Ca li for ni a Insc itu te

of Techno logy

SC I EN CE

Voillme LX, Nllmber 3,

I 997

IN THIS ISSUE

Water and

Ancient Mars

Geology Under the

Antarctic Ocean

Arsenic and the

L.A . Aqueduct Top: Every explorer wants to see what's on the other side of the next hill. When Sojourner, the Mars Path­ finder's rover, peered over a nearby crest on Sol (Mar- tian day) 76, it saw what appear to be sand dunes. If the stuff really is sand (a question that is still being debated), it implies the likely long-term prese.nce of liquid water-the most plausible agent for creating sand-sized grains. The Twin Peaks are on the horizon on the right; the "Big" Crater is on the left.

Bottom: The rover took this picture of the lander, nesting comfortably in its deflated air bags, on Sol 33. You can see the for­ ward ramp, which sticks straight out like a diving board instead of bending down to touch the Martian surface (the rover drove off the rear ramp). And if you think you see E.T.'s face, you're not far wrong­ Pathfinder's camera has two "eyes" spaced 15 cen­ timeters apart for stereo vision. For a look at what else Pathfinder has seen, turn to page 8. " N GIN E E R I N G & C 1 ENe E

Ca li for n ia Instit u te

o f Tec h no logy

2 Random Wa lk

8 Pathfinder's Fi n ds - by Dougla s L. Smi t h Twenty-one years after the Vi king land ings, JPL has once again set foot on rhe red planet- a place both stranget and more Earthli ke than we had imagined.

18 Geophysi c al Secrets Be n eath Antarctic Wate r s - by Joann M . Stock These icy seas may hold the key to reconstructi ng ancient plate mig rations.

28 So lar Fue l - by Harry B. Gray Scientists are laboring to do what plants have been doi ng for aeons-make dean fu el from sunlig ht.

34 Chinatow n Revisi t ed: Arsenic and th e Lo s Ange les Wate r S u p ply - by Janet G. Hering On the cover: The early What is arsenic doi ng in our water, and should we be worried about it? morning sun glints off the A chemical detecrive story. ice in Antarctica's Ross Sea. As the penguins frolic, a 41 Obituar ies: Eugen e Shoemaker group of Calt ech scientists is using shipboard geo­ 43 Fac ulty Fi le physical techniques to examine the seafloor fo r clues to the tectonic Engi neeri ng & Science (ISSN 001 3-7812) is published Thomas J . Tyson plates' motions. How the quarterly at the California Institute of Technology, 1200 Presidml of lhe A/llllllli AJJfxinlioll Antarctic and Pacific plates East California Boulevard, Pasadena, CA 9 1 125. Annual ]. Ernest N unnally subscription $ 10.00 domestic, $20.00 foreig n air mail; have wand ered with Vice Presidelll /0 1" Imlilllte Relntiom single copies $ 3.00. Send subscriptions co C"lltech 1-7 1, Roben 1. O 'Rourke respect to each other has Pasadena, CA 91 125. Third class postage paid at Pa...mde­ AJSocinte Vice Presidelll fo r /llstitllte Relatiom consequence's elsewhere­ na, CA. All rights reserved. Reproduction of material con­ rai ned herein fo rbidden wirhout authori7.ation. © 1997, STAFF: Editor - Jane Dietrich where the Pacific plate Califo rnia Jnstitu[c of'rechnology. Published by Caltech Managing Editor - Doug las Smith rubs past North Am el'ica, and the Alumni Association. Telephone: 626-395-3630. Contributing \Vrifer - Robert Tindol for example. The story of Copy Editol1 - Mi chael Farq uhar, PICT URE CR EDITS: Cove r, 18 , 22-24, 27 - Katrin Hafner; J ulie Hakewill what these scientists inside front cover, 8-16 - NASA; 2 - Doug Smith; 6, 7 - Wayne BIIS;IIess "'lalldger - Debbie Bradbury found, and what life Waller; 22,27 - Joann Stock; 28, 30, 33 - Bob Pn; 30-33- Cirm/afioll Malinger - Susan Lee Ben Ramirez; 31, 32 - J ay Winkler; .34,37,38,40 - Janet Her­ PhofograjJher - Robert Paz aboal'd a reseal'ch ship is ing , J en ni fer Wilkie; 35-37, 40 - Los Angck-s DWP; 41 - Judy like, begins on page 18. Amis; 4 2 - EltOn Sewell; inside back cOver - Herb Shocbridge Visit Calcech on the Web at http ://www.caltech.ed u Bill Johnson shows off a prototype putter whose head is one solid piece of metallic glass. The pizza paddle behind him is actually the biggest chunk of metallic glass ever cast, and is typical of the ingots from which the dub-face inserts are cut.

they're called, absorb energy material, and it becomes as Random Walk FORE! that would otherwise be brittle as a common ceramic. imparted to the ball. (Ulri­ Try teei ng off with a porce­ mately, of course, if you put lain golf club! Tiger Woods doesn't really enough stress on the metal In order to make chunks need them, and the average the slippage leads to metal instead of ribbons, you'd have duffer probably can't afford fatigue and fractures.) So to figure out how to cool the them, but a new set of golf if you could get rid of the melt at a more reasonable clubs that can easily add ten crystalline structure, you'd rate-a few degrees per yards or more to your drive is get a much stronger, more second, say- while still coming on the market. The flexible metal that can take forestalling crystallization. "When the li quid becomes reason you 're reading about high stresses without absorb­ Arakan Peker (PhD '94) did them in Engineering & Science ing energy. (You'd get other just that in his thesis, says complicated enough, it can't instead of GoljDig,,' (where interesting properties as Johnson. "He realized that they'll appear next monch) is well-see E&S, Winter we had to go to a very com­ figure out how to crystallize that these clubs have a face, 1990.) plicated material. We need because there aren't any nice, or striking surface, made of Metallic glasses, however, to have four or more atoms a metallic glass developed by are amorphous, not crystal­ with different chemical simple, orderly patterns it can Cal tech researchers and trade line. Like a big paper bag characteristics before the named Liquidmetal. This stuffed full of golf balls, the liquid gets sufficiently settle inco, and while i t 's stuff is perfectly elastic, says atoms are loosely jumbled, frustrated in its efforts to William Johnson (PhD '75), with no regular pattern to crystallize. W hen the liquid thinking about it, we can cool the Mettler Professor of their arrangement- no neat becomes complicated enough, Engineering and Applied arrays. A glass is really just it can't figure out how to it enough co solidify it." Science. To prove it, he drops a very cold liquid in that crystallize because there aren't a ball bearing on a titanium respect, bur an extremely any nice, simple, orderly pat­ p late-the high-tech metal viscous one-the atoms are terns it can settle into, and of choice for golf-club heads. packed so densely that they while it's thinking about it, The bearing bounces perhaps aren 't free to move or flow. we can cool it enough to a dozen times. When the Amorphous metal ribbons solidify it. We might call demonstration is repeated less than a tenth of a millime­ this the 'confusion prin­ with a Liquidmetal plate, ter thick have been on the ciple.'" Peker used a five­ the bearing bounces like a market since 1973, bur that's metal mixture of zirconium, Superball. all that has been available titanium, nickel, copper, and Ordinary metals are crystal­ until now. Ordinary metals beryllium, but even th~t only line- as the melt cools, the crystallize so incredibly glassifies over a very narrow atoms snuggle together in rapidly that bypassing the range of compositions. In eat, orderly arrays. When process means cooling the But why take this marvel­ you apply stress to the metal melt by a million degrees per ous material and make golf -by hitting a golf ball with second or more, which can dubs? Well, you've got to it, for example-one plane of only be done with very thin start somewhere. And, says atoms slips partially our of layers of metal. And the Johnson, "golf is a very alignment with the neighbor­ cooling has to be rigorously demanding application. ing plane, creating the equiv­ uniform throughout the When a good golfer hits the alent of a wrinkle in a rug. piece- a few scattered crys­ ball, the dub head is moving These dislocation defects, as tals in the interior of the at 100-110 miles per hour,

2 ENGINEERING & HlfN(f NO. 199 7 and you do this thousands of times over the life of the club." Casting a club head is no stroll down the fairway, either--drivers are hollow, irons are concave in back, and even the simple slab of the humble putter is problemati­ caL The trouble is that the metallic-glass-forming melt is a hundred to a thousand times more viscous than an ordinary molten metal alloy. "1t's more like a thermoset­ GOOD NEWS AND BAD NEWS FOR MARTIAN MARINERS ting polymer," says Johnson. "Ie doesn't flow very well. Bubbles don't float; debris doesn't sink." David Lee (PhD '94) and Michael Ten­ hover (MS '78, PhD '81) had to develop an entirely new set The good news is that Mars deep within the planet that braking maneuver, in which of manufacturing techniques Global Surveyot, which slid give rise to the magnetic the spacecraft dips into the to work with the scuff. into orbit around the ted field. (Mars presumably used upper fringes of the Martian So the first clubs have a planet on September 11, has to have a molten interior, toO, atmosphere, allowing the 2.5 - to 3-millimeter-thick discovered a Martian mag­ si nee huge, dead volcanoes drag on its solar panels to amorphous insert for the netic field. (Previous, more dot the planet's surface.) slow it down and eventually striking face, bo nd ed to a distant observations by But that dynamo is no plop it into the circular orbit steel or titanium club head. several spacecraft had been longer turning fast enough to from which it will map the They recently went on sale in inconclusive.) The bad news sustain a single, global field, planet. It will continue Japan, where golf is teally big is, you can't navigate by it. because Mars Global Survey­ aerobraking through the and folks are willing to pay The existence of a planetaty or's magnetometer swung Martian atmosphere for the top dollar for the latest tech­ magnetic field is often seen as wildly as the spacecraft next four months, until it is nological wrinkle. (It made a prerequisite for the develop­ buzzed the planet. In some flying about 378 kilometers sense to start selling them ment and continued existence places the field is pointing above the Martian surface. there first, says Johnson, in of life. A strong magnetic straight up; in others, Additional information order to cover the new tech­ field would shield a planet straight down; and in still is available at several World nology's startup costs.) But from the fast-moving, electri­ other places the field lies Wide Web sites, including now Amorphous Technologies cally charged particles of rhe parallel to the surface. This the JPL home page at http:// International, the Laguna solar wind that would other­ indicates that the field is a www.jpl.nasa.gov/matsnews, Niguel company where Peker wise bombard the upper fossil frozen into the rocks the Mats Global Surveyor et aL now work, is gearing atmosphere, breaking water of the crust, and that it has home page at http://marsweb. up to start production of full y and other molecules down splintered and rotated with jpl.nasa.gov, and the Goddard amorphous club heads here in into ions that then escape the rocks carrying it. If the Space Flight Center magne­ rhe United States. If they into space. So a strong mag­ patchwork could be recon­ tometer site at http://mgs­ meet their goal of having a netic field helps a planet keep structed, it would tell scien­ mager.gsfc. nasa.gov. set of irons on the market by its atmosphere, and with a tists a lot about the planet's The Mats Global Surveyor Aptil, 1998, says J ohnson, it dense enough, warm enough geological history. The is managed by the Jet Propul­ wi ll set some sort of record atmosphere, Mars could have strongest patches were 40 sion Laboratory, which for moving a material from had liquid water on its sur­ times the strength of compa­ Cal tech manages for NASA. a laboratory curiosity to a face. The field would also rable regions on Earth, so the JPL's industrial partner is consumer product. And the intercept cell-damaging cos­ Martian field must once have Lockheed Martin Astronau­ lessons learned while making mic rays thac would otherwise been quire substantial. tics, in Denver, Colorado, golf clubs can be applied not penetrate to the surface. The spacecraft discovered which developed and operates only to other sporting goods Planets like Earth, Jupiter, the outermost boundary of rhe spacectaft. 0 such as tennis rackets,' base­ and Saturn generate their the Martian magnetic n.eld­ ball bats, and bicycle frames, magnetic fields by means of known as the bow shock­ but to such demanding appli­ a dynamo made up of moving duting rhe inbound leg of cations as jet-engine compres­ molten metal at the core. its second orbit around the sor blades and medical pros­ This metal is a very good planet, and again on the out­ theses. D - DS conductor of electricity, and bound leg. The discovety the rotation of the planet came just before Mars Global creates electrical currents Surveyor began its first aero-

1997 ENGINEEklNG & SCIENCE NO. J 1 system. As stars age, they create elements heavier than helium in their bowels. When they die, some of this material is ejected into the interstellar medium for future scars to condense from. Thus the matter from which tomorrow's stars will be born is not what it was when the ACE 15 HIGH sun was conceived; ACE will teHus how it has changed. And finally, the most ener­ getic particles ACE can detect are the galactic cosmic rays, which come from within our NASA's Advanced Compo­ responsibility for the other galaxy but may have traversed sition Explorer (ACE), which instruments. (The spacecraft it many times, trapped in its lifted off on August 25, car­ irself was builr by Johns magnetic fieJd, before blun­ ries two Caltech instruments. Hopkins University's Applied dering i nco our solar system. ACE is headed for an orbit Phys ics Lab.) Their exact origin is still a around the point between Parked as it will be mystery, which ACE should SEE MARS IN 3-D; Earth and the sun where the between us and the sun, it is help resolve, but the relative gravitational and centrifugal probably not surprising that abundances of radioactive HEAR IT IN STEREO pulls balance. Once there, it the sun looms large on ACE's isotopes in them (the same will sample the not-so-empty agenda. The solar wind and principle as carbon-14 dat­ space of our solar system. other, higher-energy particles, ing) shows that, on average, The atoms and ions whizzing both of which come from the they are 10-20 mill ion years around out there come from sun's outer layers, are the only old, says Cummings. They f}ramatic 3-[) pictures three sources: the sun, the solar matter that humans can thus constitute a sample of from JPL's Mars Pathfinder local interstellar medium, and analyze directly, says galactic matter of intermedi­ mission will be shown during the Great Beyond. Each par­ Mewaldt. The relative abun­ ate age. a performance of Gustav ticle has a tale to tell about dances of various isotopes in ACE entered its design Holst's "Mars" at the season 's when and where it was born, those particles, which ACE phase in 1991, just in time first Caltech-Occidental and where it's been si nce. can measure and cameras and to be a guinea pig for NASA's Concert Band performance, ACE's nine instruments spectrographs can't, will tell "faster, better, cheaper" man­ conducted by WilJiam Bing, will count the particles, mea­ us more about what matter date. "We had a cost cap and who has purchased 600 sets sure their kinetic energies and in the universe was like when a fixed launch date," Cum­ of 3-D glasses for the occa­ ionization states, and even the sun condensed , 4.6 billion mings recalls. "Miraculously, sion. The pictures come discriminate between differ­ years ago. And instruments we hit our launch window, courtesy of Robert Manning ent isotopes of every chemical that measure the charge on and even had some $ 3 0 (BS '82), a trumpet player element from helium ro zinc. individual particles will take million left to give back to with the Caltech Jazz Band Between them, the instru­ the temperature of the region the agency." He credits close and Pathfinder's chief engi­ ments cover a millionfold of the sun that the particles cooperation with JPL, which neer. The concert begins at range of particle energies came from-hotter layers provided technical support 8 p.m. Saturday, November with a sensitivity 10-1,000 strip off more electrons from and experienced personnel to 15, in Caltech's Beckman times better than previous the ions they emit. ACE will help keep track of the instru­ Auditorium. The concert is missions. The two Cal tech also study the sun's enormous ments that Cal tech wasn't free and open to the public, instruments-the Cosmic magnetic field, and as a side building. (It probably dido't with seating available on a Ray isotOpe Spectrometer benefit will provide about one hurt that Ed Stone, director "first come" basis. and the Solar Isotope Spec­ hour's warning of the power­ of JPL and vice president of In addition to the perfor­ trometet- were built in the fu l magnetic storms that can Caltech, is ACE's principal mance of "Mars" from Holst's Space Radiation Lab by teams black out power grids, dis­ investigator.) "It's a model suite The Planets, the program headed by Senior Research rupt communications, and for how the Explorer program will include music by George Associate in Physics Richard even fry satellites. can run in the fmure." Gershwin and excerpts from Mewaldt and Member of the Moving up the energy O-DS the musical Ragtime. Guest Professional Staff Alan Cum­ spectrum are the so-called conductor Daniel Kessner mings (PhD '73), in collabo­ "anomalous cosmic rays," will conduct one of his own ration with researchers from which are atomic nuclei from compositions, which was JPL, NASA/Goddard, and the interstellar medium-the recently commissioned by Washington University. thin, thin gas that lies beyond a consortium of coll eges, Caltech also had overall the boundaries of our solar including Caltech.

