RE: How far can radio signals penetrate through ice?
Title: Message The probe ought to be able to move and steer, as the possibility of encountering way-blocking anisotropies in the ice is likely fairly high. The weak point in the return to surface plan is the dead comm time. Too expensive to not know what's going on. As for sonic transmission ideas, one thing we might have a huge problem with is noise. It may well be that the Europan ice sphere is a profoundly noisy place due to ice flexion and tectonic activity. Jack W. Reeve -Original Message-From: Michael Turner [mailto:[EMAIL PROTECTED] Sent: Wednesday 13 October 2004 13:17 To: [EMAIL PROTECTED]Subject: Re: How far can radio signals penetrate through ice? 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
RE: How far can radio signals penetrate through ice?
Forgive me if I haven't been paying attention but it seems we need an antenna on the surface and data collection down below. The cable connecting the two is likely to be a significant portion of the landed mass if it is armoured in any way (which seems a good idea giving the tectonic and abrasion unknowns). And if it is posited that there will be a breakthrough into a sub-ice liquid, then the probe will be hanging on that thread. It had better be beefy! Why not consider a configuration that deploys an anchored antenna array/transmitter while the main, cable-laden part of the lander melts its way down into the ice via bottom mounted radiators. Assuming the availability of a nuclear power source in the probe, you could generate as much heat as you needed to make a penetrable slurry bubble of reasonable size. Fins on top would give it some steering capability. A lateral drill/sampler could extend to periodically take uncooked samples. Comms is maintained, great sonar and compositional data can be collected on the way down and if there is a disconnect, we get all the data right up until the Europans hacksaw the cable. If there is some sensing capability in the cable itself, the transmitter package left topside would at least be able to provide some further, albeit greatly reduced, data. We have off-the-shelf bathyscaph technology and marine cable technology and would be fools to reinvent those wheels. My 2p's worth Paul At 09:10 13/10/2004, you wrote: The probe ought to be able to move and steer, as the possibility of encountering way-blocking anisotropies in the ice is likely fairly high. The weak point in the return to surface plan is the dead comm time. Too expensive to not know what's going on. As for sonic transmission ideas, one thing we might have a huge problem with is noise. It may well be that the Europan ice sphere is a profoundly noisy place due to ice flexion and tectonic activity. Jack W. Reeve -Original Message- From: Michael Turner [mailto:[EMAIL PROTECTED]] Sent: Wednesday 13 October 2004 13:17 To: [EMAIL PROTECTED] Subject: Re: How far can radio signals penetrate through ice? 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 large ballast 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 be no gravity-assist. There's the 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
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 invent
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]Subj
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?
penetrate through ice?
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
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?
Title: Message 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
Re: How far can radio signals penetrate through ice?
If radar worked through ice, it would probably work through water. Submarines echolocate by sonar, rather than radar. That should tell you something. (This, by the way, may be a flaw in Deception Point. I'd been assuming that the meteorite buried deep in Arctic ice in that novel was detected by gravitometry, but the novel has radar as the detection medium. Hm, iffy. But what do you expect of a novel predicated on this: that NASA scientists had to download and analyze BY HAND the radar data that they expected would be analyzed in the satellite using uploaded software that turned out to be buggy. Har! As if there were analysis software that could only run in a satellite. And this is not to speak of the Roadrunner Physics in the action sequences. Why, I could write a book ... ) Maybe some kind of submarine clapper could send sound signals through the ice, but if that ice is as deep as suspected, and constantly shifting, it might be a major exercise in signal filtering, and require a lot of energy. The energy requirement is already a problem that has to be solved, however. Melting/boring through that ice is probably going to require an onboard nuclear reactor. There's been talk of neutrino communications - not just underwater, but through the earth - but nothing like anything that could be practical as far as I know. You need gigantic receiver arrays, and the transmission rates would be pathetic. -michael - Original Message - From: LARRY KLAES To: europa Sent: Sunday, October 10, 2004 12:46 AM Subject: How far can radio signals penetrate through ice? 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?
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
