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Space Science

Listening to Leonids 136

Posted by michael from the ground-control-to-major-tom dept.
Bill Kendrick writes: "An interesting article was posted by NASA about reports of people hearing Leonids as they burnt up in the atmosphere. And not 5 minutes later, like you'd expect, but instantly. Apparently this is thanks to very low frequency radio signals given off by the meteors as they burn."
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Listening to Leonids More

Listening to Leonids

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  • Sounds like ELF (Score:4, Informative)

    by Arethan ( 223197 ) on Tuesday November 27, 2001 @09:39PM (#2622854) Journal
    ...or Extremely Low Frequency for those that have never heard the term before.

    The nava used this to communicate with submarines on the other side of the earth by directing ELF signals directly through the earth's core. Saw it on Discovery once. :) I'm not sure if it's still in use today. Usually the government only shows you out-of-service tech on cable networks.
    • the article said VLF, not ELF. but, hey, what's a coupla Carma between people who don't follow links anyways? ;)

    • i knew it had something to do with elves.

      and people said i was loony...

    • It, or something like it is. Go up to Annapolis, Maryland, and you can see this HUGE cluster of radio antennas used to send signals to subs anywhere in the world. (Or so I've been told, and I can guuarantee they're not radio towers so...)

    • Re:Sounds like ELF (Score:4, Informative)

      by kikta ( 200092 ) on Tuesday November 27, 2001 @10:36PM (#2623053)
      Yes, they are still in use. The primary is somewhere in the upper peninsula of Michigan. It can be received darn near anywhere. However, it transmits VERRRRY SLOOOOWLY. How slowly? I don't know the exact data rate, but to give you an idea, the Navy sends a three-letter code group that directs the sub to do whatever. Oftentimes it is to come to periscope depth, float the antenna, and copy the full message traffic from satelites. Nothing classified here, been public knowledge for years. The reason it's not a big secret is that any non-authorized ELF messages would be pretty easy to detect, and the Navy is surely changing around the groups and their lengths all the time. Watch The Hunt for the Red October and you'll hear them talking about it before they go to periscope depth to get the full message. None of the code groups can do anything wacky, like tell an SSBN (ballistic-missle sub) to nuke China, so the room for someone injecting sinister messages and the damage they could do is very minimal.

      • Sorry meant to list the frequency differences. ELF, or Extremely Low Frequency signals are between 30-3000 Hz. VLF, or Very Low Frequency signals are between 3-30 kHz. Imagine the world's biggest subwoofers. Wonder if the Navy even gets tempted to broadcast one of those Dr. Crankenstein Bass CD's on it. ;-)

    • Drove past the US Navy's Loran setup in southern Cal. last week. I remember when there was a major effort to build something along the 180KHz range in Michigan's upper penninsula for the same purpose, scrapped due to some opposition. I have heard of radio broadcast all the way down to 30-40KHz, at some time.

  • frizzy hair? (Score:5, Funny)

    by Nate Fox ( 1271 ) on Tuesday November 27, 2001 @09:42PM (#2622860)
    Simple materials like aluminum foil, thin wires, pine needles -- even dry or frizzy hair -- can intercept and respond to a VLF field.

    I bet Weird Al was having the multimedia show of a lifetime!

    • Re:frizzy hair? (Score:4, Funny)

      by Raven42rac ( 448205 ) on Tuesday November 27, 2001 @09:48PM (#2622890)
      Well if were talking about Weird Al, then the abbreviation would have to be changed to UHF, hahahaha, I kill me.

      • YES! (Score:2, Funny)

        by Anonymous Coward
        hahahaha, I kill me.
        Let's all have a turn.
    • Little known fact: Not only was Albert Einstein the most outstanding scientist of the 20th century, he was also the world champion comet listener.... No wonder he could unlock the secrets of the universe! Man, I wish I had his hair!

  • Oh.... (Score:3, Interesting)

    by NetJunkie ( 56134 ) <`jason.nash' `at' `gmail.com'> on Tuesday November 27, 2001 @09:42PM (#2622862)
    Years ago when I was a kid I remember watching the Leonids. While watching them I distinctly remember hearing some of the larger ones doing this exact buzzing. I always figured it was just a bad memory or something. Nice to know I'm not crazy. :)

    It did sound like a fizzing sound... Not very loud, but you would definately hear it.
    • I AM SO GLAD I'M NOT CRAZY

      I could have sworn I heard one of the leonids burn up, in the same fashion described here. I confusingly turned to my friend, not believing what I thought I just heard (as has been pointed out, shouldn't make a sound at all and if it does, it would be several minutes later) and asked him if he heard it. Of course, he didn't and said I was crazy. It was strange because it was perfectly clear to me, all though kind of quiet.

