RE: How far can radio signals penetrate through ice?
I am skeptic about the signal in bone rate. Sound travels through bone very rapidly akin to dense wood. Think of the hearing aids that send signals through the bone. Diamond only slows light down 50% or so. Mickey -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Paul Lavin Sent: Monday, October 11, 2004 3:11 AM To: [EMAIL PROTECTED] Subject: RE: How far can radio signals penetrate through ice? I'm not sure that the whales communicate over 100s of miles but their vocalisations can probably be heard that far away. Let's not forget that it takes some signals years to penetrate a quarter of an inch of bone... even at close range. ;-) Paul At 02:41 11/10/2004, you wrote: In the oil and gas business, seismic (sonar) description of rock formations is pretty accurate down to around 20,000 feet, then starts to get a bit fuzzy. On earth, elephants use low frequency sound to communicate over 10's of miles, through air. In the oceans, many whale species utilize the lower frequencies of sound to communicate over vast distances, apparently in the 100's of miles, perhaps further. Best bet for sound answers (sorry), check with a whale person. Any whale people listening? I'm typing at a really low frequency ... Incidentally, I'm back in SE Asia, so I'll be sharing the same clock as Michael T for a few years. Jack W. Reeve -Original Message- From: LARRY KLAES [mailto:[EMAIL PROTECTED]] Sent: Saturday 09 October 2004 16:00 To: [EMAIL PROTECTED] Subject: Re: How far can radio signals penetrate through ice? So maybe we can drop a large flat antenna on Icepick's landing site on Europa first, one that can be folded up for the trip and deployed when on the moon's surface. No, I am not trying to be funny. But wait - how big will Icepick have to be to receive and send data? Larry - Original Message - From: James McEnanly To: [EMAIL PROTECTED] Sent: Saturday, October 09, 2004 2:57 PM Subject: Re: How far can radio signals penetrate through ice? Usually it is by way of Extremely Low Frequencies. The antennae y=used for this are often acres, if not square miles in size. LARRY KLAES [EMAIL PROTECTED] wrote: I know this may be under the Classified category, but have submarines found ways to send signals through the ice packs when in the Arctic Ocean? I am just wondering if a similar technique could be used for Icepick so it doesn't have to drag a long cable after itself from the Europan surface. Thanks, Larry Sincerely James McEnanly __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com Paul Lavin The inventor of the phonograph thought he was inventing voicemail. Alexander Graham Bell was trying to invent muzak, not the telephone. What is obvious now was far from obvious then. What is obvious now is very likely to be wrong in twenty years. +44 (0) 78 5541 1391 mobile +44 (0) 20 7291 0991 London office +44 (0) 15 8246 2720 home office +44 (0) 15 8246 2536 home fax
RE: How far can radio signals penetrate through ice?
