?· He encouraged The SETI League in the construction and testing of ... in Amateur Radio astronomy,…

Download ?· He encouraged The SETI League in the construction and testing of ... in Amateur Radio astronomy,…

Post on 24-Jul-2018




0 download


<ul><li><p>September 2005 43</p><p>ince its emergence as a respectablescientific discipline nearly a halfcentury ago, the electromagneticSearch for Extra-Terrestrial Intelli-</p><p>gence (SETI) has been dominated bythree classes of practitioners: governmentagencies, academic institutions, and non-profit organizations surviving on a com-bination of private contributions andresearch grants. Recent technological ad-vances have brought a new group of play-ers into the SETI gamededicatedamateurs with a personal passion forachieving interstellar contact.</p><p>This article explores the contributionssuch nonprofessionals are making toSETI science, in the realms of experimen-tal design, equipment construction, soft-ware development, direct observation,sky coverage, signal analysis and message</p><p>SETI:The Role of the</p><p>Dedicated Amateur</p><p>interpretation. Like the amateurathlete competing in an Olympiad, theamateur SETIzen can expect to strugglefor survival, absent commercial or insti-tutional sponsorship. Grassroots amateurefforts can nevertheless supplement theaccomplishments of the professionalSETI community, bringing us all closerto the day of Contact.</p><p>The SETI OlympiadThe challenge of interstellar contact,</p><p>no less elusive than the quest 50 years agoto break the four-minute mile, isdemanding of human skill and persever-ance. Unfortunately, success in this par-ticular arena is also a function of onesignificant factor beyond human control:the very existence, in the proper time-frame, of technologically advanced extra-</p><p>Dr Malcolm Raff, WA2UNP, assembles alow-noise microwave preamplifier at aSETI League Hardware Workshop.</p><p>The Search for Extra-Terrestrial Intelligenceis moving forward on a number of fronts,</p><p>thanks in large part to amateurs whovolunteer their time and expertise.</p><p>S</p><p>Dr H. Paul Shuch, N6TX</p><p>A roomful ofinterestedamateursshare insightsand ideas atone ofThe SETILeaguesannualSETIConTechnicalSymposia.</p><p>terrestrial beings. Given that no humaneffort can impact this particular factor,what can we do to maximize our chancesfor SETI success?</p><p>For a brief time (admittedly a mereeyeblink in human history), the govern-ments of planet Earth threw their prestigeand fiscal resources at the SETI problem,sponsoring any number of scientificsearches. But it is amateurs who havemade, and continue to make, the most sig-nificant strides toward contact.</p><p>An amateur, as defined by science andthe Olympics Committee alike, is onewho strives to excel without financialcompensation. The motivation of the ama-teur is revealed by the Latin root of theword: an amateur works for love.</p><p>Ask any contemporary SETI scientistor technologist why he or she strivesagainst incredible odds. The answer is al-ways the same. What modest salary he orshe may draw is almost incidental. Anyskilled SETIzen could always make moremoney by diverting the requisite effort ina different direction. It is indeed for thelove of the game that the best and thebrightest choose to compete in the SETIOlympiad.</p><p>The AthletesNot all SETI pioneers are licensed ra-</p><p>dio amateurs (though those I will discusshere are, or were). Not all of the workdescribed here was pursued as a strictlyamateur endeavor (though some of itwas). What these SETI players share isthe spirit of amateurism that marks theirscience as being of truly Olympian stat-ure. These representative examples, by nomeans inclusive, show how the worldsdedicated radio amateurs competed, andcontinue to compete, for SETI glory.</p><p>Grote Reber, W9GFZWhen the Father of the Radio Tele-</p><p>scope (SK, December 20, 2002) built theworlds first modern radio telescope in1937, a 10-meter-diameter parabolic re-</p><p>Reprinted with permission; copyright ARRL.</p></li><li><p>44 September 2005</p><p>flector in the backyard of his mothershouse in Wheaton, Illinois, he was work-ing strictly as an amateur, and under theauthority of his ham radio license. Groteproduced the first radio map of the MilkyWay Galaxy, though it took years for hisamateur accomplishments to gain accep-tance from the worlds astrophysics pro-fessionals. His subsequent low-frequencyradio astronomy research from Tasmaniacontinued in the amateur tradition of in-dependent research for its own sake.Never one to shy away from controversy,Rebers last published paper was titledThe Big Bang is Bunk!</p><p>Phil Morrison, W8FISUndeniably one of the patriarchs of</p><p>SETI, Professor Morrison had long sincegone inactive on the ham bands when in1959 he coauthored the first serious sci-entific SETI paper. His boyhood interestin Amateur Radio had motivated his in-terest in exploring the feasibility of mi-crowaves for interstellar communication.During SETIs Golden Age he has in-spired a whole generation of engineersand scientists. On a personal note, my ownSETI interests were motivated by follow-ing in Phil Morrisons footsteps (albeitfrom a distance of 30 years). As an EEundergraduate at the Carnegie Institute ofTechnology, I had the privilege of oper-ating W3NKI, the campus ham radio sta-tion he had founded three decades prior.