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Allen Telescope Array: Listening for ETI

By Larry Klaes

Larry Klaes’ look at the Allen Telescope Array reminds us of the power of philanthropy at getting serious projects funded. It’s a topic we’ll be re-visiting as the Tau Zero Foundation comes online early in the coming year. I’m reminded also of the One Laptop Per Child project, which is seeing private donations for these educational tools supplanting government shortfalls in some developing countries. Properly targeted, the philanthropic dollar is a powerful thing, and think of the results if the ATA finds a genuine signal!

Cornell astronomer and science popularizer Carl Sagan left quite a legacy in a number of science fields, including and especially those which were considered to be somewhat fringe at one time.

One prime example of his support of a science field that was not universally accepted in earlier eras was SETI, the Search for Extraterrestrial Intelligence. At a time when many astronomers did not seriously consider the possibility of other beings existing beyond Earth and relegated aliens to UFO and science fiction tales, Sagan promoted and participated in some of the first scientific searches and contact efforts for extraterrestrial life.

One of the latest results of Sagan’s efforts in SETI was recently dedicated in a remote region of northern California. Called the Allen Telescope Array (ATA) after its most prominent benefactor, Microsoft co-founder Paul Allen, the installation can look to Sagan as an inspiration. Seattle billionaire Allen cited a conversation with the Cornell astronomer in 1995 as the catalyst that prompted him to donate $25 million to construct the most advanced SETI project yet built.

Allen Telescope Array

SETI programs have traditionally been sporadic both in terms of funding and their search parameters, going back to 1960 when former Cornell astronomer Frank Drake began the first modern effort, named Ozma, using a large radio telescope to monitor just two nearby stars — Tau Ceti and Epsilon Eridani — over a four-month period. By the early 1990s, SETI programs in the United States were in jeopardy when NASA pulled its support for the effort. Fortunately for the field, private efforts such as the SETI Institute and the SETI League picked up where the government left off, though they too often suffered from limited telescope resources.

First conceived by Frank Drake, the ATA is a revolution for both SETI and radio astronomy in general. Dedicated both to SETI projects and galactic astronomy, the array offers a sense of focus. The SETI Institute will no longer have to vie for time with other projects using various large radio telescopes around the world. The 42 twenty-foot wide dishes currently in operation will be expanded to 350 in the coming years. Not only will the ATA do wonders for astronomy using relatively inexpensive off-the-shelf technology, but it will also serve as a test bed for much larger radio astronomy projects utilizing collections of many telescopes functioning as a single unit, such as the Square Kilometer Array (SKA), planned for construction in the next decade.

Other notable features about the ATA include its ability to scan large areas of the sky rapidly. The array will be able to simultaneously scan numerous star systems and monitor over forty million radio channels. The modern technology of the ATA also allows it to filter out effectively the many sources of artificial noise from human civilization, a major bane to radio SETI, while searching for the alien ones.

The first SETI effort for the ATA will be to scan the center of our Milky Way galaxy, where billions of stars reside, for several months. The cluster of radio telescopes will then begin a more detailed assignment, examining approximately one million nearby star systems. This will be a thousand fold increase over all previous SETI efforts going back to Ozma. This number does not include the few brief explorations of some neighboring galaxies, which hold hundreds of billions of suns. Several such studies were conducted by Sagan and Drake themselves.

Allen Telescope Array dishes

The previous effort by the SETI Institute, called Project Phoenix, looked at fewer than 800 star systems for only a few weeks each year from 1995 to 2004, borrowing telescope time first from the Parkes Radio Observatory in Australia and then the Cornell-run Arecibo Radio Observatory on the island of Puerto Rico. Living in a galaxy with 400 billion stars, it is easy to see why SETI researchers are excited about the ATA.

Images: Views of the Allen Telescope Array. Credit: ATA.

Some scientists doubt that even the capabilities of the ATA will be able to detect alien civilizations in the galaxy. Aside from those who say the Milky Way is either barren of any life besides that on Earth or that few aliens are more developed than bacteria, some question whether advanced ETI would use the relatively primitive method of radio to transmit messages into deep space.

One alternative to interstellar communications is through the optical portion of the electromagnetic spectrum, specifically with lasers. A powerful laser beam could contain far more information than a radio message, including video images, which may certainly facilitate understanding between two very different cultures. Others advocate sending physical messages between the stars, something like the metal plaques and records on the Pioneer and Voyager space probes, respectively.

Some scientists declare that we are looking for the ‘wrong’ kind of aliens in the wrong kind of places, namely biological beings not too dissimilar from humans living on Earthlike planets circling yellow dwarf stars. Milan Ćirković and Robert Bradbury contend that beings that survive their cultural adolescence will become what Hugo de Garis calls artilects, vast machine intelligences far beyond our level of intellect. These artilects may prefer to exist in the dark outer regions of the Milky Way, huddled around suns inside massive Dyson Shells, where the much colder temperatures allow them to function better. Such highly advanced minds housed in such truly alien ‘bodies’ may help to explain why we have yet to detect any ETI or why no obvious messages have come our way.

Whatever the situation may be or the types of ETI that may exist in the Universe, one thing is certain: If we do not search for them, we will likely never find them, or they us. The Allen Telescope Array is a major new step in improving our chances to find what is or is not out there. What we learn from this exploration into the unknown will have a profound effect on our species and society.