4 ENG I NEERING & SCIENCE NO. 1997 Nelscllp,lI: Cllurornla Institute or Technology ,., • CA LT EC H

News & Information FALL WATSON LECTURES SET Aea, demics & R eseprc:h

Admissions ATLAS SHRUGGED

Administration

T his year marks the 75 th Alumni anniversary of the Earnest C. Calrech researchers think Watson Lenures, a series that O nline Resources they have solved part of the has not only grown tip with mystery of the "evolutionary

the Institute, bue literally Campus Wob Bulletin rOT 10/9/97 big bang" that occurred half shaped it: Beckman Audito­ a bil lion years ago. At that • El.t1U.Iilly Ay tomatlc pUlgn o! 0 Prol@!n • AM"! tolheb rium was designed in part time, life on Earth underwent • 1M 1997 I" A OtJBdclg~g\l..ll.llill ·• """"'-""leI PC!H!!Jilllo n lob I WIICI' °A ConYllc§otlon '«111\ WWlln Huffll!!" with these public lectures in • L1Jl[A[yJi\lllWIl a profound diversification • k.W:DWillDg mind. On Occober 29, David • .wJI....tlIUl..a..tl.l!n111.u. that saw the first appearance and Judith Goodstein will I" I,,,,, " in the fossi l record of virtu­ ------present "Earnest Watson and Seorch the Collecll welllor:r---mBIl .a!U.lAD.l1 AlpbQb AIfCal Hi!!eg ally all animal phyla living 'L..__ the Amazi ng Liquid Air today. With relative evolu­ Show" in homage [Q that tionary rates of more than 20 first talk in 1919. times normal, nothing like it Then, on November 5, in Cal tech's homepage, http://www. caltech.edu. has a new look. Designed by has occurred si nce. In a paper "Gamma-Ray Bursts: Dying Aurelius Prochazka (PhD '97) and colleagues Jacob Mandelson. Danny publis hed in the J uly 25th Cries from the Deep Uni­ Petrovich, and Athina Peiu Quake (wife of Assistant Professor of Applied issue of Science, the Caltech verse," Professor of Astrono­ group reports thac this evolu­ Physics Stephen Quake), the Web site was commissioned by Provost Steve my and Planetary Science tionary bursr coi ncid es with Shrinivas Kulkarni will Koonin and the Web Executive Council. Members of the council would another apparently unique describe astronomers' search appreciate feedback on the new site. For a list of members and their event in Earth history-a 90- fo r the source of these bursts, e-mail addresses, visit http://caltechfsubpagesfcredits,htmlj or e-mail the degree change in the direc­ and presem thei r surprising tion of Earth's spin axis council directly at web @cco.caltech.edu. conclusions. relative to the continents. In "Touching Mars," on Professor of Geobiology November 19, Donna Shirley, J oseph Kirschvink (BS, MS manager of JPI:s Mars Explo­ '75), lead author of the stud y, ration Program, will discuss speculates that a major reor­ the ambitious slate of one ganization of tectonic plates Mars mission every 26 during the late Precambrian momhs through about 2015 changed the balance of mass that began with the Path­ CASSINI LAUNCHED AT LAST within the Earth, triggering finder and Mars Global the reorientation. Thus, the Surveyor. regions that were previously And in "The World of Our at the north and south poles Grandchildren: Visualizing were relocated to the equator, Alternative Futures wi th the In other news from the Cape, JPL's Cassini mission to Saturn and two antipodal (or oppo­ World Wide Web," on was finally launched at 4:43 a.m. Eastern Daylight Time on site) points near the eq uator J anuary 14, 1998, Professo r October 15 , after numerous delays. The spacecraft will get became the new poles. of Planetary Science and gravity-assisted boosts from Venus (twice), Earth, and Jupite r "Life diversified like crazy Geology Bruce Murray wil1 en route, and is slated to arrive at the ringed planet in July abom half a billion years talk about the "H yperforum," 2004. Once there, it will spend four yea rs studying the Satur­ ago," says Kirschvink, "and an experiment in discourse nian system much as Galileo is doing at J upiter. Cassi ni even nobody really knows why. thar uses the World Wide has a probe of its own-the European Space Agency's Huygens, J[ began about 530 million Web to analyze complex which will parac hute into the nitrogen-rich atmosphere of Titan, years ago, and was over abom problems such as rhe long­ Saturn's largest moon. If the probe survives the landing, it will 15 million yea rs later. It is term sustainability of global study Titan's hydrocarbon-rich surface, which in some ways may one of the outstanding mys ­ development. resemble that of the prebiotic Earth. teries of the biosphere. The

199 7 ENGINEERING & S{IEN{E NO. 5 geophysical evidence that laws of physics force to equal­ largest gravity anomaly in the we've collected from rocks ize in comparatively rapid solar system. Tharsis could deposited before, during, and time scales. have formed on the equator, after this event demonsrrate During this redistribution, but more likely formed else­ that all of the major conti­ the entire solid part of the where on the planet and then nents experienced a burst planet moves as a unit, avoid­ migrated to the equator via of motion during the same ing the internal shearing true polar wander because of interval of time." effects that impose the speed rotational torques on its Grad student David Evans, limit on conventional plate excess mass. a coauthor of the paper, notes motions. (While this is Something similar must that it is very difficult to happening, of course, Earth have happened to Earth, says make large continents travel maintains its original spin Kirschvink. At about 550 at speeds exceeding several axis in relation to the plane of million years ago, 20 million feet per year; typical rates the solar system.) Thus, true years before the evolutionary tOday are only a few inches polar wander can result in burst, one or more of the per year. land masses moving at rates chief subduction zones in the "Earth has followed a hundreds of times faster than ancient oceans closed down 'plate-tectOnic speed limit' tectonic motion caused by during the final stages of for the past 200 million years convection. assembly of the superconti­ or so, with nothing approach­ An analogy of [he effeer nent of Gondwanaland, lead­ Above are three views of how ing the rates needed for this can be seen by cementing ing to a major reorganization early Cambrian reorganiza­ lead weights at antipodal of plate-tectonic boundaries. Earth's continents were arranged tion," Evans said. "Some points on a basketball. If the Geophysicists have known about 530 million years ago. The other tectonic process must ball is then set on a slick floor for many years that this type red posts are Earth's spin axis; the have been operating that and spun with the weights of reorganization could, in colors are keyed to today's conti­ would not require the conti­ along the equator, the ball theory, yield a sharp burst of nents to slide so rapidly over will spin in the manner one true polar wander. In partic­ nents. (India is under the "wana" the upper part of Earth's would normally expect, with ular, if Earth were slightly in "Gondwanaland.") Most of the mantle." the weights remaining on the "foorball shaped," wi[h a continental mass is concentrated In fact, geophysicists have equator. If the ball is spun on major, stable mass anomaly known for over half a century one of the lead weights, how­ on the equator and a more around the south pole (which is that the solid, elastic part of a ever, the axis of rotation will equal distribution of mass projecting outward in the middle planet can move rapidly with tend to migrate until the elsewhere, only slight changes picture), a rotationally unstable respect to its spin axis via a weights are again on the ball's of the smaller masses would situation. The planet compensates process known as "true polar equator. This way, the spin­ be needed to produce large wander. " True polar wander, ning ball has aligned its max­ motions. A burst of motion by shifting its axis until the excess Kirschvink explains, is not imwn moment of inertia with up to 90 degrees in magni­ mass is centered on the equator, the same as tbe more familiar the spin axis, as required by tude could even be generated as shown in the sequence of pic­ plate motion that is respon­ the laws of physics. if the maximum moment of tures above right. (Although the sible for earthquakes and As for astronomical evi­ inertia (about which the plan­ volcanism. While the latter dence that such a phenom­ et spins) became less than the axis moves with respect to the is driven by heat convection enon can occur, the authors intermediate moment (which continents, as shown here, it in Earth's mantle, true polar point to Mars. Along the is always on the equator). remains fixed with respect to the wander is caused by an imbal­ equator of the red planet is a The massive plate motions ance in the mass distribution gigantic volcano called Thar­ observed by the Kirschvink plane of the solar system.) of the planet itself, which the sis, which is known to be the group fit the predictions of

6 ENGINEERING & SCIENCE NO. 1997 "A progressive shift of this magnitude could cause oceanic

ci rc ul ation patterns ro become rather u npred ictable, jumping

from one semi-stable configuration to another on a million-year

time scale. Imagine the bavoc that would result in Europe if the

Gulf Stream were co disappear suddenly."

this "i nertial interchange" anism to do that. All of well-exposed sections of the Early Cambrian), and finish­ event rather closely. the evidence suddenly makes Precambrian-Cambrian and ing sometime during the Over the 15 million year sense with this true polar Cambrian-Ordovician eras. Middle Cambrian. North duration of this true polar wander model. " By us ing ultrasensitive supec­ America, on the other hand, wander event, the existing But what caused the evolu­ co nducting magnetometers to moved rapid ly from its end­ life forms would be forced to tionary burst? Kirschvink study the weak fossil magne­ of-the-Precambrian position cope with rapidly changing notes that these global shifts tism (paleomagnetism) left in deep in the southern hemi­ climatic conditions as tropical in oceanic circulation wi ll many rocks as they formed, sphere, and achieved a posi­ lands slid up to the cold polar also act to disrupt reg ional the researchers ca n recover the tion straddling the equator regions, and cold lands be­ ecosystems, breaking them direction of the ancient geo­ before the beginning of the ca me warm. "Ocean ci rcula­ down into smaller, more magnetic field. This points Middle Cambrian, about 518 tion parterns are sensitive to isolated communities . in the vicinity of ancient million years ago. Even the even slight changes in the "Evolutionary innovations are norch, for the same reason type of marine rocks depos­ location of the continents," much more likely to survive that a magnetic compass can ited on the various continents says coauthor Robert Ripper­ in a small, inbreeding popu­ be used to find the approxi­ -carbonates in the tropics, dan (MS '85, PhD '90), a geo­ lation, rather than in large, mate norch direction today. and clays and clastics in the chemist at the University of freel y interbreeding groups," This remanent magnetism hi gh latitudes-agree with Puerto Rico. "A progressive he notes. "And the carbon can also provide an estimate these paleomagnetically shift of this magnitude could cycles are telling us that of the ancient latitude in determined mOtions. The cause oceanic circulation major changes in ocean circu­ which the sediments were paleo magnetic directions patterns to become rather lation happened about every deposited, as the inclination are accurate within about 5 unpredictable, jumping from million years or so. That is (or dip) of rhe magnetic field degrees, the authors wri te. one semi-stable configuration cercainl y enough time fo r changes smoothly with lati­ Latitudes are quite reliable, to another on a m illion-year natural selection co weed tude-it points vertically at but because the poles moved time scale. Imagine the through the fragments left the poles and is horizontal so rapidly, even the relative havoc thar would res ult in by the last disruption, and (tangent to Earth's surface) on longitude between blocks can Europe if the Gulf Stream to form new, regional -scale the equator. Therefore, the be determined. This true were co disappear suddenly." ecosystems. Then, wham! fac t that magnetic materials po lar wander analysis predicts These jumps offer an They' re hit again and the are found pointing in other a unique "absolute" map of explanati on for yet another process repeats itself. That direCtions is evidence that the the major continental masses unique mystery of the Cam­ is a great script for increasing ground itself has moved in during this event, an anima­ brian explosion, which is a diversity, particularly as it relation to Earth's magnetic tion of which can be viewed series of nearly a dozen large seems to have happened norch, which is locked over at http://www.gps.caltech.edu swings in the marine record shortly after the evo lution time to the spin axis. I-devans/ii tpw Iscienc~. html. of carbon isotopes. "Repeated of major gene systems that Geological samples collect­ "This hypothesis relating changes in g lobal oceanic regulate animal develop­ ed by the Caltecb group in abrupt changes in polar wa n­ circulation patterns should ment." The upshot was that Australia (which has some of der to evolutionary innova­ ventilate organic carbon evolution proceeded nea rly 20 the best-preserved sediments tions could be tested in many buried in the deep oceans, times faster than its normal of thi s age from all of Gond­ ways," notes Kirschvink, "as producing ~hese carbon rate, and the life of the planet wanaland) demonstrate that there are some interesting wiggles," Ripperdan says. diversified into many groups this entire continent rotated events in the paleontological "We used to think that they still living today. counterclockwise by nearl y record during the following were somehow due co repeat­ Kirschvink an d his collabo­ 90 degrees, starting at about 200 million years which ed expansion and contraction rators base their conclusions 534 million years ago (coinci­ might have been triggered by of the entire biosphere, but on dara coll ected from 20 dent with [he onset of the similar processes. There's lots no one cou ld think of a mech- years of work on numerous major radiation event in the of work to do. " U- RT

1997 fNG t NEE RtNG & S( ltNCE NO. 7 by Douglas L. Smith

Above: The spacecraft came The Pathfinder landed on the Fourth of] uly, and now Labor Day has come and gone. The to rest where the flood- "plucky Mars rover" has dropped off the front plain of Ares Vallis, a page of the nation's newspapers. But the mission channel carved aeons ago continues, and with some three months of data in by the sudden release of hand, the mission's scientists are beginning to take stock of their results. What follows is an enough water to fill the amalgam of hard data, preliminaty interpreta­ Mediterranean Sea, spills tions, and informed speculations on everything into the vast flatnesses of from Mars's ai r to its core. Chryse Planitia. This On the meteorological front, Pathfinder started taking atmospheric data on the way in. The panoramic view of the spacecraft's Atmospheric Sciences Instrument landing site shows some of (ASI)/meteorological package contains instru­ the names that have been ments similar to those of the Viking missions of 20 years ago, but considerably more sensitive, says assigned to rocks and ]PLS Tim Schofield, leader of the ASIImet team. other features. (None of And while the temperature data taken on the these names have any way down are unreliable because of the unsteady 1._..... official standing.) The airflow around the recessed instruments, Julio Magallhaes of NASA's Ames Research Cenrer, rover's movements over at Moffett Field, California, has constructed a the mission's first 38 sols temperature profile from the atmospheric drag (Mars days) are shown by recorded by the accelerometer. (See picture on the dark line. The rover page 10). The data resemble those from Viking I , which landed more than 800 kilometers away at spent the next 33 sols in very nearly the same latitude and elevation, albeit the area bounded by somewhat earlier in the northern-hemisphere Wedge, Flat Top, Moe, and summer. Pathfinder's temperature readings were, on average, 20 kelvins (K) lower at altitudes above Shark, known as the Rock 60 kilometers-probably beca use Viking rouched Garden. As of September down at four in the afternoon, while Pathfinder Above: Pathfinder landed within 20 kilometers of its aim 26, the rover, named bounced in at three in the morning, local Martian time. From about 60 kilometers on down, Path­ point, a feat that one member of the navigation team has Sojourner, had more than finder's data match Viking's to within five orten likened to playing a par ~ rour hole with the tee in Los 100 meters on the degrees. This leaves unresolved the debate about Angeles and the hole in Houston, with a regulation ball and odometer. When last whether Mars is getting colder-ongoing tele­ cup. By triangulating from the Twin Peaks and other land­ seen, the rover was in the scopic observations of the lowest 20 kilometers of atmosphere of the planet as a whole have been marks on Pathfinder's horizon that also show up in photos vicinity of a rock named reading about 20 degrees cooler rhan in the days from the Viking orbiters, the spacecraft's position is now Chimp (gray insert). of the Vikings. Furthermore, the telescopes don't known to within I S meters. see that much dust in the air-important because

8 ENGIHEERING & I{IENCE NO. 1997 the dust is heated directly by sunlight-while days, in the meteorological equivalent of the Pathfinder's camera is seeing as much dust as the panoramic views, the lander tOok data at four­ Vikings did. second intervals for an entire sol.) During the Pathfinder did find it as much as 50 K nippier exrended mission, Pathfinder goes to sleep at at altitudes between 60 and 100 kilometers, how­ night to conserve power, so weather data is taken ever. This again is probably due to day-night dif­ during daylight hours. But once every couple of ferences, possibly accentuated by thermal tides in weeks or so, the scientists make the spacecraft stay the atmosphere, a phenomenon seen on Earth that up all night to see what they're missing. Path­ would be accentuated by Mars's thinner air. These finder's weather reports average 10 degrees warm­ tides begin at the planet's surface, where heated air er than Viking 1 's during the day, and 12 degrees expands by day. This creates a wave that travels warmer at night. Part of the reason may be that upward, with the amplitude of the temperature the Pathfinder site is darker and thus absorbs heat variation increasing with height. At about 80 better; its rocks also retain heat longer than did kilometers, the temperature bottomed out at the finer sand and dust at the Viking site. 92 K--cold enough to freeze carbon dioxide, But the barometer watch is going to be the real which makes up some 95 percent of the Martian gold. "Temperature and wind just tell you what's atmosphere. There's speculation that this dry ice happening where you are," says Schofield. "But may form clouds, but if so, they haven't been seen. pressure readings tell you about the whole column Since the landing, Pathfinder's weather station of atmosphere from the surface all the way up." Below: The green cross in has been recording barometric pressure, tempera­ Pathfinder landed in the northern hemisphere this view from the Hubble ture, wind direction, and speed. For the 30 sols­ during late winter in the southern hemisphere, Space Telescope marks the as the Martian day of24 hours, 37 minutes, and when pressure wanes planetwide because some 20 twenty-odd seconds is called----of the primary percent of the atmosphere's carbon dioxide freezes Pathfinder landing site. mission, it took data day and night. (On some out into the south polar ice cap. Pathfinder Right: The two Viking landers are also shown on this Mars map; the arrow points to Ares Vallis. -,

---' July 9, 1997

'997 £NGINEERING & HlfNCE N O . • a daily sweep clockwise through every point of the compass, lingering in the south overnight- a progression so regular duting the first 30 sols that any resident Martians at the landing site could set their watches by it. T here's also cool scuff in the temperature data. The meteorology mast carries three thermometers at heights of one-quarter, one-half, and one meter. (The Vikings only had one temperature sensor each.) There's a dramatic temperature stratifica­ tion- if you were standing next to the lander at midday, your shoes would be 10 degrees horeer than your belt buckle, because the sun-warmed ground heats the ai r in contact with it. (The pat­ tern reverses after sundow n, because the ground loses heat faster than the air, but the nighttime spread is only a few degrees.) All three sensors Above: Pathfinder's principal parts. On July S, the lander reach a daily peak in the early afternoon, and then portion was renamed the Carl Sagan Memorial Station. cool overnight until dawn. Superimposed on this Below: During its descent, Pathfinder found the air cooler gende swell are spiky feacures-15-degree varia­ tions over tens of seconds--caused by bubbles of than Viking I did-cold enough to make dry-ice douds at heated, unsteady air convecting and mixing. Even one point. These temperature measurements were actually after dark, when the warm air is on top and one derived from an accelerometer-the rate at which the might assume things would be calmer, the night­ time winds periodically overturn the layers. spacecraft decelerates as it descends is a function of When the bubbles of hot air coa lesce inco a atmospheric drag, which in turn depends on the air's vertical pipeli ne you get a dust devil , which is the density. Air that's cooler than expected is denser, and thus weathermen's hottest quarry. The weather station generates more drag, than would be expected at a given

altitude. The data is good down to about nine kilo~eters, when the parachute opens.

-___ u.• ... ____ us .. caught tbe depth of this cycle on Sol 20, when :i ,:'i~:.' ~ the pressure bottomed out at about 6.7 millibars . ,,:;kI· . .\ ~, . (a millibar is a thousandth of the atmospheric j pressure on Earth's surface). But the pressLUe is ~,". "'''''" ', rising rapidly with the spri ng thaw, reac hing 7.2 " mb on Sol 83, and Schofield expects it to peak at about 9 mb within the next hundred sols. Summer on Chryse Planitia is a lot like summer in Los Angeles, at least as fa r as co nsistency ., .. goes--one day is prerey much like the next. -- But as autumn draws on, Schofield expects to see more variety-weather frones roll ing down from Above: A sol's worth of output from the three thermo­ the poles, juSt as they do on Earth. And the extra couples (temperature sensors). In this decimal representa­ 1111 100 1/1 ItO III \1& tJJ m heat that Mars gets from being closer to the sun in T....,w.(KtIlIIIl tion of time, .0 sols is midnight and .S sols is noon. Sun­ the southern summer may bring on those famous planer-enveloping dust storms. Bur before these rise and sunset are at roughly .25 and .15 sols re~ pectively. long-term patterns unfold, the day-to-day data The data are plotted as the difference from the mean value are revealing short-term patterns of their own. of all three sensors at that moment, accentuating the The winds in the lander's vicinity, for example, temperature spread between the top and bottom sensor. blo~ in a topographically driven cycle. They're called "slope winds," says Schofield, and on the By day, the bottom sensor is the warmest (peaking this simplest level they work like this: at night, cold day at a balmy 270 K, or very nearly 0° C) , but at night, air descends from the highlands hundreds of the ground cools faster, and the bottom sensor is the kilometers south of the landi ng site, sighing down through the canyons toward the lander. During coldest. The spikes are caused by winds mixing the air the day, the sun heats the flatlands around the masses. The temperature resolution is 0.0 I K. lander, and the wa rm air rises back up through the canyons. The upshot is that the wind makes

10 ENGINEfR(NG & ~(( EN (E NO. 199 7 Sol 25 - Dust Devil 6.74 60

40 ~ 6.73 = • 2. '" ~ ~

'" •"0 • :1. ~ 0 , 6.72 34' = • -= • 3IO ~ ?'-" ..• ..,'" 6.71 300 -I~~~ .!:J" 28.

