payload “geobraked” into the most of the wafers of sap- desert floor at a speed of 311 phire, diamond, and other kilometers per hour. brittle materials that made U. S. Air Force 388 Range Squad Range 388 Force Air S. U. Things didn’t look good up the five rotating collector when the recovery team arrays were in smithereens, the Above: The pocket-watch-shaped arrived minutes later. The wafers from each array were of capsule hit the desert floor edge- shell had split open, and the a different thickness, so each inner canister was cracked. piece can be traced back to its on and buried itself to about half Switching to Script B, the original array—essential for its diameter. crew secured the charge that determining which sample Left: The culprit is believed to should have released the had been collected when. The be a gravity switch like this one, parachutes. Only then could fragments were meticulously the capsule be dug out and photographed, numbered, which was supposed to sense the trucked to a clean room at and packaged—in more than capsule’s deceleration when it hit the nearby Dugway Prov- 3,000 small containers—and the top of the atmosphere and ing Grounds. The bulk of shipped to the Johnson Space the wreckage was sent on to Center for decontamina- initiate a sequence of events that Genesis’s builder, Lockheed tion, archival preservation, would have deployed a drogue Martin, for analysis, while the and eventual distribution to chute followed by a winglike para- science team tried to salvage various labs. Since the latter foil such as skydivers use. something—anything!—from would have involved sawing the 26 months’ worth of up the wafers anyway, one NASA/Lockheed Martin The switch was apparently material that had been col- could say we’re actually ahead installed backward. lected atom by laborious ion of the game. —DS 2 ENGINEERING & SCIENCE NO . 3 2 0 0 4 Left: Caltech professor of nuclear geochemistry Donald Burnett, Genesis’s principal investigator and lead scientist, picks through desert dirt for bits of the arrays, each of which was designed for a different particle stream. Below: The shards were sorted, and samples from all 14 types of wafer were recovered. A few of the silicon-on-sapphire and gold-on-sapphire wafers actually survived intact. Bottom: Three of the solar wind concentrator’s four segments were unscathed. About 85 percent of the fourth segment was salvageable. Above: In the Friends series finale last May, dimwit actor Joey Tribbiani (Matt LeBlanc, at right) moved to Hollywood. He now shares an apartment with nephew Michael (Paulo Costanzo, center), a grad student at guess where? Clever, sympathetic writing gives this odd couple plenty to do, and Joey’s brassy sister Gina (Drea de Matteo, late of The Sopranos) and neighbor Alex Garrett (Andrea Anders, at left) earn a lot of laughs as well. Joey airs Thursdays at 8:00 p.m. on NBC. A TKINS , S CHMATKINS A health-conscious public up to long-chain molecules may be shunning carbs, but containing a thousand or Caltech chemists are em- more sugar units. (The latter bracing them. Professor of include chitin, the stuff of Chemistry David MacMillan insect exoskeletons; glycogen, and his graduate student Alan a source of ready energy for Northrup have discovered muscles and other tissues; a simple way to make their starch; and cellulose.) basic unit—the six-carbon “For the last 100 years, sugar—in two steps. This is scientists have needed many a major improvement over chemical reactions to differ- current methods, which can entiate five of the six oxygen require a dozen or more reac- atoms” in the basic sugar unit, tions. Natural carbohydrates explains MacMillan. “We range from these simple sugars simplified this to two steps = = Above: Six-carbon sugars have five carbon atoms that can be either “right- handed” or “left-handed.” This “handedness” determines which groups of atoms end up above and which end up below the ring plane; the rings have also been drawn unclosed. Glucose is at left, mannose at right. 2 0 0 4 ENGINEERING & SCIENCE NO . 3 3 by the invention of two new chemical reactions that are P OSTCARDS FROM T ITAN based on an old but power- ful chemical transformation known as the aldol reaction.” There are eight naturally oc- curring sugar structures in car- JPL’s Cassini spacecraft had its first close encounter with one of bohydrates, and the method Saturn’s moons on October 26, when it buzzed by Titan at an al- works for four of them. titude of 1,200 kilometers. Larger than Mercury, Titan fascinates The method also allows easy scientists because its dense, opaque atmosphere of nitrogen and access to sugars not found in hydrocarbons—thicker than a Stage 3 smog alert—is believed to nature, which is invaluable for resemble the one from which life’s precursor compounds formed medicinal chemistry, biology, on Earth. (But with a surface temperature of −180 °C, we don’t and a number of diagnostic expect Titan to be inhabited.) Here are a few of the first pictures techniques. For example, a released from the flyby. rare form of carbon known as carbon-13 is widely used as a tracer. Starting with 13C- labeled ethylene glycol, which is cheap and readily available, MacMillan and Northrup made a sugar molecule that contained 13C exclusively in only four chemical steps—a feat that previously took 44. “Carbohydrates are essential to human biology, playing key roles in everything from our growth and development to our immune system and brain functions,” says John Schwab, a chemist at the National Above: These near-infrared images show the surface at a wavelength Institute of General Medical Sciences, which supported the sensitive to methane. The large, bright feature in the center right of the research. “They also play criti- right-hand image is a “continent” named Xanadu, although whether the cal roles in plants, bacteria, dark stuff adjoining it is really a slushy methane ocean remains to be seen. and viruses. But because they The dark, narrow streaks in Xanadu may be rivers or glaciers of gasoline. are so difficult to work with, carbohydrates are not nearly The fact that they and the broad dark features run west to east (upper as well understood as DNA left to lower right) means that they are probably wind-driven. On its next and proteins. MacMillan’s visit to Titan, Cassini will release the European Space Agency’s Huygens Above: This near-ultraviolet photo technique will allow scientists of the global haze that hangs to more easily synthesize and probe, which on January 14, 2005, will parachute into the black square, a study carbohydrates, paving region shown enlarged in the left-hand image. Huygens will explore Titan’s hundreds of kilometers above Titan the way for a deeper under- atmosphere all the way down, and if the probe doesn’t drown—it has legs has been processed to approximate standing of these molecules, but is also designed to float—it may transmit data and pictures from the natural color. which in turn may lead to new classes of drugs and diag- surface for up to 30 minutes before it freezes to death. nostic tools.” Right: Cassini’s radar scanned a The paper was published region some 150 by 250 kilome- online August 12 by the Sci- ence Express website, and will ters at a resolution of about 300 appear in the journal Science meters. Few, if any, craters can be at a later date. —RT seen, showing that the surface is geologically young. But aside from the fact that it’s clearly a very complex place, and that the darker areas are probably smoother than the bright ones, not much else has been deduced yet. 4 ENGINEERING & SCIENCE NO . 3 2 0 0 4 T HE S W A T T EAM I T ’ S I S T ! If you think it doesn’t do of sensory neurons in the much good to swipe at the fly flies, and that these neurons that’s going after the potato seem to be dedicated to the salad, guess again. You may sole task of responding to it. Information is everywhere. them—which were originally be discouraging the fly’s col- By inhibiting these neurons’ It’s not just facts and words, designed for the Industrial leagues from taking up the synapses, the researchers were but things like the instruc- Age. “We need a new intel- raid. Caltech’s David Ander- able to block the ability of tions in our genome that lectual framework to harness son, the Sperry Professor of flies to avoid CO2. “This tell our cells when to divide these advances,” says Bruck.

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