For more information on the ATA, check out the ATA section on the SETI Institute Web site.

Comments on this entry are closed.

  • tacitus December 5, 2007, 16:28

    Yeah, for all the doubts over the efficacy of the current SETI efforts, there’s always the old adage “You’ve got to start somewhere.”

    One thought does spring to mind regarding radio waves as a transmission medium. Assuming there are alien civilizations out there who want to make contact, then even if they have advanced on to more efficient (and less detectable) means of interstellar communication it would seem to be possible that they would want to leave an old radio beacon on, perhaps transmitting some sort of bootstrap message that would show us how to log in to the GWW (Galaxywide Web). (Okay, so Carl Sagan already used that sort of idea in Contact).

    On the other hand, perhaps they only used radio waves for a brief moment in their history before they moved on to other means, perhaps even before they became a space-faring species. In that case they may not thing it’s worth the effort using radio waves since it may only be the long-distance communications method of choice for, say, a couple of hundred years before any civilization worth its salt discovered a better means for interstellar emails and chatrooms. :)

    In any case, I applaud ATA’s efforts and all those involved. As I said, we have to start somewhere, and wouldn’t it be a handsome payoff it they actually succeed!

  • andy December 5, 2007, 17:35

    It’s interesting how the non-SETI potential of this telescope is hardly discussed. I guess that’s the media for you.

    Suppose the ATA does detect an unambiguous and verifiable alien transmission. What then? For the moment, I’ll ignore such speculative (and probably neurologically-unsound) scenarios such as the transmission turning out to be a “Langford basilisk”, in which case we’re all in trouble, even if the aliens didn’t intend for the transmission to work like that.

    Almost certainly, the announcement of a detection will lead to METI efforts, in which we could be heading into dangerous territory. Given the apparent resistance on the part of the community to a discussion or debate about the wisdom of METI, and a lack of any kind of clear global policy in this matter (and surely a global policy is necessary: anyone who decides to reveal our presence on this planet to an alien civilisation cannot help but be acting for all humanity), we don’t know what will happen.

    What should certainly be avoided is “we discovered aliens, and we transmitted greetings before we even told the rest of humanity they existed”, neutralising any point in having public debate.

  • stargazerdude22 December 5, 2007, 17:39

    I suspect that we may have already detected non-repeatable and transient, scintillated signals (such as the “WOW!” signal?) and if we to mine our existing data better…? But I suppose for proof a signal needs to be repeatable and independantly verified. Looks like we have a handful of ‘candidate’ but not ‘repeatable’ signals. The whole concept of the ATA is so exciting, a great way to start (God bless you, Paul Allen). Next, we need an all-sky, real time search and at a much wider frequency range; an SKA on the far side of the moon would be the best. Perhaps my children will see that…

  • ljk December 6, 2007, 10:52

    There are very few major radio telescopes on
    this planet dedicated to SETI. That is newsworthy
    in itself.

    As for advanced ETI leaving on radio beacons
    to help uplift less sophisticated species, what
    would be their motivations for this? Rich people
    tend not share their wealth just to make others
    rich without some ulterior motive to their
    benefit behind it.

    Maybe the rest of the galaxy is more ethical
    and altruistic, but….

  • dad2059 December 6, 2007, 11:04

    A worth-while endeavor to be sure and one I love. But I think our limited radio and optical telescope time should be focused more on Near Earth Object detection and potential Earth orbit crossing objects.

    Once we ensure our own survival, then we can focus on the luxury of ET communication.

  • Ronald December 6, 2007, 11:42

    I don’t want to spoil the enthousiasm, but: I personally think we are jumping ahead with a too big leap here, or in other words: first things first.

    What I mean is this: I would rather see this money being spent on large optical and interferometry systems, able to detect earth-sized planets and analyze there athmospheres for biosignatures.

    It seems like a logical first (or next) step to look for the planets first, then for (any) biological life on them. The chances of success in those two endeavors are also much greater than those of finding advanced intelligent life.

    And private money could surely do a useful job here: SIM has been postponed, TPF postponed indefinitely.

  • ljk December 6, 2007, 12:16

    That sounds a bit too much like those who say we
    should stop spending money on space and spend it
    here on Earth – even though NASA gets less than
    1 percent of the federal budget each year.

    There are already systems dedicated to detecting NEOs.
    Besides the ATA, there are only a few other telescopes
    focused on SETI, and most of them are optical. Most of
    the money spent on the ATA was from a private donation
    by a guy who can certainly afford it.

  • bob krekorian December 6, 2007, 14:35

    The search for an extraterrestrial civilizations is one of the most intellectually stimulating and potentially rewarding pursuits open to humanity. As someone who worked on the NASA SETI project for 15 years and was the one who told the SETI Institute about Paul Allen’s interest in SETI, I am dismayed to see what is happening.

    The Allen Telescope Array is supposed to revolutionize SETI research. But when one factors in antenna particulars that will bring down the sensitivity of the radio telescope, it loses its value to SETI.

    Why would radio astronomers consider building a SETI telescope at Hat Creek, California? What Carl Sagan referred to as prime SETI frequency territory will be severely impacted by cell-phone transmissions at this site. Katabatic winds coming off the Hat Creek rim make this an ideal place for a paragliding launch site, but bad for radio astronomy. Winds in excess of 100mph destroyed the University of California radio telescope at Hat Creek in 1993.

