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Let's suppose that you have a super-duper detector that can identify the element from a single decay event (by virtue of its particular decay mode and energy). Let's also assume that the detector is completely efficient, and has a capacity of 1 litre of seawater. |
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Let's further assume that you are prepared to wait 1 hour for each result. That means that you want one decay event per hour, per litre of seawater. |
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We now need to define the halflife of the element. It wants to be as short as possible (highest activity), whilst lasting long enough to conduct the search. On the other hand, it will be sitting idle on the plane for a long time; if you're prepared to replace the material on the plane once every six months, then you could go for a half-life of (say) six months. |
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With a six month half-life, you're going to need about 10,000 atoms per litre of seawater (to give you your 1 decay per hour per litre). |
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Next comes the question of dispersal. I have no idea how to estimate this, but it seems reasonable to assume that the plume of material released from the plane will disperse into a column of water that is, say, 100 miles wide, 1000 miles long, and maybe a mile deep. Of course, this depends on ocean currents; it also assumes rapid mixing between ocean layers, which probably doesn't happen (meaning that your tracer never makes it to surface waters), but let's be optimistic. So, our tracer is dispersed in roughly 100,000 cubic miles of seawater. |
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Now, we needed 10,000 atoms per litre; and 100,000 cubic miles is about 4x 10^17 litres, so we want about 4x 10^21 atoms. However, this assumes a uniform dispersal, whereas in fact the concentration will decline as we move away from the aircraft (or off the line of the current passing over the aircraft). So, to stand a chance of picking up the initial signal, we'd want say 10x that average concentration of atoms - or about 4 x 10^22 atoms in total. |
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Oddly enough, this isn't much - about a tenth of a mole of the substance. If its atomic weight is around 200 (ie, transuranic), we're looking at about 20 grams of the material. |
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Now, I don't want to spoil all the fun, so I'll leave it to [8th] to tell us which man-made isotope can be produced economically in gram quantities and has a half-life of about a year. |
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We leave that as an exercise to the reader. |
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Yes, we had already done that calculation and determined that 100g of a sparingly-soluble compound, or a soluble compound in a slow-release matrix, would be more than sufficient with a margin of safety. |
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Or just a big chunk of cyanide, and the large number of dead fish, whales etc |
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Cyanide would dilute much too fast- the effect would be extremely localised. |
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It might turn out to be easier to just keep track of the planes while they're in the air, so that their point of ocean surface interface could be determined by careful scrutiny of the data. Or, perhaps better yet, ask the pilots to avoid driving into the sea. |
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The main problem with this Idea relates to all the
above-ground atomic-bomb tests of the1950s and
1960s. The world's background radiation level went up
a bit, and the sources of that radiation include a vast
variety of not-normally-occurring radioactive nuclides. |
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I suspect you might need to specify a particular
chemical compound that dissolves slowly in water, and
one atom in that compound would be radioactive,
choosing one that would, due to short half-life, no
longer be in the environment to any significant extent.
Perhaps tritium (12 year half-life; any tritium left over
from the bomb tests would have half-decayed five or six
times by now. You would want to detect the particular
compound more than you want to detect the tritium,
but you can use the tritium to ensure you have a sample
of the compound, see? |
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Natural abundance of tritium is about 1 part in 10^18 of hydrogen. Hence, a litre of water would naturally contain about 10^8 tritium atoms. |
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Also, since tritium is an alpha emitter, detecting it efficiently would be difficult. |
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Ok, a large barrel of Dimethylmercury and that's my final offer.. |
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I can't help feeling that this is all very innecessay. |
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First of all, how many commercial airliners, other than MH370, have been lost at sea in the last 30 years and were carrying conventional black boxes? I suspect it's a fairly short list. |
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Second, if the list were long enough to warrant additional measures, then there is already the facility to track airliners using satellites - my understanding is that this option was turned off on MH370, but it can't cost much just to glue all the on/off switches in the ON position, and thereby track all commercial aircraft. |
