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Science Technology

Fast, Accurate Detection of Explosives 270

Posted by ScuttleMonkey from the nose-for-crime dept.
It doesn't come easy writes "Fast, highly reliable detection of residues that could indicate the presence of explosives and other hazardous materials inside luggage is now possible with technology under development at Purdue University. Recent improvements to a previously developed prototype have proven successful at detecting at the picogram (trillionths of a gram) level in lab tests, about 1,000 times less material than previously required. From the article: 'In the amount of time it requires to take a breath, this technology can sniff the surface of a piece of luggage and determine whether a hazardous substance is likely to be inside, based on residual chemicals brushed from the hand of someone loading the suitcase.'"
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Fast, Accurate Detection of Explosives More

Fast, Accurate Detection of Explosives

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  • Vulnerable to a "chaffing" attack? (Score:5, Insightful)

    by patniemeyer ( 444913 ) * <pat@pat.net> on Monday October 03, 2005 @11:08PM (#13709955) Homepage
    Ok, here's something I've always wondered about. If you have these exquisitly sensitive machines that can detect even a few molecules of material, aren't they by the same token super-vulnerable to being attacked by "chaffing" or overloading?

    Couldn't a bad guy simple walk around the airport with some material on his shoes and permanently, for all time, destroy the effectiveness of the instruments? I mean, how could one possibly clean a whole airport down to a few molecules worth of the stuff?

    Isn't that a *huge* hole in any "super sensitive" chemical detection system?

    • Skunk Analogy (Score:3, Interesting)

      by tempest69 ( 572798 )
      The overload attack does have some merit. However it wont be "for all time" or even close. The best analog would be a skunk, their odor is detectable to humans in similar quantities. Thier odor is really offensive in higher quantities. However the smell of skunk can be cleaned to a reasonable level in a short amount of time, depending on what got "sprayed". For instance a couch, your gonna have to pitch it, the smell is there for good. If it's your dog, you might try tomato juice before pitching the d
      • Thank ghod my couch isn't as interested in attacking skunks as my dog is.
      • However the smell of skunk can be cleaned to a reasonable level in a short amount of time, depending on what got "sprayed".

        I wouldn't be so sure you can clean a building so easily. For example, if someone spills butyric acid in a school, the school gets closed for a week, and the strong smell remains for a long time. This was something people loved to do around here, until they started to get punished really harshly.

        Unless you build every single element to be watertight (prohibitive cost), any building is
      • what if the sunk sprays your whole house? which option will you chose then- the tomato juice, or ditching it? Because by your analogy, that would be the equivilent of someone covering an airport in known substances
      • Many airports are carpeted, at least in some areas, and cleaning up moving walkways is probably not that easy either, especially the rubber-tread ones. Then there's the luggage rack on the parking shuttle busses... If you've got a super-sensitive machine, and somebody wanted to overload it, there are way too many opportunities.

      • Re:Skunk Analogy (Score:4, Informative)

        by wowbagger ( 69688 ) on Tuesday October 04, 2005 @06:53AM (#13711212) Homepage Journal
        First of all: you don't use tomato juice as it is ineffective. The best way to neutralize mercaptan is to use a mix of baking soda and hydrogen peroxide solution, which will oxidize the mercaptan and destroy it, without staining whatever you are cleaning.

        Now, as for the explosive detector: I have a real problem with this, as if it is so sensitive as to be able to detect explosives after M. Random Terrorist has carefully cleaned up, it is probably sensitive enough to trigger on the residue left on me if I have done some home construction with my powder activated nail driver - which uses a .22 blank to drive nails into concrete.

        It will probably also trigger on any heart patient using, or even carrying, medical nitroglycerin. So, obviously, the next bunch of Al Qeidea terrorists will all have very convincing papers indicating they are heart patients.

    • Ok, here's something I've always wondered about. If you have these exquisitly sensitive machines that can detect even a few molecules of material, aren't they by the same token super-vulnerable to being attacked by "chaffing" or overloading?

      Its worse than that. You have to look at the false positive and negative rates for detection. If you have a test that is 99.9% specific, it will still fail in practical use in an airport, as that means that 1/1000 people will come up positive. (I think I have the right statistical measure here, but apologies if not). If you have alot of people going through you will still have a big problem -London had 1 000 000 FLIGHTS last year, so the equivalent of 1000 plane loads of people will come up positive per year. This is the same issue as using automatic detection of terrorists - Its one thing to match/no match a known ID (eg biometric passport) to a person, its another to match every passer by to every known terrorist.

      Coming back to chemical detection, this level of sensitivity will mean that every person who uses GTN for angina (commonly known as "Anginine" tablets or sprays) runs the risk of coming up positive. This amounts probably about a million people in US, and lots more elsewhere in the world. GTN (used in microgram doses in the treatment of poor blood supply to the heart; the precursor to a heart attack) is actually tri nitro glycerine, and is just a wee touch explosive in larger quantities.