</p><p>John Kraus, W8JKArguably the most creative antenna</p><p>designer of his generation, Kraus (SK,July 18, 2004) is best remembered for thelate Big Ear radio telescope that he de-signed and built at Ohio State University.Big Ear conducted the longest runningcontinuous SETI sky survey in history.</p><p>Dr John Kraus, W8JK, was an inspiringteacher, prolific author, prominentantenna designer and one of the fathersof modern radio astronomy.</p><p>SETI League members use a variety of digital signal processingsoftware tools to examine candidate signals in the time andfrequency domains.</p><p>SETI League member Marcus Leach, VE3MDL, built his ownsoftware-controlled receiver for wideband SETI scanning.</p><p>COURTESY VE3MDL</p><p>John Kraus grad student Bob Dixon,W8ERD, succeeded him as Director ofthe OSU Radio Observatory. Dixon isnow leading a team of dedicated amateursin the design of the omnidirectional Argusradio telescope.</p><p>Paul Horowitz, W1HFAStill active on the Amateur Radio</p><p>bands, a passion he has pursued sincechildhood, Horowitz heads HarvardUniversitys SETI efforts, and designedthe Project META and BETA searchesfunded in part by the Planetary Society.He is the author of the worlds most popu-lar Electronics Engineering undergradu-ate textbook. Lately he has been turninghis interests and expertise toward Opti-cal SETI.</p><p>Kent Cullers, WA6TWXA world-class leader in digital signal</p><p>processing, Cullers is better known to the</p><p>public as Kent Clark, the character basedupon him in the popular film Contact. Thefirst (and probably still the only) blind in-dividual to earn a PhD in the highly vi-sual discipline of astronomy, Kentdeveloped the signal detection algorithmsfor the late NASA SETI program, andlater for The SETI Institutes Project Phoe-nix targeted search. If he has seen fartherthan other men, it is because Kent Cull-ers stands on the shoulders of some veryclever code.</p><p>Seth Shostak, N6UDKSeths face is familiar on television,</p><p>and his voice a fixture on broadcast ra-dio, in his professional role as public pro-grams scientist for the SETI Institute. Thatvoice is less often heard on the ham radiobands, but it is there that Shostak firstgained exposure to the technologies heroutinely exploits as a senior SETI scien-tist. He encouraged The SETI League inthe construction and testing of its W2ETIMicrowave Moonbounce CalibrationBeacon, and was the first radio amateurto detect its weak signals reflected off thelunar surface (albeit with the 305-meter-diameter Arecibo Radio Telescope).</p><p>Richard Factor, WA2IKLIf SETI is truly the science that refuses</p><p>to die, that is due in large part to this NewJersey industrialist. An active ham sinceboyhood, Factor was dismayed at Congres-sional cancellation in 1993 of the NASASETI program. Then, putting his moneywhere his mouth is, he founded the non-profit SETI League, to involve the worldsradio amateurs in privatizing the search.Though not as active as he would like to bein Amateur Radio astronomy, Factorsgreatest contribution has been his leader-ship role as SETI League president and pri-mary source of financial support. He canclaim much of the credit for the 126 Ama-teur Radio telescopes that SETI Leaguemembers now operate all over the world.</p></li><li><p>September 2005 45</p><p>The Organizing CommitteeFounded by Richard Factor in 1994 as</p><p>a response to the demise of the NASASETI program, The SETI League, Inc isa grassroots Amateur Radio club of glo-bal scope and galactic span. It coordinatesthe SETI activities of 1450 experiment-ers in 66 countries on six continents. Itsmembers design hardware and softwarefor a coordinated all-sky survey, publisharticles, conduct conferences, constructand operate equipment, and collectivelycontrol more radio telescopes than existin the rest of the world, combined.Funded entirely by membership dues andindividual contributions, The SETILeague currently has no paid employees,with all its functions being performed byvolunteers.</p><p>The SETI Leagues main medium ofcommunications is its extensive Webpresence (see www.setileague.org),along with half a dozen specialized e-maildiscussion lists, whereby members canpursue a variety of collaborative projects.The organization also publishes ContactIn Context, an on-line peer-reviewed sci-entific journal, and provides Webmasterservices for the SETI Permanent StudyGroup of the International Academy ofAstronauticsall on an operating budgetof just a few thousand dollars per year. Inaddition to their scientific and engineer-ing activities, SETI League members areinvolved in publicizing and popularizingSETI, having conducted hundreds ofmedia interviews and having appeared indozens of television documentaries.</p><p>The backbone of The SETI League isits Field Organization, a cadre of 65volunteer Regional Coordinators aroundthe world, who offer their expertise andassistance to SETI enthusiasts, whetherSETI League members or not.