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It still amazes me that in a world under so much surveillance from numerous sources, and with so many tracking devices, that a plane full of passengers can disappear, and remain unfound. |
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Indeed ... don't you think it's highly suspicious that there's no evidence of a conspiracy... ? |
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// how many commercial airliners, other than MH370, have been lost at sea in the last 30 years and were carrying conventional black boxes? // |
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Twenty-eight of 50 seats or larger. Some were close to shore and were tracked by radar, so the search area was small, and searchers arrived fast enough to find a defined debris plume. |
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OK so, of those 28, how many FDR/CVRs were not located within, say 2 weeks of them becoming submarinic? |
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22; 7 have never been found (although the debris field has been located in 4 of those). |
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Hmm. This idea almost becomes slightly relevant. So, of those 22, how many were English planes? |
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Also, are you actually making these numbers up? |
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None. And the numbers come from the ICAO - it's all on their website, altho you have to trawl through several PDF files to collate the data. |
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If anything, the numbers are an underestimate, as they only relate to international flights. On average, one hull a year goes into the ocean, and is "lost". |
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hmmm... perhaps a substance on the exterior of the hull could dissolve in salt water to time release buoyant traceable particles. |
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Ah, well then the problem declines somewhat in terms of urgency. |
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Very much, although a small amount of explanation may be appropriate. |
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No large civil aircraft are entirely manufactured within this sceptr'd isle, despite Airbus Industrie buying wings from BaE Systems. |
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Similarly, few airlines can be reasonably characterised as wholly "English" (Apart from the Grey Tail Airline, which doesn't count, as it's the property of H.M. the Q.) and those that can don't operate long transoceanic services. |
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"British" <spit> Airways is not so much an airline as a heterogeneous assembly of self-interested mouth-breathing numpties, organised in the customer-facing departments into three distinct, conflicting factions - rudeness, inefficiency, and waste. |
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The main thing is to travel in an airframe that has a large margin of safety in its design (such as the DC-3) and has been constructed "up to a spec, not down to a price". |
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No, they don't go very fast, or very high. But you can't pull the tailfin off by a normal use of the rudder (which has happened to an Airbus). They don't have non-optional self-igniting lithium-ion batteries. They're easy to inspect, because very little is covered up on the interior. Yes, gas turbines are better than piston engines ... the more, the better. |
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If an aircraft seats more than about a dozen people, don't go on it. And insist on your choice of seat i.e. right at the front, so you can keep an eye on what's happening. |
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//No, they don't go very fast, or very high. .... Yes, gas turbines are better than piston engines ... ..If an aircraft seats more than about a dozen people, don't go on it. And insist on your choice of seat i.e. right at the front, so you can keep an eye on what's happening.// |
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You must be an absolute delight to go on holiday with. |
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Actually, highly rated, although the original Lycoming powerplants were better than the current outfit. |
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// You must be an absolute delight to go on holiday with // |
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We are - in the right circumstances (which never include commercial air travel). |
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Instead of expensive radioactive 8thium, one could fill the device with distinctive plane shaped Styrofoam wads, each imbued with plastic particles carrying a code corresponding with the plane. On prolonged submersion the container either dissolves (it is made of melba toast) or explodes (it contains sodium metal in oil), releasing the wads. These float merrily away. One then triangulates the source based on subsequent retrieval sites and knowledge of ocean currents. |
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// These float merrily away..... knowledge of ocean currents // |
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Anything floating on the surface is subject to wind forces, which can be highly variable. |
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To be effective, such a device would need to have a large area underwater, and a minimal area above. That would make it much harder to spot visually. |
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An RF transponder recharged by a wave-oscillation generator (bobbing magnet in coil) might be an option. |
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hmm... radiolabeling things is a phenomenal technique.