      Just my 2c worth.

      Michael
      • I must look a little shady, because I *always* get 'randmonly selected' to be drug/bomb 'sniffed' at airports getting swabbed and waiting for a machine to go beep.

        The thing is i work in a chemical lab and often handle ammonium nitrate (plant tissue cell culture, great ingredient for pipe bombs i am lead to believe) yet have never had the machine go haywire at me. I always mention this to the nice security guys before the test so i hope they wont shoot first if it ever does go beep beep beep beep...

        Interesti
        • I must look a little shady, because I *always* get 'randmonly selected' to be drug/bomb 'sniffed' at airports getting swabbed and waiting for a machine to go beep.,/i>


          It' because you post on Slashdot!


          It's all a conspiracy!!!

        • Some advice; Never give a reason why you might test for explosive residue. Agree. Nod. Be on your way. They have to look like they're doing something, remember, and there simply aren't that many terrerists to go around.
        • So a friend of a friend is a firearms enthusiast, and had a duffle bag that he used to carry a bunch of guns and ammo when he went off shooting targets or Bambi's mother or whatever. Later he used that same duffle bag as carry-on luggage when he was flying somewhere, and he got lucky and got his bag swabbed by security. The machine was Not Happy about what it found, because in fact there _was_ explosive residue on the bag, and much hand inspection occurred. From what I remember, they did let him and his
      • I'd bet London searches the bags of over 1000 plane loads of people each year. This just gives them a reason to pick people rather than random :)
      • If you have a test that is 99.9% specific, it will still fail in practical use in an airport, as that means that 1/1000 people will come up positive.

        Some of the false positives may be true, but not a threat.

        I went to a wedding. Someone used a party popper. I'm now a positive. I shook hands with my neighbor. He just came home from the skeet field.We shook hands.. I picked my kids up from track. They used a starter pistol...
        I just walked in the park. They used weed and feed on the lawn....

        The background n
    • On the other hand, seems like, they are depending too much on residues left on the luggage by the handler who loaded the explosives. Couldn't it be a possibility that the bombs(what else?) have been neatly packed and the luggage loading handler hasn't come across any residue? Or let's say it's an assembly line where the next handler who hasn't touched the explosive closes the luggage.

      These people are so very much more insightful than an ordinary man on this subject. What are the chances they'll give their g
    • Isn't that a *huge* hole in any "super sensitive" chemical detection system?

      Hmmmm... chaffing, super-sensitive, huge hole.... is this a subliminal advertisement for condoms?

    • No, not really... (Score:4, Insightful)

      by xanthines-R-yummy ( 635710 ) on Monday October 03, 2005 @11:49PM (#13710131) Homepage Journal
      This is basically a portable mass spectrometer which is very very very accurate as well as sensitive. It's so accurate, it can give the identities of proteins as well its sequence. Now, this "portable" (I use quotes, because its as portable as mass spec machines can be) model probably won't be THAT accuarate, but probably more so than any other machine. It would be hard to get false positives out of this thing because of its accuracy.

      As for chaffing. I don't think this machine was meant to analyze the atmosphere of the entire airport. You just swab the bag and run it through the machine. There are ways to make the readings meaningless, but this would indicate some fishy behavior and cause for "other" means of investigation (ie "Bend over, son.").

      This would be a real boon for forensic science in general, if they've managed to make one for a relatively cheap price in addition to its size. Now you don't have to wait for the lab, you can bring it with you.

      • Re:No, not really... (Score:4, Funny)

        by Otto ( 17870 ) on Tuesday October 04, 2005 @12:03AM (#13710168) Homepage Journal
        As for chaffing. I don't think this machine was meant to analyze the atmosphere of the entire airport. You just swab the bag and run it through the machine.

        So when some guy spreads a lot of explosive dust all over the lobby, and you set your bag down and pick up some of that dust, then the machine will detect it and suddenly you've got a rubber gloved finger poking your ass?
        • You'd hope the screeners would wonder why they suddenly started getting a 100% hit rate and figure it out. I guess you'd hope more that you're not the first one to get, umm... searched, before they figure it out. ;)

          Besides, for precisely those reasons you'd swab the inside of bags as well as the outside.

          • Re:No, not really... (Score:5, Insightful)

            by fishbowl ( 7759 ) on Tuesday October 04, 2005 @01:46AM (#13710457)

            "You'd hope the screeners would wonder why they suddenly started getting a 100% hit rate and figure it out."

            You're overestimating the intuition possessed by law enforcement and security people.