6.70 260 60 tlO 180 24. • Seconds

Above: A dust devil's is recording an average of one devil every other Surveyor, which slipped into orbit on September signature is written on the day, and on a big day it will see three. These tiny 11 . MGS will spend the next several months tornadoes register as brief, sharp pressure drops­ "aerobraking"-raising its solar panels up into wind and pressure sensors. in the largest one to date, the pressure plummeted a V and dipping repeatedly into the very top of The wind suddenly changes about .05 millibars, or 1 percent of the ambient the Martian atmosphere, where the drag will slow (rom its prevailing direc­ pressure, in a few seconds. (For comparison, a the spacecraft and eventually drop it into the nice, tion, accompanied by a terrestrial tornado causes about a 10 percent circular orbit from which it will map the planet. pressure drop.) If the dust devil passes directly But suspended dust sops up heat from the sun, sudden, sharp pressure overhead, the lander also records a sudden reversal warming and swelling the atmosphere. With the drop. As the dust devil of wind direction and a temperature drop. Dozens atmosphere extending farther our into space, MGS passes overhead, the wind of dust devils had been inferred from Viking wind could be sailing through air that's three to four and temperature data, but the pressure data lacked times thicker than expeCted, and the extra friction abruptly whips around to fine enough resolution to see them. They could be could overheat and perhaps even incinerate the the opposite direction; the an important dust-raising mechanism between spacecraft. Pathfinder's barometer should give pressure and wind readings local and global storms, says Schofield-a host of enough advance notice, in the form of a sudden then rapidly return to the little guys all over the planet could easily help increase in the difference between the daytime and keep the observed background levels of dust aloft. nighttime pressure, for JPL to raise MGS's orbit to normal as the dust devil They could be-we don't know yet whether they a safe height, and the Hubble Space Telescope will moves on. actually carry dust. They may not get enough be keeping a watchful eye as well. oomph from the tenuous Martian atmosphere to The dust gives the air at the landing site an pick up anything, in which case they'd be invis­ optical density of about O.5-the visual equivalent ible, like the wind shear at airports. Pathfinder's of a smoggy day in L.A., says Mark Lemmon, a camera hasn 't caught one yet, bur rhat's jusr a research associate at the Lunar and Planetary matter of time. (Schofield and his team plan to Laboratory of the University of Arizona, in Tucson. search all the images returned so far to see if they (The U. of A. led the team that developed the can spot one in the background.) But there are mission's camera, puckishly known as the IMP, or hints that the dust devils really are dusty---on Imager for Mars Pathfinder.) Optical density is a Sol 62, a photocell that monitors the light striking measure of the number of dust particles in a given the solar panels noted a dimming in the ambient volume of air, but the math gets complicated by light five minutes after a dust devil passed by. assumptions about particle size (believed to be a The phenomenon lasted for 10 minutes or so, little less than a micron, or millionth of a meter, and could be the receding dust devil's shadow. based on how they scatter light), and whatnot. Schofield estimates this dust devil's diameter An optical density of 1.0 means that if all the dust at about a quarter of a kilometer, based on the suddenly precipitated, it would cover the ground shoulder-to-shoulder width of the pressure in a layer exactly one particle thick. The optical minimum and his best guess at its rate of traveL density has remained rock-steady so far, but that This jibes with numerous transient blobs of will change with the advent of dust-stOrm season. roughly similar size seen by the Viking orbiters' five of the densest 10 days have been very recent, cameras. Some of the blobs cast shadows indicat­ but the peak was only 0.6. "You wouldn't notice ing that they stood six to seven kilometers tall. the difference visually if it was 0.5 one day and 0.6 When the dust devils g ive way to a planetwide the next," says Lemmon, "but you might if it dust storm, it could endanger the Mars Global happened suddenly. " The group measures optical

199 7 ENGINEERING & HIENCE NO. " leads the field of terrestrial twilight studies.) The consensus is that the clouds probably lie at about 13-15 kilometers altitude, and tbat they're "Red sky at morning, probably made of water. But this is based on sailors take warning." several assumptions-for one thing, the clouds aren't reflective enough for the IMP to pick up the Martian mariners would water's spectral signature. (The IMP can measure live in a constant state of the cotal amount of water aloft by looking at the terror, as this predawn IMP sun through a special fi lter-an exercise at the extreme limits of IMP's se nsi tivity.) shot shows. The colors are Designers of future Mars missions need to know real-the red sky is due to whether the dust settles fast enough co pose a seri­ dust suspended in the air, ous problem for solar-powered devices. Geoffrey but nobody knows what's Landis of NASA's Lewis Research Center in Cleveland, Ohio, principal investigatOr of the in the blue clouds. rover's Materials Adherence Experiment (MAE) and a photovoltaics expeCt, had predicted a cover­ age rare of 0.22 percent per day. The MAE is logging about a quarter of a percent per day, which Landis thinks is no problem for Pathfinder density by pointing the IMP at the sun, and com­ bur could present difficulties for missions of a year paring the apparem brightness CO what it would or longer. The experiment consists of a glass plate be without the intervening dust. They also check covering a small solar cell on the rover. Once a the sun when it's low in the sky co look at layering day, the glass rotates out of the cell's line of sight, in the atmosphere, an d have determined that most and the ce ll 's output with and without the cover of the dust hangs in the lowest 13 kilometers. plate is compared. The plate is moved by a thin But the most remarkable atmospheric phenom­ wire of an alloy call ed nitinol, which contracts enon that the IMP has captured to date is the blue when heated. Once the wire has cooled, the glass clouds that are seen occasionally about an hour and returns to its initial position. Meanwhile, an a half before dawn. Illuminated by the sun from adjacent sensor weighs the dust depos ited on a below the horizon, they burn off rapidly under quartz crys tal by recording its change in vibration direer sunlight. NOthing much is known about frequency. The whole package draws an infinitesi­ them, except for the inference that whatever mal amount of power-the price for riding the makes them up must be about 0.1 microns in size rover-and is slightly larger than an Elvis stamp. because it scatters blue light. ("This is going to be If the rover is a six-wheeled geologist, as it's one of the mOSt complicated analyses we'll frequently been called, then its rock hammer and have co do," says Lemmon. "We'll have to model toupe is the Alpha Proton X-ray Spectrometer Mats's sphetical form, and the sun angle, and all (APXS). The APXS is three instruments in one, these other geometric effects." Lemmon plans co and is designed to give a complete elemental consult with a research group at the University analysis of the soils and rocks the rover encounters. of Alaska at An chorage that, in a classic example So far, all the results reported about the chemical of making lemonade when li fe gives you lemons, composition of the landing area's soi l and rocks have come from the X-ray mode because the alpha-scattering and proton-emiss ion portions of the instrument, which analyze the li ght elements, are having calibration problems and will have to be recalibrated. Because nobody knows how long the rover will last, the team is focusing on collect­ ing data rather than analysis, says Tom Economou, senior scientist at the Enrico Fermi Institute at the Sojourner does an APXS University of Chicago and coinvestigator for the analysis of a rock named APXS. As of September 26, the APXS has taken nine rock and seven soil samples. Moe. The APXS sensor The biggest surprise actually came from head is the inverted Barnacl e Bill, rhe firsr rock ro be sa mpled. The demitasse cup pressed conventional wisdom said that Mars, being about against the rock. It takes half Earth's diameter, would have cooled fairly quickly as planets go. Therefore Mars rocks all sol to get a reading. shoul dn't have undergone much remelting, and were expected to be primordial basalts-I.ike Earth 's ocean floors, the rock samples brought back from rhe moon , and rhe so-called SNC

11 EN GINEEIING & SCIE NCE NO. 1997 Left: The ratios of various meteorites, which are believed [Q be Mars rocks 0.6-,------, blasted co Earth by a meteorite hit on the red elements to one another, MARS planet. Instead, Barnacle Bill had way toO much EARTH rather than the elements' si lica, indicating that at least part of Mats's interi­ 0.5 • Nakh!iles absolute abundances, can or bad been through enough cycles of melting and • be more useful in com· cooling for some silicon [Q separate from the 0 0.4 heavier elements and float like soap scum to the parative mineralogy. The gZ BASALT • Zag. m, top of the mantle before condens ing i nro rock. L EETA790CH B APXS data from rocks at The exact mineralogy isn't known yer, partially 0.3 I ---. Shergouy ~ Pathfinder's landing site because of rhe lack of good oxygen data from the ::::> ANOESITF<: EETA7'9001A - /\\ Scooby' 000 ..... VIKING (stars) are more Earthlike alpha-scattering portion of the spectrometer, and ~ 0.2 ... J!J~ SOILS partially because Economou would have to get a « • ~ * . Soils than the soils (yellow confirming set of readings from a terrestrial sam­ o •• I ogl circles), which resemble ple of the same mineral. "J get e-mails and sam­ 0'0' "rBarnaCle Bill Yogi· .Dust • ALH A7700S ples every day from people who think they've Chasslgn~ the Viking soil samples found an Earth analog to what we' te seeing," ALH 84001 • (red circle) and various he says. "It'll take years to analyze all of them." o 0.2 0'4 0:6 0.8 1.2 Martian meteorites (red Subsequent rocks have either tesembled Bar­ IRON/SILICON squares) in composition. nacle Bill or have been roughly basaltic. But The star labeled "Yogi - even the basaltic rocks aren't entirely as expeCted, having more sulfur and chlorine than either theit Dust" is an aUempt to earthly counterparts or the SNCs. What this correct for the dust layer means is uncertain, but it shouldn't come as a total on Yogi's surface, surptise, says Economou-nobody knows what part of Mars the SNCs came from, but it's not unreasonable to suppose that the rock mineralogy varies from place ro place, as Earth's does. On the The wheel thing. The Wheel Abras ion Experiment (left) other hand, the soil APXS results have been identical not only with one another but with the consists of IS panels- three metals each in five films soils at the two Viking lander sites, separated by ranging from less than 100 to a few hundred atoms thick, nearly 180 degrees of longitude. This strongly deposited on black, anodized aluminum for contrast. The indicates that the soil , presumably carried on the wings of the wind, is the same all over the globe. soil·mechanics experiments depend on knowing the As Sojourner plods from sampling poim ro position of the rover's suspension system (below). This sampling poim, it takes note of what's underfoot. tells you how much weight is resting on the wheel, and The Wheel Abrasion Experiment, also run by how deeply it has dug in (which gives the surface area in NASA Lewis, consists of a bunch of thio films of aluminum, nickel, and platinum that tun in contact with the soil). Contact area times weight is a ribbon around the middle of the right centet "normal stress," which is ploUed against "shear stress" wheel. As the rover goes about its business, the (derived from the contact area and the torque needed to soil slowly grinds rhe fi lms away. You can scratch just begin turning the wheel) to give a straight line from an aluminum pan with a fingernail, and a nickel with your car keys, but platinum is pretty tough whose slope the friction angle is derived, stuff, so the rate at which the various films get chewed up wi ll give us some idea of how hard or shatp-edged the soil particles are. Twice each sol, the rover spins the test wheel to dig into the soil , and a photocell senses changes in the fi lms' reflec­ tivity. The wheels have accumulated a lor of dust, compli cating the interpretation, but signs of wear are beginning to show, says Dale Ferguson, the experiment's principal investigator. Locki ng five wheels and spinning the sixth one can tell you a lot of other things about the soil's mechanical properties, says Henty Moore, the Pathfinder Rover Scientist and scientist emeritus with [he U.S. Geological Survey in Menlo Pack, California. Perhaps the most important patameter that can be measured this way is the friCtion angle. When the soil is not cohesive-and this stuff isn't-the friction angle is nearly equal to the angle of repose, which is the angle at which the

1997 ENGINEHING & SCIENCE NO. " Sojourner as geologist. The rover drove over some com ~ pressible soil en route from Barnacle Bill to Yogi, as the above view from the rover's camera looking back toward the lander shows. At right, the rover digs in a wheel near a rock named Shaggy on Sol 23. And the rover's camera

goes where the IMP can't, as in the rover's~eye view or

Stimpy, below. Stimpy's fluted, pockmarked surface sug~ gests sandblasting by the wind; windblown deposits of drirt can be seen to the right. Flat Top is visible behind Stimpy; off in the distance, partially hidden by the top strip or missing data, is a profile or Yogi unseeable from the lander.

soil naturally "cones" in piles. The frinion angle of a natural, dry material is rel ated to its bulk density, wh ich in turn underli es its radar and thermal propercies as seen from afar. The rover's "ground trurh" agrees quite well with the values derived from satellite and Earch-based measure­ ments, says Moore, which is all the more remark­ able in that these techniques look at average values from much larger swaths of terrain than Sojourner could ever possibly sample. But since the bulk density comes out the same either way, it inspires confidence in the accuracy of the remote methods. Sojourner also learns about the soil by driving through it and looking at the tracks. Three basic types of soil have been classified this way. The first is a low-density, compressible soil, like the scuff near Casper. The rover leaves sharp. clear Hacks there-the individual tines on the wheels' cleats are visible. Only a talclike powder will catch such fine detail, says Moore, who es timates the gtain size as less than 40 microns-very like the dust teturned by the Apollo missions. (The Viking 1 lander saw similar-looking soil , but of course couldn't drive on it.) A possibly identical material called "drift" accumulates in the lee of the boul­ ders. The second soil type, wh ich Moote calls "cloddy so il," is quite dense and is a mixtute of dirc clods, small rocks, and sand- to silt-sized particles that mechanically resembles what

14 [NGINEElING & ~(IEN(E NO. 1997 Left: Seen through the IMP's geology filters, the bright red drift (f), the dark gray rock named Cradle (3), and two kinds of soil (2 and 4) each have their own distinct spec­ tral signature. (Spectra 2-4 have been plotted against the drift's spectrum in order to highlight their differences.) The strong upward kink in the two soils' spectra at visible wavelengths (less than 0.78 microns) indicates that they ..., 1.2 are more weathered and have more FeU_containing "- minerals than does the rock. Soil 2, which is intermediate ..... 0 1.0 • • • •• • • in color between the drift and the rock, has intermediate ...,0 spectral characteristics as well, while the dark red soil (4) Q) has a spectrum that suggests either a higher Fe+) content > 0.8 ..., or a larger particle size . rn Q) 0.6 0:: Q) Viking 2 found. Cloddy soi l covers most of the u to c: 0.4 area, and has been found underlie the finer soils ...,rn • 1 Bright drift in places where the rover wheel has dug deeper u • 2 Dark soil at Cradle than a centimeter or two. The rover leaves rracks Q) 0.2 • 3 Cradle rock in this stuff, but not crisp ones. And finally, "- there's the "indurated" soil. of which Scooby Doo Q) • 4 Dark red soi I at Lamb 0:: is an example-a cohesive crust that's so tough 0.0 that the rover's wheel JUSt skitters across the 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 surface instead of d igging in. Wavelength in Microns And while the rover explores individual features of the landscape, the lander is getting the Big Picture. Litera ll y. The IMP, as well as taking stereo pictures for rhe rover ream to navigate by and the rest of us to ooh and ahh over, has a se t of Left: The geology filters' 12 "geology" fi lters that span the visi ble and near­ output can also be con ~ infrared spectrum from 0.43 to 1.0 microns and verted into false-color are keyed to specific minerals that the scientists expected to find, allowing spectral data to be taken images to summarize a from anything the lander can see. According to region's spectral properties [he University of Arizona's Dan Britt, coi nvest iga­ at a glance. In this view tor and project manager for IMP, the Super of the Mermaid Dune area, Panorama and the Super-Resolution Panorama now being completed are two "Cadillac data sets" blue is the least weath- that people will be studying for the next decade. ered, green is intermediate The Super Pan covers the entire sce ne in all 12 weathering. and red is the geology fil ters and three color fi lters, in stereo-- a compendium of the spectral characteristics of most weathered. all 2,039 visible rocks (pity the poor soul who counted them!) and the intervening soil patches. And while previous images have been compressed by 6:1 or more, chis color daca is 1:1. (The geolo­ gy data gets a very mild 2:1 compression.) The Super-Resolution Pan wri ngs extra detail fro m the camera by taking 25 lossless views of every .vista, which are then combined in supercomputers at NASA Ames to sharpen the image by a factor of four to eight. The IMP's view of the rocks dovetails with [he APXS data, wh ich means that elemental composi­ tions can be assigned to a host of rocks that the lander can see but the rover ca n't reach. Yogi and the other big rocks are more weathered, says Britt,

199 7 ENGINEERING & S(IE NCE NO. IS comes in two ionic forms: it dissolves Out of irs 2 native rock as Fe · , but dissolved oxygen converts it to Fe ·3. Fe+3 is insoluble, and rapidly precipi­ tates. On Earrh, Fe-3 eventually becomes hematite (a popular gemsrone) or goethite (the primary constituent of rust), neither of wbich is strongly magnetic. Fe2 can linger in solution for years before eventually setrling out as the terrestriall y less common iron oxides maghemite (the magnetic coating on cassette tapes and floppy disks) or mag­ netite (humankind's first compass, also known as lodestOne). So dust consisting of clays with a strong magnetic component will imply that liquid water pl,ayed a long-term role in the dust's forma­ tion. The IMP looks at the array eve ry few days to see if the accumulating dust matches any of the parterns these minerals made on an identical array on Earth, and once a week tries to identify the mi nerals spectroscopicall y through the geology filters. The dust appears to be a composite of The bright object off in the which means they've been sitting in their present mainly silicate particles containing maghemite, locations for quite a while. They also tend to be says Jens Martin Knudsen, lMP coinvestigator middle distance of this rounded, like boulders in a scream, implying that from the University of Copen hagen. portion of the Super­ they were sculpted by water- presumably while Resolution Pan isn't a being tumbled for hundreds of miles down Ares data-processing artifact or Vallis from parts unknown. The smaller, jagged rocks like Shark and Wedge are less weathered, a sign of an alien and thus relative newcomers. They're also higher civiliution-it's in si li ca, so they must have come from a different Pathfinder's backshell. place. One popular co njecture has them being impact ejecta from the so-called Big Crater to which was cut loose just the south. two seconds before the Britt classifies Scooby Doo and its kin as a spacecraft hit t he ground. third kind of rock that he calls "caliche-like," after The spacecraft, swaddled a cemented mineral common in the Tucson area. When it rains in the desert, calcium-rich salts in its airbags, bounced leach out of the upper soil and begin to percolate from there to its present downward . But before rhey've penetrated more location. This image fortu­ than a foot or so, the water evaporates in the itously caught a glint of scorching heat, concentrating them into a layer­ caliche-that has many of the properties of con ­ sunlight off the backshell, crete. Says Britt, "There's a big debate about making it easier to spot. wherher the cali che-like stuff should be classified as soil or rock. The people from moist climates who have never cried digging in it call it soil. Those of us from arid regions ca ll it rock. And since I'm the chair of the mineralogy and geo­ chemistry science group, it's rock." Pathfinder carries two arrays of five bull's-eye magnets of The IMP is also a vital part of the Magnetic increasing strength from left to right. The uppe~ array is Propenies Experimem being run by rhe Niels Bohr Institute for Astronomy, Physics, and for airborne dust; t he lower array is near the landers base, Geophysics at the University of Copenhagen, in hopes of collecting sand grains as well. These two Denmark. Iron and liquid water are chemically images of the upper array are from Sol 64. The black-and­ rhe best of friends, so the state of Mars's iron can white image has been contrast-enhanced to reveal that tell us a lor about the histOry of Mars's water and the former potential for life therein. Iron is the dust is sticking to four of the five magnets. The dust's third most abu ndant element in the Martian soil color is suggestive of maghemite, but the fact that little, if (after oxygen and silicon), and the magnets carried any, appears to be sticking to the weakest magnet so far by the Viking landers rapidly became samtated implies that there's a lot of nonmagnetic silica mixed in. with dust. So Pathfinder carries arrays of weaker magnets, whose rate of dust accumulation should tell us how srrongly magnetic the dust is. Iron