      Now this article comes out. You people can not imagine my elation. I HAVE BEEN VINDICATED!!!!

      *dances*
      • When I was about 12 or so, I was watchign the perseids, and saw the biggest darn meteor I've ever seen; it streaked brightly across a long stretch of the sky, and I SWEAR it WHISTLED. I had long thought that I must have been imagining that whistle, but now maybe not...
  • I was playing the stereo so could not hear anything, sigh! On the other hand I saw 10 doubles, one exploder, a number of green and red ones. Not to mention a few mini bursts 3-5 in a couple of seconds. All in all rather nice shower! Although I'm still sleep deprived because of it.

    I saw one shoot like an arrow from orions bow :)

    • this was definitely the best shower i've ever seen...i've been catching at least the perseids every year for the last couple decades, and i've never seen anything like this. even though i was watching from a farmer's field fairly close to a large city (Edmonton, AB - and, yeah, it's not that big, but it's too damned bright), at the peak you could see really bright ones every couple seconds. brilliant colours, sudden bursts of five or six. hands down the coolest was the one that blew up. never seen anything like it.

      really cool was getting to share it with my best friend's kid, though. i was about her age when i got hooked. it's good to be able to pass the torch.

      rambling on...i've also never seen so many people out watching before. it gave me a warm fuzzy feeling, seeing so many people actually interested in what was going on up there.

  • More likely ... (Score:4, Funny)

    by Rosco P. Coltrane ( 209368 ) on Tuesday November 27, 2001 @09:45PM (#2622881)
    One /. reader at Nasa close with his computer close to the antennas saw this earlier post [slashdot.org] and tried out the program.
  • Sydney 2001: clouds clouds clouds. I'll check again in 2034!
    • Any particular reason you can't watch them next year?, I haven't read any of the articles before the shower but I know for a fact that every year there is a Leonoid meteor shower, that this year might have been more intense than other years, but there should be one next year anyway.

  • northern (and southern) lights do this too... (Score:3, Flamebait)

    by killthiskid ( 197397 ) on Tuesday November 27, 2001 @09:50PM (#2622901) Homepage Journal
    I remember reading about the same type of thing occuring during very intense northern lights. Same sort of thing, where the event and sound occured at the same time, and there couldn't possibly be time for the sound to travel the distance.

    IRC, it was the same sort of thing, an ELF interaction directly in the brain.

    So my thought is, could we use this for actual communication? Cause voices in someones head?
    • an ELF interaction directly in the brain.

      Only if you have a head full of pine needles. And it's not the sound that travels to the ground, it's radio waves at light speed which stimulate aforementioned pine needles to make sounds you can hear, presuming, of course, there is sufficient sap running from your ears to the pine needles to make the connection.
    • You know I have always had memories of having heard the northern lights. I grew up hugging the arctic circle so they were common enough to be indistinct memories. I tried to hear them whenever I was far from the city and failed (Where I thought it would be easier, but it may in fact have been impossible there). Now I feel a little less silly.

      The northern lights seem much calmer. But the fact that you can see them move, and they are far away and huge means there could be a lot of crackling going on up there.

      BTW The I'm pretty sure the voices in MY head aren't explained by this. THEY know me too well. ;)
  • This strikes me as a very neet discovery. Technoligy modeled after nature could, in time, provide us with some nice toys because of this. 100% wireless, unpowered speakers is one thought that comes to mind, I'm sure there are many more uses. Of course, there would be some major problems involved in using this in everyday life, but history shows that nothing can stand in the way of progress.
    • Little known fact unless your into Amatuer Radio is that during Meteor showers the range of certain radio frequencies is dramatically extended. These Frequencies are mainly the 2m band (~144MHz correct me if I'm wrong) and are extended from just over line of site to over 1500Km. It's been a long time since I've done any of this stuff so please forgive any inaccuracies.
  • on rocketships, or watching meteors just got really expensive.
  • I didn't get a chance to hear OR see the meteors because all of southest Michigan was covered by fog. Too bad it was a once in a lifetime thing.