        • Rubber? Here's the new glove... (Score:4, Funny)

          by ari_j ( 90255 ) on Tuesday October 04, 2005 @02:36AM (#13710597)
          Dude, you are entirely out of touch (bad pun, down!)...the Homeland Security Act changed the type of gloves that are used for airpot cavity searches. The new gloves [alleycatscratch.com] are not exactly rubber.
    • The local law enforcment started putting drug sniffing dogs in the major train stations here (A few places around Australia). The resulting protest had people squirting passers by (and walkways so people would walk through it) with bong water thus contaminating everyone there with dog-detectable levels of drugs...

      Not that i condone drug use, but that type of attack obviously does not require all of one's brain cells...

    • Re:Vulnerable to a "chaffing" attack? (Score:5, Informative)

      by Vellmont ( 569020 ) on Tuesday October 04, 2005 @01:35AM (#13710435) Homepage

      If you have these exquisitly sensitive machines that can detect even a few molecules of material, aren't they by the same token super-vulnerable to being attacked by "chaffing" or overloading?


      I think a few molecules might be a bit of an over statement. Nitroglycerin has a weight of 227g/mole. A mole is 6.02*10^23. So one molecule of nitroglycerin weighs 3.77 * 10^-22 grams.

      A picogram = 1*10^-12 grams.

      1*10^-12/(3.77*10^-22)=2.65* 10^9, or 2.65 billion molecules. That's a ways from a few.

      I think your point still is valid though. Could someone contaminate an area such that it couldn't be cleaned sufficiently? My guess is it probbably could be. You don't have to get rid of all the material, just enough so that you're below the level of detection.
    • When you install the machine and periodically thereafter you would "null" it. That means you adjust the needle to read zero when there is nothing in the detection chamber. I used an oxigen sensor resently. The first step is to expose it to just plain air and adjust it to read 21% (air is about 21% oxigen, 79% nitrogen) After doing this it can detect very small amounts In both cases you have to tell the machine "This is the normal background." After this the machine detects changes.

  • Oh great... (Score:5, Insightful)

    by Dr. Zowie ( 109983 ) <slashdot.deforest@org> on Monday October 03, 2005 @11:10PM (#13709963)
    now, when I fly, I have to worry not just about whether I handled matches or toy cap guns or went to the shooting range in the last 24 hours, but also whether my neighbor, my dog, or the taxi driver handled any nitrate-laden deli meat in the last month.
    • If you have a little one who's still in diapers, he or she leaks nitrates all over the place (in urine); my daughter's car seat used to set off explosives detectors even though we'd cleaned it.
    • As I said in an earlier post, this is a portable (relatively) mass spectrometer. It gives you very very accurate results and it will know the difference between your hotdog, gundpowder, and high explosives. I don't know enough about firecrackers and capguns to know if they'll be interpreted as explosives, though. Is gunpowder a common enough compound to be ignored? Down here in the south, people go hunting all the time and thus gun shot residue is all over them. Hopefully, the TSA won't enter gunpowder and
      • I believe that saltpeter used to be extracted from urine.
        So diapers could set off an ultra-sensative machine.

        Are you sure a mass spectrometer would distinguish between ammonia compounds (in Urine) + Potassium Nitrate and a high grade explosive like Ammonium Nitrate?

        It's been a while since I used one.

        • Re:Oh great... (Score:3, Insightful)

          by Walkiry ( 698192 )
          >Are you sure a mass spectrometer would distinguish between ammonia compounds (in Urine) + Potassium Nitrate and a high grade explosive like Ammonium Nitrate?

          The instrument? Yes. It all depends on what the software used to control when the detector beeps with a positive does. Let me explain.

          I work at a biotech company and we do a lot of mass spec stuff. The instruments we have are extremely accurate; the Q-tof mass spectrometer, for example, can resolve the isotopic peaks of a protein fragment very
    • IIRC, in Michael Crichton's book Congo, a rival company managed to put traces of turnip on employee's suitcases, forcing them to be detained as their baggage triggered sensors looking for illegal drug smuggling. Could there be many other false positives in nature concerning such equipment? I don't want to set off the radiation alarms because I had broccoli in my dinner.

    • I could only see this being useful in a line of filters. OK, so potential passenger #213 turns up positive for nitrates... focus or pay close attention to the next scan on passenger #213. A positive might not mean immediately detaining somebody or even much slowing their progress, but rather discreetly adding some checks as they go through the proces.

      Not that I really thing this won't be used stupidly, but hey one could hope.

  • Good luck to explosives manufacturers... (Score:4, Insightful)

    by DrInequality ( 521068 ) on Monday October 03, 2005 @11:10PM (#13709972) Homepage
    Good luck to explosives manufacturers - there go your chances of ever flying again!
    • Good luck to explosives manufacturers - there go your chances of ever flying again!