</p><p>The EventsSETI amateurs are challenged by and</p><p>involved in a number of technologicalpursuits. A brief sampling:</p><p>The DiscusThe antenna of choice for amateur</p><p>backyard radio astronomy is the discardedC-band home satellite TV dish. These 3to 5-meter-diameter parabolic reflectorsexhibit in excess of +30 dBi of gain inthe Waterhole spectrum between 1.4 and1.7 GHz, and provide modest resolutionwith their 2 to 4 beamwidths. They cangenerally be had for the asking in com-munities where TVRO technology hasbeen replaced by digital Direct BroadcastSatellite television distribution. Severalhundred Amateur Radio telescopes arealready on-line or under constructionaround the world, using just such anten-</p><p>The SETI Horn of Plenty, a waveguidehorn antenna for 1.3 to 1.7 GHz designedby the author, has been duplicated bydozens of SETI League members aroundthe world, for classroom demonstrationsas well as observational radio astronomyand SETI.</p><p>Tommy Henderson, WD5AGO, showsoff two horn antennas used for radioastronomy. The larger of the two (on anaz-el mount) is optimized for 1.4 GHzhydrogen line observations. Tommy isholding a smaller horn for 5.7 GHzmethanol line measurements.</p><p>nas as their basis. A suitable L-bandfeedhorn can be readily fabricated out ofhardware store materials and tin snips byany experimenter reasonably skilled insheetmetal working techniques.</p><p>The 21 cm Closed CircuitOnce those L-band photons falling</p><p>from the sky have been captured by asuitable antenna, it remains for the dedi-cated amateur to amplify, filter and pro-</p><p>cess them in a suitable microwave re-ceiver. Amateur Radio astronomers havemodified military and government surplusequipment, employed commercial receiv-ers produced for the ham radio and tele-communications markets, and, morerecently, designed their own dedicatedSETI receivers from scratch. Every yearat its SETICon Technical Symposium,The SETI League hosts a microwave cir-cuit construction workshop, to train itsmembers in the skills necessary to pro-duce a workable hydrogen line receiver.</p><p>The BinathalonThe output of the typical microwave</p><p>receiver is analog baseband, generally inthe audio range. This signal is convertedto a string of binary digits for signal analy-sis, often in a personal computer soundcard. More advanced analog to digitalconversion at a receivers intermediate fre-quency stages is recently becoming a pre-ferred method of preparing the receiversanalog output for digital signal process-ing (DSP). Amateur Radio astronomersare working on the next generation ofDSP hardware, software and algorithms,to ferret out the hallmarks of artificialityburied in receiver and cosmic noise.</p><p>Synchronized ScanningWith over 100 Amateur Radio tele-</p><p>scopes now engaged in a coordinated all-sky survey, it is necessary to efficientlyallocate the search space among partici-pants, in terms of sky coverage, frequencyspectrum, and time. A major challenge forThe SETI League has been to developmeans of ensuring maximum spectral andsky coverage, with minimal overlap, con-strained by the equipment capability andlocation of each individual participatingstation. Real-time coordination via theInternet turns a hundred individual instru-ments into a zeroth-order interferometerof impressive capabilities. Still, the chal-lenge remains to automate the coordina-tion process, especially as more stationsare added, growing the Project Argus skysurvey toward its eventual goal of 5000participating Amateur Radio telescopesand real-time all-sky coverage.</p><p>The Broadband JumpThe typical commercial communica-</p><p>tions receiver has an instantaneous band-width on the order of a few kilohertz.Given the enormity of the spectral spaceacross which valid ETI signals are likelyto be dispersed, the time factor to analyzea reasonable portion of spectrum is inor-dinate. New receiver designs are needed,which can process and digitize hundredsof kilohertz, or preferably many mega-hertz, of bandwidth in real time. SETI</p></li><li><p>46 September 2005</p><p>Dual quad-helix arrays for 1296 MHz,one right-hand and the other left-handcircularly polarized, are part of The SETILeagues W2ETI Moonbounce CalibrationBeacon.</p><p>The SETI@home project run by the University of California,Berkeley, though not a SETI League initiative, has stimulatedthe interest of SETI supporters around the world. SETI Leaguemembers are among the several million users who lend theirspare computer cycles to the analysis of archival data from theArecibo Observatory in Puerto Rico.</p><p>COURTESY N6TX</p><p>League members have recently been ap-plying new components designed for thewireless telecommunications industry tothe challenge of seeking out narrow-bandemissions across broad chunks of theelectromagnetic spectrum.</p><p>The High-Frequency HurdlesAlthough there is a certain romance</p><p>associated with searching for ETI acrossthe traditional Waterhole frequenciesspanning the spectral emission lines ofneutral hydrogen and hydroxyl (the dis-association products of water), four de-cades of SETI in this portion of L-bandhave thus far failed to produce positiveresults. The higher frequency reaches ofthe electromagnetic spectrum are a ripearea for SETI exploration, and a numberof Amateur Radio astronomers are nowequipping...</p></li></ul>


View more >