A skeptic that is not an acute observer of life? (Europan or otherwise) ;-) Obviously Mickey has not yet tried to get an idea into a teenager's head... It takes years, believe me! The transmission rate doesn't seem to increase appreciably with age in some subjects. Paul At 15:27 12/10/2004, you wrote: I am skeptic about the signal in bone rate. Sound travels through bone very rapidly akin to dense wood. Think of the hearing aids that send signals through the bone. Diamond only slows light down 50% or so. Mickey -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Paul Lavin Sent: Monday, October 11, 2004 3:11 AM To: [EMAIL PROTECTED] Subject: RE: How far can radio signals penetrate through ice? I'm not sure that the whales communicate over 100s of miles but their vocalisations can probably be heard that far away. Let's not forget that it takes some signals years to penetrate a quarter of an inch of bone... even at close range. ;-) Paul At 02:41 11/10/2004, you wrote: In the oil and gas business, seismic (sonar) description of rock formations is pretty accurate down to around 20,000 feet, then starts to get a bit fuzzy. On earth, elephants use low frequency sound to communicate over 10's of miles, through air. In the oceans, many whale species utilize the lower frequencies of sound to communicate over vast distances, apparently in the 100's of miles, perhaps further. Best bet for sound answers (sorry), check with a whale person. Any whale people listening? I'm typing at a really low frequency ... Incidentally, I'm back in SE Asia, so I'll be sharing the same clock as Michael T for a few years. Jack W. Reeve -Original Message- From: LARRY KLAES [mailto:[EMAIL PROTECTED]] Sent: Saturday 09 October 2004 16:00 To: [EMAIL PROTECTED] Subject: Re: How far can radio signals penetrate through ice? So maybe we can drop a large flat antenna on Icepick's landing site on Europa first, one that can be folded up for the trip and deployed when on the moon's surface. No, I am not trying to be funny. But wait - how big will Icepick have to be to receive and send data? Larry - Original Message - From: James McEnanly To: [EMAIL PROTECTED] Sent: Saturday, October 09, 2004 2:57 PM Subject: Re: How far can radio signals penetrate through ice? Usually it is by way of Extremely Low Frequencies. The antennae y=used for this are often acres, if not square miles in size. LARRY KLAES [EMAIL PROTECTED] wrote: I know this may be under the Classified category, but have submarines found ways to send signals through the ice packs when in the Arctic Ocean? I am just wondering if a similar technique could be used for Icepick so it doesn't have to drag a long cable after itself from the Europan surface. Thanks, Larry Sincerely James McEnanly __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com Paul Lavin The inventor of the phonograph thought he was inventing voicemail. Alexander Graham Bell was trying to invent muzak, not the telephone. What is obvious now was far from obvious then. What is obvious now is very likely to be wrong in twenty years. +44 (0) 78 5541 1391 mobile +44 (0) 20 7291 0991 London office +44 (0) 15 8246 2720 home office +44 (0) 15 8246 2536 home fax Paul Lavin The inventor of the phonograph thought he was inventing voicemail. Alexander Graham Bell was trying to invent muzak, not the telephone. What is obvious now was far from obvious then. What is obvious now is very likely to be wrong in twenty years. +44 (0) 78 5541 1391 mobile +44 (0) 20 7291 0991 London office +44 (0) 15 8246 2720 home office +44 (0) 15 8246 2536 home fax
Re: How far can radio signals penetrate through ice?
Let's not conflate signals andinformation withknowledge and wisdom, people. It took me two decades of ostensibly adult life before I developed the habit (still observed more in the breach) of facing life's quandaries with the question: "What would Dad do?" My batting average went up to match his level, modest as that has been. Anyway, I go with an acoustic solution, if it turns out to be impossible to cable a submarine probe to surface communications. Tap signals underneath, and listen for them on top. If you tap hard enough (and remember, we're talking about a lot of power just to get through the ice, so power will be available under the ice), the sound might be picked out out all the noise from shifting, grinding ice. The bit rate might be low, but eventually