Much in biology has been worked out by sticking a hot
isotope on something and seeing where it goes. You
could argue that the convenience of 32-P led the
slightly weird obsession with kinases that happened
while I was being educated in a complex mix of now
obsolete technologies. |
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Labeling with stable isotopes is being used more
frequently nowadays, they're pretty good for tracing
metabolic flux and because of stability, there's no
damage and your signal doesn't vanish. |
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Radiolabeling isn't being used as much anymore for, I
think, the same reason labeling aircraft isn't ideal: you
have to physically get some of your label and detect it
with film/scintillation counter/mass spec. You can't
continuously monitor it, every time is an end point, for
a given sample anyway. |
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Conversely, fluorescence can be continuously
monitored. You don't need the sample, just energy
from the sample, and that doesn't need to run out
because you can supply it externally. This is totes
amazeballs. So fluorescence is a good way to go. Now, I
know the military put fluoroscein or some other tedious
chemical that betrays their lack of imagination in their
aircraft, but there's better ways. I've reviewed the
literature on the optical properties of oceans and the
data suggests that they're blue. |
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To stand out, red would be an appropriate color. So we
need floating red fluorescent quantum dots. The
reflectance of ocean in the near infra red is almost
nothing, even within that there are a couple of notches
of extra low reflectance. So you can tune your quantum
dot to absorb all light from UV to the orange and emit
what ever frequency works for you. |
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I think we can do better than that though, water has a
funny way of reflecting only S polarized light (certain
boring details about angles apply here but they're easily
manageable). Quantum dots can be oriented in such a
way as to emit light in whatever polarity you want, so
why not emit the light perpendicular to what little red
light is reflected? Well, all the little floating dots are
going to be randomly oriented in the water, unless that
it, you magnetize it. Then you can reference your dots
to the Earth's magnetic field, and the polarity can be
controlled. |
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So, plane crashes in ocean. Water releases floaty-
polarized-magnetized-qdots which all bob around on
the sea surface. Then, using one of the many Earth
facing satellites or the aircraft of your choice, fly
around looking for 705nm +/- 5nm p-polarized light
from the ocean surface. |
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Alternatively, you could have some algae spores
modified to express a fluorescent protein. Then make
sure they have a supply of whatever limits their growth,
phosphorous, nitrates or whatever. That has the
potential to amplify the signal. Might not grow in the
cold though, and could get eaten. |
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// educated in a complex mix of now obsolete technologies. // |
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Presumably it would be possible to engineer a "smelling" molecule not found in nature, and train sharks to associate it with food. Then all you need to do is hang on to the string attached to the shark's tail. |
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Nobody likes sharks very much, and there are lots of them, so it shouldn't be a problem to trial the idea. |
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NB don't spill the odourant on you. |
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//floating red fluorescent quantum dots.// |
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I think you'd need infeasibly large amounts of q-dots. Yes, they're super-duper fluorophores, but mainly because they don't photobleach. They have good quantum yields, and I guess they must have a large cross-section for excitation, but they're not four orders of magnitude better than regular dyes - maybe two? And each q-dot is relatively massive (a few nm across, at least - way bigger than regular fluorophores), which means you get far fewer of them for a given mass. |
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I'm pretty sure that you would really, really, really really struggle to detect a single q-dot in a litre of distilled water in a reasonable period of time. And seawater will be full of algae and used condoms and other stuff that will fluoresce. And I'm not sure that you can magnetize q-dots. |
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Maybe it would work if you could find a really good fluorophore that could be dissolved at high concentration in the fuel. It would have to be dirt cheap, and it would ideally be combustible in a useful way, but planes carry tons of fuel, and tests have shown that diving into water can rupture fuel tanks. |
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//I'm pretty sure that you would really, really, really
really struggle to detect a single q-dot in a litre of
distilled water// |
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That depends. It's actually pretty easy to count
individual photons. So the signal can be absolutely tiny.
I think a single quantum dot would be easy to detect. I
don't have a 1 litre cuvette though, so I'll consult a
homeopath about diluting below 1 and try it after. The
problem is noise. There's absolutely loads of stuff that
absorbs UV/blue and emits blue-green, but red
autofluorescence is very rarely a thing. I was thinking
that whatever coating is used to make them float could
contain a tiny magnet, actually they may flock in this
case. |
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Well, I've detected single q-dots, and it required a microscope with a 60x objective fed into a photon-counter. The signal from one q-dot was pretty decent, but that's in a volume of maybe a few cubic microns. It also needed fairly insane amounts of excitation - I can't remember how much, but I know that I ended up burning things when I tried to go a few fold higher. |
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If you really, really wanted to find one q-dot in a litre of water, you'd need to pass the water through a channel in a microfluidic, and image the whole width of the channel. You might get away with a 20x20µm channel, moving at maybe 20µm per msec, so that's 4000µm3/msec, or 4,000,000µm3/sec, which is an insanely slow flow rate - something like 8µl/sec, meaning that it would take something like 30 hours to analyse your litre of seawater. And I just flat don't believe that there's not a single autofluorescent particle in that litre of water, that would give you a false positive. |
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As for magnetizing the coating - these things are the size of a small protein molecule. Even if the coating could be some suitable metal, I don't think you can have magnets that tiny - something to do with a minimum domain size. Dynal beads are polystyrene with fairly big (?100nm?) embedded iron particles, and they're not magnetizable. It would be cool if I were wrong, though. |
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On the other hand, anyone could lash up a transponder that would break away and float, with enough power to be picked up easily over a very wide area using cheap equipment. I think this is a problem that has many easy solutions. |
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What about an absurdly large number of small DNA
fragments? How many molecules would say 10kg get you?