I. ENGINEfRlNG & ~(IENCE NO. 1997 But dust devils may strip off weakly magnetic northern summer.) The mass lost from the polar dust, says Britt, so the results have to be inter­ cap, and hence its change in thickness, can be preted with care. A further complication is t hat calculated from the change in spin rate. This some or all of the dust may be of recent vintage, would double-check a calculation done using as the surface of Mars cont.inues to rust to this atmospheric pressure-change data from the day. Dust inherited fwm the underlying rocks Vikings, which indicated that the caps may be will contain titanomagnetite, which has been astonishingly thin: the loss of about 50 centime­ found in many Mars rocks (including the SNC ters' worth of carbon dioxide "snow"-a knee­ meteorites). If there's titanium in the dust adher­ deep layer- is enough to make the cap retreat ing to the magnets, it would mean that water southward some 1,400 kilometers. (The northern played a smaller part in the dust's formation. The cap gains and loses a thickness of about 15 dust's titanium level should be revealed when the centimeters.) rover returns to the ramp it disembarked from on Another extended-mission gleam in the eye is July 5. A magnet at the ramp's foot, placed there to measure the masses, and hence the densities, to answer this very question, awaits the APXS. of some nearby as teroids, from which something And finally, there's the question of what lies about their composition can be inferred. This underground. Mars Global Surveyor's discovery was actually done for three asteroids in the Viking that Mars does, in fact, have a vestigial magnetic days, and involves watching how Mars's orbit is field (see Random Walk) implies that Mars used perturbed as an asteroid passes by. The ranging to have a liquid core of nickel-iron, as Earth does. data is acguired by measuring the round-trip time Such a core's heat-driven cburnings could have of flight of a signal from Earth to Pathfinder and sustained a magnetic field strong enough to fend back. "This comperes directly with telemetry, and off celi-damaging cosmic rays-another prerequi­ so far telemetry wins," says Folkner. "But the site for ancient life. JPL's William Folkner, leader only as teroids we know the masses of are those of the rotational and orbital dynamics team, is three and Mathilde, which the NEAR mission trying to determine whether the core is still a just visited, plus a couple more for which the data liquid, albeit one too cool and sluggish to convect, aren't very good. If we could learn three or four or whether ir has long since solidified. Folkner's more densities from Pathfinder, that would double g roup tracks the Doppler shift in Pathfinder's our data set." They've compiled a list of a dozen radio signals. By combining rhis data with old or so asteroids they'd like to try if they get the results from the Viking landers, they have been chance. able to calculate Mars's polar moment of inertia to Let's hope they do. The spacecraft gave its within 1 percent. Extended-mission data should handlers a very nasty scare by falling silent on shave off an additional factor of three, enough to September 28. Contact was briefly reestablished distinguish between the core sizes, densities, and on October 7. It looks like the lander's batteries, temperatures predicted by various geophysical which had lasted three times longer than their models. Some models posit that the core is colder planned lifetime, have expired. This in itself than Earth's, for example, because Mars is smaller is not a problem, as the lander, which also relays and cooled more rapidly; others argue that the core instructions and data to and from the rover, is should actually be warmer, at a given pressure, designed to operate indefinitely on nothing but than Earth's, because the outer core, which solidi­ solar power. However, the unscheduled transition fied first, would insulate the interior. Folkner's to solar-only mode appears to have caused the group has already ruled out the models that pre­ onboard clock to guit. If so-among other conse­ dict a core less than 1,300 kilometers in diameter, guences-the spacecraft would have no idea when but otherwise can't yet declare a winner. and where to aim the high-gain antenna to find With a little luck, a liquid core might manifest Earth. Furthermore, the dead battery could be itself directly. As every fourth-grader knows, a siphoning off power from the solar array. As of hard-boiled egg spins differently than a raw egg. this writing, the flight team has successfully If the core happens to have a rotational period disconnected the battery from the rest of the that's some whole-number fraction of the Martian power system. They think they've reset the clock yeat-two-thirds, say-a resonance will show up as well. but Pathfinder has since gone silent again. in the planet's nutation rate. (Nutation is the With the spacecraft uncommunicative, nobody "nodding" of the planet's rotational axis as the axis knows if the commands being uplinked to it are itself precesses; think of a pleated lampshade as getting through, but the engineers are plugging seen from overhead-the circle of the lampshade away at the problem. Once they get Pathfinder is the precession, and the pleats are the nutation.) back to its old convivial self, they'll use the IMP Meanwhile, as the south polar cap recedes, the to hunt for the tover, which is programmed to gas it liberates thickens the air around the eq uator head in the lander's general direction if contact enough to detectably slow the planet's rotation, is lost for mote than five days-a precaution built just as a figure skater spins more slowly with arms into the software in case the rover inadvertently outstretched than with folded arms. (The same moved our of radio range. And then, with luck, thing happens, to a lesser degree, during the Pathfinder will be back to business as usual. 0

1997 ENGINEERING & SCI£NC£ NO. 17 Right: This map of the age of the seafloor around Antarc­ tica shows that, with the exception of some older floor around the Weddell Sea (the purple and dark blue at bottom), the continent is surrounded by young seafloor from spreading mid-ocean ridges (red). The gray parts are still a mystery. Below: Mount Erebus, an active volcano near McMurdo Station, is thought to be the surface expression of a hot spot with its volcanic source deep in the Earth, below the . tectonic plates. Relationships between this and other hot spots around the globe may give clues to how the plates have moved.

18 ENGINEERING & SCIENCE NO. 1997 Geophysical Secrets

Beneath Antarctic Waters o 1020 3O"'Q 50 60 70 80 90 1001101201301"0150 11\ AjF iD. MilliauorYelt. by Joann M. Stock

Cruising around Antarctica is a perk that a group of us from Cal tech have enjoyed over the past few years. You might be curious about how we book one of these cruises. First of all , we write a proposal and send it CO the Na­ cional Science Foundation, which bas an Office of Polar Programs and an Office of Marine Geology and Geophysics. If the proposal is approved , we're scheduled for time on board one of the NSF ships. We had proposed several projects to answer some nagging place-tecconic questions abom the history and evolution of the Antarctica place, which may hold the key to undersmod­ ing movement of some of the other plates and ocher global geophys ical problems, such as relative motions among the hot Spots. The idea behind plate tectonics is that the surface of the Earth is composed of a number of relatively rigid plates that move with respect to one another at speeds of a few inches per year. The deformation-fault slip, earthquakes, mountain building, seafloor spreading-between the plates is concentrated along the plate boundaries, of which there are several different kinds. For instance, the Pac ifi c plate is moving along the San Andreas fault system si de­ ways relative to North America. In some places tbe plates are collid ing, and in others the plates are moving apart. The latter describes the case we were interested in-where the Pacific and Australia plates are moving away from Antarctica. And the evidence of the Few geophysical data have been collected around much of Antarctica because movement lies at the bottom of the ocean, in ie's so out of the way .... So we wene ehere ou rselves. the seafloor formed by the spreading ridges that mark these plate boundaries. The ocean floor is younger dose to the spreading ridges and gets older as it spreads away. The map above shows the age of the ocean floor: red is very young, grading thmugh yellow and green into blue and purple, whi ch is very old ocean floor. You'll notice that much of the area around the Antarctica plate is surrounded by very young regions that fo rmed at mid-ocean ridges. There's a lirde bir of older seafloor in the Weddell Sea and a lot of gray representing the gaps in our knowledge-no one knows exactly what the age of the seafloor is in those places. In fac t, fo r much of the region surrounding Antarctica, there is very little detailed information. There haven't been very many scientific expeditions here compared to other parts of the oceans. There's good reason for this, as we discovered. The particular knowledge gap that we were trying to close in our own surveys concerns the development of the Antarctic plate. It was part of a larger group of continental blocks called Gondwanaland, which, more than a hundred m illion years ago, included Mrica, South America, Australia, India,

1997 ENGINEfIING & iC lENCE NO. I. Antarccica, and fragments of New Zealand. We can tell how fast the plates spread apart and in which direCtion by studying the seafloor, and what we find when we calcul ate the relative rates of motion along the plate boundaries, while these plates were separating, is that there had to be some other deformation somewhere. if these plates were rigid, you would expect that the motion across the spreading center, the conver­ gence in one place and the extension in another, would add up to zero. Bm in fact, scientists who have reconstructed the positions of the plates over the last 70 million years have found that the mo­ tion doesn't add up correc d y; there's some motion missing. This motion had to be either through Antarctica or through the Pacific plate, in the area of New Zealand. From what's known about New Zealand geology during that time, we don't think there was deformation goi ng on there early in this period, between abollt 72 to 56 million years ago, Antarctica divides into east so any ex tra deformation in that period had to be and west fairly neatly accounted for in what was thought of as a single, rigid Antarctica plate. And for the last 42 million along with the eastern and years, the Pacific plate, Australia, and Antarctica western hemispheres-but have indeed behaved more or less as rig id plates. not exactly. The Antarctica is surrounded by spreading ridges, and it's been growing in the sense of oceanic Transantarctic Mountains material being added to the edges of the continent (the yellow ~ green band as the ridges spread away from the center. This crossing through the extra deformation might be accounted for within center of Antarctica in the Antarctica or on the seaflo or that is co nsidered part of the Antarctica plate. New Zealand is the topographical map below) other possibility, before 42 million years ago. So form the actual boundary our exped itions focused on surveyi ng rhis region of between East Antarctica ;;;::;~~~t~~~~,::;r? the West Amarctica margin, between the Ross Sea and West Antarctica for West Antarctica and SOll th America and between the Ross Sea and New Zealand , to try to figure out what really geologists. East Antarctica East Antarctica happened in the early histOry of plate fo rmation. is much higher above sea What do we mea n by "West" Antarctica if every leve l than the western half; direcrion from the South Pole is north? "West" is determined by longitude lines. The part of Ant­ the Transantarctic Rift arctica that lies within longitudes that are wi thin System (the green basins 180 deg rees east of the Greenwich Meridian (south to the right of the of the Indian Ocean, south of Africa, [ndia, and mountains) has undergone Australia) is called East Antarctica. And West Antarctica is the pare that lies in the western a lot of geological longitudes, or the western hemisphere, south of extension and has sunk the Atlantic and Pacific Oceans and South below sea level. America. What we actually consider the boundary between East and West Antarctica doesn't coincide exactly with the longitudes, but rather with a fun­ damencal geological boundary that runs through the conri nem very roughly along the longitudinal divide. And we can tell from the topography that there is something very d ifferem going on in "these twO halves of the Antarctic continenr. East Ant­ arctica is fairly high above sea level, while West Antarctica is a lot lower in elevation. A fairly steep tOpographic gradient rllns right along the boundary between the rwo pares of the continent, -3500 .. _-·1 500 -----0 1500- -2500- -3500 4! FJcvation. Mle lcra a boundaty that also ex tends offshore into some of the region that we were surveyi ng.

10 EN GINEERING & SCI ENCE NO. 199 7 Members of the crew deploy the seismic streamer off the Nathaniel B. Palmer's rear decl<, a precarious place to be in rougher weather than this. The ship also towed a magnetometer behind it, and mounted on the ship itself are a gravity meter and an array of instruments to map a three-dimensional swath of the seafloor beneath the ship (below).

Almost all of Amarccica is covered with glaciers, Few geophysical data have been collected around and ie's hard co know what rocks are beneath much of Antarctica because it's so out of the way. them, although a few exposures of rock that poke It's not on major shipping lanes, for example. So up through the ice have given geologists some we went there ourselves. And we found out for idea. We do know that East Antarctica is com­ ourselves why not many people go there. In addi­ posed of much older rocks than most of West tion to the problems of the sea ice, the weather can Antarctica. The major geological boundary be very bad. We had 50-foot seas for a while, and between East and West Antarctica is a huge some waves got up to 60 feet. I got very seasick, mountain range, the Transantarctic Mountains, and spent much of the bad weather in my bunk. next to a big basin- the large green areas on the But the weather wasn't bad all the time. right in the map on the opposite page. This The 308-fe -Iong Nathaniel B. Palmer is the adjacent area of West Antarctica, the zone called kind of ship you need for work in Antarctica. It the Transantarctic Rift System, has suffered a lot can break ice three feet thick at a speed of three of geological extension; it thinned out and sank knots, and it can deal with the difficult weather below sea level. It may have suffered as much as a conditions. (The other ship we cruised on-the thousand kilometers of relative opening. Active Maurice Ewing, run by the Lamont-Doherty Earth volcanoes, i neluding Mount Erebus near McMurdo Observatory- is not an icebreaker, bur we didn't Station, indicate that some tectonic activity is still need this capability every time.) The Nathaniel B. going on here. Almost all of West Antarctica is Palmer doesn't just do geophysics; it's a multi­ below sea level and covered permanently with ice, disciplinary ship, run year-round by the National and you can't get to the rocks at all. Even the Science Founda(ion, and is also involved in marine surrounding seafloot is usually covered with sea biology, oceanography, aquatic chemistry-you ice, but if you can get close to it during the name it. The NSF tries to coordinate investiga­ swnmer season, when the ice has retreated, you tions, so often different groups of investigators can study the seafloor using marine geophysical who want to go to the same place for different techniques. reasons find themselves tOgether on the ship. One The geophysical techniques sense what is on the year we shared the ship with two ocean engineers seafloor, since we can't actually get down there and from MIT, who were building a remote-controlled measure things directly. We're particularly submersible device that could swim around by interested in looking at features formed by a spreading center, or "ridge," between two tectonic plates, which leaves behind magnetic anomalies on ship the seafloor that we can measure with a magne­ magnetometer tometer. It might also leave g ravity anomalies "' /9ffi~: ::.' that we could measure. If the ridge stops spread­ tt!\ air guns seismic streamer ing and dies, it may leave a trace that we can see in l i! \ the symmetry or the relief of the seafloor. And we / f \ \ also look for offsets in the spreading ridge system, j / .I ;,1. \ mult1beam called transform faults, whose extinct traces some . { \ echo sounding ,/ J I. \ distance away from the spreading center are called ., . \ fracture zones. These track the direction of rela­ tive motion between the plates.

1997 ENGINEERING & SCIENCE NO. 11 Above: The Nathaniel B. Palmer at dock. The picture of a 60-foot wave itself and make meas urements under the sea ice; terns of magnetic anomalies that we can identify about to crash over the and another year we shared space with researchers and date. We can match up these characteristic bow of the ship was taken from the National Oceanic and Atmospheric Ad­ patterns with what we obse rve from the ship; this ministration who were collec ting gas and water will tell us how old the seafloor is and allow us to from the bridge; the mast samples. Although these projects had no impact map out which way the plates were spreading. at far right on the ship can on tbe work that we were doing, sometimes we But we need a lot of mag netic data to cover as be seen against the wave can aCtually use data that others have collected much of the seafloor as possible. which is why we for scale. on cruises. For example, another group might often combine our observations wirh the magnetic be towing a magnetometer on a cru ise that's pri­ anomalies observed by previous cruises. marily for some other purpose, and we can analyze Our seismic system consists of air guns that the data for our own work. bounce pressure pulses off the seafloor and also off The standard geophysical equipment we use on sedimentary layers beneath the seafloor, essentially rhese ctuises includes some inscruments mounted making seismic waves that travel through water on board and some towed behind rhe ship. We and rock. The pulses are received by a series of usually do tow a magnetometer behind the ship, as hydrophones along the streamer, which we tow well as a seismic streamer. There's a gravity meter more rhan 12 ship leng eilS (o n 3,600 ft. of cable) mounted on the ship and an array of cransmitters behind the ship. The seismic data give us a profile and receivers for multi beam echo-sounding built of rh e seafloor. We can also see derails of the into the hull; this allows us to map out a three­ sedimentary layeri ng below the bottom, which is dimensional image of a swath of the seafloor be­ important for helping us understand the timing neath us. With the magnetometer we're looking of deformation. how deep the basins are, and so for variations in the mag netic field that are related on. Analysis of these seismic data is very rime­ to changes in magneti zation of the seafloor caused consuming and computer-intensive. so we do what by symmetric seafloor spreading. These occur we can on board , but have to save mosr of it for because Earth's magnetic fie ld reverses rhrough later when we're back in our labs. The seismic system's air time, every million years or so, and when rhe lavas We also tried to dredge rocks off rhe seafloor. guns bounce pulses off the cool at the mid-ocean ridge, they acquire the mag­ First we have to pull in all the rest of the gear seafloor and the sedimen­ netization of the field at that time. Then, if the we're towing so that it doesn't get tangled up. tary layers beneath, back field reverses , the next batch of lavas gets magne­ Then we tOw a chain-link dredge bucket on tized in the opposite direction. This creates pat- enough cable for it to reach the bo ttom. We drag up to hydrophone receivers it along for a while and then bring it back uP. just along the 3,600 feet of hoping to get some rocks. cable towed behind the .... When we' re deployi ng our equipment-the seismic streamef dredger and various instruments-off the ship's ship. Most of these data, - - - --? rear deck, we have to wear float suits that are-full which provide a profile of of foam. So if you are unfortunate enough to fall " the seafloor, have to be hydrophones overboard, you wouldn't live very long in the icy analyzed by computer back water, but at least your body would float and the crew could find you. And when the back gate is in the labs on shore. aCtually open you have to have a rope tied around sedimentary J.y .... your waist, so you can't go very far if you're washed overboard. Other than that, however,

11 ENGINEERING & SCIENCE NO. 199 7 Even in March (left), there's a lot of ice to navigate through around Antarctica, and by September. at winter's end. the continent is so completely surrounded by ice that no ship wou ld be able to get through.