  • tacitus December 6, 2007, 17:00

    Space agencies are already spending billions on the hunt for NEOs and extrasolar planets, so I don’t begrudge a single dime of Paul Allen’s money that’s going towards the ATA (which will be used for more standard radio astronomy research as well as for SETI anyway). We’re never going to get all the money we would like to spend on all these astronomy projects but still I think the human race is able to walk and chew gum at the same time.

    Extrasolar planets is about the sexiest line of research in astronomy these days. They will not fail for lack of funding.

    SETI is the ultimate Hail Mary — very unlikely to succeed, but if it does, it could be just about the most profound and world-changing discovery in all of human history. The money Allen is spending is a pittance compared with NASA’s annual budget, and I think it’s worth every penny.

  • Adam December 7, 2007, 6:43

    Hi tacitus

    I don’t know about billions – the NEA hunt has only had a few million spent on it using shared-time telescopes. The exoplanet hunt has had less than a billion, mainly Kepler and COROT, and neither of those is purely devoted to the hunt. Sure billions will be spent on OWL and VLTs, but they’ll be doing a lot of other work. A dedicated mission would be the Planet Finder and Imager, but they’re on the funding back-burner currently.

  • ljk December 7, 2007, 9:50

    To Bob Krekorian – if the region that the ATA is located
    in is so unfavorable, and was known to be so since at
    least 1993, then why did the SETI Institute build it there?

    The ATA is supposed to be able to handle terrestrial
    interference. And perhaps a large number of smaller
    dishes, which are designed to be rather easy to maintain,
    repair, and replace, can handle high winds better than
    one large dish?

  • ljk December 7, 2007, 10:20


    Aliens Apart

    By Seth Shostak

    Senior Astronomer, SETI

    posted: 06 December 2007

    06:35 am ET

    For years scientists have wrestled with a puzzling fact:
    The universe appears to be remarkably suited for life. Its
    physical properties are finely tuned to permit our existence.
    Stars, planets and the kind of sticky chemistry that produces
    fish, ferns and folks wouldn’t be possible if some of the
    cosmic constants were only slightly different.

    Well, there’s another property of the universe that’s equally
    noteworthy: It’s set up in a way that keeps everyone isolated.

    We learned this relatively recently. The big discovery took
    place in 1838, when Friedrich Bessel beat out his telescope-
    wielding buddies to first measure the distance to a star other
    than the sun. 61 Cygni, a binary star in our own back yard,
    turned out to be about 11 light-years away. For those who,
    like Billy Joel, are fond of models, think of it this way: If you
    shrank the sun to a ping-pong ball and set it down in New
    York’s Central Park, 61 Cygni would be a slightly smaller
    ball near Denver.

    The distances between adjacent stars are measured in tens
    of trillions of miles. The distances between adjacent civilizations,
    even assuming that there are lots of them out there, are
    measured in thousands of trillions of miles – hundreds of
    light-years, to use a more tractable unit. Note that this
    number doesn’t change much no matter how many planets
    you believe are studded with sentients – the separation
    distance is pretty much the same whether you think there
    are ten thousand galactic societies or a million.

    Interstellar distances are big. Had the physics of the
    universe been different – if the gravitational constant were
    smaller – maybe suns would have been sprinkled far closer
    together, and a trip to your starry neighbors would have
    been no more than a boring rocket ride, kind of like cruising
    to Sydney. As it is, no matter what your level of technology,
    traveling between the stars is a tough assignment. To hop
    from one to the next at the speed of our snazziest chemical
    rockets takes close to 100,000 years. For any aliens who
    have managed to amass the enormous energy reserves
    and ponderous radiation shielding required for relativistic
    spaceflight, the travel time is still measured in years (if not
    for them, then for those they’ve left behind).

    This has some obvious consequences (which, remarkably,
    have escaped the attention of most Hollywood writers.) To
    begin with, forget about galactic “empires” or more politically-
    correct “federations.” Two thousand years ago, the Romans
    clubbed together an empire that stretched from Spain to Iraq,
    with a radius of about 1,200 miles. They could do this thanks
    to organization and civil engineering. All those roads (not to
    mention the Mediterranean) allowed them to move troops
    around at a few miles an hour.

    Even the most distant Roman realms could be reached in
    months or less, or about one percent the lifetime of your
    average legionnaire. It makes sense to undertake campaigns
    designed to hold together an extensive social fabric when
    doing so requires only a percent or so of a lifetime.

    In the 19th century, steamships and railroads increased
    the troop travel speeds by a factor of ten, which extended
    the radius of control by a similar amount. The British could
    rule an empire that was world-wide.

    But here’s the kicker: Even if we could move people around
    at nearly the speed of light, this “one percent rule” would still
    limit our ability to effectively intervene – our radius of control –
    to distances of less than a light-year, considerably short of the
    span to even the nearest star other than Sol. Consequently,
    the Galactic Federation is a fiction (as if you didn’t know).
    Despite being warned that Cardassian look-alikes were
    wreaking havoc and destruction in the galaxy’s Perseus Arm,
    you couldn’t react quickly enough to affect the outcome. And
    your conscripts would be worm feed long before they arrived
    on the front lines anyway.

    In other words, aliens won’t be getting in one another’s face.