the message would get out. However, is there any reason tothink optical fiber couldn't be madestrong enough to withstand the crushing pressures, as the bore closed up behind the probe melting its way through the ice? Underwater acoustic communications with a transceiver attached to that fiber on the underside of the ice might keep the probe in contact with the surface. -michael turner [EMAIL PROTECTED] - Original Message - From: Paul Lavin To: [EMAIL PROTECTED] Sent: Tuesday, October 12, 2004 11:35 PM Subject: RE: How far can radio signals penetrate through ice? A skeptic that is not an acute observer of life? (Europan or otherwise) ;-)Obviously Mickey has not yet tried to get an idea into a teenager's head...It takes years, believe me! The transmission rate doesn't seem to increase appreciably with age in some subjects.PaulAt 15:27 12/10/2004, you wrote: I am skeptic about the signal in bone rate. Sound travels through bone very rapidly akin to dense wood. Think of the hearing aids that send signals through the bone. Diamond only slows light down 50% or so.Mickey -Original Message-From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Paul LavinSent: Monday, October 11, 2004 3:11 AMTo: [EMAIL PROTECTED]Subject: RE: How far can radio signals penetrate through ice?I'm not sure that the whales "communicate" over 100s of miles but their vocalisations can probably be heard that far away.Let's not forget that it takes some signals years to penetrate a quarter of an inch of bone... even at close range.;-)PaulAt 02:41 11/10/2004, you wrote:In the oil and gas business, seismic (sonar) description of rock formations is pretty accurate down to around 20,000 feet, then starts to get a bit fuzzy.On earth, elephants use low frequency sound to communicate over 10's of miles, through air.In the oceans, many whale species utilize the lower frequencies of sound to communicate over vast distances, apparently in the 100's of miles, perhaps further.Best bet for sound answers (sorry), check with a whale person.Any whale people listening? I'm typing at a really low frequency ...Incidentally, I'm back in SE Asia, so I'll be sharing the same clock as Michael T for a few years.Jack W. Reeve -Original Message-From: LARRY KLAES [mailto:[EMAIL PROTECTED]] Sent: Saturday 09 October 2004 16:00 To: [EMAIL PROTECTED]Subject: Re: How far can radio signals penetrate through ice?So maybe we can drop a large flat antenna on Icepick's landing site on Europa first, one that can be folded up for the trip and deployed when on the moon's surface. No, I am not trying to be funny.But wait - how big will Icepick have to be to receive and send data?Larry- Original Message - From: James McEnanly To: [EMAIL PROTECTED] Sent: Saturday, October 09, 2004 2:57 PMSubject: Re: How far can radio signals penetrate through ice?Usually it is by way of Extremely Low Frequencies. The antennae y=used for this are often acres, if not square miles in size.LARRY KLAES [EMAIL PROTECTED] wrote: I know this may be under the Classified category, but have submarines found ways to send signals through the ice packs when in the Arctic Ocean? I am just wondering if a similar technique could be used for Icepick so it doesn't have to drag a long cable after itself from the Europan surface.Thanks,LarrySincerely James McEnanly__Do You Yahoo!?Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com Paul LavinThe inventor of the phonograph thought he was inventing voicemail.Alexander Graham Bell was trying to invent muzak, not the telephone. Whatis obvious now was far from obvious then. What is obvious now is verylikely to be wrong in twenty years.+44 (0) 78 5541 1391 mobile+44 (0) 20 7291 0991 London office+44 (0) 15 8246 2720 home office+44 (0) 15 8246 2536 home fax Paul LavinThe inventor of the phonograph
Re: How far can radio signals penetrate through ice?
