C ALIFORNIA I NSTITUTE OF T E C HNOLOGY engineeringE& andS science Volume LXXI, Number 1, 8 IN THIS ISSUE The Final Frontier The Last Big Slice of Pie The Fates of Cells On March 11, 2008, space shuttle Endeavor carried not one, but two Caltech alums to the Interna- tional Space Station. Here, astronauts Garrett Reisman (MS ’92, PhD ’97), left, and Robert Behnken (MS ’93, PhD ’97) posed for the camera before Behnken embarked on the mission’s fourth space- walk. After the successful mission, which included installation of a module of the Japanese laboratory, Kibo, on the ISS, Endeavor touched down on the night of March 26 at Cape Canaveral—but without Reisman. He will remain on the ISS as the flight engineer, not returning until space shuttle Discov- ery, scheduled for launch on May 25, comes to pick him up. Reisman also took some special cargo on behalf of his former advisor, Hayman Professor of Mechanical Engineering Chris Brennen, whose wife suddenly died of cancer in August 2007. Accompany- ing Reisman on his cosmic journey are the Bren- nens’ wedding rings, fused together. engineering& and science California Institute o f T e c h n o l o g y Volume LXXI, Number 1, 2008 E S 2 Random Walk 12 50 Years in Space — by Douglas L. Smith International leaders in the space and aeronautics industry convened at Caltech to share their thoughts on the first 50 years of space exploration—and what’s in store for the future. 22 Auctioning off the FCC’s Crown Jewels — by Elisabeth Nadin When the FCC recently auctioned off bandwidth previously reserved for broadcast television, Caltech researchers were enlisted to ensure that everyone got a fair shot at the prized goods. 28 When Cells of a Feather Don’t Flock Together — by Marcus Woo Cells don’t behave the same way, even if they’re nearly identical. So how do they decide what to do? 34 Ad Astra per GALCIT — by Douglas L. Smith A new master’s degree program launches graduate students into the space industry. 39 Letters Obituaries: Seymour Benzer, David C. Elliot, Herbert B. Keller On the cover: Mission spe- 41 cialist Robert Behnken (MS ’93, PhD ’97) seen during a six-hour, 53-minute Engineering & Science (ISSN 0013-7812) is published Robert M. Kieckhefer spacewalk, his first, outside quarterly at the California Institute of Technology, 1200 President of the Alumni Association the International Space East California Boulevard, Pasadena, CA 91125. Annual Robert L. O’Rourke subscription $20.00 domestic, $30.00 foreign air mail; Vice President for Public Relations Station. Behnken and fel- single copies $5.00. Send subscriptions to Caltech 1-71, low mission specialist Rick Pasadena, CA 91125. Third-class postage paid at Pasadena, Linnehan were installing CA. All rights reserved. Reproduction of material con- STAFF: Editor — Douglas Smith tained herein forbidden without authorization. © 2008, Writer — Marcus Woo parts for a two-armed California Institute of Technology. Published by Caltech Contributing Writers — Signe Bray, Elisabeth Nadin, Jill Canadian servicing robot and the Alumni Association. Telephone: 626-395-3630. Perry, Jackie Scahill, Kathy Svitil, Michael Torrice Copy Editors — Allison Benter, Barbara DiPalma, Michael named Dextre. PICTURE CREDITS: Cover, inside front cover, 13, 17, 19, 20, 38 — NASA; 2 — Paul Rothemund, Robert Lang; 3 — USPS; 8, Farquhar, Elena Rudnev 12 — NASA/JPL-Caltech/U. of Arizona; 11 — Audrey Wu, Dick Business Manager — Debbie Bradbury Sneary Illustrations; 13 — USGS, NASA; 18 — Boeing, NASA/ Circulation Manager — Susan Lee SVS; 19 — NASA/JAXA, NASA/JPL; 20 — NASA/GSFC; 15, Photographer — Robert Paz 21, 36, 37 — Bob Paz; 22, 26 — FCC; 25 — Jacob Goeree; 28-33 Graphic Artist, Layout — Douglas Cummings — Elowitz lab; 23, 25, 31 — Doug Cummings; 34–35 — NASA Landsat; 37 — Caltech Archives; 42 — Elliot family; 44 — ACM Visit us online at http://EandS.caltech.edu Random Walk F ROM THE L AB TO THE G ALLERY Right: Rothemund’s DNA origami of North and South America ren- Matisse, Picasso—and tions of the AFM scans etched dered as a three-dimensional glass now, DNA and computa- into glass blocks, using the etching. tional origami. Science, art, same techniques used to make technology, and design come laser-etched glass paper- Below: Lang’s Snack Time depicts together in a new exhibit at weights. the wedding feast of a female the Museum of Modern Art Lang has combined his love praying mantis on her unfortunate in New York. The show, en- of mathematics and paper- male partner. And yes, this was titled Design and the Elastic folding, becoming one of the Mind, includes work by two pioneers in computational folded from a single uncut square Caltech alums—origamist origami—the art and science of paper. Robert Lang (BS ’82, PhD of designing origami