      Nonsense. It's not like they'll tackle you if you set off the machine -- you just can't go through the new super-fast check, so you get shunted into the line with the explosive-check wipe tab thingies and/or manual bag search... just like we *all* have to go through currently in most airports.

      It's all about speeding things up for most people -- yes, there are some who won't benefit, but they likely won't be worse off.
      • These won't replace the metal detectors, so I don't see them speeding up the search process. It's just another way for the screeners to search for another dangerous item (explosives) in addition to their metal detector search for weapons, and maybe even get even laxer in their X-Ray security (they already miss a high proportion of weapons in baggage, even in homeland security tests when they announce they're going to stash weapons)
      • There's the bigger question of whether it might, just *might* allow them to scale things back a little bit.

        I know the knee-jerk reaction is something akin to, "NO! TEH NEOCONZ WOULD NEVER DO THAT!!!!!111" but they did scale back the carry-on list recently. If it allowed better responses, they might be able to do fewer lame things. In addition, gunpowder residues might be able to stop people from bringing guns on planes, either intentionally or inadvertently. This doesn't mean that X-rays should go away,
    • Interestingly enough, most people who deal with explosive, pyrotechnics, etc, are registered with the Bureau of Alcohol, Tobacco, Firearms, and Explosives. My uncle does fireworks shows for Disney, and he often gets flagged by immigration whenever he enters or leaves the country. It typically means a bit longer delay than the unflagged person, but I imagine it would also give some measure of protection were his luggage to be detected to contain traces of explosives.
    • Good luck to explosives manufacturers - there go your chances of ever flying again!

      Not just manufacturers. In Western Australia, and presumably other parts of the world, most mines operate on a fly-in fly-out basis. People work onsite for a fortnight, then fly back to the city for a week to live with their families. A fairly large proportion of those are exposed to explosives or their by-products pretty much constantly while they're on site.

      The existing sniffers don't appear particularly sensitive. A few months ago I flew to site, worked with the shot crew for a day, including contact with ANFO emulsion and primers (TNT), then flew home. I expected the detector to pick it up, so I kept the work order on hand to explain the situation to security, but it didn't happen - not a peep.
      • Wouldn't those be charter flights though? and therefore not subject to inspection since they wouldn't be going through the terminal?
        • Wouldn't those be charter flights though?

          Not here. There used to be a lot of charters in the early days, and there are still a few, but FIFO has been in place for more than fifteen years in WA. The big carriers pretty quickly wised up to the revenue they were losing, so now most of those mining centres go through public airports.

          I'm not sure about the specific machines they're using, but the security person had what looked like a black plastic ping-pong paddle they waved over our clothes & luggage

    • Mine Workers (Score:3, Interesting)

      by adoll ( 184191 ) *
      I work in a mine. Nitrate laden dust is generated each day during the blast, and that dust gets everywhere and on everyone. So I have explosive residue in my clothes, hair and (probably) luggage.

      Guess what happens when my crew walks into the airport to fly into the minesite for our two week shift?

      -AD
    • Not to mention anyone that owns or fires a firearm (including anyone in the military), uses fertilizers, or takes any number of medications.

  • Other (ab)uses (Score:4, Interesting)

    by Kill Switch ( 182973 ) on Monday October 03, 2005 @11:14PM (#13709986)
    This is certain, just like the current TSA baggage screening, to be used to justify unlawful searches for drugs and other contraband. In fact, just like those baggage searches, this will undoubtedly become the #1 use of this technology, in fact I would bet good money that it is part of the intent of the people funding the development of this stuff. Just wait and see.

  • Quickest Means Possible (Score:4, Insightful)

    by Namronorman ( 901664 ) on Monday October 03, 2005 @11:16PM (#13709994)
    People fly because they want to go somewhere as fast as possible. With recent rules and regulations regarding airports, it's been becoming slower and slower to fly anywhere. Perhaps with the advancement in technology such as this, we can slowly relieve the stress of having to fly somewhere.

    • Re:Quickest Means Possible (Score:4, Interesting)

      by tgl ( 462237 ) on Tuesday October 04, 2005 @12:05AM (#13710176)
      No kidding. My recent business trips have mostly been Pittsburgh-to-and-from-Toronto. Door to door is about seven hours if I drive, and six hours if I fly (compared to about four hours before 9/11). Any more BS added onto the airport security check, and they lose this passenger permanently.
    • My dad already operates on the policy that if the destination is within 600 miles, he drives. The hassle and bureaucracy around flying have made it easier (and cheaper) just to drive. Though, gas prices hinder the price side of that equation a little bit...