Title: Re: How far can radio signals penetrate through ice? Paul's humorous example was merely aimed at faulty processor speeds after the signals were transmitted, they got there at appropriately fast rates. Seriously folks, we already have the capability to signal process out random noise, so not to worry. Michael's point about power is a good one. Whatever makes it as a lander on Europa will likely not be power limited in the sense that NASA probes are today. BUT, it would have to be a pretty strong cable to hold up a fiber connection through all that ice, unless it was very stable, which it might not be. The Loihi Seamount HUGO fiber cable lasted about 3 months. It had some plastic and steel armor, but not enough. It was about 1 inch in diameter. See the SOEST web site for HUGO details: www.soest.hawaii.edu Gary Let's not conflate signals andinformation withknowledge and wisdom, people. It took me two decades of ostensibly adult life before I developed the habit (still observed more in the breach) of facing life's quandaries with the question: What would Dad do? My batting average went up to match his level, modest as that has been. Anyway, I go with an acoustic solution, if it turns out to be impossible to cable a submarine probe to surface communications. Tap signals underneath, and listen for them on top. If you tap hard enough (and remember, we're talking about a lot of power just to get through the ice, so power will be available under the ice), the sound might be picked out out all the noise from shifting, grinding ice. The bit rate might be low, but eventually the message would get out. However, is there any reason tothink optical fiber couldn't be madestrong enough to withstand the crushing pressures, as the bore closed up behind the probe melting its way through the ice? Underwater acoustic communications with a transceiver attached to that fiber on the underside of the ice might keep the probe in contact with the surface. -michael turner [EMAIL PROTECTED] - Original Message - From: Paul Lavin To: [EMAIL PROTECTED] Sent: Tuesday, October 12, 2004 11:35 PM Subject: RE: How far can radio signals penetrate through ice? A skeptic that is not an acute observer of life? (Europan or otherwise) ;-) Obviously Mickey has not yet tried to get an idea into a teenager's head... It takes years, believe me! The transmission rate doesn't seem to increase appreciably with age in some subjects. Paul At 15:27 12/10/2004, you wrote: I am skeptic about the signal in bone rate. Sound travels through bone very rapidly akin to dense wood. Think of the hearing aids that send signals through the bone. Diamond only slows light down 50% or so. Mickey -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Paul Lavin Sent: Monday, October 11, 2004 3:11 AM To: [EMAIL PROTECTED] Subject: RE: How far can radio signals penetrate through ice? I'm not sure that the whales communicate over 100s of miles but their vocalisations can probably be heard that far away. Let's not forget that it takes some signals years to penetrate a quarter of an inch of bone... even at close range. ;-) Paul At 02:41 11/10/2004, you wrote: In the oil and gas business, seismic (sonar) description of rock formations is pretty accurate down to around 20,000 feet, then starts to get a bit fuzzy. On earth, elephants use low frequency sound to communicate over 10's of miles, through air. In the oceans, many whale species utilize the lower frequencies of sound to communicate over vast distances, apparently in the 100's of miles, perhaps further. Best bet for sound answers (sorry), check with a whale person. Any whale people listening? I'm typing at a really low frequency ... Incidentally, I'm back in SE Asia, so I'll be sharing the same clock as Michael T for a few years. Jack W. Reeve -Original Message- From: LARRY KLAES [mailto:[EMAIL PROTECTED] Sent: Saturday 09 October 2004 16:00 To: [EMAIL PROTECTED] Subject: Re: How far can radio signals penetrate through ice? So maybe we can drop a large flat antenna on Icepick's landing site on Europa first, one that can be folded up for the trip and deployed when on the moon's surface. No, I am not trying to be funny. But wait - how big will Icepick have to be to receive and send data? Larry - Original Message - From: James McEnanly To: [EMAIL PROTECTED] Sent: Saturday, October 09, 2004 2:57 PM Subject: Re: How far can radio signals penetrate through ice? Usually it is by way of Extremely Low Frequencies. The antennae y=used for this are often acres, if not square miles in size. LARRY KLAES [EMAIL PROTECTED] wrote: I know this may be under the Classified category, but have submarines found ways to send signals through the ice packs when in the Arctic Ocean? I am just wondering if a similar technique could be used for Icepick so it doesn't have to drag a long cable after itself from the Europan surface. Thanks, Larry
RE: How far can radio signals penetrate through ice?