    • Re:Oh well... (Score:2, Informative)

      by NecroPuppy ( 222648 )
      How is it once in a lifetime?

      The Leonid meteor occurs every 33 years, and take place over several years.

      Europe, for instance, is supposed to have the best view next year.

  • gaming? (Score:3, Interesting)

    by circletimessquare ( 444983 ) <circletimessquar ... il.com minus cat> on Tuesday November 27, 2001 @10:12PM (#2622975) Homepage Journal
    they talk about things like auroras, meteors, and nuclear blasts setting off these vlf radio signals... so maybe someone out there with more knowledge of the science of the energy levels required to set off these vlf radio frequencies will smack me down on this... but how friggin' cool would this be for gaming?

    can you imagine playing a fps and getting hit by something that sets off objects in your room crackling and vibrating? maybe a tie-in is possible with this article [slashdot.org] ;-P
    • can you imagine playing a fps and getting hit by something that sets off objects in your room crackling and vibrating?

      What, like your fillings? I'll pass , thanks.

      You'd better make sure you've got a faraday shield around your room, or you'll piss off the neighbours real quick.
      But wait! having a faraday shield around your room will likely attract the attention of the spooks as well! Might as well just have a big-ass Tesla Coil [tcbouk.org.uk] in there for the swat team to find when they kick in the door. I'd pay good money to see that :-)

  • Angry Humpbacks (Score:4, Funny)

    by hubbabubba ( 309496 ) on Tuesday November 27, 2001 @10:21PM (#2623001)
    I hear this sort of thing really pisses off whales.

  • ELF/VLF listening (Score:5, Interesting)

    by yack0 ( 2832 ) <keimel@nOspAM.gmail.com> on Tuesday November 27, 2001 @10:34PM (#2623046) Homepage
    This is reminscent of some stuff I initially heard about on an NPR episode of 'Lost and Found Sound' which was a feature they were running in the last year or so.

    Stephen McGreevy, a professor at some college, IIRC, in California has been listening to Aurora Borealis' for years and has actually made recordings of some of the things he's heard and made CD's for retail sale. He also sells receivers to people so they can listen to the earth as well.

    Related links:
    His home page for VLF radio [triax.com]
    The page he wants people to bookmark [auroralchorus.com], cause his current provider bites.
    His second CD [triax.com]
    The VLF receiver page [qnet.com]

  • Amazing that they posted it (Score:5, Informative)

    by Chairboy ( 88841 ) on Tuesday November 27, 2001 @10:36PM (#2623050) Homepage
    I'm amazed that they posted it. It seems as if most government agencies (NASA included) are using the 9/11 attacks as an excuse to pull information offline.

    Please note that NASA has become increasingly unwilling to divulge information about what happens on the space station. Routine information such as the 'ships log' and audio feeds are no longer shared or available.

    I apologize for this off-topic message, but more people should understand that this article, while fascinating, is nothing compared to the reams of important data that is being maliciously sequestered by an organization paid for with tax dollars. For every piece on meteor sounds, there are 10 pages of technical data on spaceflight, human research, and more that is being systematically hidden.

    I predict that the information will become available through some type of Lexis-Nexus style pay system in the future so that you can have the privilege of paying for the data twice.

    Bread and circuses, my friend. Look at the rest of the story, and make NASA give us what we own.
    • My guess is that NASA is under pressure not to release information on routine space life because China is now pursuing their space program.

      I think the government attitude is to make China do all their own dang research. The longer the Chinese take to be able to send men into space, the better. That means more time for our big SDI plan, right?

      Not that I agree with any of this, I'm just speculating.
  • suitable transducers are surprisingly common. Simple materials like aluminum foil, thin wires, pine needles -- even dry or frizzy hair -- can intercept and respond to a VLF field

    So, all I need is a monitor [slashdot.org] and some pine needles and I have my own portable radio system! Woohoo! Think of all the applications!

    Uhh.. wait a minute...

  • Take a look at the Long Wave Club of America [lwca.org], they listen to low RF frequency sounds generated by things like lightning.
  • so...since the Vogons can now have their freaky communications device, and we *already* have babelfish what are we waiting for next?

    I guess I'll hold out for the frictionless car.
  • This was described in a New Scientist [newscientist.com] feature, first issue this year, and the same explanation was given.