    There’s a similar argument to be made for communication.
    We seldom initiate information interchange that takes longer
    than months (an overseas letter, for instance). More generally,
    we seldom begin any well-defined project that lasts more
    than two or three generations. The builders of medieval
    cathedrals were willing to spend that kind of time to complete
    their gothic edifices, and those who bury time capsules are
    occasionally willing to let a hundred years pass before the
    canisters are dug up. But what about a project that takes
    several centuries, and possibly millennia? Who’s willing to
    do that? Only Stewart Brand’s “Long Now Foundation” seems
    to have the guts for this type of enterprise, proposing to build
    a clock that will keep time for ten thousand years.

    Clearly, these simple observations must have implications for
    SETI which, as we noted, involves transmissions that will be
    underway for hundreds to thousands of years. In particular,
    if there are signals being bandied about the galaxy for
    purposes of getting in touch, either (1) the aliens are
    individually much longer-lived than we are, which – if
    you’re a fan of circuit-board sentience – implies that they’re
    probably not biological. Or (2) we’re missing some important
    physics permitting faster-than-light communication, and
    extraterrestrial signaling efforts don’t include burping
    light and radio waves into space.

    Many readers will, in a display of endearing perversity,
    choose (2). Maybe they’re right, but that flies in the face of
    what we know. And what we know argues something worth
    bantering about at your next cocktail party – namely,
    that the time scales for travel and communication are
    too long for easy interaction with beings whose lifetimes
    are, like us, only a century or less. So while the cosmos
    could easily be rife with intelligent life – the architecture
    of the universe, and not some Starfleet Prime Directive, has
    ensured precious little interference of one culture with another.

  • bob krekorian December 7, 2007, 18:07

    ljk asks why these people chose Hat Creek as the site for a SETI radio telescope. Arrogance, incompetence and the need to associate themselves with the University of California are some of the reasons. Please note that Frank Drake never proposed the small dish concept as the way to build a SETI radio telescope. Here are some items regarding Hat Creek that may be of interest to reader.

    According to Leo Blitz, the [UC,Berkeley] Radio Astronomy’s Lab’s director, “this is probably the best spot in the country to put the array.” Referring to the Allen Telescope Array at Hat Creek,CA. The Astronomy Magazine, Sept,2004, Listening for a whisper by Seth Shostak.

    “You may not be able to get a cell-phone signal, find a radio station or easily persuade your rabbit ears to tune in a televised baseball game, but the radio quiet above Hat Creek makes the wilds of eastern Shasta County a prime zone for exploring the frontiers of science”. The Redding Record Searchlight, April 4,2004, Hat Creek silence is scientific gold for astronomers by Bruce Ross.

    “It’s quiet here — radio quiet which is just what we need,” says Professor Jack Welch about Hat Creek. The San Francisco Chronicle, Feb 14,2002, article by David Perlman.

    These comments do not coincide with reality. There are people living near the Hat Creek Observatory, there is a large RV campground 1/2 mile away, the distance to the main highway 89 is one mile and there is snow at the 41 degree geographical latitude.

    See http://astocker.com/pg/04/06hatcreek/

    cell-phone bands second harmonic
    808 – 821MHz 1616 – 1642MHz
    851 – 866 1702 – 1732
    869 – 894 1738 – 1788
    928 – 929 1856 – 1858
    931 – 932 1862 – 1864
    932 – 935 1864 – 1870
    941 – 944 1882 – 1888
    944 – 960 1888 – 1920

    Operational fixed radio transmissions at Burney,CA which is 10 miles from Hat Creek.

    1805MHz 5974.85MHz 6595MHz 6735MHz
    2112 6034.15 6615 6755
    2192.8 6063.8 6645 6765
    2199.82 6123.1 6715.625 6775
    5845 6152.75 6725 6795
    5945.2 6545 6730 6805

    Hat Creek is a poor site for a SETI radio telescope especially when one compares it to the Leigh Ranch. The Leigh Ranch is 880 acres of privately owned land situated in the Los Padres National Forest surrounded by mountains ranging from 2000 to 5000 feet in elevation. It is noteworthy that US National Forest land is a defacto radio quiet zone in that radio transmitters are prohibited except in a few designated areas. Here is what Professor Frank Drake said in a letter to the owner of the Leigh Ranch. “The Leigh Ranch is really a beautiful place. The topography at the Ranch and the absence of human activity, makes it an extremely good site for a radio telescope”.

    The people behind the Allen Telescope Array are the same ones who were the leaders of the NASA SETI project with its failure to develop functional and reliable targeted search signal processing equipment. The use of this equipment by the SETI Institute for the last 10 years raises some serious questions.

    See my letter to the US National Forest Service that was published as a letter to the editor in the March 5,2003 issue of the Burney,CA InterMountain News – Hat Creek Observatory. It is on the http://www.openseti.org website, SETI Institute’s Ethics and Integrity Questioned.
    Yahoo window [seti ethics] will also get it.

    Not long ago, SETI Institute board member Linda Bernardi called me and asked what I was trying to achieve? Here is my answer. We hope to see the day when there is a SETI group that makes scientific integrity and engineering excellence its foremost objectives in the quest to detect extraterrestrial life. SETI needs a Dr. Ellie Arroway.