Title: Re: How far can radio signals penetrate through ice? Some good ideas being floated around here... but if thelander was prepared for the worst-case depth of 100 km and the tether was only 2 cm thick (which probably would not be good enough without exotic materials), that would be over 30 cubic meters of cable.Sounds like a very heavy lander. Sean -Original Message-From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]On Behalf Of Gary McMurtrySent: Tuesday, October 12, 2004 2:14 PMTo: [EMAIL PROTECTED]Subject: Re: How far can radio signals penetrate through ice? Paul's humorous example was merely aimed at faulty processor speeds after the signals were transmitted, they got there at appropriately fast rates. Seriously folks, we already have the capability to signal process out random noise, so not to worry. Michael's point about power is a good one. Whatever makes it as a lander on Europa will likely not be power limited in the sense that NASA probes are today. BUT, it would have to be a pretty strong cable to hold up a fiber connection through all that ice, unless it was very stable, which it might not be. The Loihi Seamount HUGO fiber cable lasted about 3 months. It had some plastic and steel armor, but not enough. It was about 1 inch in diameter. See the SOEST web site for HUGO details: www.soest.hawaii.edu Gary Let's not conflate signals andinformation withknowledge and wisdom, people. It took me two decades of ostensibly adult life before I developed the habit (still observed more in the breach) of facing life's quandaries with the question: "What would Dad do?" My batting average went up to match his level, modest as that has been. Anyway, I go with an acoustic solution, if it turns out to be impossible to cable a submarine probe to surface communications. Tap signals underneath, and listen for them on top. If you tap hard enough (and remember, we're talking about a lot of power just to get through the ice, so power will be available under the ice), the sound might be picked out out all the noise from shifting, grinding ice. The bit rate might be low, but eventually the message would get out. However, is there any reason tothink optical fiber couldn't be madestrong enough to withstand the crushing pressures, as the bore closed up behind the probe melting its way through the ice? Underwater acoustic communications with a transceiver attached to that fiber on the underside of the ice might keep the probe in contact with the surface. -michael turner [EMAIL PROTECTED] - Original Message - From: Paul Lavin To: [EMAIL PROTECTED] Sent: Tuesday, October 12, 2004 11:35 PM Subject: RE: How far can radio signals penetrate through ice? A skeptic that is not an acute observer of life? (Europan or otherwise) ;-)Obviously Mickey has not yet tried to get an idea into a teenager's head...It takes years, believe me! The transmission rate doesn't seem to increase appreciably with age in some subjects.PaulAt 15:27 12/10/2004, you wrote: I am skeptic about the signal in bone rate. Sound travels through bone very rapidly akin to dense wood. Think of the hearing aids that send signals through the bone. Diamond only slows light down 50% or so.Mickey-Original Message-From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Paul LavinSent: Monday, October 11, 2004 3:11 AMTo: [EMAIL PROTECTED]Subject: RE: How far can radio signals penetrate through ice?I'm not sure that the whales "communicate" over 100s of miles but their vocalisations can probably be heard that far away.Let's not forget that it takes some signals years to penetrate a quarter of an inch of bone... even at close range.;-)PaulAt 02:41 11/10/2004, you wrote:In the oil and gas business, seismic (sonar) description of rock formations is pretty accurate down to around 20,000 feet, then starts to get a bit fuzzy.On earth, elephants use low frequency sound to communicate over 10's of miles, through air.In the oceans, many whale species utilize the lower frequencies of sound to communicate over vast distances, apparently in the 100's of miles, perhaps further.Best bet for sound answers (sorry), check with a whale person.Any whale people listening? I'm typing at a really low frequency ...Incidentally, I'm back in SE Asia, so I'll be sharing the same clock as Michael T for a few years.Jack W. Reeve-Original Message-From: LARRY KLAES [mailto:[EMAIL PROTECTED] Sent: Saturday 09 October 2004 16:00To: [EMAIL PROTECTED]Subject: Re: How far can