    To see the article, you'll need to get a trailist account with their archive [newscientist.com]. Once you have it, go here [newscientist.com], or search for "Sizzling Skies" in the 06 Jan 01 issue.

  • Of course, human ears can't directly sense radio signals. If Keay is right, something on the ground a "transducer" must be converting radiowaves into sound waves. In laboratory tests, Keay finds that suitable transducers are surprisingly common. Simple materials like aluminum foil, thin wires, pine needles -- even dry or frizzy hair -- can intercept and respond to a VLF field.
    Does this mean that you could transmit audio to someone wearing braces? I shudder at the possibilities. Now excuse me while I put my tinfoil hat back on... :)

    [and we laughed at those people all this time!!!]

    • Does this mean that you could transmit audio to someone wearing braces?

      Argh don't say it, i'm sure some spammer will jump onto the idea to transmit ads directly into peoples heads if they have braces, fillings etc...
    • I'm not going to spend the time to look this up, but my memory is that there have been some real, documented cases of people picking up audible radio signals with the metal fillings in their teeth. I know that this story has urban legend status, but I thought it was based on some real cases, possibly using different alloys than what's used these days.

      Perhaps someone else can jump in and expand on this or correct me...

      • The signal strength has to be very high. I remember hearing stories about WGY AM in Schenectady, NY doing an experiment where they substantially increased their already high power levels at their transmitter. (They're one of the original stations, back then selling radio spectrum wasn't a big money business for the government so they issued licenses for much higher power levels. They'd never do that now since lower power means that same frequency can be sold again to another station in another are many more times.) Anyhow, on the even higher power, people were picking up the radio on fillings, braces, electric fences, and all kinds of other things... people who were happy this was just a temporary experiment.
  • Does anyone have information as to what exactly a Leonid is?
    Sorry for the ignorance...
  • I'm printing about 50 copies of this and passing it around at work tomorrow. You see folks, I and my wife heard several of these during the Leonid showers and became a laughingstock when we told the astro-geeks at work. The only meteors that make noise, they claimed, were ferrous stones that penetrated to the lower atmosphere. Since the Leonids contained no meteors of this type, they thought I was just being stupid or lying to impress people.

    Those of you who didn't hear this need to understand that it is a very quiet effect. I was watching the show up in the Sierra Nevada mountains south of a little town called Buck Meadows...about 20 minutes from Yosemite National Park. I was like 50 miles from the nearest city (with several mountains in between), 20 miles from the nearest highway, and MILES from ANYTHING louder than a squirrel. Heck, I could hear the hum of the high tension power lines over a mile and a half away and compared "fireball ratings" with a couple other skywatchers more than a thousand feet up the mountain...and didn't even have to raise my voice. It was that quuiieett, and we still barely heard this effect.
    • I heard one also. There were about four of us lying on a bank at my parents' cabin, up in the pine woods of N. Minnesota. It was bright as hell. I'll go to my grave swearing it illuminated the trees. We all just looked at each other. I don't think anyone even mentioned it; it seemed too nutty. It rustled like an instantaneous wind. And it sounded just the way the woods propagate any creak on a quite night. Turns out it was the woods. Cool.

      In all, a hell of a show and well worth turning out at 4am.
    • I personally didn't hear any Leonids this time, but I did hear a fair number of very bright meteors during a summer meteor storm we had some years back (maybe eight or ten years ago -- I don't think it was the Perseids).

      We were lying on our backs on the wet grass, and I would report that, yes, the sound was instantaneous with the passage overhead. At the time I interpreted this to mean that the meteors were passing quite close overhead, but on reflection this is implausible because the sound was instantaneous, so the meteors we heard would have had to have been passing well less than a mile overhead, and we heard maybe half a dozen. Unfortunately, we weren't keeping count.

      In some cases the sound was a quick and faint hiss, but in a couple of cases the sound was like slurping the last of a milkshake, heard through a long tube -- that is to say doppler shifted white noise. I would not describe the loudest ones I heard as very quiet; it was loud enough -- not to be startling, but to be comparable to a person next to you saying something at a low conversational level.

      I am quite aware that hearing meteors is a way to get branded as a kook, but when you have seen a number of meteors (including one or two impressive fireballs) with somebody and suddenly both of you turn to each other and say, "Did you hear that?", it's pretty convincing, at least to me. There are more things under heaven and earth than are dreamt of in our philosophy -- which is why we have to go out and experience them ourselves.