shipboard life is pretty cushy compared to some stand watch 24 hours a day, in 6-hour shifts, mon­ other kinds of field work. In the Mexican desert, iroring the computer screens and making sure that for example [see E&S Fall 1993), you have to do all the equipment is functioning and that we are your own cooking. There's no water, so you can't registering all the data that we need to be col­ As the Palmer cuts through take showers. It's hot; there are rattlesnakes; your lecting. As the data come in , they're constantly the ice (below right). its truck breaks down; you get lots of flat tires ... being analyzed and processed to the extent that we wake quickly fills in again Bur on ship there's much more infrasrructlue can do that on board. So if a problem with an behind the ship. Ice on supporting you-technical support people as we11 instrument occurs, we can try to get it working as the ship's crew. (The Nathaniel B. Palmer again and nOt lose roo much data. Sometimes in board ship, as this carries a crew of25 and about 37 scientists.) The the southern oceans you might nOt really notice stairway shows, can be crew members make their own fresh water from that you're working such weird hours-like almost as dangerous as the the sea water and they have plenty of it; you can midnight to 6 a.m.- because it stays light so stuff in the sea. have a hot shower any time you want one. They long. On one of our cruises in December and have laundry machines. They have someone else January, it didn't get dark at all for four weeks; the doing the cooking. We even have recreational sun doesn't set when you're that far south at that activities. When the weather is good, you can go time of year. out and build snowmen on the helicopter deck. If The time of year that we do this work is pretty the weather is not so good, but you can sti11 stand important, because the sea ice surrounding Ant­ up, you can play Ping-Pong in the cargo hold. We arctica expands dramatically in the austral winter had a couple of Ping-Pong rournaments with the and then shrinks again in the austral summer. All crew and gave out prizes of Cal tech hats and T­ the area we wece surveying would have been chock­ shirts. full of ice in September, and we wouldn't have There are also comprehensive computer facili­ been able to wack there. In March it was a little ties, as well as lab space where you can lay our better, bur we still ended up plowing our way maps, make big color plots, and hold meetings to through ice, which was already building up again discuss the latest scientific results. Team members toward the end of the summer. Large icebergs aren't too much of a hazard because they can be seen on the radar and the ship can ad just course to avoid them. The problem situation is with ice three feet thick or more. As the prow of the ship physically breaks up the ice, big chunks of ice flow by the side of the ship and fill in the wake behind, often endangering our equipment. We tow most of the equipment below the surface. but the ice chunks also extend down some distance. So; whoever is in charge of each science watch spends a lot of time running up and down from the bcidge, consulting with the captain and the mates about the ice, trying to decide if we need to pull the equipment out, if we should go a different way, or if we have to give up and turn around. H ow do we decide on our course in the first

1997 ENGINEERING & iClENCE NO. place? We use satellite gravity dara [Q guide us in picking the ship tracks. Satellites measure the height of the sea surface by bouncing a radar Wearing and carrying signal off it. Even though the sea surface is pretty identical NSF-issued gear, rough and ragged, if you average a number of Joann Stock (from observations in the same place, you come up with a smooth version of the potential surface of the bottom). Katrin Hafner, ocean (the geoid). This tells you something about and Igor Sidorin, wait at the topography of the ocean floor, because varia­ the U.S. Navy station in tions there cause gravity anomalies that affect the the Christchurch, New shape of the sea surface. Knowing the general posi tion and shape of features on the ocean floor, Zealand, airport for the even if not the exact details, is an immense help to cargo plane to McMurdo us in deciding where to go. For example, there's a Station. This was the gravity anomaly in the Tasman Sea that corre­ February 1996 cruise, sponds to a ridge that stopped spreading 56 mil­ lion years ago between Australia and New Zea­ marked in blue on the land. (Such an event might be related to plate map below. tectonics elsewhere; for example, some subduction zone stopping or starring somewhere else on Earth affects the mantle flow patterns and causes reper­ cussions in the spreading system.) We could plan our ship track-that cruise was in late 1995 and early 1996 on the Ewing-to look at that tidge, making sure that we gOt data in the places that we wanted. Qur various cruises are shown on the map at left. [n 1992- 93, we went from Punta Arenas near the tip of Chile along the West Antarctica margin over to the Marie Byrd seamounts and back. We went on two cruises in 1995-96: one out of New Zealand to survey the South Tasman Sea, and the other from McMurdo going along the edge of West Antarctica and ending up in south­ ern Chile. In February and March of 1997. we went from McMurdo up to New Zealand. In each case we were planning our tracks to cover specifi c areas of the seafloor that would answer our ques­ tions about plate tectonics, to look at the spread­ ing ridges between plates, and to see where the fracture zones come inca the continental margin, which will help us reconstruct the plate-tectonic history of the region from East Antarctica to Australia. We also looked at some enigmatic features of the seafloor that had never been surveyed and found some new and interesting things. If you look at the tracks in detail, they look very erratic. There are little kinks where the ship had to turn into the waves so that not so much watet would come crashing onco the back deck ~hile the equipment was being deployed; and some funny squiggles where the ship kept turning to avoid big The Caltech group participated in four Antarctic cruises chunks of ice, or even icebergs. And sometimes, if between 1992 and 1997, three on the Nathaniel B. Palmer we needed satellite access for e-mail or essential (NP) and one, around New Zealand, on the Maurice Ewing communications, we would have to turn east or west for a while because the satellites, which are (EW). Two of the trips (red and blue) concentrated on the sparse in the southern oceans in any case, are low area off Marie Byrd Land, and the other two on the Ross on the horizon and our antenna couldn't pick them Sea and Tasman Sea between Antarctica and New Zealand. up if we were heading south. The little boxes along the tracks mark places where we were trying to establish exactly where a panicular feature lay

14 ENGINEEAING & SCIEN(E NO. 1997 on the seafloor; for example, trying to fix the ,so w ,,,,w position of a fracture zo ne with ou[ magnetic, ANOMAL V 31A. 7 1 MA gravity, and seismic measurements. Locating the fra cture zone will help us match it back to its counterpart fracture zone near New Zealand, to Right: Data collected off determine the positions of the plates when the Marie Byrd Land in West fi rst rifting occurred. We already know where these fracture zones li e on the New Zealand side, Antarctica led the bur we didn't know exactly where they were in researchers to conclude An tarccica. that 71 million years ago In 1996 we also surveyed in a region where we thought, from our previous studies, that there three spreading ridges might have been an old plate boundary within came together in a triple West Antarctica. This region is all now just part junction, where the Pacific of the Antarctica plate, but we thought it might and Antarctic plates came once have been twO plates, and we wanted to try to confirm this. That has turned out to be the case, up against a third, the although the boundary is somew hat obscured by Bellingshausen plate. sea mounts-volcanoes thar had erupted on the seafloor after spreading had occ urred. They poke up through rhe seafloor and remove the ev idence positions of the plates 71 million years ago, in of the magnetic anomal ies that had been there. which the Pac ific plate was moving relative ro Based on the ages that we determined for the another plate called the Bell ingshausen plate, Antarctica seafloor (isochron lines, or lines of which was moving relative to West Antarctica. constant age), we ca n see that something happened This is a very important res ult, because it tells us near the Marie Byrd seamounts to split it open. chat if we want to know the posi tion of the Pacific Much of this region was actuall y formed by sea­ plate relative to Antarctica, we have to use the floor spreading at some ridge that is now dead. data from the region between the Campbell Plat­ Comparing this with a map of the whole South eau, near New Zealand, and Marie Byrd Land. Pacific area, we were forced to conclude that these They give us a different answer from what was done magnet.ic isoc hrons were formed by two separate before, using the data fa rther to the northeas t. spreading ridges and thac there had been a third We also found another place with evidence of Above: One of the spreading ridge trending south toward West relative motion within a plate that formerly had underwater volcanoes off Antarctica from the ttiple junction of the three been thoug ht to be a single plate. It's the Adare Marie Byrd Land, imaged ridges. We ended up with a model (above) for the Trough, whi ch connects up to the West Antarctica by the ship's multi-beam echo sounding system. The Cal tech group tried to dredge rocks from this seamount with little luck . Right: Isochrons indicating seafloor age are superim­ posed on an image from gravity anomaly data around the Marie Byrd Land seamounts. The red line, marked 27. tracks seafloor that is 62 million years old; the blue line (30) is 67 million years old; purple (32) indicates 72 million years. These isochrons enable research- ers to reconstruct spreading ridges on the seafloor.

1997 ENGINEERING & SCIE NC E NO. lS ridge system and is part of a region that seems to 70 MILLION YEARS AGO.... have endured seafloor spreading between East and West Antarctica. It isn't very much motion, only NEW abom 150 or 200 kilomerers, which probably all ZEALAND took place before roughly 35 million years ago. This is important to models of past plate motions because it allows us to place some constraints on how much relative motion there could have been between East and West Antarctica. Other models have proposed as much as a thousand ki lometers of "missing" motion, but we don't see that-at least not in the last 70 million years. You can tell from the geology that there must have been some exten­ ANTARCTICA sion or stretching, and we try co close that out by lapping East and West Antarctica back together by 200 kilometers and then trying out various reconstructions of the p lates. OUf magnetic­ Right (above): About 70 anomaly data g ive us more constraints in fitting million years ago, as the different pieces of Antarctica back together, Gondwandaland was and we can tell which reconstructions wi ll work continuing to break up, and which will not. plate moves over a hot spot, it leaves behind a trail H ot spots, which have been used as an alterna­ of volcanoes. Australia and Antarctica tive method of reconstructing plate positions, offer One example of a hot SpOt track is the H awaiian were separating into another possible constraint (Maune Erebus, which chain of islands, which is part of a longer group of continents opening up the I mentioned earlier, may be a hoc spot). Hot SPOtS seamounts (underwater volcanoes) called the are thought to have some source of volcanism from Tasman Sea as they spread Hawaiian and Emperor seamounts. Si nce the ages beneath the plates, possibly deep in the Earth, in of these submari ne features are known, we can apart from the Pacific the mantle or at the core-mantle boundary. As a map the progression of the Pacific plate over the Plate and New Zealand. hot spot that gave rise to them. We can tell that Right (below): A closer the Pacific plate has to be movi ng northwest -. --"'--.-. look at the isochrons relative to some fixed hot spot because of the Anomaly 28/29 directio n in which it's dragging the volcanoes. A around the Campbell number of hot spots are thought to exist on the Plateau region (light Earth, and it has also been postulated that they are green) off New Zealand all fixed relative to one another- that there is some fixed reference frame deep in the mantle or (dark green). Anomaly at the core-mantle boundary where these hot spots 28/29 indicates where the originate. If this were so, you could apply it to spreading was about 63-65 help reconstruct the past positions of the plates. million years ago, while But if you assume that the African hot spots formed a fixed reference frame relative to the anomaly 30/31 shows its others, and then reconstruct the Pacific plate position 67-69 million relative to Antarctica and Africa, you find that this years ago. The spreading doesn't work. Using the data that we collected co ridge of the plate get plate motions for Pacific-Antarctica-Africa, if we try to hold the H awaiian hot spot fixed to the boundary (black line) can African hot spots, it doesn't reproduce the geom­ be reconstructed from etry of the Hawaiian seamount chain. This forces these Campbell Plateau us to conclude that the hot Spots must be moving Anomaly 30/31 relative to one another. data, critical to determin- Others have argued that perhaps the Antarctica ing the relative positions plate was rea l1 y more than one plate, with a of the Pacific and thousand kilometers of opening along the Trans­ Antarctic plates. antarctic rift sys tem. If these plate reconstn~c t ions of the Pacific plate or the African plate are all wrong, then perhaps the hot spots could co nstitute a fixed reference frame. We can conclude, how­ ever, from our new data in the Ross Sea that West Antarctica and Eas t Antarctica were separate during the last 70 million years, but the amount of relative motion was less than has been pOStu­ . , lated-a few hundred but not a thousand kilome-

26 ENGINEE RI N G & SCIENCE NO. 1997 million years. We haven't yet incorporated the results from our cruises inca these kinds of models, but we expect they're going to be important. Our new data from the Antarctica plate will probably also help solve a disagreement, arising from plate reconstructions, about the Pacific plate's latitude relative to the Hawaiian hot spot. Now our task wi ll be to analyze all of these data we 've collected. But in the meantime we' re planning another cruise in May to gather still more data to help us reconstruct the Pacific plate relative to ocher plates. We won't need an ice-breaker this time, and there won't be any snowmen on the helicopter deck. We'll be surveying the seafloor around the Manihiki Plateau-sailing from Right: An iceberg catches American Samoa to H onolulu. [J the late afternoon light. Below, right: Happy to be on land again, after the Nathaniel B. Palmer ters. We know there's no easy way to reconcile J oann Stock delivered the Watson Lectttre on which this docked in Lyttelton, these different har spar traces. This strengthens article is based last March, shortly after returning from the case for the hot spots to be in relative motion her latest journey to Antarctica. She travels a lot-her New Zealand, last winter with respect to one anarher. article in the Fall 1993 issue ofE&S described her field are (from left): Jane W hy, you might ask, do we care about the work in Baja California, which has beerJ rifted away Heinemann, Magali Billen, position of the Pacific plate wi th respect to from the North American plate as the Pacific plate slides Joann Stock, and Katrin Antarctica? It's actually very important fo r a past. Since then Stock has continued to work in Baja number of reasons, but, in particular, it helps us California as well as A ntarcticaj she has also been Hafner. form a clearer p icture of what's going on closer to granted tenure and had a daughter, Gabriella Wernicke, home. For example, if we want to determine the now going on 3. (Stock', husband i, Professor of Geology relative position of the Pacific plate with respect Brian Wernicke.) Stock received her BS and MS in to North America for some time in the past, we geophy,ic, (1981) and her PhD in geology (I 988) from would reconstruct, by means of the spreading MIT and has been as,ociate professor of geology and ridges, the position of the Pacific plate relative to geophy,iC! at Caltech ,ince 1992. Antarctica, Antarctica to Afr ica, and M ri ca to Also involved in the Amarctica research were Steven North America. But this model assumes that the Cande of the Scripp, Imtitution of Oceanography; Carol Antarctic plate was entirely rigid, with no internal Raymond ofJPL; Dietma.' Muller of Sydney University deformation between the east and west parts. in Australia; and Robert Clayton, professor ofgeophy,iC! Whether this is a valid assumption depends on the at Caltech. Several Caltech grad J/udent' have al,o time we're looking at. The marion between the participated in these o·uises: Tim Melbourne, Magati Pacific and North America plates is of importance Billen, jane Heinemann, Nathan Niemi, Igor Sidorin, to geologists trying to understand the history of andJudy Zachariasen, as well as undergrad Katy the geologic evolution of western North America, Quinn. Katrin Hafner, member of the professional staff, where we see evidence of volcanism and deforma­ was al,o part of the group and took many of the photo­ tion, which we are trying to link to the plate graph, in thi, article. The work was ,upported by the motions. The details of what was going on in the National Science Foundation. Antarctica plate provide a key to the other plate motions and, ultimately, to a better understanding of western North America. Because our results help us figure out the amount of deformation in Antarctica, we can then reconstruct the position of the Pacific plate with respect to all the arher plates. Once we can do this, we can then build other observations into our models- for example, the wandering of the Earth's magnetic pole. The Earth's magnetic pole coincides with the planet's spin axis, which bas wandered a certain amount with respect to the plates or to tbe hot spots. The various models that assume that the hot spots are fixed , or are not fixed, give different pictures of how the magnetic pole has actually wandered over the past several

1997 ENGINEEIING & SCIENCE NO. 27 So lar Fue l Harry Gray and Mr. Sun en­ by Harry B. Gray joy each others' company.

In the next century, burning hydrocarbons­ oil, gas, and coa l- is going co be a no-oo. And it won't be for the reason you think, which is green­ house warming-it won't be because Cleveland wi ll bake, and Pasadena wi ll drown. We have to stop burning hydrocarbons as soon as possible because they're wonderful raw materials. We des­ perately need them to make dyes and drugs and T-s hirts and chairs and automobiles- it's crazy to burn them. So sometime in the next century you'll see a massive conversion of thi s fossil-fuel ­ burning world of ours into a world that burns clean fuel. There are reall y only two dean fuels: hydrogen (H ) and electrons. H ydrogen is clean, 2 because when you burn it you get water back. (A nd, of course. the water can be split again to .) make more H 2 Electrons are clean only if they're generated clean ly, and the beSt way to do that in the long term is by nuclear fus ion. I'll be over­ joyed the day that fusion power comes to pass, but I'm a chemist , so this article is about chemists and other scientists who have tried to convert sunlight and water into oxygen (02) and hydrogen. First, I'm going to give you a short course in solar energy. (In fact, this article is a bunch of short courses. You can either buy thick textbooks and get hernias from carrying them around, or you can read this.) T here are three fundamentals of solar-energy conversion. T he first is light cap­ ture- absorbing the sunlight. basically. The second is eleerron transfer-pushing a sunl ig ht­ exci ted elecrron off its home atom in order to harvest it. The third is catalys is-dle effi cient making and breaking of chemical bonds usi ng the harvested electrons and the oxidized atoms they've left behind. Each fundamental builds on t he pre­ ceding ones, so if we can do all three, we're most efficient. If we only capture li ght. we turn sun­ light to heat, wh ich can then create steam to run turbi nes to make electricity. We've known how to do that for a long t ime, but it's very ineffi cient. A few yea rs ago, we took the next step, and fi g-

2. ENGINHRING & IClfNC E NO. 1997 We have to StOP burning hydrocarbons as soon as possible because they' re

wonderful raw materials. We desperately need them to make dyes and drugs

and T-shirts and chairs and automobiles-it's crazy to burn them.