  • Comment removed (Score:5, Funny)

    by account_deleted ( 4530225 ) on Monday October 03, 2005 @11:19PM (#13710009)
    Comment removed based on user account deletion

  • I'd say it's a good thing (Score:4, Insightful)

    by JavaRob ( 28971 ) on Monday October 03, 2005 @11:23PM (#13710024) Homepage Journal
    Yes, it's vulnerable to false positives -- for example, some construction workers are going to have to go through the slow way every time they fly.

    That's okay, though -- the positive thing here is that the initial check can be made much much faster. Most luggage and most people can just be zipped through (they'll hardly need to stop walking!)... which leaves more resources available to help the inevitable false positives get processed in the old, slow way (with the little explosive-check tabs, or a search by hand) as efficiently as possible.

    That's what matters, isn't it? Speeding the whole thing up, to make a reliable screening feasible.

    • Re:I'd say it's a good thing (Score:5, Insightful)

      by mgv ( 198488 ) <Nospam DOT 01 DO ... veltman DOT org> on Monday October 03, 2005 @11:36PM (#13710077) Homepage Journal
      Yes, it's vulnerable to false positives -- for example, some construction workers are going to have to go through the slow way every time they fly.

      That's okay, though -- the positive thing here is that the initial check can be made much much faster. Most luggage and most people can just be zipped through (they'll hardly need to stop walking!)... which leaves more resources available to help the inevitable false positives get processed in the old, slow way (with the little explosive-check tabs, or a search by hand) as efficiently as possible.

      That's what matters, isn't it? Speeding the whole thing up, to make a reliable screening feasible.

      Well, if it was used sensibly, that would be ok.

      The risks are still two fold:

      1) If the rate of false positives is low, alot of people will get through quickly. However, if you are one of the false positives, you may well get a very bad deal at the airport. Having been singled out on one trip to the US for no apparent reason (Probably because I took a "one way" flight so maybe they thought I was not planning to return!) I can assure you its no fun if you end up on the wrong end of a statistical test.

      2) If there are too many false positives, people get blase. After all, how many people in the history of all plane flight have put explosives on a plane? A few dozen maybe, probably less than 100 all up. But any test will likely have many more false positives, and this will mean that these people get ignored.

      3) You may still be using the wrong test, and get falsely reassured. After all, the September 11 hijackers would have passed a chemical detection test, so they would have been fine to board, no? Again, the real problem here wasn't that the test systems failed, it was the human management of the system - people weren't serious enough about the tests that were already in place.

      So, you end up putting alot of money into doing something that will help very few flights, incovenience a large total number of innocent people, and possibly not protect the public at all.

      After all, 3000 people died on September 11 due to a rare incident that is unlikely to ever happen again. 3000 people die every day in road accidents around the world. Which do you think gets society the best return for its time and energy? Yes, we have to stop terrorists, but just how far is it worth going here?

      Michael
      • people weren't serious enough about the tests that were already in place.

        No, the REAL problem was a policy of giving the hijackers whatever they wanted. Even with warnings that an attack like 9/11 was being planned, they were not changed.

        There's simply NO WAY you could hijack a loaded 747 with a boxcutter today, you'd have every able bodied person on the plane on top of you in no time flat.

        The flaw was not that they got box cutters on the plane, it was a flaw in our policy.

        Even pre-9/11 the same t
      • "After all, 3000 people died on September 11 due to a rare incident that is unlikely to ever happen again. 3000 people die every day in road accidents around the world. Which do you think gets society the best return for its time and energy? Yes, we have to stop terrorists, but just how far is it worth going here?"

        While I agree, it's worth considering that the 3000 people that die every day in road accidents don't manage to upset the United States economy. September 11th closed the skys for 3 days.

        Th
        • While I agree, it's worth considering that the 3000 people that die every day in road accidents don't manage to upset the United States economy. September 11th closed the skys for 3 days.

          I think you would find that both have an effect on the economy, one is just more obvious than the other, mostly because we don't hear about the vehicle stuff in the media.

          My point is just about having a balance in what we deal with. Terrorism, yes, it needs to be dealt with. But an excessive response is more damaging than

  • Hooray for Increased Accuracy (Score:4, Interesting)

    by OpenGLFan ( 56206 ) on Monday October 03, 2005 @11:25PM (#13710034) Homepage
    The last time I flew it was from a friend's outdoor wedding. Apparently the chemical sensors didn't like the outdoors-ness of my shoes, and because I was flying from scenic Colorado the security officers were used to this.
    TSA Agent: "Been outdoors much? Hiked through the woods?"
    Me: "Yes, some friends had a wedding in the middle of a field."
    TSA Agent: "Thought so. Happens all the time."

    They took my shoes and, after they failed to go boom, brought them back. I'm not bothered by this at all, but I wonder how many false positives people in these places have to deal with. Current detectors use neutron activation to detect the nitrogen in explosvies and, apparently, fertilizers used by the hotel grounds staff. Hopefully this will fix that particular problem.