  • ljk December 18, 2007, 15:21

    Realtime monitoring for the next generation of radiotelescopes

    Authors: David G. Barnes, Grenville Armitage

    (Submitted on 17 Dec 2007)

    Abstract: The forthcoming generation of radiotelescopes pose new and substantial challenges in terms of system monitoring. Information regarding environmental conditions, signal connectivity and level, processor utilisation, memory use, network traffic and even power consumption needs to be collected, displayed in realtime, and preserved in a permanent database.

    In this paper, we put forward the Ganglia monitoring system as a scalable, robust and efficient architecture that appears well-suited to the data collection aspect of radiotelescope monitoring, and we discuss approaches to the visual display of the streaming metric data produced by Ganglia.

    In particular, we present initial work in the use of 3-dimensional (3-d) multiplayer game technology for instantaneous status monitoring and enquiry, and we describe the extensions to this work required for radiotelescope monitoring.

    Comments: Submitted to Workshop on Applications of Radio Science (WARS 2008), accepted

    Subjects: Astrophysics (astro-ph)

    Cite as: arXiv:0712.2617v1 [astro-ph]

    Submission history

    From: David Barnes [view email]

    [v1] Mon, 17 Dec 2007 03:04:17 GMT (1330kb)


  • ljk February 1, 2008, 16:35

    Galactic Wi-fi?

    A search for narrow-band signals may be a very
    good SETI strategy.


  • Edg Duveyoung February 2, 2008, 9:11

    NASA to beam Beatles song to North Star

    I hope I’m not going against posting protocol to post this article in an old thread. The other SETI-METI threads are closed. The below article shows that somehow our brains never considered that corporate advertising will be supporting an almost perfectly meaningless METI project that seems to be merely a stunt to put NASA in the news and in a good light by riding the coattails of the Beatles. I’m, well, stunned. What next? We had a golf ball hit on the moon, why not a Chorus Line of astronauts high-stepping a nifty little number on the shuttle’s wing?


    WASHINGTON (AP) — The Beatles are about to become radio stars in a whole new way.

    NASA on Monday will broadcast the Beatles’ song “Across the Universe” across the galaxy to Polaris, the North Star.

    This first-ever beaming of a radio song by the space agency directly into deep space is nostalgia-driven. It celebrates the 40th anniversary of the song, the 45th anniversary of NASA’s Deep Space Network, which communicates with its distant probes, and the 50th anniversary of NASA.

    “Send my love to the aliens,” Paul McCartney told NASA through a Beatles historian. “All the best, Paul.”

    The song, written by McCartney and John Lennon, may have a ticket to ride and will be flying at the speed of light. But it will take 431 years along a long and winding road to reach its final destination. That’s because Polaris is 2.5 quadrillion miles away.

    NASA loaded an MP3 of the song, just under four minutes in its original version, and will transmit it digitally at 7 p.m. EST Monday from its giant antenna in Madrid, Spain. But if you wanted to hear it on Polaris, you would need an antenna and a receiver to convert it back to music, the same way people receive satellite television.

    The idea came from Martin Lewis, a Los Angeles-based Beatles historian, who then got permission from McCartney, Yoko Ono and the two companies that own the rights to Beatles’ music. One of those companies, Apple, was happy to approve the idea because is “always looking for new markets,” Lewis said.

    Perhaps coincidentally, the song’s launching comes a day before the release of the DVD of the Julie Taymor movie named after the Beatles hit.

  • James M. Essig February 2, 2008, 17:57

    Hi Edg Duveyoung;

    I hope I am not going against the protocol by making this statement either. However, I hope any ETI who intercept this song will like it . I hope that it will be top on their charts for a while. I think the song as beautiful. Even as a conservative minded Catholic midddle aged man, I still listen to and greatly enjoy the classic Rock of the 70s and 80s as well as much of the 60s music. I think this is one of the best songs that came from that era.


    Your Friend Jim

  • ljk May 7, 2008, 15:37

    SETI scientists get a new tool in search for extraterrestrial life


    By Julie Sevrens Lyons

    Mercury News

    Article Launched: 05/07/2008 01:39:11 AM PDT

    HAT CREEK VALLEY – In a meadow of one of Northern California’s pristine national forests, 2,000-pound radio telescopes are popping up like mushrooms.

    Made of aluminum and resembling something out of the movie “Contact,” they point to the heavens and wait in silent attention. Scientists hope they will one day detect radio waves sent from a faraway planet.

    Thousands of years after mankind first asked one of the most pressing philosophical questions – are we alone in the universe? – Silicon Valley scientists are poised to bring us closer to an understanding.

    The hunt for little green men has moved from Hollywood back lots to the Bay Area’s back yard.

    “In many cultures throughout history, we’ve always wondered: Is there anybody else? Are we the only ones who can look up at the universe and wonder? I live in the first generation of humans that can try to answer this,” said Jill Tarter, director of the Center for SETI Research at the SETI Institute in Mountain View.

    Full article here:


  • ljk June 3, 2008, 11:52

    An article on ATA from the Los Angeles Times:

    An array at Hat Creek near Mt. Shasta points an ear to the
    cosmos. If E.T. tries to phone on any of 10 billion channels,
    Earth will be ready to listen.

    By John Johnson Jr., Los Angeles Times Staff Writer

    June 1, 2008

    HAT CREEK, CALIF. — In this remote volcanic valley near Mt. Shasta, 42 telescope dishes have sprouted amid the soaring ponderosa pines, listening for a voice from space.