ured out how to do both li ght capture and electron wonderful name for a guy who's doing artificial transfer. This requires lighr-sensitive semiconduc­ photosynthesis!) Eli's no fool-while the rest tors-photovoltaics such as silicon that convert of us were trying co work up these incredible sunlight into electricity. We now have durable catalysts from scratch, he figured he could take silicon devices with reasonable efficiencies-say, God's invention, and just add one component-a 10 to 15 percent of sunlight converted to electric­ catalyst that couples protons and electrons to make ity. In fan, we could convert Los Angeles into a hydrogen. That catalyst is platinum, so Eli got so la r city right now, and we probably should. Bur some leaves, took the chloroplasts- the photosyn­ if we make electrons , we've got to use them on the thetic organs-out of them, filled a little Baggie spot or lose them. We can store them on a small full of chloroplasts, put in a platinum solution, scale in batteries, of course, but my point is more dried off the chloroplasts, added some fresh water, general: we've got to be able to store the energy shone sunlight on them, and boom! hydrogen and on a larger scale for use later. So the goal is to do oxygen. It's beautiful. So we know this ca n be all three steps, so that we can store the elenrical done, because Eli's done it. God plus Eli-God energy in chemjcal bonds-the hydrogen­ did aU the hard pares, and Eli added a platinizing hydrogen bond, in this case. solution to a Baggie. And guess what? Eli picked Now for the short course in photOsynthesis: up a percentage point of efficiency! (How'd he do photOsynthesis is extremely simple. A good book that? There must be an error somewhere in the on photOsynthesis runs about 1,600 pages. You paper.) Eli's water splitting is 7 percent efficient, can't read 1,600 pages withoUt falli ng asleep, so which co rresponds CO a semiconductor making you may as well take my word that photosynthesis electrons at 10 perce nt or higher efficiency because is easy to understand. You start with sunlight, the hydrogen is stored chemical energ y. This is CO , and water, run them through a green leaf, incredible. What's the catch? Why don't we all 2 and you get O 2 and carbohydrates. God took the quit and go home? three-step solar-energy scheme, and optimized The reason we can't quit-and if you don't each component. Chlorophyll is pretty good at remember anything else, I want you to remember capturing the sunlight that reaches the Earth's this-is that efficiency by itself is not enough. If surface. The electron acceptOrs-the organic you read about a process that's 7 percent efficient, molecules that siphon off the electrons after the you should then ask the following question: how light's been captured-are nearly 100 percent long does it last? Will it keep going? The·answer efficient. And God made something ['m still here is, no! God made chloroplasts full of wimpy marveling at- a beautiful manganese cluster that organic molecules that break apart. After being catalyzes the evolution of oxygen. Photosynthesis exposed co light for several hours, Eli's platinized is 6 percent efficient overall in converting sunlight leaf poops out and it's history. God doesn't mind, CO stored chemical energy. You may not think because if any part of the photosynthetic system that's much, but it's been enough to run this breaks down, the leaf just makes more. (The leaf planet for a very long time. is a wonderful synthetic chemist!) But in artificial We know that we can turn a leaf that makes photosynthesis, we can't do that. We've gOt to carbohydrates and O into a water-splitting system make something that lasts forever. Not only 2 that makes H z and 0 ", because Eli Greenbaum at does it have to be efficient, it's got to be durable. the Oak Ridge National Laboratory in Oak Ridge, Rugged. No wimpy organic molecules. Tennessee, has done it. (Greenbaum-what a I'm proud to be an inorganic chemist. Inorganic

199 7 ENGINEERING & SCIENC E NO. 29 we irradiated it for a billion years, we'd only make enough hydrogen to drive your car a couple Inorganic chemists are of blocks! So you've got to have both durability and efficiency. rhe Marines of chemis- We know, in principle, how to do this. We have to build a molecule that will absorb light try. We knew we could efficiently (step one of the grand photosynthetic plan). The absorbed energy pushes the molecule make a simple, into an activated state, denoted w.ith a star, in which all the light energy has been imparted i norganic, artificial to one electron, kicking it into a more energetic orbit. While the electron is running around photosynthetic system frenetically, it's more loosely attached to its home that would last forever. atom, which gives us a window of opportunity to do step two of the grand plan-electron transfer. A properly designed molecule will encourage the excited electron to forsake its home atom and visit deep IN some other part of the molecule, creating a posi­ light tive charge-a "hole"-on the jilted atom, and a negative charge wherever the electron winds OXYGEN WATER tip. This negative charge, this electron, can then be diverted to a catalytic center to make hydrogen, and the hole can find another catalyst to make oxygen-step three. But time is working against us. If we don't separate the active state into positive and negative charges in a few picoseconds (trillionths of a sec­ ond), the electron sheds its excess energy and WATER HYDROGEN returns to the ground state. And once we separate the charges, we have to hold them apart for at least a thousandth of a second-a millisecond--or possibly a second, long enough to interface with the catalysts. If the electron falls back inca the lNlight 2 H Oz hole, we just get a little heat and we're toast. So 2 H20 -----:-:[C'--'e]-=[R"--uO=-z=-] --.. 2 + we have to make the recombination rate slower than the rate at which we can siphon off the elec­ trons. How in the world are we going to do this? Rudy Marcus, who's here at Caltech, won the Above: How to turn sun- chemists are the Marines of chemistry. We knew Nobel Prize in 1992 for telling us how to start we could make a simple, inorganic, artificial this process. [See E&S, Fall 1992.) About 40 light into hydrogen with­ photosynthetic system that would last forever. years ago Rudy predicced what's now called the out wimpy organic mole­ We didn't need CO inputs, because we didn't inverted effect: that you could build molecules 2 cules. At the top of the want to make carbohydrates-they're too compli­ where the recombination rate would go up for a cycle, ultraviolet light cated. All we wanted to do was run water in, and while as you increased the energy of the reaction,

1 run hydrogen and oxygen out. We made our and then come back down. Everybody knows that kicks a cerium atom (Ce+ ) system out of cerium, which is a tough, macho if you put more energy inco something, it should into an excited state metaL We hit Ce3 with deep ultraviolet light, go faster and faster, but very few people thought 1 (*Ce+ ), which promptly and it split water to hydrogen. This left us with that at very high reaction energies the rates would sheds the extra energy and Ce\ which with a ruthenium-oxide catalyst start going back down again. Bur in the mid-'80s, converted water to oxygen and gave ce3 back. a group at the University of Chicago and the an electron by jolting a Our system was all rugged metals, with no organic Argonne National Laboratory was finally able co hydrogen atom off a water components-it would never run down. Unfortu­ verify the inverted effect. Mter that, we figured H 10 molecule, becoming Ce . nately, it was not very efficient-less than 10. out how to build inverted-effect molecules, and percent efficient in practice! The problem is A ruthenium-oxide cata- now we've got tons of them. that we don't get deep UV light down here on On the opposite page is an example that uses Iyst scrounges replacement the Earth's surface, because the ozone layer in the ruthenium and pyridine. (You'll notice that we've electrons from other water stratosphere acts as a filter. Out beyond the ozone gone back to wimpy organic molecules. We fig­ molecules, liberating layer, this system will be very useful for space ured, why not-let's throw a bone to the organic travelers and space colonists, but here on Earth, chemists. So I apologized to all the organic chem­ oxygen. (The complete set it's back to the drawing board. We hit the beach, ists and said we're gonna need your wimpy mole­ of reactions is too complex aU right-we made the system so rugged that if it cules back again. But this time we put them on to show.) covered the entire surface of the Pacific Ocean, and some nice, firm metals.) The ruthenium-pyridine

'0 ENGINHRING & ICIENCE No.3 1997 So I apologized [0 all

the organic chemiHs

and said we're gonna

'"~ need your wi mpy •c w visible Jigh. molecules back again.

But this time we put

them on some nice,

firm metals.

complex absorbs visible light, which helps with reaction center is known, and guess what? There the light-captme part of the problem. The elec­ are a helices everywhere you look! Light hits a (fon transfer from rhe excited state co the charge­ pair of chlorophyll molecules, crearing an excited separated state (with the eleccron on the pyridine. state that does electron transfer to a charge­ Above: This ruthenium and the bole on the ruthenium atom) is very, very separated state. Then the electron hops around fas t-about 50·60 femrosecoods (a femtosecond from molecule to molecule and finally ends up on (Ru +l ) ~ pyridine (the is a thousandth of a picosecond!). And the charge­ a quinone. And between the quinone and the first hexagon) complex obeys separated state lingers for about a microsecond­ chlorophyll pajr is a long stretch of a. helix, so rhe the Marcus inverted effect. a millionth of a second. So Rudy gOt us parr way, When it absorbs light, an but we need to buy another faccor of a thousand to a million in time-to reach a mi llisecond or a electron immediately second in separation time-co give the energized jumps from the ruthenium molecule enough time to make hydrogen and to the pyridine. And there oxygen. the system pauses for a To figure out how to buy this extra time, Jay Winkler [PhD '84]. who's a Member of the Beck­ moment-the charge­ man Institute, I, and several other researchers in separated state (negative the Beckman Institute Laser Resource Center here in blue, positive in red) is at Cal tech have been studying electron tunneling slightly less energetic than over long distances. [See £&S. Fall 1991.] In general , these experiments involve putting an elec­ the initial excited state, tron donor and an electron accepcor on opposite but the electron has too ends of various kinds of molecules-for example, much energy to fall back a protein structure called an alpha helix (shown in yellow in the figure at right), or another protein into the hole very fast. structure called a beta strand (shown in green). , Then we zap the electron donor with a laser beam, kicking an electron loose, and we meas ure how long it takes the electron to arrive at the acceptor. We've also varied the molecular geology, as it were, within a given structural class, and we've shown that electrons tunnel through some fea­ tures faster than others. This means that electrons can't go through empty space-they have to tun­ A molecular drag race. Each electron donor (D) is separat­ nel through chemical bonds. And you can see for yourself that if electron tunneling goes through ed from its acceptor (A) by some 20 carbon-atom diame­ bonds, it's going to take forever to go through ters as the photon flies. Th e electrons, however, have to the twisty a helix. while the ~ strand is a straight tunnel along the chemical bonds shown in color. It takes shot. So, in relative terms, a ~ strand is a conduc­ an electron 1- 10 seconds to travel the corkscrew a helix tor, and an a helix is an insulator. And. of course, God figured this out before we (yellow, at left). but a mere thousandth of a second to zig­ did. The structure of the natural photosynthetic zag down the much straighter ~ strand (green, at right).

1997 ENGINEERING & \(IEHtE No.3 " fuel without liberating 0 2' It [Urns our that 02 Right: Nature's photosyn­ causes the poop-out problem. Whenever we make thetic center, as embodied 0 2' we run the risk of also producing an energetic form of oxygen called singlet oxygen-a very in Rhodobacter Sphaeroides reactive molecule that oxidizes everything, includ­ and elucidated by Ermler ing the organic molecules that make up our photo­ et al. Light hits the pair synthetic sys tem. That's why we all eventually die--oxygen is good for us, but it's also bad for of chlorophyll molecules us. In the long term, we all get oxidized-some (red), sending electrons of us faster than ochers. leapfrogging along the So we're now trying to figure out how to make accessory chlorophylls catalysts that will take electrons and holes and make new materials as well as fuel. In a new and (orange) and pheophytins improved water-splitting scheme, oxygen won't be (green) to the quinones allowed to escape, but instead will be incorporated (blue). The yellow curls into molecules that can serve useful purposes. One between the quinones and possible system for doing this is shown at right. Ie's purely a conceptual drawing-nobody has the chlorophyll pair are 0; made such a thing yet, bue a lot of people are helices; the long tail from working in this area. In addition, we're going one quinone that appears electron and the hole don't crash back together to have to learn how to get materials from carbon and make heat. The initial hops from the chloro­ dioxide, water, and solar energy, because we're to reach back up to the phyll pair onward only go forward, never back­ going to run out of hydrocarbons before long. chlorophyll sticks out of ward, because of the inverted effect. But by the People say we have enough coal for a few hundred the plane of the page and time the electron actives at the quinone, the years, but a few hundred years is nothing in the is not an electron-transfer inverted effect has played out, so you need life of our planet. an insulatOr-an a. helix. It's beauriful. I'm encouraged by ou r prospects, because we've route. The purple blob is The one remaining problem is the catalytic made enormous progress in related fields-foe an iron atom. step-how do we split water after we've manipu­ example, the methanol fuel cell is here right now. lated all these electrons and holes? Nature does I believe you'll see one in your car, and possibly it with the manganese system below, which no in your house, in the next few years. It uses a chemist has ever been able to make. And the ruthenium-platinum anode to oxidize methanol to manganese system evolves 0 2 very efficiently, carbon dioxide. This generates electrons that flow but we don't wane to do that. Planes make 0 2 through a wire to run your car motOr or you r com­ and carbohydrates, bur we wane to make H2 for puter or whatever, and eventually return to the cathode and reduce oxygen to water. So you put methanol in and get electricity out. In about 10 or 15 years your car wi ll run on electricity. General Motors' EV-l, which uses a big lead-acid battery that goes only 50-60 miles on one charge, is already on the road. Bur the car of the future wi ll have an advanced, lightweight battery, not a lead-acid battery; a methanol fuel cell; and, eventually, a solar-paneled roof, so that Energy >-t+-l!'§l!,()j the battery can charge during the day while the car is sitting in the parking lot. The fuel cell will be fat long-range driving- co San Francisco, say; if you're just driving around town, you'll run on sunlight. GM has a methanol-fuel-cell car on the drawing board now that will come out in 2004, and they aren't the only company that's getting into the game. Mercedes-Benz has plans co mass­ 2 H20 Oz + 4 H+ ptoduce 100,000 such cars a year by 2005, accord­ ing to the Los AngeleJ TimeJ, and Toyota, Chry-sler, and Ford have all announced fuel-cell projects. Above: The molecular scaffolding surrounding the oxygen­ These cars will nor only be environmentally better, generating manganese system (the cluster of Mn's and O's they'll be better in absolute terms. People are at the bottom) is almost an inverted version of the going to Ulant these cars! W ho wouldn't want something that looks like a Poesche, burns rubber, photosynthetic center. Electrons follow the arrows from and gets (in the more advanced models that have the P680 (a kind of chlorophyll) to the Pheo (a solar roofs) over a thousand miles per gallon? So pheophytin) to the qui nones Q ~ and Q,. when they become avai lable, people are going to

ENGINHRING & SCIENCE NO. '997 be knocking each othet down [Q get them. There's going [Q be a big rush, and then people will say, gee, while we 're at it, let's convert Los Angeles ineo a solar city. And I'm not just talking about places like L.A. and Tucson-everybody's got sunlight. Every year HYDROGEN since the mid-'70s, physicists, chemists, and engi­ FUEL- neers have improved solar efficiencies as well as the durabilities of solar materials, and we're almost to the point wbere we can get good solar conversion, using layered semiconductors, even when we can't see the sun through the clouds. In the next 10 years we'll have solar power generation working so well that it will be a shame if we don't use it widely on the planet. In my view, the overall change to solar fuel RAW will take a dramatic demonstration of a vehicle -_ MA TERIALS (or a stationary power plant) that runs much better than anything else has ever run, because changing the infrastructure in this country is going [Q be very, very difficult. There's great resistance ro Above: The "T. rex" scheme (or splitting water. (This just sounds more dignified than the change, and it's going to cost a lot of money. "sock puppet" scheme!) The dinosaur's head is a shorthand representation of the sort of Right now, we could put silicon on the roof of molecular scaffolding that surrounded the chlorophylls and quinones on the previous page. your house. You 'd sell electrons to the power plant during rhe day and buy them back at night, Sunlight hits the ruthenium-pyridine complex as before. briefly separating an electron and at the end of the moneh you'd get a check (blue) and a hole (red) under the Marcus inverted effect. Meanwhile, in T. rex's mouth, the instead of a bill. But if we put a solar roof on metal atom (M) strips an electron from a water molecule while catalyzing the conversion of every house in Los Angeles, there'd be a huge capital cos t, so there'd have to be tax cred its [Q oxygen to oxygenated materials. The liberated electron tunnels up the green p strand to help out. All sorts of people would have to clamor the surface and falls into the hole on the ruthenium, leaving the electron on the pyridine for change, in order to get the appropriate tax free to make hydrogen fuel. The electron doesn't tunnel backward because of the insulating legislation passed. On tOP of all this, Southern a. helix (yellow) between the pyridine and the metal. California Edison would have to agree to buy elecccons from some of its customers. I hope we will phase out fossil fuels in a rational way, but I'm afraid the change won 't be orderly. We won't say, "Gee, we need these hyd rocarbons for materi als. We're burning the most valuable resources we have. This is really stupid." We should be using dean fu els wherever we can right Designed for suburban commutes and urban drives, the now, and we should be learning how CO convert EV-I is already on the road. the rest of our fossil-fuel-guzzling technologies before we're forced inca a corner by some war or other disaster. It's going to cost a lot of money to make this conversion, but after we do it, we 'll have a planet that runs on dean fu el-an ecologi­ cally sounder, infinitely more sustainable place to live. D

Harry B. Gray, Beckman Professor of Chemistry and director of Caltech's Beckman Institute, came to Caltech from Columbia University as a visiting professor in 1965, and returned for good in 1966. For his research in bioinorganic chemistry and inorganic photochemistry, he received the National Medal of Science /rom President Reagan in 1986 and the Priestley Medal from the American Chemical Society in 1991. His work on elec­ tron tunneling in proteins is supported by the National Science Foundation and the National lnstitlttes of Health. This article was adapted fr01ll a SURF (Summer Undergraduate Research Fellowship) seminar.

1997 ENGINEERING & SCIENCE N O. To find the source of the arseni c in this water supply, we have to go back up to the Owe ns Vall ey. . The focus of our studies has been the geothermal inputs of a rsenic at Hot Creek Gorge. Chinatown Revisited: Arsenic and the Los Angeles Water Supply by Janet G. H ering

In hi s 1974 film Chinatown, Roman Polanski Aqueduct, however, came at the price of the pros­ created an enduring modern myth based loosely perity of Owens Valley, a thriving agricultural area on the fascinating history of the Los Angeles at the turn of the century. The problem was Aqueduct. Although separating all the details of exace rbated when, beginning in 191 9, Owens historical fact from fiction is beyond the scope of Valley groundwater was pumped into the Los this presentation, it is worth examining some of Angeles Aqueduct co supplement the drought­ this history, particularly from an engineering depleted surface waters of the Owens River. perspective. We will also see how this develop­ Within a decade the Owens Valley was trans­ Above: L.A. Aqueduct ment of water resources set the stage for environ­ formed , in the words of Will Rogers, into a workers set a record for mental problems that persist co rhe present day. "valley of desolation," hard-rock drilling at the Even though massive hydraulic works character­ Despite the political machinations surrounding ize water supply rhroughom the western United rhe L.A. Aqueducr and its eco nomic impacts on Elizabeth Tunnel, just States, it's still hard co realize JUSt how dramati ­ the Owens Valley, irs engineering accomplish­ north of the San Fernando cally the patterns of development in Los Angeles ments still must provoke admiration. Although Valley. have been shaped by water resource management. the entire aqueduct is gravity-fed, some impressive Left: Steam rises off the Los Angeles originally obtained its water from mountain ranges stand between the Owens Valley three sources-rainfall, groundwater, and the Los and Los Angeles. The drilling of the tunnels bubbling hot springs of Angeles River-all of which supported a popula­ through these mountains was one of the most Hot Creek Gorge; tion of about LOO ,OOO people in 1900. This num­ technically challenging aspects of the entire geothermal activity loads ber had almost doubled by 1904, and there was project. Recognizing this, Chief Mulholland relatively high concentra­ widespread concern at the time that development ordered the tunneling begun before the rest of the would soon be limited by insufficient water, In­ aqueduct construction, The Elizabeth Tunnel tions of arsenic into the deed, at the dedication of the Los Angeles Aque­ through the Sierra Madre Mountains was drilled creek, which flows into the duct in Novembet 1913, William Mulholland, from both the north and south ends simulta­ Owe ns River and eve ntu- chi ef engineer of the Los Angeles Department of neously to meer in the cenrer, an eng ineering feat Water and Power (DWP) and architect of the Big ally to Los Angeles. that would be considered challenging even today. Ditch, declared of the city: "We have the fertile A world 's record for hard-rock drilling was set lands and the climate. Only water was needed to there-567 feet in a single 24-hour period with make this tegion a rich and productive empire, crews working around the clock. In the entire and now we have it," drill ing period of 1,239 days, they dtilled 26,860 Certainly, tbe ex isting level of growth in Los feet. Angeles would have been impossi ble without Another remarkable engineering task was the many water projects, of which the Los Angeles constru ction of the g iant siphons that were built AqueduCt was only the first. A number of other as an alternative to tunnels in some areas. When aqueducts, including the California Aqueduct this project was started, there was no motorized (from the Sacramento Delta down through the transport powerful enough to move the huge Central Valley) and the Colorado River Aqueduct, siphon pieces (8 to 12 feet in diameter), so they followed, making possible the population of 9 were transported by mule trains, The siphons million that Los Angeles supports coday, as well as were the most vulnerable links in the aqueduct; extensive agricu.lture throughout Central and the Jawbone Siphon, one of rhe longest, fa iled the Southern California. first time the aqueduct was opened, delaying the The development made possible by [he L.A. actual opening for repairs, The siphons were also