Fw: Marsbugs Vol. 11, No. 40
- Original Message - From: Dr. David J. Thomas To: [EMAIL PROTECTED] Sent: Monday, October 11, 2004 2:31 PM Subject: Marsbugs Vol. 11, No. 40 The 11 October 2004 issue of Marsbugs: The Electronic AstrobiologyNewsletter is available online.Text: http://www.lyon.edu/projects/marsbugs/2004/20041011.txtPDF:http://www.lyon.edu/projects/marsbugs/2004/20041011.pdfWord: http://www.lyon.edu/projects/marsbugs/2004/20041011.docArticles and NewsPage 1 NASA CONGRATULATES SPACESHIPONE'S X-PRIZE WINNASA release 04-329Page 2 FREQUENT STARBURSTS STERILIZE CENTER OF MILKY WAYHarvard-Smithsonian Center for Astrophysics release 04-31Page 3 SOPPING SALTS COULD REVEAL HISTORY OF WATER ON MARSIndiana University releasePage 4 STUDY SUGGESTS COMPONENT OF VOLCANIC GAS MAY HAVE PLAYED ASIGNIFICANT ROLE IN THE ORIGINS OF LIFE ON EARTH-CARBONYL SULFIDEFORMS PEPTIDE BONDSBy Jason Socrates BardiPage 5 EXTRASOLAR PLANETS: A MATTER OF METALLICITY By Henry BortmanAnnouncementsPage 5 KENNEDY SPACE CENTER SABBATICAL PROGRAM FOR UNIVERSITY FACULTYNASA/KSC solicitation NNK04ZOP001OPage 6 SCIENCE TECHNOLOGY WEB AWARDS 2004 From Scientific AmericanPage 6 CANSAT COMPETITIONFrom Bill Bird, Iowa Space Grant ConsortiumPage 6 ASTROBIOLOGY AT THE 14TH WESTERN PHOTOSYNTHESIS CONFERENCEBy David J. ThomasMission ReportsPage 6 CASSINI SIGNIFICANT EVENT REPORT FOR WEEK ENDING 8 OCTOBER2004NASA/JPL releasePage 8 GENESIS SOLAR SAMPLES ARRIVE AT JOHNSON SPACE CENTER NASA note J04-040Page 10 MARS EXPLORATION ROVERS UPDATESNASA/JPL releasesPage 10 MARS EXPRESS UPDATESESA releasesPage 12 MARS GLOBAL SURVEYOR IMAGESNASA/JPL/MSSS releaseDavid J. Thomas, PhDAsst. Professor of BiologyLyon College, Science Division2300 Highland RoadBatesville, AR 72501 USAPhone: 870-698-4269Fax: 870-698-4692http://www.lyon.edu/webdata/users/dthomasNASA/JPL Solar System Ambassadorhttp://www2.jpl.nasa.gov/ambassadorEditor of Marsbugs: The Electronic Astrobiology Newsletterhttp://www.lyon.edu/projects/marsbugs
Fw: Latest News from the Astrobiology Magazine
- Original Message - From: Astrobiology Magazine To: [EMAIL PROTECTED] Sent: Monday, October 11, 2004 5:33 AM Subject: Latest News from the Astrobiology Magazine Extrasolar Planets: A Matter of Metallicityhttp://www.astrobio.net/news/article1241.htmlThe 130 extrasolar planets discovered so far are in solar systems very different from our own, in which life-bearing planets like Earth are unlikely to exist. But an obscure characteristic of these planets and their stars has led astronomers to predict that our galaxy is brimming with solar systems like ours. The key to their prediction is something called metallicity. Beaming Up a Software Doctorhttp://www.astrobio.net/news/article1240.htmlThe Mars rovers were launched without a complete software unit. As the red planet loomed ever closer, the control code was beamed up. This model of not just transfering new mission protocols, but actually letting the protocols carry some 'self-healing' may play an increasing role for future explorers.Saturn's Perfect Stormshttp://www.astrobio.net/news/article1239.htmlTo see a hurricane grow on Earth, one's best view is from orbit. But on the windiest planet in the solar system, Saturnian clouds can gather to sizes greater than our tiny blue planet.Popping the Escape Hatchhttp://www.astrobio.net/news/article1238.htmlThe Mars Opportunity site continues to intrigue scientists as they decipher the chemistry deeper in Endurance crater. The rise in chlorine and fall in sulfur may suggest alterations by evaporating water in the crater's past.Monday, October 11 For more astrobiology news, visit http://www.astrobio.netTo unsubscribe, send subject UNSUBSCRIBE to [EMAIL PROTECTED]
RE: How far can radio signals penetrate through ice?