      The explanation in the article seems to be consistent with what I observed, particularly the fact the sound was instantaneous with the overhead meteor.

  • I Listened to the Leonids (Score:5, Informative)

    by Sigfried_Blip ( 526923 ) on Tuesday November 27, 2001 @11:38PM (#2623213) Homepage
    Now this isn't as cool as hearing meteors unaided with my ears. But while I was outside watching the Leonids here in Cupertino, I was also watching and listening to NASA's Meteor-radar [spaceweather.com] with a linux program called baudline [baudline.com]. There was a lot of activity that night, about a hit a second. Unfortunately I can't correlate the radar hits with the visuals since I live in California and the meteor radar is in other states (NM TX and AL). Still it was cool.

    Right now the meteor radar is getting a hit about every 20 seconds. Sweet, I just saw a 70 second streak with a doppler shift of about 183 Hz. That is screaming at about 17X earth rotation! (If I wasn't so lazy I'd calculate that in MPH or m/s)

    How did I do it? I just piped the real-time NASA stream into the standard input (stdin) of baudline, then equalized it with about 10 seconds of quietness, and then watched and listened away. I used this command line:

    mpg123 -s http://icecast.msfc.nasa.gov:8000/forward-scat | baudline -stdin -channels 1 -overlap 100 -fftsize 2048 -mem 9 -record -samplerate 22050 -session meteor_radar

    If the geocities site for baudline craps out, try again later, or try the mirror site [telocity.com]. The downloaded md5sum for baudline_0.87_i686.tar.gz should be 72f949826ac81a461a8b4b5c5551f366

  • Another question about the shower... (Score:3, Interesting)

    by BeBoxer ( 14448 ) on Wednesday November 28, 2001 @12:27AM (#2623350)
    One thing several of my friends and I wondered about is why the meteors didn't all travel in the same direction? The velocity of the Earth during the shower was basically constant. The velocity of all the particles in the cloud of debris that make up the shower should be the same, otherwise the cloud would have dispersed generations ago. If the two velocities are the same, then the path of the meteors should have all been the same. But while most of the meteors clearly traveled from East to West in accordance with the rotation of the Earth, quite a few appeared to come from the North and South! Does anyone know what causes this?
    • The debris results from a comet which intersects the path of the earth from the vicinity of the constellation Leo, thus the name. The shower emanates from this point in the sky and the meteors' trajectories can occur in any degree around this point. They are weighted E-W for the reason you mention. The path followed by the comet each go round is slightly different, as well, which makes for better viewing some years than others.
    • There are a few different things going on.

      The reason they are called the Leonids is that the main orbital path the meteroids are on before they strike the earth is such that it points back in the general direction of the constellation Leo at the point where the earth crosses the comet's orbit each year (meteor showers come from debris broken off a comet).

      If you make a black-on-white copy of a starchart, and draw a line on it for each meteor you see when it happens, with an arrowhead in the direction of travel, at the end of the night you will see the most of the paths generally radiating away from Leo, like spokes radiating from the hub of a bicycle wheel. This is like what you'd see if you stood in the middle of a multilane highway as cars sped past you, facing where they come from - you'd see the cars angling to the right and left, but "radiating" from one spot in the distance.

      If a meteor's path is very short, it is headed in your general direction. If it just a bright spot, then it is headed straight for you, so you know when to duck. If it is very long, it is headed away from you.

      I don't know if it is still practiced, but there used to be organized efforts among amateur astronomers to map meteor paths during showers so their orbits could be calculated. Now I guess it would be more practical and accurate to do it with radar. To do make such a calculation, the observers also need to write down the time they saw each meteor.

      Even so, the meteors won't all be radiating from a single point. There will be a lot of randomness. Part of this will be because the meteoroids are spread out in space, to either side of the comets orbit, each on its own slightly different orbit.

      Also, as it approaches the earth, the earth's gravity will disturb the orbit of the meteoroid. If the meteoroid is heading straight to the center of the earth just before it hits, then it will just go faster. If it's heading a ways to one side of the earth, then its path will be deflected in towards the earth, and when it hits it will be at a highly deflected path. If it's even farther to the side, it won't hit the earth but it's orbit will be disturbed, and many orbits of a planet through a comet's path will introduce a lot of scatter in future showers.

