Slashdot Mirror

← Back to Stories (view on slashdot.org)

Fast, Accurate Detection of Explosives

Posted by ScuttleMonkey on 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.'"

29 of 270 comments (clear)

  1. Vulnerable to a "chaffing" attack? by patniemeyer · · Score: 5, Insightful

    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?

    1. Re:Vulnerable to a "chaffing" attack? by mgv · · Score: 4, Informative

      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

      --
      There is no cryptographic solution to the problem where the intended receiver and the attacker are the same entity.
    2. Re:Vulnerable to a "chaffing" attack? by 6th+time+lucky · · Score: 3, Interesting

      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...

    3. Re:Vulnerable to a "chaffing" attack? by Vellmont · · Score: 4, Informative


      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.

      --
      AccountKiller
    4. Re:Vulnerable to a "chaffing" attack? by ChrisA90278 · · Score: 3, Informative

      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.

    5. Re:Vulnerable to a "chaffing" attack? by pe1chl · · Score: 4, Insightful

      The whole principle of the detector is that it is not possible to clean it sufficiently...
      If that were possible, the terrorists could clean their stuff before having it checked.

  2. Oh great... by Dr.+Zowie · · Score: 5, Insightful

    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.

    1. Re:Oh great... by fishbowl · · Score: 5, Interesting


      >I thought carrying an unloaded pistol in your checked baggage was legal anyway.

      It depends on your destination, as always.

      You cannot fly into Massachussetts or DC, for instance. But I routinely take firearms on trips from Arizona to Oregon. There's a little drill at the baggage check, where you have to say certain words verbatim; the weapon has to be unloaded in a locked container, and any ammo has to be in the packaging as it came from the factory and also locked.

      There's always a little stressful situation at the counter where you have to take the gun out of the box, show them it's unloaded (open the revolver, rack the slide, etc.). Invariably, there's someone in line behind me that freaks out on this.

      Then you have to carry your bag to a special X-Ray line, and tell the X-Ray guy what's in there. They make sure you have the only key.

      At the destination, nobody ever seems to care, or know, what's in the suitcase, and rifle cases are always just piled with the golf bags.

      But there's nothing to it. Get this -- in AZ, it's perfectly legal to wear a pistol openly in a holster on your hip, in the airport, all the way to the first checkpoint (but absolutely not past it!).

      --
      -fb Everything not expressly forbidden is now mandatory.
  3. Good luck to explosives manufacturers... by DrInequality · · Score: 4, Insightful

    Good luck to explosives manufacturers - there go your chances of ever flying again!

    --
    DROS - Open-Source Robot Software
    1. Re:Good luck to explosives manufacturers... by ozmanjusri · · Score: 4, Interesting

      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.

      --
      "I've got more toys than Teruhisa Kitahara."
  4. Other (ab)uses by Kill+Switch · · Score: 4, Interesting

    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.

  5. Quickest Means Possible by Namronorman · · Score: 4, Insightful

    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.

    --
    $fortune
    Tomorrow has been canceled due to lack of interest.
    1. Re:Quickest Means Possible by tgl · · Score: 4, Interesting

      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.

  6. Oh, this should be fun. by DrEldarion · · Score: 5, Funny

    Expect every airport to be shut down for a week after the 4th of July.

  7. I'd say it's a good thing by JavaRob · · Score: 3, Insightful

    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.

    1. Re:I'd say it's a good thing by mgv · · Score: 4, Insightful

      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

      --
      There is no cryptographic solution to the problem where the intended receiver and the attacker are the same entity.
  8. Hooray for Increased Accuracy by OpenGLFan · · Score: 3, Interesting

    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.

  9. Even faster and cheaper by MiKM · · Score: 5, Funny

    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.

  10. Re:Defeatable by multiple wrapping? by Anonymous Coward · · Score: 3, Funny

    Does anyone have any ideas?

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

  11. Sorely Needed by evil+agent · · Score: 4, Insightful
    Not at airports, but subways. A local news station did a report 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?

    --
    End transmission.
  12. Nah by JavaRob · · Score: 3, Insightful

    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.

  13. No, not really... by xanthines-R-yummy · · Score: 3, Insightful
    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.

    1. Re:No, not really... by Otto · · Score: 3, Funny

      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?

      --
      - Give a man a fire and he's warm for a day, but set him on fire and he's warm for the rest of his life.
    2. Re:No, not really... by fishbowl · · Score: 5, Insightful


      "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.

      --
      -fb Everything not expressly forbidden is now mandatory.
  14. Re:Defeatable by multiple wrapping? by (negative+video) · · Score: 4, Informative
    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.

  15. it seems by ColaMan · · Score: 4, Insightful

    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.

    --

    You are in a twisty maze of processor lines, all alike.
    There is a lot of hype here.
  16. Rubber? Here's the new glove... by ari_j · · Score: 3, Funny

    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 are not exactly rubber.

  17. It's posts like these... by Anonymous Coward · · Score: 3, Insightful

    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 article could be used for the purpose of suppression of course. We are just supposed to accept the fact that it will sometime in the future under the guise of a totalitarian government. Notice how we are supposed to just accept his didactic terms the parent lays out? That's called propaganda.

    The parent is why I'm moving away from the left. It seems the lefts (and /.) groupthink supports irrationality, conspiracy theory and poorly thought out historical analogies. Is the Bush admin doing a bad job? Yes I totally agree. But I don't think we are ever going to be taken serious in our claims or actions to change the system when some of our fellow progressives are completely irrational in the way that they present themselves.

    The parent post is pretty offtopic from the subject at hand but I had to respond.

  18. Re:Skunk Analogy by wowbagger · · Score: 3, Informative

    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.

    --
    www.eFax.com are spammers