Title: Message We're re-inventing the wheel here. Seems that there was a plan wherein a series of puck-like transceivers could be left in the ice upon descent, one every so many hundred or thousand meters. Not a bad idea, except for the dead batteries issue sooner or later. Re the cable. no way it needs to be that big. Assuming an optical data line (0.75 mm), a primary conductor (2 mm, aluminum? - good weight vs. conductivity ratio), and a heating element/shroud (0.5 mm thick, stainless or titanium weave, each say 50 m electrically isolated, representing individual elements), I can't see why the cable would have to be more than 3 - 4 mm diameter= 07. - 1.26 line m3 @ 100 km. Regularly heating the cable would allow it to always seek its slackest situation in the ice, eliminating tectonic shearing of the cable. Element heating could be cycled, or even activated based upon in-situ cable stress - reacting to tectonics when required. The cable would unspool from the probe upon descent. In truth, a 2nd signal could piggy-back on the primary conductor, so its got built in redundancy. Sounds like off-the-shelf stuff to me. Jack W. Reeve -Original Message-From: Sean McCutcheon [mailto:[EMAIL PROTECTED] Sent: Wednesday 13 October 2004 02:39 To: [EMAIL PROTECTED]Subject: RE: How far can radio signals penetrate through ice? Some good ideas being floated around here... but if thelander was prepared for the worst-case depth of 100 km and the tether was only 2 cm thick (which probably would not be good enough without exotic materials), that would be over 30 cubic meters of cable.Sounds like a very heavy lander. Sean -Original Message-From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]On Behalf Of Gary McMurtrySent: Tuesday, October 12, 2004 2:14 PMTo: [EMAIL PROTECTED]Subject: Re: How far can radio signals penetrate through ice? Paul's humorous example was merely aimed at faulty processor speeds after the signals were transmitted, they got there at appropriately fast rates. Seriously folks, we already have the capability to signal process out random noise, so not to worry. Michael's point about power is a good one. Whatever makes it as a lander on Europa will likely not be power limited in the sense that NASA probes are today. BUT, it would have to be a pretty strong cable to hold up a fiber connection through all that ice, unless it was very stable, which it might not be. The Loihi Seamount HUGO fiber cable lasted about 3 months. It had some plastic and steel armor, but not enough. It was about 1 inch in diameter. See the SOEST web site for HUGO details: www.soest.hawaii.edu Gary Let's not conflate signals andinformation withknowledge and wisdom, people. It took me two decades of ostensibly adult life before I developed the habit (still observed more in the breach) of facing life's quandaries with the question: "What would Dad do?" My batting average went up to match his level, modest as that has been. Anyway, I go with an acoustic solution, if it turns out to be impossible to cable a submarine probe to surface communications. Tap signals underneath, and listen for them on top. If you tap hard enough (and remember, we're talking about a lot of power just to get through the ice, so power will be available under the ice), the sound might be picked out out all the noise from shifting, grinding ice. The bit rate might be low, but eventually the message would get out. However, is there any reason tothink optical fiber couldn't be madestrong enough to withstand the crushing pressures, as the bore closed up behind the probe melting its way through the ice? Underwater acoustic communications with a transceiver attached to that fiber on the underside of the ice might keep the probe in contact with the surface. -michael turner [EMAIL PROTECTED] - Original Message - From: Paul Lavin To: [EMAIL PROTECTED] Sent: Tuesday, October 12, 2004 11:35 PM Subject: RE: How far can radio signals penetrate through ice? A skeptic that is not an acute observer of life? (Europan or otherwise) ;-)Obviously Mickey has not yet tried to get an idea into a teenager's head...It takes years, believe me! The transmission rate doesn't seem to increase appreciably with age in some subjects.PaulAt 15:27 12/10/2004, you wrote: I am skeptic about the signal in bone rate. Sound travels through bone very rapidly akin to dense wood. Think of the hearing aids that send signals through the bone. Diamond only slows light down 50% or so.Mickey-Original Message-From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Paul LavinSent: Monday, October 11, 2004 3:11 AMTo: [EMAIL
Re: How far can radio signals penetrate through ice?
