Today

James Alfred Van Allen Frank B. McDonald, Michelle R. Thomsen, and Donald A. Gurnett

Citation: Physics Today 59(12), 77 (2006); doi: 10.1063/1.2435692 View online: http://dx.doi.org/10.1063/1.2435692 View Table of Contents: http://scitation.aip.org/content/aip/magazine/physicstoday/59/12?ver=pdfcov Published by the AIP Publishing

This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to IP: 128.255.33.61 On: Fri, 11 Jul 2014 20:19:15 James Alfred Hey! Van Allen You need a low-noise amplifier? Go to www.femto.de and find handy James Alfred Van Allen, who led Amer- ican science into space, died of heart high performance signal recovery tools, failure on 9 August 2006 at the age of 91 UNIVERSITY OF IOWA like … in Iowa City, Iowa. His 1958 discovery of what are now known as the Van Allen … Low-Noise Voltage Amplifier – radiation belts produced great excite- Series DLPVA-100 ment in both the scientific community and the general public and marked the beginning of the modern era of space science. Van Allen was born in Mount Pleas- ant, Iowa, on 7 September 1914. He showed an early interest in mechanical and electrical devices, and a high-  Input Noise down to 400 pV/Hz school teacher inspired his fascination  Variable Gain up to 100 dB (x 100,000) with science. At Iowa Wesleyan Col-  Input Impedance up to 1 T lege, he majored in physics, helped pre- James Alfred Van Allen  Manual and Remote Control pare seismic and magnetic equipment for one of Richard Byrd’s Antarctic ex- peditions, and graduated in 1935. He altitude balloons (“rockoons”), had … High Speed Current Amplifier – nose cones and large tail fins machined earned his PhD from the University of Series HCA Iowa in 1939 with a thesis on nuclear for military rockets in the Iowa machine physics. shops, and had students assemble and As a research fellow at the Carnegie test the payloads. Various payloads of Institution of Washington’s Department single Geiger counters, ionization of Terrestrial Magnetism, Van Allen chambers, scintillation counters, and continued his work in nuclear physics. proton precession were He became interested in geomagnet- launched on four expeditions to Thule, ism, cosmic rays, and solar terrestrial Greenland, during the summers of  Bandwidth DC up to 200 MHz, 1952–54 and on extensive Arctic and physics through acquaintance with Rise-Time down to 1.9 ns Antarctic flights throughout the 1957 Scott Forbush and Harry Vestine and  Optimized Models for Large Source the work of Julius Bartels and Sidney International Geophysical Year. One Chapman. In mid-1940 he joined DTM’s significant finding was a new “soft” Capacitances up to 2 nF national defense effort developing charged-particle component of low-  Ideal for Fast and Large Area proximity fuses and moved with the energy electrons in the auroral zone, the Photodiodes program when it was transferred to the first direct confirmation of the particles producing auroral luminosity. Applied … 19” Lock-In Amplifier Board – Physics Laboratory. In late 1942 he was On 31 January 1958, some four commissioned as a naval officer; he in- months after the Soviet Union launched Series LIA-BV(D)-150 troduced to the South Pacific fleet Sputnik 1, the University of Iowa cosmic- radio-proximity fused projectiles and ray experiment—a single Geiger counter reported on their effectiveness. After developed by Van Allen and graduate the war he returned to APL, where he student George Ludwig—was placed in organized a high-altitude research orbit on Explorer 1 by a Jupiter C rocket. group and initiated development of The limited data from Explorer 1 were a new high-performance sounding confusing, with periods of normal rocket, the Aerobee. counting rates, periods of rapid changes, and intervals of zero counts. From 1947 to the creation of NASA  in 1958, Van Allen was chairman of the The confusion was clarified by Explorer 3, Working Frequency up to 120 kHz group that became the Rocket and launched on 26 March 1958, which con-  Phase Independent Output Satellite Research Panel. This informal tained the Iowa experiment and a  Manual and Remote Control group played a key role in fostering miniature magnetic tape recorder. Van  For Low Cost, Multi-Channel and OEM upper atmospheric research and the Allen, Ludwig, graduate student Carl Applications initial group of satellite experiments. McIlwain, and former student Ernest In 1950 Van Allen returned to the Ray, an Iowa assistant physics profes- University of Iowa to head the physics sor, realized the satellite was encoun- department, a position he held until his tering vast regions of intense radiation “retirement” in 1985. He continued that at times saturated the Geiger- Sophisticated Tools for Signal Recovery studying cosmic rays and how to get counter response, producing a null FEMTO® Messtechnik GmbH above the shielding of Earth’s atmos- counting rate; the regions were later Paul-Lincke-Ufer 34 phere in a practical and inexpensive named the Van Allen radiation belts. D-10999 Berlin/Germany Tel.: +49-30-4 46 93 86 way. For the latter he followed up on an Over the next several years, Iowa Fax: +49-30-4 46 93 88 idea to launch rockets from high- was the center of the new world of e-mail: [email protected] www.femto.de