1997 EN GI Nl lRING & SCI ENCE N O. The Los Angeles Aqueduct carries water about 250 CROIMEY LAKE miles-from Lake Crowley to the Fairmont Reservoir in the San Fernando Valley. Over part of its length, giant siphons, such as the Jawbone Siphon below, pipe the water over

mountains. The enormous vulnerable to sabotage. After exhausting all other siphon sections had to be possibilities to forestall the export of Owens Valley lugged to their positions water through the aqueduct, Valley residents OWENS ~'. resorted to dynamiting the siphons. by mule train (above, (dry) ,; Nonetheless, the aqueduct, begun in 1907, was right). LAKE .' opened on schedule and within budget on Novem­ : ber 5, 1913. About one in five Los Angeles in­ '.' habitants, who were obviously much happier about the project than the people of Owens Valley, joined the parry for the San Fernando opening. In the view of the people of Los Angeles, the aque­ OWENS duct would enable the city to achieve its true potential as a world-class city. They were right. VALLEY As we will see, it may be that present-day Owens VaHey residents may recover through the courts at least some of what their ancestots could not, even with dynamite, retain. But for the meant.ime, the L.A . Aqueduct sys tem provides a sizeable percentage of the city's water supply by transporting water from the Owens Valley. Snow­ melt runoff from the Sierra Nevada drains inca the Owens River, a tributary of Lake Crowley, the terminal reservoir in the aqueduct system. From Lake Crowley, the water is transported approxi­ mately 250 miles through the aqueduct to the Fairmont Reservoir in the San Fernando Valley and treated at the fi ltration plant in Sylmar. In general, the quality of this water is excellent. The DWP has done a very good job in protecting the watershed and preventing any contamination of the water. But one of the water's natural consti­ tuents-arsenic-does pose a pocenrial problem. The plot at the cop of the nex t page shows data from 1968 CO 1991 collected by the DW P at their Sylmar filcration plant. As the bars show, the concentrati on of arseni c over this roughly 25-year Saugus Palmdale period averages approximately 20 micrograms o (millionths of a gram) per liter. Since the currene drinking-water standard, or maximum contami­ nant level (MeL), is 50 micrograms per liter, the DWP values are well below it. The U. S. Environ­ o Sylmar mental Protection Agency is, however, reevaluat-

•• EIIGIN£ERING & SCIE N CE NO • J997 40- it coming down from the Owens River. ~ OJ 35 As its name indicates, Hot Creek is a geotheJ­ :::;- mal area. It's in an active volcanic reg ion, wbe .re 30 ~ a massive volcanic explosion occurred about OJ "- 25 750,000 years ago, with lesser eruptions more recently. The area, which is at an altitude of 1:,,000 "'E 20- feet, is characterized by geothermall y altered rocks ~ '"Cl 15 and by the hot springs that provide most of d e 2 10 - local place names. Arsenic occurs at extremely ::;:" elevated concentrations in the geothermal ",vaters 5 and is derived from degassing of arsenic (a vo lu i le 0 element) from the magma. The focus of our ~ ~ N 0 ~ ~ ~ N 0 a; 18 :2 ;; <0 ~ ~ ~ '"~ ~ ~ ~ ~ ;: ~ studies has been the geothermal inputs of arsefl ic §l '"~ '" '" '" '" '" '" '" ill '" ~ ~ '" ~ ~ '"~ '"~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ '"~ at Hot Creek Gorge. Average Annual The gorge itsel f is about half a mile long \vidl very steep sides. Geothermal pools li e along barh sides of the creek, and a large number of springs Above: Concentrations of occur within the streambed itself. This gives tile arsenic at the DWP's water a comfortable co nstant temperature i n dc f low- to mid-70s (22-24 degtees C) year-round, Sylmar filtration plant making it a popular place for swimmers. Many from 1968 to 1991 lie well of the pools along the bank, however, are close below the current drinking­ to boiling. water standard of 50 We studied the arsenic concentrations ill! cbest pools and in the creek as well as the oxidarjoD micrograms per liter. If state of the arsenic. In natural waters, arsenic that standard drops to 2- commonly occurs in two oxidation scates, [he 20 Ilg/l, however, there will more oxidized + V state and the less oxidized (O f be trouble meeting it. more reduced) +III state. As(V), 0 1' a.rsenat e, is [h e thermodynamically stable form in water ex:pose:a to the atmosphere; As(III), or arsenite, is stahle under more reducing conditions. The oxidation state in which arsenic occurs in water is important because it affects t he toxicit:y of arsenic, its mobility in aquatic syst ems, and m e efficiency with which it can be rem oved in treat:­ mem ptocesses. As(III) has been shown to be more acutely toxic than As(V). This distincrioo may be less consequential for chronjc exposure The schematic view of the ing the standard, and the range under consider­ and carcinogenesis since As(III) and As(V) can Ce region north of lake Crow- ation is between 20 and 2 micrograms per liter. interconverced within the body. The mobiliry ci ley (above) shows that It's clear that the DWP is goi ng to have a problem arsenic in natural waters is often governed by tbe most of the water (Jowing meeting a standard in that range. In 1993, the sorption of arsenic OntO mineral surfaces- these World Health Organization recommended a value interactions are generally stronger with As(V) rlan into the aqueduct system, of 10 micrograms per liter, based both on health with As(III). Many treatment processes similarJy indicated by the width of effects and other considerations. Epidemiological rely on sorption and are thus more effective for the gray bands, comes studies in Taiwan and in the West Bengal region As(V). from the Owens River. The of India have shown that chronic exposure to ar­ At Hot Creek, we found that, in the hot b" b­ se nic in drinking water causes health effeccs that bling pools, As(III) was roughly 60 to 70 petceo: flux of arsenic, however, range from skin diseases to cancer. of the total arsenic concentration. At depth, £he shown by the size of the To find the source of the arseni c in this water contribution of As(III) might be even higher, bu­ white arrows, comes supply, we have to go back up to the Owens we were unable to sample geothermal water rh a..( ValJey. Studies conducted by the U.S. Geological had nOt already been exposed to the atmosphere:. predominantly from Hot Survey in the 1970s quantified the fluxes of water In the gorge area of the cteek, we found less of che Creek Gorge (above right), and arsenic to Lake Crowley. In the illustration atseni c as As(IIIl--only 40 to 50 percent, the which is contributing above, the width of the shaded lines shows that remai nder be ing As(V). Interpreting this inforDla· relatively little water. the water flux to Lake Crowley comes predomi­ tion, however. is complicated by t he variable coru nantly from the Owens River; ve ry little flow, in arsenic concentrations in the creek water, whic (Diagram from Eccles, comparison, comes from Hot Creek Gorge. The result from the numerous and scattered sources elf USGS Water Resources size of [he arrows indicates the flux of arsenic, and arsenic within the gorge. Investigations, 1976.) here you can see the opposi te: the arsenic comes This finding led us to the boundary of the mostly from H ot Creek Gorge, with very little of hydrothermal area and to look downst ream froro

199 7 ENGINEERING & HIENCE No.1 J7 it. We found that the concentration of total arsenic was quite constant, indicating that we were, in £'lct, downstream of the source of any significant arsenic inpurs to rhe creek water. The percentage of As(II1) dropped from about 30 pet­ cent at that boundary down to nearly 0 about a mile downstream. What's interesting here is the contrast between total arsenic, which is conserved, and As(lII), which is being lost; the total arseni c concentration is not changing, but As(III) is being oxidized ro As(V). We could estimate the rate of oxidation based on the time of travel fot this one-mile stretch of the river by assuming that the water is simply traveling in a plug-flow manner and by measuring its velocity, which is abom 0.4 meters per second. This gives a half-life for this ox id ation process of Variou s species of aquatic about a third of an hour, which is very fast. As(III) plants, such as the grass­ is thermodynamically unstable with respect to As(V) in the presence of oxygen, but that reaction like one at right, grow just is very slow, with a half-li fe on the order of 100 We then designed an experiment to co mpare our downstream of the days. So we cannOt account for this fast reaction field observations of rapid As(III) oxidation with a hydrothermal area, where simply by the teaction of As(II/) with oxygen. number of different controlled cases. In the first they provide a home for a W hat, then, is the oxidizing agent? case, we took a sample of the macrophytes along In trying to discover this agent we looked at a with anything that happened to be attached ro multitude of bacteria number of possibilities, including indireer photo­ their surface, and simply enclosed the sample in a (below), which appear to chemical reactions and reaccions with constituents container of some of the surrounding water. In the oxidize arsenic. second case, we shook off anything attached to the plants' surface and, removing the plants, left only the surface materi al, which has a large component of bacteria, in the container of stream water. We also had two abiotic controls. In the first of these, we took the sample with the surface material from the macrophytes and put it through a sterile filtration system-a 0.2 micrometer filter that removes most bacteria fai rl y effectively. And in the second case, we added antibiotics ro the subsample containing surface material from the plants to eliminate any bacterial activity. To make a long story shore, in the first twO cases, with rhe plants plus surface material and the surface bacteria alone, we saw rapid arsenic oxidation. When we elimi­ nared the biological activity, either by the srerile filtration or the antibiotic treatment, the arsenic from sediments (manganese oxide, for example). oxidation did not occur. But both of these were toO slow to provide the Some of our data appear opposite. The cop explanation. The last possibility that we looked graph shows the loss of As(lII) with distance from at was a biologically mediated reaction. Right the geothermal inputs; total arseni c is conservative. around the boundary of Hot Creek's hydrothermal The lower three graphs show the results of the area, particularly just downstream of the hydro­ incubation studies. In the upper panel, As(III) is thermal inputs, we observed very lush vegetation seen co be rapidly oxidized in the presence of of various species of aq uatic plants (or macro­ surface material from the macrophytes. This same phytes). One of these has slender stems and grass­ data (marked "unfiltered") is shown in logarithmic A scanning electron like leaves and another a thick foliage of small form in the middle panel. In contrast, the abiotic, micrograph of the Hot leaves that form dense mats on the water. Since sterile-fi1tered sample shows no As(III) oxida­ Creek Gorge plant material the water temperature in this stream remains rion-rhe As(III) concentration remains constant cons rant throug hout the year, this plant life is also over the course of the incubation. The anribiotic shows the striations of the present year-round. These macrophytes haven't treatment in the bottOm plot looks a little more plant leaf itself, covered by yet been positively identified, but the predomi­ complicated, because antibiotic activiry is nor an abundant microbial nant species resemble planes growing in the instantaneous. Antibiotics are nor a poison. They community. geothermally influenced Waikato River system in don't kill the organism immediately, but rather New Zealand. they interfere with its metabolic processes, and it

•• ENGJ NE HJNG & SCJENCE NO • 1997 50 4 .., ~40 0 e- • ~ ~ "~ 2 0 ;;: 20 • 2. 0 if. The plot at right shows 10 • 1 ~ As(lIl) as a percentage of 0 0 t he total concentration of 0 400 800 1200 arsenic, measured Distance Downstream of the Gorge (meters) downstream of Hot Creek Gorge. Total arsenic To make a long Story snort, in rhe firs t cwo cases, with rhe plants plus surface remains constant, but As(lII) decreases material and the surface baneria alone, we saw rapid arsenic oxidadon. dramatically.

, All of t he lower three plots takes a certain incubation time for that to happen. ] These observations indicate that the As(IIl) show the ratio of As(lII) ";50.8 oxidation that we observed is due to the activity of concentrations to their 8 microorganisms. W hen we compare all of our ¥ 0.6 initial value over time. ~ batch studies with the rates we measured in Hot ~ Creek, we get a very good co([espondence, Th e top one represents §' 0.4 ~ indicating that the microbial oxidation of As(III) two experiments done 00 0 < 0.2 can indeed account for the oxidation that we see in with water containing the the creek. surfac e material from the 0 " .... <1 .n -'- This is important, because the treatability of 0 15 30 45 60 75 90 105 120 arsenic depends on its oxidation state. One of the macrophytes (the squares time (minutes) possibilities that the DWP is considering, if they are ambient As(lII) and t he do need to meet a more stringent drinking-water t riangles represent an standard for arsenic, is to site a treatment facility additional spike of As(III)). near the source of the arsenic, rather than wai t ing till the water arrives at the Sylmar filtration plant The concentration under ~ filtered 0 ------...... where they would have to deal with a much larger both conditions drops to ~§ volume. The gauging station that already exists S u ro in just under an hour. ~ on Hot Creek is one of [he possible sites [hat the ~ -1 In t he next plot, this data ~ DWP might consider fo r a treatment fac ility. Om ~ S studies show that such a facility could rely on the is shown in logarithmic ~ -2 ~ indigenous microorganisms in the stream to do form. Fir st ~ ord e r loss of -< unfiltered rhe work of oxidizing As(III) [Q As(V). Then ~ -3 As(lII) is observed in the .!l As(V) could be efficiently removed from the water by anyone of a number of treatment technologies, unfiltered system, but -4 such as sorption onto alumina or iron-coated sand. 0 15 30 45 60 75 90 105 120 when the water is run Arsenic and the L. A. Aqueduct have also had time (minutes) through a sterile filter to environmental consequences for the Owens Valley. remove t he bacteria, the These are not part of my current research, bur since they are the focus of intense current interest As(lII) concentration does and some litigation, I'd like to mention them not decline. The bottom here. One of these problems is the aitborne antibiotics (solid) plot shows what happens ::-;:-- ~~. ~ ... ::-:-. ~::-=--.... =-=-. ::-:-.:: =---::-:-. ::-:-. arsenic blowing off the Owens lake bed. Before the to As(lI!) in the presence agueduct was co nstructed, Owens Lake, at approx­ imately 73,000 acres, was the third largest lake in of antibiotics added at the Cal ifornia. It was a terminal alkaline lake, with beginning of the ex p eri~ very high salinity and most probably very high no antibiotics (open) ment (solid squares), aft er arsenic concentrations as well-similar to those in Mono Lake. With the construction of the aque­ three hours (solid duct diverting water from the lower Owens River, triangles), and after 72 _ 4 L-~~~~~~~~~~ o W ~ W W 100 IW Owens Lake just dried up. Thousands of acres of hours (solid circles). time (minutes) land that had formerly been covered with water

1997 ENGINEERING & SCIENCE NO. .9 are now dry. And when the wind blows, which it There has been a long-raging battle between Los does quite frequently in that area, an enormous Angeles and the Owens Valley over the need to amount of dust swirls off the lake bed. This dust control this airborne pollution, specifi cally PM- poses two problems: one is tbe PM-I0 value, that 10. The Great Basi n Air Quality Management is, particulate matter with a diameter of 10 District, which includes Owens Valley, has issued microns. This size of particles is the most a number of rece nt administrative rulings that troublesome, because they're small enough to be require reconstituting part of the lake by irrigat­ transported relatively long distances and large ing sufficiently to establish a salt-marsh kind of enough to cause health problems. You inhale grassy vegetation. The rest of the lake bed would them but you don't exhale them; PM-lO particles be covered with gravel. Even this would involve a settle or are captured in the lungs. The national significant return of water to the Owens Valley, a ambient air-quality standard fo r PM-I0 particles step the DWP is not eager to take. is 150 micrograms per cubi c meter in 24 hours. The second issue is the loss of the riparian eco­ When the wind is blowing hard on Owens Lake, system on [he lower Owens River, which, like the PM-lO value has been measured ar 3,000 Owens Lake, dried up when the water was Above: Th e gauging station micrograms per cubic meter, 20 times the diverted to Los Angeles. After a long court battle on Hot Creek might be a national standard. over the enviro nmental impact of groundwater convenient site for a The other problem with the dust is its arsenic pumping in the valley, the DWP and various content. There is no national air-quality standard representatives of the Owens Valley signed a treatment facility for for arsenic concentration, but there's StilJ reaso n to "memorandum of undetstanding" a few months removing the arsenic close be concerned about it. The arsenic concentration ago, which would allow for the rehydration of the to its source, employing in the dust is approximately 100 parts per mi l­ lower Owens River and re-establishmenr of its lion, so the particulate arsenic concentration in the local microorganisms ecosystem. The measures agreed upon, however, the air during one of these windstorms is about would not solve [he ptoblem of the particulate for oxidation. 0.3 micrograms per cubic meter. Unfortunately, arserue blowing off rhe dry lake bed. Below: A large crowd cele­ there's not much to compare this to, but we can The historical conflicts involving water quantity brates the release of Owens look at a 1994 Canadian study, which fo und that have persisted from the turn of the last century the mean concentration in the ai r over 11 cities and will probably contin ue through the turn of River water at the Owens­ and one rural area was on ly 0.001 micrograms per the next one. But the issues of water quality, in mouth Cascades near Syl­ cubic meter. We could also make the comparison terms of ecosys tem health and human healt h, will mar, on November 5, 1913. with occupational exposure standatds- Ievels that probably become equall y important in the years Los Angeles has thrived on are generally mnch higher than you would want ahead. lJ in ambient air. The peak airborne arsenic concen­ this water in the interven- trations near the Owens lake bed are wi thin a jng decades, but old and factor of 10 of the suggested N IOSH (National new problems persist. Institute for Occupational Safety and Health) standard of 2 micrograms per cubic meter. J anet Hering joined the Caltech faculty as associate professor of environmelltal engineering science in 1996, and no time was lost in recrlliting her for a Seminar Day session last spring, from which this article is adapted. Hering 1'eceived her AB in chemistry from Cornell in 1979, AM in chemistry from Harvard in 1981, and PhD in oceanography from MIT and the \Voods Hole Oceanog1'aphic Imtitlttion il1 1988. She then worked as a research fellow for the Imtitute for \Vater Resources and Water Pollution Control in Diibend01f, Switzerland, before coming to UCLA as an assistant professor in 1991. She was named associate professor in 1995 and t'emains an adjunct professor there. Her 1'esearch centers on the chemistry of trace inorganic contalllinants in natural waters and soils and in water and wastewater t·reatment. A Iso involved in this project were J ennifer \'(Iilkie, who ,·ecently finished her PhD at UCLA, and Caltech grad stlldents Tina Salmassi and Penelope Kneebone. Historical information for this talk came frolll The Great Thirst (Hundley, 1992), Vision or Villainy (Abraham and Hoffman, 1981), and Ri vers in rhe Desert (Davis, 1993). The work was sllpported by /tmciJ Jrom the University of Califomia Wiater Resources Center and the National Science Foundation.