    Every few seconds the 20-foot-wide dishes, scattered over dozens of acres, pirouette in perfect synchronicity, like dancers practicing their pas de deux before opening night.

    Rick Forster, a slight, 59-year-old astronomer with the long beard of a man who has spent years in the solitude of the forest, said that after fine-tuning the dishes over the next few weeks to function as a single, giant ear, the real show will begin: listening for E.T.

    The Hat Creek Radio Observatory will be the biggest radio telescope in the world specifically designed to search for extraterrestrial intelligence when the full 350-dish array is completed in the next few years.

    “It’s nuts to think we’re alone,” said Forster. He works with the SETI Institute and UC Berkeley, which are jointly installing the array.

    “It’s just a matter of looking in the right direction, at the right time, at the right frequency, with the right algorithm,” he said.

    Full article here, plus some nice photographs with it:


  • ljk June 24, 2008, 10:20

    The father of radio astronomy

    June 12, 2008

    The late Grote Reber is recognised as both the father of radio astronomy and the first person to build a big dish telescope to explore the cosmos. The American moved from his home in the USA to Tasmania in the 1950s and assisted this country to establish a lead in the field.

    Now a museum has been opened by the University of Tasmania to commemorate his work and David Fisher takes us on a tour with astronomer Professor John Dickey

    Full transcript here:


  • ljk April 7, 2009, 13:06

    The Allen Telescope Array: The First Widefield, Panchromatic, Snapshot Radio Camera for Radio Astronomy and SETI

    Authors: Jack Welch, Don Backer, Leo Blitz, Douglas Bock, Geoffrey C. Bower, Calvin Cheng, Steve Croft, Matt Dexter, Greg Engargiola, Ed Fields, James Forster, Colby Gutierrez-Kraybill, Carl Heiles, Tamara Helfer, Susanne Jorgensen, Garrett Keating, John Lugten, Dave MacMahon, Oren Milgrome, Douglas Thornton, Lynn Urry, Joeri van Leeuwen, Dan Werthimer, Peter H. Williams, Melvin Wright Jill Tarter, Robert Ackermann, Shannon Atkinson, Peter Backus, William Barott, Tucker Bradford, Michael Davis, Dave DeBoer, John Dreher, Gerry Harp, Jane Jordan, Tom Kilsdonk, Tom Pierson, Karen Randall, John Ross, Seth Shostak Matt Fleming, Chris Cork, Artyom Vitouchkine Niklas Wadefalk, Sander Weinreb

    (Submitted on 6 Apr 2009)

    Abstract: The first 42 elements of the Allen Telescope Array (ATA-42) are beginning to deliver data at the Hat Creek Radio Observatory in Northern California. Scientists and engineers are actively exploiting all of the flexibility designed into this innovative instrument for simultaneously conducting surveys of the astrophysical sky and conducting searches for distant technological civilizations.

    This paper summarizes the design elements of the ATA, the cost savings made possible by the use of COTS components, and the cost/performance trades that eventually enabled this first snapshot radio camera. The fundamental scientific program of this new telescope is varied and exciting; some of the first astronomical results will be discussed.

    Comments: Special Issue of Proceedings of the IEEE: “Advances in Radio Telescopes”, Baars,J. Thompson,R., D’Addario, L., eds, 2009, in press

    Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)

    Cite as: arXiv:0904.0762v1 [astro-ph.IM]

    Submission history

    From: Geoffrey C. Bower [view email]

    [v1] Mon, 6 Apr 2009 18:43:22 GMT (1153kb)


  • Colby Gutierrez-Kraybill June 23, 2009, 23:24

    Hello, I have been a staff member of the Radio Astronomy Laboratory at UC Berkeley since 2001 and have made minor contributions to the design and building of the ATA at HCRO (I am honored to have my name amongst the authors of the IEEE paper you posted about on April 7th, 2009).

    With due respect to Mr. Krekorian, I would like to address some of the issues he raised in his comment, made 1.5 years ago:

    1) High winds in Hat Creek Valley
    Yes, there was a large (85ft) telescope that was destroyed by high winds in in the 1990’s. That dish was first installed in 1962 and was operating for those 30 years and recorded the data that lead to the first discovery of interstellar masers as well as interstellar molecules like water and ammonia.

    Winds in the valley are not consistently high and are seasonal. High winds are a simple fact of almost every observatory I’ve visited as they tend to be perched on high plains or mountain tops. In the last year, there have been a handful instances of having to stop operations due to winds that exceeded 40mph.

    2) Human activity nearby
    In fact, highway 89 is 3 miles away from the main gate of the observatory and there are no camp grounds closer than 2mi. I currently live on the HCRO site, and our nearest neighbors are 1.5mi away on Bidwell Rd. (3 houses total) and the next after that are 2mi away (another 5 houses total). Hat Creek itself is a community of about 200 people total with perhaps 100 houses spread along a ~3mi section of Highway 89. See my final point about how interferometers work in terms of why this is not a big issue.

    3) Snow in Hat Creek
    So what? The operating range for the ATA is 0.5GHz – 10.5GHz and snow only affects our viewing at the higher frequencies (over 5GHz). Even then, the pattern of snowfall for the area is to have at most 6inches stay on the ground for a few weeks at ~2-3 periods during winter and any that accumulates on dishes can be melted off with a solid winter afternoon’s sunshine.