This articlewww.physicstoday.org is copyrighted as indicated in the article. Reuse December of AIP content 2006 is subjectPhysics to Todaythe terms 77at: http://scitation.aip.org/termsconditions.See www.pt.ims.ca/9471-36 Downloaded to IP: 128.255.33.61 On: Fri, 11 Jul 2014 20:19:15 space science. Van Allen and his group budgetary issues in 1972, he was in- provided the principal scientific instru- strumental in helping recoup the op- mentation for the five Explorer and first portunity and chaired the initial science four Pioneer missions in 1958–59. Seven working group planning the Mariner of the missions established the exis- Jupiter–Saturn (Voyager) mission. As tence of inner and outer radiation belts he said in his autobiography, “It did and a general understanding of the not escape our attention that the con- boundaries and properties of the figuration of the outer planets was trapped radiation. independent of budgetary-political The Iowa space group grew steadily, considerations in the White House evolving into one of the world’s premier and the Congress” (Annual Review of institutions for . Van Earth and Planetary Sciences, volume 18, Allen’s instruments were on Mariner 2, 1990, page 24). the first mission to another planet— After the Jupiter and Saturn encoun- Venus—in 1962 and on Mariner 4, the ters, Van Allen’s Pioneer instruments first mission to Mars, in 1965. Although continued to blaze a knowledge trail no radiation belts were found at either through the outer heliosphere, and the planet, his instruments yielded valu- data from Pioneer 10 and 11 extending able observations of cosmic rays and to beyond 75 AU allowed Van Allen to solar energetic particles, topics he en- return to cosmic-ray studies. Over the thusiastically followed even in his post- period 1975–97, the landscape of ener- retirement research. getic particle and interplanetary phe- In the late 1960s, as a member of the nomena was constantly evolving with National Academy of Sciences space the 11-year , large-scale dis- science board and of NASA’s lunar and turbances from the Sun, and the ever- planetary missions board, Van Allen increasing heliocentric distance. At was a tireless advocate for exploration great distance, Van Allen’s basic of the outer planets. His efforts came to philosophy of simplicity and reliability fruition when his Geiger Tube Tele- was rewarded once again: The aging scope was selected for the Pioneer pay- Pioneer 10 spacecraft power source was load and contributed to results from the so limited that only his experiment Pioneer 10 and 11 flybys of Jupiter in could be operated, and on 31 March 1973 and 1974 and the Pioneer 11 flyby 1997 it provided the last science meas- See www.pt.ims.ca/9471-37 of Saturn in 1979. The GTT weighed urements from the Pioneer mission—a only 1.64 kg and consumed just 25 mA fitting finale to a remarkable journey from the power supply. On the three through the space age. planetary encounters, his experiment Among Van Allen’s many awards for hit pay dirt: Jupiter’s enormous magneto- his contributions to space science were sphere contained incredibly intense the National Medal of Science, the radiation belts and magnetospheric Crafoord Prize of the Royal Swedish phenomena, and Saturn had an exten- Academy of Sciences, and the American sive magnetosphere. One aspect of the Geophysical Union’s Bowie Medal. Van Pioneer encounters with Jupiter and Allen served as AGU president from Saturn that Van Allen particularly en- 1982 to 1984. joyed was the observation of the inter- The consummate teacher and men- action between the radiation-belt parti- tor, Van Allen took delight in teaching cles and the neutral material in introductory undergraduate astron- Keplerian orbits about the planets; he omy, and his graduate students were was able to announce the detection of always the heart of his research teams. several previously unknown satellites He guided his students to 47 MS de- through their absorption signatures in grees and 34 PhDs, and many went on the energetic particle data. Compared to positions of leadership and influence with later planetary missions, Pioneer in the field. Most important, he treated was small. But it looms large in the his- all his students with respect, listening to tory of the planetary program, and in them, learning from them, and guiding many ways it was Van Allen’s most them with wisdom and kindness. He satisfying mission since 1958–59. was an inspiration to the generations The foundation laid by Pioneer al- who followed his lead into the fascinat- lowed exploration of the outer planets ing world of space research. to proceed with confidence, and Van Frank B. McDonald University of Maryland, College Park Allen continued to provide leadership Michelle R. Thomsen and advocacy for the new missions that Los Alamos National Laboratory followed. When the “Grand Tour” mis- Los Alamos, New Mexico sion to take advantage of the once-in- Donald A. Gurnett 179-years alignment of Jupiter, Saturn, University of Iowa Uranus, and Neptune fell victim to Iowa City ᭿

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