with ’86) and Paul Rothemund (BS mathematical techniques. ’94), a senior research associ- The exhibit showcases some of ate in computation and neural his intricate creations, as well systems and computer science. as the TreeMaker software he Rothemund, one of wrote to make his increasingly Caltech’s two 2007 MacAr- complex designs. thur “genius” grant winners, Both types of origami are invented “DNA origami,” displayed alongside a myr- in which he turns strands of iad of provocative exhibits, DNA into any desired flat including a honeycomb vase, shape, from a smiley face to pig bone tissue grown into the the outline of a contient. He shape of wings, and furniture took DNA from a harmless modeled after human bones. virus and developed a method The show runs through May to fold and pinch strands 12. —MW together. The result is a pow- erful way to build nanoscale structures out of DNA. The shapes measure about 100 nanometers, or 100 billionths of a meter, across—about one thousandth of a hair’s breadth. In addition to atomic-force micrograph (AFM) prints of Rothemund’s creations, the exhibit includes representa- Right: Have a nano day! 2 ENGINEERING & SCIENCE NO . 1 2 0 0 8 On March 6, the post office issued its second series of four American Scientists stamps. This set includes Caltech Nobelist Linus Pauling (PhD ’25). The back- ground art refers to his discovery that sickle-cell anemia is a molecular disease—the first to be recog- nized as such. Caltech is two-for-two in this series of stamps: the first set, issued in 2004, included fellow laureate Richard Feynman. G ETTING N ANOWIRED One day, they could be on the other hand, is one of from larger systems like car is not only cheaper, but can everywhere, powering your the most abundant elements engines, and may also be used also be done with lower- computer and keeping its mi- in the universe. The micro- in refrigeration devices. The quality silicon. The trick to croprocessor cool at the same processor industry has also researchers, who include Wil- turning nanowires into solar time. They’re silicon nanow- made processing silicon inex- liam Goddard (PhD ’65), the cells is a unique geometry, an ires, narrow devices hundreds pensive and easy. But because Ferkel Professor of Chemistry, idea first developed by gradu- to thousands of times thinner silicon is also an excellent con- Materials Science, and Ap- ate student Brendan Kayes than this piece of paper. Two ductor of heat, it didn’t seem plied Physics; Jamil Tahir- (MS ’04) in 2005. Regular groups of Caltech researchers promising as a thermoelectric Kheli (MS ’86, PhD ’92), a solar cells are flat, and absorb are discovering the remarkable material—until now. senior staff scientist with the photons face-on. The newly properties of silicon nanow- By growing silicon into Materials and Process Simu- freed electrons then move ires, enabling the wires to nanowires, researchers in lation Center; and gradu- along the same direction, par- harness solar power and to act Heath’s lab improved silicon’s ate students Akram Boukai allel to the incoming photons. as refrigerators by converting thermoelectric efficiency by (PhD ’08), Yuri Bunimovich They’re collected at the surface heat to electricity, and vice a factor of 100. One of the (PhD ’07), and Jen-Kan Yu, of the silicon slab, where they versa. reasons for the enhanced per- reported their findings in the then join the electrical cur- The latter group, led by formance might be a phenom- January 10 issue of Nature. rent. Additionally, the cells James Heath, the Gilloon enon called phonon drag, ac- Silicon nanowires may also have to be thick enough to Professor and professor of cording to the team. Phonons help solve the energy crisis. capture all of the photons. chemistry, found that silicon are heat-carrying vibrations Researchers in the labs of In the new photovoltaic could be an efficient thermo- that travel across the material. Nate Lewis (BS, MS ’77), the cells, silicon nanowires sit electric material when made Constricted by the small size Argyros Professor and profes- alongside one another like into wires only 10 nanometers of the nanowire, the phonons sor of chemistry, and Harry blades of grass. Light is (10 billionths of a meter) don’t scatter off the sidewalls Atwater, the Hughes Professor absorbed along the length of wide. “At these tiny dimen- in the nanowire. Instead, they and professor of applied phys- the wires, which, at tens of sions, nature is doing things travel unimpeded down the ics and materials science, are microns, are still long enough that were previously not wire and drag electrons with using the wires to build a new to snatch all the photons. The thought possible,” he says. them, which improves ther- kind of photovoltaic cell.