    Even given the deleterious effects of snow, it doesn’t destroy our ability to observe, it makes data taking at the high frequencies inadvisable, all the lower frequencies are still available.

    4) Radio frequencies used in Burney
    So what? Burney is ~17miles away (direct) and is behind a few hills/mountains that rise 1000ft above the valley floor.

    The sad fact is that most of our interference is from the sky itself, in the form of communications/timing/etc satellites such as Iridium, XM/Sirius radio, GPS and so on. However, those are all very narrowband transmissions, and if you add up the bands that Mr. Krekorian put into his comment, it adds up to less than 5% of the available bands to the ATA frontends (~10GHz).

    5) Leigh Ranch
    HCRO has been in operation since the late 1950’s and and is half on USFS land with the other half being leased from a private land owner. The observatory is surrounded by USFS lands on 3 sides (North, South, West), embedded within the Lassen National Forest. The east side is private farm land that extends for 1mi to the Hat Creek Rim, and to the east of that are hundreds of square of miles of BLM lands. To the west, is the 1000 Lakes Wilderness. The south, more Lassen National Forest and to the north, more Lassen National Forest that eventually meets Shasta National Forest. The observatory itself is surrounded by lava fields, making it essentially impossible to develop and also creating a secluded environment that is not prone to massive forest fires (though, there have been fires that approached the site in the 1990s).

    Geographically, the Hat Creek Valley is in a bowl shaped depression, with scarps and peaks that vary from 1000ft-4000ft above the valley floor.

    6) SETI detectors
    The SETI detection system that the SETI Institute has installed at HCRO was built a full decade before it was brought to HCRO in 2005 and was used in long term operations at Aricebo. It has been functioning quite well at HCRO, and is being used to help design and build the next generation detection systems.

    My own point:

    1) Interferometry and radio frequency interference
    For an interferometer or a phased array (a collection of sensors with their outputs combined to measure interference patterns or with signal delays for focusing on a small patch of a field of view) light that is not coming directly from the field of view is generally *not* in phase with the signal you are examining.

    This means that much (but not all) weak interfering signals that show up in the side lobes of antennas does not make observations irrecoverable. They can interfere, but, the interference is inherently muted or simply does not show up in our backend imaging/signal processing systems. Infact, right now we have bigger problems with interference by the sun itself during the day at many frequencies.

    By using “small” dishes with an interferometer, we gain massive field of view (4 square degrees on the sky at ~1.4GHz) and great resolution (once we have 1km baselines and 350 dishes).

    2) Linda Bernardi’s call
    I think Mr. Krekorian should take Linda Bernardi’s call to heart and examine his own motives for what appears to be semi—to outright—mis-informed attacks on our work on the ATA and on the SETI Inst itself.

    The simple truth is that the ATA has benefited greatly by the partnership between UC Berkeley and the SETI Institute and is strongly considered in the wider astronomy community to be a testbed for ideas that will be used in the SKA. For a relatively small price tag (~$75mil total for 350 antennas+backend systems), the ATA is on its way to being one of the best radio instruments in its class on the entire planet and will be useful instrument for many decades.

  • Bob Krekorian July 28, 2009, 13:37

    Bob Krekorian – Former NASA SETI Signal Detection Analyst

    Referring to the Allen Telescope Array: Listening for ETI article and comments made by ljk and Colby Gutierrez-Kraybill. See the Centauri Dreams website.

    The big question is how much sensitivity is lost with the Allen Telescope Array (ATA) compared to a single aperture antenna with the same collecting area? I say about 50%. A computer model could answer this question, but it does not exist. Here are factors that would bring down the sensitivity for SETI research.

    1) The SETI Efficiency of Array Radio Telescopes – memo By Frank Drake, Aug 2000. The SETI Efficiency is always less than a single filled aperture with the same collecting area. The maximum SETI efficiency for realistic arrays is 0.91.

    2) Antenna efficiency. This is a measure of the smoothness of the antenna reflecting surface. Radio telescopes today would be between 0.7 to 0.8. The ATA would be between 0.5 to 0.65.

    3) System temperature is inversely proportional to antenna collecting area. Doubling system temperature is equivalent to halfing the collecting area. Radio telescopes like Arecibo and Green Bank have a system temperature like 20 to 25 degrees K since the feed system is cryogenically cooled with liquid nitrogen. This is not practicable with 350 individual dishes and one would expect the system temperature of the ATA to be at least double that of Arecibo or Green Bank.

    4) The ATA is supposed to observe multiple stars (points on the sky)
    simultaneously, but parabolic antennas can maximize sensitivity at only one point on the sky at any given time. The antenna pattern is a first order Bessel function and the sensitivity drops off shapely as you go off the main lobe axis. At 3GHz and 0.5 degrees off the main lobe axis, the sensitivity drops to 0.5. At 10GHz and 0.13 degrees off the main lobe axis, it drops off to 0.13.

    5) Log periodic designs are a well established wide-band antenna technology, but one in which the phase center travels along the structure as the frequency varies. When a log periodic antenna is used as a feed for a reflector structure like the ATA, the phase center location can not be maintained at the reflector focus over the frequency range and defocusing results. IEEE Transactions on Antennas and Propagation, Vol.AP-33 No.7, July 1985.