Then could you just run huge volumes of seawater through a
hybridization filter, or basic DNA binding media, elute at the
end of the day and PCR it up? |
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I wouldn't go the route you describe for 1 QDot, you could
just design your optics to focus a 1000 gallons or whatever
down to a point, do a v long exposure, confirm any positives
with a brief spectrum. |
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// absurdly large number of small DNA fragments? // |
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Zooplankton. The sea is full of hungry little bugs that are going to munch even the tiniest bit of protein they can find. |
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//What about an absurdly large number of small DNA fragments?// It'd last a few days. |
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Back when I was doing lots of single-molecule PCR, I tried putting a huge amount of a specific DNA in my garden pond. I forget the amounts, but it would have been something like 1 copy per microlitre initially. |
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It was detectable in water samples a few hours later; sporadically detectable the next day; non-detectable after that. I concluded that DNA probably gets degraded very quickly in pondwater. |
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On the other hand, there are DNA analogues which are a lot more durable, and might survive much better in the sea. |
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Re. the q-dots, (a) I don't think you can focus down in the way you describe and (b) there is absolutely no way on Earth that you could detect and characterize a single qdot in against the autofluorescence in that kind of volume. |
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I know that at the halfbakery we go to extremes to make things more interesting. |
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But why not just make the aircraft out of many small pieces that will detach when it impacts the water? Like, wing thingies and such. |
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Or for that matter, why do the recorder/transponder thingies sink with the plane? Design them so their feelings get hurt when the plane gives up flying for snorkeling, and have them automatically jump off and trigger EPIRBs to entertain themselves while they float. |
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DNA is composed of amino-acid base pairs, and a sugar-phosphate polymer. Since amino acids are the basis of proteins, any filter-feeder is going to be quite happy to ingest bits of DNA along with everything else, and digest it; after all, every living cell contains it, and all animals eat either plants or other animals or both, so they can clearly digest it along with everything else - they'd be stupid not to ... |
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//DNA is composed of amino-acid base pairs// Uh, [8th], you are being intentionally facetious, are you not? Please tell me I don't have to go and fetch the idiot hat down from the top shelf again |
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<grasps key, gives clockwork another turn> |
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<listens hopefully for TWANGGGGGG noise from [MB]> |
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Nice save, possibly too late. |
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Appearing stupid for the sake of humour is really only a viable option when it cannot be confused with appearing stupid as a result of stupidth. |
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It would have been trivially easy to cut and paste from Wikipedia ... |
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Think of it as subtle revenge for your "beaches are not envelopes" setup line. |
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OK, shame to waste it ... |
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"Shore-ly you must be joking ?" |
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..... @ ...... @ ....... @ ....... |
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envelope
1.a flat paper container with a sealable flap, used to
enclose a letter or document.
synonyms: wrapper, wrapping, wrap, sleeve, cover,
covering; More
2. a covering or containing structure or layer.
"the external envelope of the swimming pool" |
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//"the external envelope of the swimming pool" In other
words: A beach. |
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" "Shore-ly you must be joking ?" " |
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[normzone] waves back ... |
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Funny, we were expecting a tide of abuse .... |
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A kick in the groyne would work better. |
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Perhaps from novices, but surely not from your piers ... |
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Soliton sonar emitter pointed straight up, it might reach beyond the surface then search planes could fly through it. |
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Also there is a novel kind of soliton called a "dissipative soliton" that, even though it is named that, travels 100 times further than an ordinary soliton |
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// Soliton sonar emitter pointed straight up // |
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How long does it transmit for ? |
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And after the aircraft gets smithereened, how do you keep it pointed straight up ? |
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Why not have a secondary storage device, to which the CVR
and FDR send a copy of everything they record, mounted
just under the roof of the aircraft near the tail, under a
pyrotechnically jettisonable panel? When the aircraft strikes
water or land, as detected by a pressure sensor running
from the tip of the nose all the way along the underside to
the tail, it is ejected by a rocket or a mortar-like launcher
and immediately deploys both a ballistic parachute and a
fully enveloping airbag that stays inflated for a while,
similar to the ones the MERs used to land. It also has a
satellite radio beacon and a GPS receiver, and it is
positively buoyant. This way, even if the main recorders are
destroyed or lost into a subduction zone or something,
there's another copy of the data that is easier to retrieve.
The main recorders will keep recording after the backup
device ejects, in case there's anything else important that
happens later (and to give them an excuse to continue
existing as separate devices). |
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