Title: Message Good points, and I'd forgotten about the idea of a string of puck transceivers. They would probably be distributed so that if one fails, the whole network doesn't go down. OK, here's a really dumb idea: don't communicate. Just return to the surface with your data payload. We're assuming something that can melt its way down. Why can't it also melt its way up? Presumably it has an onboard nuclear reactor, with a long MTBF. If you evacuate a ballast tank (filled with liquid water, which of course is denser than ice) and point the thing up instead of down, it'll melt its way back up, right? That makes the whole thing bigger, because you need a largeballast tank, but not much heavier as a delivered product, since that tank will mostly be either empty volume or volume filled with either locally derived water(on the way down) or water vapor (on the way up.) Against this is the argument that you won't know what's going on for long periods of time.If something goes wrong with the basic transport mechanism - melting through ice whether gravity-assisted or buoyancy-assisted - you probably won't find out what the problem was, short of visiting the failed probe using something like the same technology that failed on you. I guess if there's some backup power, the acoustic transmission idea could work in a pinch (as it were). Low bit rates that would be unacceptable for large-scale oceanography data dumps might still be tolerable for hardware diagnosis. (I know, because I've written diagnostics that talked over some slow channels.) One argument against this return-trip idea would seem to be the massive lateral pressures. How could water melted from the top, on the return trip,make its way around the sides?Well, you have to solve this problem for going down as well. I think if you just let the melted water go through a channel inside the probe from the leading head to the tail, it works for going up or down.. While you're at it, speed up the propulsion system by generating steam behind the probe, regardless of which direction it's going. The ice will close up over the probe in short order on the way down, so having a steam-filled cavity will push the probe like a piston in a cylinder, with the probe boiling the water behind it. You already have to melt very cold ice (which will have roughly the same specific heat as water), so going the extra mile and boiling the water as well probably isn't going to cramp your energy budget much, and it may be the faster way, compared to simply having a hotter heating element. This would also work even better on the return trip, because coming back up there will beno gravity-assist. There'sthe bootstrap point where it's initially melting upward while still suspended in water under the ice ceiling. I suppose you could have a rear steam jet for that purpose. Or a ballast tank that you'd need anyway for underwater maneuvers might provide enough buoyancy to get you started. Here's an idea for EXTREMELY low-bit-rate communication in the meantime. The probe can dissociate the hydrogen and oxygen in the frozen H2O it's melting through. It can leave behind pockets of H2 and O2 gas, with a small disposable igniter or an igniter attached to a wire that that the probe drags behind it. Or it can even just use space immediately behind it as the explosion cavity, with a reusable igniter built into the probe. That way, even if it gets wedged, it still has a chance of communicating. Ignition will cause an explosion/implosion. And a powerful one: the H2/O2 mix will be very dense, just to compensate for the pressures down there. Ignition could be triggered on a schedule given by an onboard clock, with a clock-tick granularity of, say, a few seconds, to compensate for any acoustic variability in the ice. A probe on the surface hears an explosion, reads its ownsynchronizedclock value, subtracts some frequently-adjusted value based speed-of-sound and current depth, and takes the low-order 8 bits of the result. Voila: you've received a byte. By the nature of the arrangement, it'll be a while before you can get your next byte, admittedly. If the probe has some effective control over the volume of gas ignited, that's another potential source of bits, although those bits will probably have more noise, the deeper the probe descends. However, even the "noise" in these explosions can have scientific value, as I believe Jack Reeve can better explain to you. Oil prospecting has been using underground explosions to characterize subsurface features for a long time. A lot of information can be collected about the local structure of the ice. I think this can all be prototyped here on Earth - the Greenland ice cap is certainly deep enough. -michael - Original Message - From: Reeve, Jack W. To: [EMAIL PROTECTED] Sent: Wednesday, October 13, 2004 1:06 PM Subject: RE: How far can radio signals penetrate