  • Defeatable by multiple wrapping? (Score:3, Interesting)

    by Michael Woodhams ( 112247 ) on Monday October 03, 2005 @11:27PM (#13710043) Journal
    Here's a possible countermeasure.
    Construct your bomb. Shrink wrap it in plastic, taking care to get as little explosive residue on the outside as possible. Take it away from the bomb construction area, and wash the outside with strong soap etc. Give the result to another person.

    They take it to somewhere clean of explosives residue, shrink wrap it in another layer, and carefully wash it, then hand it off to a third person who repeats the entire process again.

    If you can reduce the explosives residues detectable by a factor of 100 or 1000 each time you do this, it can't take many iterations to reach undetectability - so long as the plastic is impervious to leakage. (Of course, then you need some way to program your hermetically sealed bomb. Also, you've forced many more people to become involved, which greatly increases the chance of betrayal before the bomb reaches its target.)

    If this is practical, it must already have been tried to defeat drug-sniffing dogs. Does anyone have any ideas?

    • Re:Defeatable by multiple wrapping? (Score:3, Funny)

      by Anonymous Coward
      Does anyone have any ideas?

      Yes. How about not trying to get any of the rest of us involved in your terrorist activity?

    • Re:Defeatable by multiple wrapping? (Score:5, Informative)

      by (negative video) ( 792072 ) <.moc.ocax-ocet. .ta. .em.> on Tuesday October 04, 2005 @12:00AM (#13710157)
      Construct your bomb. Shrink wrap it in plastic, taking care to get as little explosive residue on the outside as possible. [lather, rinse, repeat]
      Typical wrapping materials are rather porous, and several important explosives diffuse to some extent even through nonporous plastics. It is possible to seal explosives, but you have to really know what you are doing and even then a single microscopic dust particle can tip off the detector.

      Regarding the article, nanogram sensitivity (a trillion molecules of TNT) is utterly unimpressive. The vapor pressure of most explosives is so low that you need femtogram sensitivity to directly sense vapor. For an explosive like RDX that has an absurdly low vapor pressure, you really want attogram sensitivity (about a million molecules). You can heat up dust and surfaces to vaporize more explosive, but with a mass spectrometer you then run into a problem with selectivity: many ordinary boring compounds will have the same molecular weight as the explosive--the signal will be swamped by the noise. (Hmmm ... the article says they're using clever ionization, and tandem spectrometry. That helps a lot, but they still have a hell of a problem to solve.)

      The article says "'If you tried to detect a particular compound out of a mixture of thousands of different substances, you might begin to see the limitations of this method,' Talaty said. 'But real-world explosives are not that complex.'" What, people walk through airports with purified blocks of luggage? No! You get a suitcase drenched with sweat (which includes urea), solvents, ammonium nitrate from natural sources, perfumes, plasticizers, plastic monomers and short chain polymers, various mineral oils, a whole boat-load of volatiles from living things, and many more. The background signal is a freaking nightmare. I work in the explosive detection field, and I sure wish it was as easy as they say.

  • I wonder as to how useful this technology will be in the fight against terrorism. If you were a terrorist, would you carry your kit with you on the plane or would you aquire all the materials locally when you arrive at your destination? I imagine crime networks who plan to set off bombs have their own stockpile of ingredients that they get from their own country and build them when they need them. Or am I completely off the mark and some regions don't have access to certain materials and need to import/smug

    • Nah (Score:4, Insightful)

      by JavaRob ( 28971 ) on Monday October 03, 2005 @11:40PM (#13710092) Homepage Journal
      This is specifically about *airport* security. It's about keeping the planes safe. A terrorist seeking to blow up an airliner would have a tough time if he acquired his supplies at his destination.

      Of course, this brings up the point that even if we *did* manage to make planes super-safe, it remains simply impossible to protect all of the other soft targets all over the country. There are so many legitimate uses of explosive materials and the ingredients thereof that they can't all be secured, and any place that people are in large numbers is a potential target (including any school, stadium, office building, church, theater, etc.)... BUT Americans are nervous about planes after 9/11, so even though seeing the same attack again is unlikely, it makes constituents feel safer if we pump lots of money into airport security.

      It's a shame that this is how we go about "waging the war on terrorism", but that's how the world works.
      • Nope. That's how liberals go about waging the war on terrorism. Conservatives go about waging the war on terrorism by killing the f'ing terrorists.
    • The point is to explode the bomb on the plane. The reason planes are big targets is because one well placed bomb can take out 200 people... you would be hard pressed to kill so many people so easily elsewhere.

      But I agree with you, terrorists are not going to carry a bomb on a plane just to transport it. They will be built from local materials.