      Now let me shill for amateur astronomy. I'm grinding my own telescope mirror. [geometricvisions.com] You can join the Amateur Telescope Maker's mailing list and they'll tell you how - read the FAQ [jacksonville.net]. Dan Cassaro can sell you a mirror grinding kit [jacksonville.net]. You can get books with instructions (you need a whole book, it's pretty involved) from Willman-Bell [willbell.com]. You can find lots of tips on the Telescope Making WebRing [crickrock.com].

      Or you can buy telescopes from Meade [meade.com] and Celestron [celestron.com] or shop at the shop at the astronomy mall. [astronomy-mall.com] Finally, there's a new ATM portal at www.telescopemaking.com [telescopemaking.com].

    • It's because the meteorites don't all hit the Earth head-on. As the planet moves through the cloud of particles, it plows straight into some and misses others entirely. A few pass by close enough to get captured by the Earth's gravity and spiral in. The direction they are moving when they burn up depends on where they were when they got captured (which could be over the poles) and how much of an orbit they manage to make before hitting the atmosphere. So they can actually streak in from any direction.

    • In addition (Score:3, Informative)

      by wiredog ( 43288 )
      In addition to what has already been posted, not every meteor you saw was neccessarily a Leonid. You can see one or two meteors an hour on any night. If it's dark enough.
  • But I come from an area where Marine Layers (read:fog) is common and have missed a lot of the past Leonid and Perseid showers. I was lucky enough to be on a trip near Death Valley and camped in the bed of my pickup and saw the shower near California's Red Rock Canyon SP.

    However, about 8PM on the evening of the 25th I was still seeing shooting stars as I drove back up the coast, so there's still a few out there if you're patient and would like to see them.

  • Kitchen stoves and speaker wires (Score:3, Interesting)

    by goingware ( 85213 ) on Wednesday November 28, 2001 @12:40AM (#2623373) Homepage
    I didn't hear the Leonids, but I have had some experience with unusual radio receivers.

    The kitchen stove in the house I lived in in Moscow, Idaho when I was 12 would pick up a local radio station. It sounded very quiet, but if the room was still you could make out the words in the announcer's voice.

    Curiously, it only started doing that the last couple months we lived there, and it was only that one station that was received, although there were several in the area.

    Later on, I lived around the corner from a CB fanatic that had a quite illegal overpowered station in his home. He had a fifty foot antenna set up in his backyard. If he broadcast while we were listening to the stereo, it would blast the room with his racket.

    I found that I could receive him clearly on a cheap 2 inch audio speaker that had one foot of wire soldered to each terminal and stretched out in opposite directions. That's it.

    A neighbor took up a petition to ask the FCC to bust him but they never would.

    I mentioned both of these phenomena to an electrical engineer once and he thought it shouldn't happen because there was nothing to rectify the signal. I'm not so sure how it could work, maybe impurities or oxidation in the metal forming a natural diode, or nonlinear effects from all the power, or something I don't know.

    Someone previously asked if you could receive radio on dental braces. Yes you can, I've never heard it happen but I've heard of it happening to other people.

  • I noticed that one post made mention of some ELF towers in Annapolis. Since I live in Annapolis, and had never heard of this, I got rather curious. After a quick Google search, I came up with a few interesting things:

    • Although not as old as NAA, NSS is still in operation on VLF. In fact, it is the oldest continuously operating very low frequency station in the entire world! NSS is located on the small peninsula known as Greenbury Point on the northeastern shore of the Severn River, directly across from the United States Naval Academy at Annapolis, Maryland. Found on http://members.aol.com/k6dc/history.htm [aol.com]. Check this link out for some good info and pics!
    • LF (Low Frequency) and VLF (Very Low Frequency) antennas there are no longer used by the Navy and were made available for some experiments by AMRAD ... The Antenna, approximately 400 ft long, is suspended between two towers approximately 300 ft high. Found at http://www.amrad.org/projects/lf/March1999NSS/ [amrad.org]. More good pics of antennae and info on this link.
    • 28. "ELF Communications System Isn't Needed, Might Not Work, GAO Says," Aerospace Daily, March 22, 1979, 107 (cites GAO classified report, The Navy's Strategic Communications System, PSAD-79-48); Seafarer ELF Communications System Final Evaluation Impact Statement for Site Selection and Test Operation (Washington, DC: Dept. of the Navy, December 1977). Found on http://www.ndu.edu/inss/books/milgeo/milgeoch4n.ht ml [ndu.edu]
    • The Coast Guard is establishing a temporary safety zone covering all waters within a 2,000 foot radius of each of three Very Low Frequency (VLF) towers located between Greenbury Point and Possum Point, near Annapolis, Maryland. Potts and Callahan, Inc. will be demolishing the three towers with explosives. This safety zone is intended to restrict maritime traffic in order to protect mariners from the hazards associated with the demolition. http://www.epa.gov/fedrgstr/EPA-IMPACT/1999/Novemb er/Day-29/i30882.htm [epa.gov] This was in December, 1999.