40 £ N GtNEERt N G & Ht ENCE N O. 199 7 and was also involved in istry of the Colorado plateau the Ranger and Surveyor country, studies of the Struc­ miss ions. ture and mechanics of meteor After leaving Caltech for craters, the search for planet­ Flagstaff, Arizona, in 1985, crossi ng as teroids, and studies Shoemaker focused his studies of the magnetostratigraphy of Obituaries on impact craters, as teroids, sedi mentary rocks. and comers. His observing H e codiscovered the team, which included hi s mineral stishovite, which is a wife, Carolyn. discovered hi gh-pressure form of quartz several thousand asteroids and produced only during large 33 comets, including Comet impact events. This discov­ Schoemaker-Levy 9, which ery established the extra­ crashed inro Jupiter in 1994. terres trial origin of many Shoemaker's many other cryptoexplosion structures. scientific accomplishments Shoemaker was elected to included seuing up the Inter­ the National Academy of planetary Geological Time Sciences in 1980; he received Scale, based on crater densi­ the National Medal of Science ties on planetary surfaces. in 1992, and the Bowie This allows age estimates Medal (rhe highest award of E UG ENE M. S HO EM AK ER to be made for terrains from the American Geophysical 1928-1997 other planets based on space Union) in 1996. photographs. His other research included exploration for uranium de­ posits and salt structures in Eugene M. Shoemaker, one Colorado and Utah , research of the world's foremost plane­ on rhe geology and geochem- tary scientists, was killed in an automobile accident in Australia on Thursday, July 17. His wife, Carolyn, was also injured in the accident. Shoemaker first came to A Celebration of Life for Eugene Shoelliaker war held in Flagstaff Cal tech as an undergraduate, Octoher 11. Harrison ('Jack" Schmitt (BS '57, Apollo 17 astronaut, and earned his bachelor's and former senator frml1 Nelli Mexico) delivered the main address, from degree in 1947 and his mas­ which the following is adapted. rer's in 1948. He received a second master's degree and When I received the phone caU about this celebration of life his doctorate from Princeton for Gene, I was reading Undaunted Courage, Stephen Ambrose's University, and returned to remarkable narrative about Meriwether Lewis, Thomas Jefferson, Caltech in 1962 as a visiting and the opening of the American West. J could not absorb professor. He served as a Ambrose's words without relating those events, people, and research associate in astro­ consequences to our own experiences in the 19605. geology here from 1964 ro As 1 reached the end of the book, I was reminded particularly 1968, as professor of geology of Gene's most unique quality during those heady days. I could Carolyn and Gene Shoemaker in 1969- 1980, and professor of not help but compare Gene as leader, as well as a scientific front of t he Alu mni House during geology and planetary science explorer. to Captain Lewis and an earlier Corps of Discovery. 1980-85. Shoemaker served Paraphrasing just a little, as Ambrose said of Lewis: "How he Commencement weekend as chairman of the Division led is no mystery. His techniques were time-honored. He knew in June 1997. of Geological and Planetary hi s [people). He saw to it that they had [regular inspiration, Sciences from 1969 ro 1972. neces-sary resources, sufficient rools). He pushed them to bur He also worked for many never beyond the breaking point. He got OUt of them more. than years with the U.S. Geologi­ they knew they had to give. His concern for them was that of a cal Survey, and was affiliated father for his son. He was head of a fami ly." with the Lowell Observatory Many of us saw our lives moved forward professionally because at rhe time of hi s death. He of Gene's knack for inspiring people to go far beyond what any was a principal investigator of us believed we could do. We kn ew then as we know now thar for geological field investiga­ we worked with one of the truly great scientists and visionaries tions for the Apollo lunar of this latest age of exploration. Like Lewis, "[h]is intense curi­ programs from 1965 ro 1970, osity abollt everything new he saw around him was infectious.

I 9 9 7 ENGINEERING & HI EN (E NO. 41 On the February 1966 cover of £&S, Gene Shoemaker holds a handful of tektites, which he thought were remnants of lunar material ejected from the Moon's

surface during impact from a high~ speed object. Such objects (meteorites, asteroids, comets) Shoemaker believed. also created the craters visible on the Moon, Mars and Earth. a theory now universally accepted.

him," he added. Well, I had emotion, the excitement, and, no idea who Gene Shoemaker we believed, the science of the might be, but Danny and I future. A few days later, had overlapped at both Cal­ Gordon Swann and others tech and Harvard. If Danny arrived and, with Gene's daily thought what Gene was inspiration, an eclectic group doing was interesting, it went to work. almost certainly was! We began learning our Not having any idea what I new lessons by trial and error, Certainly he would be was getting into, I headed Out mostly error-lessons that anyone's first choice for a of Cambridge in my '55 ultimately were to become companion on an ex tended Chevy Business Coupe for part of the foundations of camping trip." Route 66, Flagstaff, and the Gene's Apollo field geology Before I arrived on the old Astrogeology Branch experiment, underpinning Shoemakers' doorstep in Flag­ Headquarters. I became a almost everything Apollo staff in 1964, Gene and I little suspicious only when accomplished scientifically on wrote twO tenees that had Danny and others in Menlo the Moon. With Arizona literally crossed in the mail. decided nor to relocate in freshmen, Spence Titley, long He was contacting people on Flag. What did they know hours, and Jim Beam, we set the Geological Survey's list of thar I didn't know? Exci ting about answering questions those who had passed its things, however, were about never asked before. 1963 employment exam, and to happen. How do you communicate I was looking fot a job. After arrival at the old detailed geologic notes by Interesting and adventur­ museum offices in the pines tadio across the 240,000 ous jobs in geology seemed at the north edge of town, miles of space, when Swann nonexistent to this new PhD and JoD Swann's enthusiastic keeps stepping on your lines? in 1964- none in academia, welcome, Gene provided me How should the lunar surface and the ongoing slump in with a tough choice between debris, latet to be defined by metal prices didn't help in joining Don Elston, Ray Gene as the now famous lunar other areas where "hard-rock" Batson, and others on the regolith. be sampled,.when and field experience might be ongoing Surveyor television the old International Travel­ applied. Fo[cunareiy, I re­ project, or heading up work Ails can't get us to Torn membered that in 1960, after on a new NASA contract to McGetchin's Mexican Hat helping line up a trip to look develop lunar field geological kimberlite location? How do for West Coast eclogites, Bob methods. Surveyor was very you photographically docu­ Coleman had taken me down real and had exc.iting science ment a sample location and a dark hallway in the Survey's potential. Lunar field work orientation without using Menlo Park facility and intro­ was in the misty, undefined more than an absolute mini­ duced "Gene Shoemaker, who future, but there was really no mum of extraordinarily valu­ is doing weird things like cboice: as important as able time, when Schmitt can't mapping the Moon. Danny Surveyor was and would rurn keep the Polaroid film out of Milton is even working for out to be, in Apollo lay tbe the Hopi Bucres' dust? What

42 ENGINHRING & SCIENCE NO. 1997 intellectual foundation for this history of science to record that for the first time we had gained a first-order understanding of another planet. Gene, "more than any other individual, was responsible for the incorporation of geology into the In 1992, Gene joined a University of Wisconsin team Ame rican space program. " We might add thac, more than any other individual, he was responsible as chief scientist on a proposal to operate twO scientific for our present consideration of the Moon and Mars as places for future seulements rovers si multaneously and co­ operatively on the surface of of our children and grandchildren. the Moon. Our objectives were to unravel the three­ dimensional nature of the regolith and to define the basis for bringing its energy resources back to Earth. Who would have thought when we first gathered in Flagstaff in training vocabulary do YOll The question I asked myself, for our presenr consideration the '60s that Gene's legacy use when your field men are however, was, "If someone of the Moon and Mars as would include the potential not geologists but rather are actually does land on the places for fueure sertlements for providing for the long­ headstrong test pilots? Moon, and if I passed up a of our children and grand­ term energy and environmen­ Ultimately, all our questions chance to try to be that children. tal needs of humankind? had answers, but none was person. would I regret it?" Gene's influence within the Gene would have. Yes, obvious when Gene started The answer being obvious, space agency in rhe 19605 indeed! With the usual geology down rhis parh of the rest is histOry-helped was f.'1r greater than even he unbounded enthusiasm, he lunar exploration and along, I strongly suspect, by imagined. He become a joined in our preparations, stardom. Gene's position as chair of the looming spirit behind rhe saying to the group during a Also during this period, Academy's sc ientist-astronaut most critical managers of the luncheon pep talk, ''I've November 1964 to be more selection committee. Apollo program-George waited 30 years to do this!" exacr, NASA and rhe Na­ Some time coincident with Low, Bob Gilrurh, Gene With a vigor, joy, and tional Academy of Sciences this astronaut selection Krantz, and Sam Phillips. wisdom beyond that ever jointly asked for applicants process, Al Chidester assigned They knew rhar Apollo could expected of anyone, Gene for the first selection of me, along with Newell Trask, do more than meet John celebrated his own life and scientist-astronauts. The to do the final work for publi­ Kennedy's challenge "to pur the lives of those around geological horizon Gene had cation of Gene's Copernicus men on the Moon and return him. 0 seen so clearly for so long had lunar quadrangle map. No them safely to Earth. " Gene's suddenly brighrened for single study affected the continuing enthusiastic Harrison H. Schmitt others. Even though, as grad­ course of lunar science more presence and his pressure for uate students in 1963, some than Gene's early telescopic NASA to rake advantage of of us had joked about rhe and photographic examina­ this extended capability, led possibility of going co the tion of the crater Copernicus. to the inclusion of the Field Moon, when an Academy Building on hi s skillful field Geology Team as part of the report stated that "the first and theoretical work on Apollo Mission Team, from person on the Moon should Meteor Crater, and his equipment selection to crew be a hard-rock geologist," no pioneering definition of a training to mission control significant thought or rele­ stratigraphic system for the activities. It wasn't every­ vant action had followed. Moon, Gene created the thing we wanted or could After one and only one scientific base for mapping have done, but it was there, conversation with Gene on a the Moon and now, by exten­ and it was of critical fall afrernoon in 1964, and sion, mapping humankind's importance. after a few more seconds of third home, Mars. As Don Thinking back on this consideration, I decided to Wilhelms has written, Gene. pervasive and unprecedented volunteer to ~e an astronaut. "more than any other indi­ experiment in lunar field Gene clearly knew what he vidual, was responsible for geology, and on Gene's pivot­ would have done, having rhe incorporation of geology al influence on the plans for decided this point many years ioro the American space lunar sample analysis, brings before anyone else. I was program." We might add Meriwether Lewis and concerned about my commit­ that, more than any other Thomas Jefferson to mind ment to Gene and the Survey. individual, he was responsible again. Gene provided the

19 97 ENGINEERING & SCIENCE NO. J 43 tigaror, Howard Hughes Medical Insti cute; Andrew Ingersoll, professor of plan­ etary science; J eeroid Mars­ den, professor of control and dynamical systems; and Faculty File Douglas Rees, professor of chemistry. The Academy is an honorary society that recog­ nizes achievement in the natural sciences, social sci­ ences, arts, and humanities, and conducts a varied pro­ gram of projects and studies HONORS AND AWARDS responsive to the needs and problems of society. Recipients of the 21st annual ASCIT teaching awards from the Associated Students of Cal tech were For her work at the inter­ $100,000 one-year grants University Annual Prize for Glen George, BS '8 1 and '82, face of chemistry and biology, from the Seaver Institute. Best Paper in Economic De­ lecturer in computer science Jacqueline Barton, the Arthur Gharib's grant will support sign. Entitled "The Alloca­ and electrical engineering; and Marian Hanisch Memo­ his "Implantable Heart tion of a Shared Resource Kevin Gilmartin. associate rial Professor and professor of Pump" project; Sternberg's Within an Organization," professor of literature; Emlyn chemistry, has been awarded grant is for a one-year exten­ the paper was written with Hughes, associate professor of rhe 1997 Nichols Medal by sion of his research project in Charles Noussair. physics; Charles Steidel, PhD the New York Section of the molecular genetics, "Genetics David Middlebrook, pro­ '90, associate professor of American Chemical Society. of Genes in Cancer Cells." fessor of elec[[ical engineer­ astronomy; and Richard Wil­ She is the first woman to Established in 1955 by Frank ing, has been selected to son, professor of mathematics. receive the award in its 95- R. Seaver, the Seaver Institute receive the 1997 Richard P. In addition, AScrT recog­ year history. focuses its giving program on Feynman Prize for Excellence nized two outstanding grad­ Erick Carreira, associate four essential areas: scientific in Teaching. The prize, made uate teaching assistants: Sean professor of chemistry, has and medical research, educa­ possi ble by an endowment Mauch, applied math, and received the National Fre­ tion, public affairs, and the from Cal tech Associates lone Brian McKeever, mathematics. senius Award from the Vir­ cultural arts. and Robert Paradise, is The Graduate Student ginia Polytechnic Institute. Kevin Gilmartin, associate awatded annually for "un­ Council (GSC) bestowed its Samuel Epstein, the Wil­ professor of literatute, has usual ability, creativity, and 1997 teaching awards on liam E. Leonhard Professor of received rhe 1996-97 Arnold innovation in undergraduate James Beck, PhD '78, pro­ Geology, Emeritus, has been 1. and Lois P. Graves Award and graduate classroom and fessor of applied math and elected a Foreign Fellow of in the Humanities from the laboratory teaching." The civil engineering, and Ken­ rhe Royal Society of Canada American Council of Learned Feynman Prize selection neth Farley, associate profes­ by the members of the So­ Societies. commitee cited Middlebrook's sor of geochemistry. Kerry ciety's Academy of Science. Emlyn Hughes, associate 40-year history of teaching Vahala, BS '80, PhD '85, pro­ Peter Dervan, the Bren professot of physics, has re­ not just a body of knowledge, fessor of applied physics, and Professor of Chemistry and ceived a Sloan Fellowship but a way of thinking-"how Simon Wilkie, assistant pro­ chair of the Division of from rhe Alfred P. Sloan to simplify complex subjects, fessor of economics, received Chemistry and Chemical Foundation of New Yotk and how to marry theory and GSC's menror awards, which Engineering, has been elected City. The fellowships, award­ experiment." recognize "those professors to the Institute of Medicine ed for studies in science, tech­ Edward Stone, Caltech vice who display a commitment to of the National Academy of nology, economics, and public president, director of JPL, the personal side of their stu­ Sciences. Membership is policy, include $35,000 in and the David Morrisroe dents' education and who based on professional achieve­ unrestricted research funds. Professor of Physics, has been offer steadfast guidance at the ment and on involvement John Ledyard, professor of inducted into the Aviation beginning of the student's with issues that affect public economics and social sciences Week and Space Technology career." Awards for outstand­ healrh. and chair of the Division of Hall of Fame. ing graduate studenr teaching Motteza Gharib, PhD '83, the Humani ties and Social Four Caltech faculty were assistant went to Amit Man­ professor of aeronautics, and Sciences, and David Potter, recently elected fellows of the wani, Sam Roweis, and Erik Paul Sternberg, professor of visiting associate in econom­ American Academy of Arts Winfree, all of computation biology and investigator, ics, have been selected by Koc and Sciences: Pamela Bjork­ and neural systems; and Dave Howard Hughes Medical University of Istanbul as joint man, associate professor of Polidori and Mike Yanik, Institute, have each received winners for 1996 of the Koc biology and associate inves- both of applied mechanics. [J

44 ENGINEERING & SCIENCE NO. 1997 Offlce of Gift and Estate Planning

A C APITA L I DEA

When Duane McRuer in the trust go to Caltech. retired as president and "We have a long-term rechnical directOr of Systems commitment to Cal tech that's Technology, Inc. (STI), rhe grown through the years," internationally recognized says McRuer, who was elected Duane and Betty McRuer research company that he co­ to the baaed of direccors of founded 40 years ago, he had the Cal tech Associates last acquired a significant amount year. "We could have es tab­ on to their twO children, says McRuee, who plans to of stock as a result of leaving lished a charitable remainder estate taxes would take all designate that the trust his company's Employee trust to support other insti­ but 15 percent of its value. eventuall y suppOrt student Srock Oprion Plan. McRuer tutions, but Caltech is our "Both of our children are aid or endow a professorship. had several choices to deal main interest and wi ll con­ successful and will be taken "Almost everything I learned with the stock: he could hold tinue to be. This was an at­ care of," says McRuer. "If you at Cal tech helped my career. onto it and collect the divi­ tractive way co help Caltech." put these things in a chari­ It gave me the broad knowl­ dends, sell it and face a whop­ McR uer, who received table remainder trus[, you edge in science that enabled ping tax biU, or usc it to help Caltech's highest honor, the pay no capital gains taxes." me to expand from one thing Caltech, his alma marer. He Distinguished Alumni Plus, McRuer says that estab­ ro another. The charitable chose the latter. Award, in 1983, helped build lishing the truSt provided remainder crust was a con­ Mc Ruer, who received both STI into one of the world's [hem with a tax deduCtion for venient estate-planning rool his bachelor's degree in leading research firms , which a charirable donation to Cal­ and a neat way of helping mechanica l engineering in focuses on guidance and tech and has a[ least doubled Cal tech, which I believe is the 1945 and his master's degree control problems for a wide the income that they were finest educational institution in electrical engineering in range of vehicles, from cars getting from the stocks' in the world." 1948 from Calrech, has been to rotor crafts to hypetsonic dividends. Can tact us for more a longtime supporter of the aircraft. Since he and his co­ "But the key factor in all information, or ask for our Institute. He has also set a founder, Irving Ashkenas this was helping Cal tech," brochure. goal to leave a substantial (also a Caltech g raduate- parr of his estate to the Insti­ BS '37, MS '38, '39) believed tute. Retiring from his com­ that people in their company pany gave him the chance to were its primary assets, they help Calrech by using rhe set up an Employees Stock Su san A. Walker, CFP stock to establish a charitablc Ownership Plan (ESOP) that Office of Gift and Estate Planning remainder unitrust with the allowed the employees to buy Institute last December. It the company. After seiling his California Institute ofTechnology provides him and his wife, STI stock back to rhe ESOP, Mail Code 105-40 Betty, who worked ar STI for he bought a broad spectrum Pasadena, California 911 25 35 years as treasurer and of securities. In considering comract administrator, with the long term, the McRuers (626) 395-2927 in come for the rest of their found thar if rhey sold rhe planned-:ifts@starbase l.caltech.edu lives and helped him avoid securities they would pay a http://www.caltech .edu/-development/gep/gep.html capital gains faxes. When 40 percent capital gains tax, they die, the remaining funds while if they passed the stock

1997 £NGINEERING & HIEN{ E MO. 45