  • Even faster and cheaper (Score:5, Funny)

    by MiKM ( 752717 ) on Monday October 03, 2005 @11:30PM (#13710052)
    Fire. In all my experience as a pyromaniac, it has quickly and with 99.99% accuracy told me whether or not a substance was flammable.

  • Awareness of recent world events (Score:3, Informative)

    by caitsith01 ( 606117 ) on Monday October 03, 2005 @11:32PM (#13710061) Journal
    I'm surprised - very surprised - that there's no reference to the recent bombings in Bali in the article post. I mean, an article about instantly detecting explosives, three days after a serious terrorist attack... I can't help but feel that if it had been Hawaii and US citizens killed rather than Bali and Indonesian/Australian citizens killed this link would have been made.

    Anyway, this is an interesting development, but should not lead us to stop traditional methods of bomb detection, particularly searches and x-rays. These machines sound wonderful *so long as* you are using an explosive with which they are familiar.
    • It doesn't appear as if this machine would be useful in preventing Bali-type bombings. It sounds a little Draconian to check every piece luggage before entering a hotel or club, doesn't it? It would be much harder to examine every bag since they don't need to be tagged in anyway, like on an airplane. There, they weigh every back one by one, tag them, and then scan them (in some form or other) already. This obviously doesn't happen in hotels.

      You're right about not abandoning other methods of screening though

  • Just spray a fine aerosol containing traces of the target molecules. Everyone in the airport terminal will trigger the detectors...

  • Sorely Needed (Score:4, Insightful)

    by evil agent ( 918566 ) on Monday October 03, 2005 @11:39PM (#13710085)
    Not at airports, but subways. A local news station did a report [foxchicago.com] on the lack of security in Chicago's transit system, the CTA. According to the report:

    "More people rode the CTA today than will pass through O'hare and Midway over the entire Thanksgiving weekend. Yet the feds only provide a penny per passenger for security on buses or trains... compared to seven or eight bucks for each plane passenger."

    Doesn't really make sense, does it?

    • > the feds only provide a penny per passenger for security on buses or trains... compared to seven or eight bucks for each plane passenger.
      >
      > Doesn't really make sense, does it?

      Well, how much does a bus/train ticket cost? How about an airplane.

      Spending $8/passenger when the fare is only $1.25 doesn't make much sense, does it?
    • Yet the feds only provide a penny per passenger for security on buses or trains... compared to seven or eight bucks for each plane passenger."


      Nobody has yet diverted a subway full of fuel and crashed it into tall buildings or government buildings such as the Penatgon or Whitehouse.

      The threat posed by an airline is different than just the passanger list.
  • Comment removed based on user account deletion

  • TOF and chemical ionization; also, another article (Score:3, Informative)

    by Wilson_6500 ( 896824 ) on Tuesday October 04, 2005 @12:03AM (#13710169)
    Just in case there are any chemical physicists reading this...

    Assumedly, if this system is small enough to be backpack-sized, it's not a time-of-flight mass spec... right? The article's short on details on the actual mass spec--they seem to focus on their ionization technique more than on the spectrometer itself. But, then again, I guess that's where they're focusing their research.

    I'm not too impressed by this "reactive chemical spray" system, but maybe that's because I'd be more concerned with airborne rather than adsorbed/adhered molecules. It seems needlessly destructive to be spraying corrosives onto a person's luggage, unless we're talking, like, microgram quantities--although if you're just taking off a few molecular layers, and if the reactive components are rarefied in a less reactive gas, maybe it's not a big deal. Still, couldn't the same sort of "wipes" that you see used with modern airport ion mobility spectrometers be used to spare travelers from being exposed to these "reactive" compounds? Too, it seems a bad idea to require that airports keep machines sitting around in terminals with cylinders of reactive gasses. Once again, the quantities one would be dealing with are what concern me.

    They mention that their system suffers low selectivity. Selectivity, from what I understand, is pretty important in other fields, like nerve-gas detection, for instance, in order to force down false positives. What's keeping their system at a low rate of false positives as they claim?

    I suppose I could read their papers; this article really is just a press release, after all. Being a lasers sort of guy, I guess maybe I'm just biased towards photoionization.

    Also, even though this isn't really germane to my post here, I found another press release here [purdue.edu] is an article from just about a year ago that talks about this same DESI system.
  • Has it ever occurred to you that the war on terror's refined capacities to detect explosives could also be used to suppress a "rebellious" majority population? (that is to say, to enforce a dictatorship in the USA?)