    So it looks like the Navy did, in fact, have a rather groundbreaking ELF setup back in the day. Unfortunately those antennae seem to be gone now, but hey, technology marches on. Now that I'm reading some of these articles I know exactly which antennae they're talking about, and I do remember noticing that there seemed to suddenly be fewer of them a couple years ago...

  • Colin Keay (Score:2, Informative)

    by jmp ( 84073 )

    It's good to see that Dr Keay's research has been gained respectability.

    I was an undergraduate at the University of Newcastle when he was working on this, and attended a talk he gave on the subject. Perhaps I got it wrong, but I gained the impression that some of his colleagues thought he was wasting his time researching this rather controversial topic.

    Respectability is important in the hard sciences, and this must have seemed to some to be more like paranormal psychology than physics. Good on him for sticking to his guns.

    You can read more about Geophysical Electrophonics at Colin Keay's home page [hunterlink.net.au].

  • I remember being out at night on my bicycle, probably 15 years ago or more. I saw a meteor fly overhead from west to east with a bright green glow. I had always placed a sound with that incident! I had never really thought about the time that sound would need to propagate through the atmosphere! I was only 15 or so when it happened. Neat!

    This is why I really like Slashdot. Little by little, proving that I'm not completely insane. Now that I think about it, I think my older brother did look at me strange when I told him I heard the meteor. :)
    • If the only evidence pointing to insanity was hearing meteors, then you probably aren't. Back in 1973, I heard a hissing Perseid (a -6th magnitude fireball) that I've never beem able to explain until now. But I was wearing glasses in a campsite in pine woods.
      -aiabx

  • Meteorite communications are apparently old-tech (Score:3, Interesting)

    by serutan ( 259622 ) <snoopdoug@@@geekazon...com> on Wednesday November 28, 2001 @03:22AM (#2623689) Homepage
    According to this old ABCNews article [go.com], communications systems that work by bouncing radio signals off momentary streaks of ionized air created by meteorites have been in use for decades. I remember reading about a truck tracking system based on this. Kind of cool actually.

    They work on the principle that if you send out a weak, omnidirectional radio signal it will randomly be reflected to the right target every so often by a streak of ionized air from one of the 80,000 or so meteorites that hit the atmosphere every second. If the target radio sends out a return signal quickly enough, it will be reflected back along the same path to the sender. The ionized streak of air lasts about a second, which is long enough to shake hands and send a little data back and forth, like a truck's position or an updated delivery schedule. Radio signals can be reflected several thousand miles this way.
  • Hmmmm. This type of thing sounds like it could be related to the "Taos Hum," that mysterious humming sound that many folks in Taos, NM, and a few other towns, supposedly hear on an ongoing basis.

    Or, the Taos Hum could just be mass hysteria or attention mongering :-)

    Here's [eskimo.com] a link to a page with some info about it.

    -me

  • I watching a meteor shower in October 1981, maybe the Perseids, and 8 seconds after each one we heard a distinct 'pop' as of a distant gunshot. My father (a physics teacher) wrote to Patrick Moore [bbc.co.uk], who hosts the BBC's The Sky at Night programme [bbc.co.uk], and he replied saying that this was impossible. Maybe we were hearing a reflection of this fizzing sound, but it doesn't seem loud enough to carry over 3 kilometers.
  • They sounded like "ooooooooh" and "ahhhhhhhhh."
  • Now you can shut up anyone watching a sci-fi movie who complains that sound doesn't travel through outer space. Clearly the TIE fighters are just emitting ELFs, and probably intentionally too...

    ALF could probably hear ELFs and VLFs with all that fur.

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