    6) A variety of errors, both random and spatially correlated, are introduced across an array by imperfect components and signal distribution networks, and reduce the precision of array excitation. The Phase Array Antenna Handbook, chapter 7, Robert J. Maillouy, 1994

    Frank Drake never advocated the ATA concept for a SETI radio telescope. Show me a paper, an article, a memo, anything where he did.

    In 2000 the ATA was estimated to cost 25 million dollars, now it is estimated to cost 75 million dollars. Ouch.

    Hat Creek is a poor site for a SETI radio telescope. I spent three years looking for a California site for a SETI radio telescope and found the beautiful Leigh Ranch. Send your address to me at bkrekorian@yahoo.com and I will send you a picture of the site. Frank Drake also thought the Leigh Ranch was the right place to build it and I have many pictures of him there.

    Why was the UC 85 foot radio telescope at Hat Creek destroyed by high winds 1n 1993? The answer lies in understanding the physics of Katabatic winds. Katabatic winds are defined as winds that flow from high elevations like mountains or hills down their slopes to the valleys below. A downsloping wind can develop in the early morning when a pool of cool high elevation air begins to descend from the highlands due to the high density of the cold air. Snow at the high elevations contributes to the cooling of the air. Wind is driven down the slope by gravity and can be strengthened by the landscape that can channel and force the airflow to converge. A high pressure system over the upper elevations usually triggers the mechanism. The most powerful and important katabatic winds are in Antarctica that can reach velocities of 200mph and influence the Earth’s weather system. This is what happened at Hat Creek and why it’s such a great place for hang gliding.
    See Yahoo [hang gliding hat creek] and the YouTube video.

    I believe I can make a major contribution to SETI. See my guest editorial on the SETI League website. Yahoo[krekorian beacons].

    Six years have passed and I am still waiting for SETI Institue board member Linda Bernardi to get back to me as she said she would to have a meeting.

  • ljk August 19, 2009, 2:03

    Quest to find life beyond Earth gets technological boosts

    The SETI Institute’s Allen Telescope Array is a collection of 42 antennas in Northern California that seeks out deep-space radio messages that could be broadcast by an advanced civilization.

    By Andrea Pitzer, Special for USA TODAY

    The search for intelligent life in the universe is still on.

    Despite the absence of interstellar tourists to date, astronomers at the SETI Institute (Search for Extraterrestrial Intelligence) are hoping that we are not alone.

    And with new spacecraft to locate planets circling nearby stars, as well as more effective listening devices here at home, scientists have more tools at their disposal to find Earth-like planets or signs of other life forms.

    But the possibility of intelligent life is what interests scientists at SETI. Using SETI’s 42-antenna Allen Telescope Array in Northern California, they can listen in many directions for unusual radio signals coming from space.

    According to institute astronomer Seth Shostak, Carl Sagan posited that more than a million civilizations might be capable of broadcasting signals. Scientist and author Isaac Asimov hypothesized that the number might be half that. SETI astronomer Frank Drake has estimated the number might be closer to 10,000.

    Full article here:


  • ljk April 26, 2011, 14:04

    Paul, this news needs to be spolighted ASAP, thank you. There are three news items linked here.

    We’re sorry, but SETI can’t take your call right now

    By John Timmer | Last updated April 26, 2011 11:12 AM


    To quote:

    Unfortunately, California is suffering a severe and protracted budget crisis, while the National Science Foundation has cut back on its share of the operating costs. As a result, there is no money to pay for the personnel and power involved with a standard observational schedule. The SETI institute had been focusing on fundraising to build more dishes to expand the array, and hasn’t focused on covering operational costs with its fundraising.

    According to Scientific American, SETI had hoped to use the facility to start scanning the planet candidates identified by NASA’s Kepler Observatory. That plan is now on indefinite hold. Now, its best option appears to be to convince the Air Force to use the facility for tracking purposes, while SETI squeezes in observations in the dishes’ spare time. In the meantime, the search for ET will have to be done as observatory time becomes available.

    Budget crunch mothballs telescopes built to search for alien signals

    By John Matson | Apr 24, 2011 06:00 AM |


    SETI Institute to shut down alien-seeking radio dishes

    By Lisa M. Krieger


    Posted: 04/25/2011 07:20:22 PM PDT

    Updated: 04/26/2011 09:23:23 AM PDT

    If E.T. phones Earth, he’ll get a “disconnect” signal.

    Lacking the money to pay its operating expenses, Mountain View’s SETI Institute has pulled the plug on the renowned Allen Telescope Array, a field of radio dishes that scan the skies for signals from extraterrestrial civilizations.

    In an April 22 letter to donors, SETI Institute CEO Tom Pierson said that last week the array was put into “hibernation,” safe but nonfunctioning, because of inadequate government support.

    Full article here:


    To quote:

    SETI senior astronomer Seth Shostak compared the project’s suspension to “the Niña, Pinta, and Santa Maria being put into dry dock. “… This is about exploration, and we want to keep the thing operational. It’s no good to have it sit idle.

    “We have the radio antennae up, but we can’t run them without operating funds,” he added. “Honestly, if everybody contributed just 3 extra cents on their 1040 tax forms, we could find out if we have cosmic company.”


    About $5 million is needed over the next two years, according to Tarter. She hopes the U.S. Air Force will help, because the array can be used to track satellite-threatening debris in space. But budgets are tight there as well.