    Just pointing out that the Bush administration has made more war against civil liberties, privacy and personal freedoms than any administration in my lifetime, and that Bush's election really looked like it was tampered, and that the 911 incident LOOKS ALOT LIKE HITLER'S RISE TO POWER. (read ab
    • You're insane. Absolutely utterly insane. You say the election looks tampered (which one? any evidence), imply that Bush caused 9/11 so he could solidify his power (he was already the President) and that he started the war in Iraq to train the troops to start a totalitarian state here.

      You're absolutely batshit insane.

    • It's posts like these... (Score:3, Insightful)

      by Anonymous Coward
      It's posts like these on /. and around the Internet that are starting to push me further and further away from the left side of politics and /. itself. For instance this story is about a specific technology used to find traces of chemicals. It doesn't have an inkling of political skewing about it.

      So now we have the parents post (currently modded +4 interesting) who claims that this new technology could be used to suppress the population. The parent never bothers to extrapolate on how this technology in the
    • Has it ever occurred to you that the war on terror's refined capacities to detect explosives could also be used to suppress a "rebellious" majority population? (that is to say, to enforce a dictatorship in the USA?)
      [Cut the rest of the political rant]

      How does this stuff get moderated up? People need to remember that driving a car is a privledge, not a right (and judges will be happy to remind you of that after you break a few driving laws). Similarly, when you get on any form of mass transportation (a
    • Has it ever occurred to you that the war on terror's refined capacities to detect explosives could also be used to suppress a "rebellious" majority population? (that is to say, to enforce a dictatorship in the USA?)

      If every time that something is put into place for the public safety or other benign purpose someone shouts "dictatorship", how many people will be paying attention when our civil liberties actually are taken away?
  • The equipment used by the Department of Homeland Paranoia is great... for detecting cheese* and kitty litter**. It seems to have a very poor track record of detecting explosives, guns or other nasties [nwsource.com]. I would be more impressed with the article (which I read, even though this is Slashdot) if it showed if the researchers had tested against substances that are chemically deceptively similar but which are definitely quite different.

    *Cheese releases fumes that many chemical sniffers will register as those of an

  • they'll just get one person to put it in one bag, then someone else to put it into another bag, then a third person to actually load this package into the real luggage... and a completely clean person to do the carrying. Then there'll be no traces on the outside of the actual luggage

  • it seems (Score:5, Insightful)

    by ColaMan ( 37550 ) on Tuesday October 04, 2005 @01:18AM (#13710394) Journal
    It seems to me that you could certainly circumvent this easily enough, with just some social engineering. Carry a lot of sniffer-activating things in your luggage. Travel 15 times on the route, or until you reliably know the security people.

    After 15 times, the conversation goes like so:

    You: "Hi Steve."
    Security: "Hi John."
    Detector : beeep! bip! beep! bip! beep! BEEEEEEEP!
    You: "Damn detector. Can't they tone those things down a little?"
    Security: "Every time you go through, these things go off."
    (opens luggage)
    Security: "Cheese, fertiliser, and trinitite. Again."
    You: "Well, a man's got to earn a living some way. Isn't there some form or something I can fill out to get out of this?"
    Security: "Nope. Everyone gets checked."
    (closes luggage)
    Security: "Off you go."

    Travel 15 times without the bomb so everyone gets to know you.
    The 16th time, travel with the bomb concealed somewhere in your luggage, but
    leave the cheese , fertiliser and trinitite on top. Odds are pretty good that you'll get on that plane.
  • Really, if you want to know if someone's a terrorist, just
    ask them! These people are evil, but no-ones evil enough
    to lie to a US airport security guard are they?!?
  • At least we'll be able to tell who has been near someone carrying explosives.

    If you work in a quarry, travelling's about to get a whole lot harder...

  • NH4NO3 == Explosive == Garden Fertilizer (Score:3, Interesting)

    by evilandi ( 2800 ) <andrew@aoakley.com> on Tuesday October 04, 2005 @04:25AM (#13710859) Homepage
    Great, so the system can detect farmers and gardeners [wikipedia.org] at longer ranges?

    The UK/France Channel Tunnel [wikipedia.org] security checks use guards with cotton gloves to wipe around the inside of passengers' cars. The gloves are then analysed by computer- this means a complete explosives search can be done in two minutes, rather than having to rip the car's body panels apart. Unfortunately, this has a huge false positive rate for anyone who's been in contact with fertilizers; my uncle, who is a keen gardener, got questioned at the end of an SMG for quite a while before he mentioned that he'd been carrying bags of nitrate fertilzer in his trunk just a few days prior.

    Whilst that's inconvenient for gardeners and farmers, its also a safety risk for the rest of the passengers; after all, it gives a convenient alibi for saboteurs. I certainly wouldn't want to board a train in the same carriage as the Falls Road [wikipedia.org] Allotment Society [wikipedia.org].

    These toys provide useful indicators of where to concentrate resources on, but they should never replace good old fashioned trained security staff.

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