Actually, usually the only variable is the amount of time the beam is running. The power emitted is set by the size of the power supply and the antenna array. You'll notice that with your microwave on the shelf, the only variable is time, not really emitter power.

That's because the emission of a radar or other microwave emitter is resonant at the frequency of the waveguide. Very simply put, there usually isn't much spare capacity. You can't kill somebody with a police radar or laser. It's a physics thing.

Think about it. What is necessary to double the power output? Is the power supply really twice the size it needs to be? Three times? How much more power is needed above the scanner's threshold, at which it produces a beam for which clothing is transparent - an inherent property of the beam's makeup?

In this case, show me the manufacturer's specifications. That's the information source needed to avoid some sensational talking head trying to sell Kleenex.

Actually if I was a pilot or even air crew I would refuse to be scanned. There is a set load of how much radiation a person should be exposed to overtime. That load can raised by having an X-Ray at the doctor's, eating a banana, and air traveling among other things. The government want to already give a group of people who get exposed daily to radiation to even more. I would not be surprised in a raise in air crew suffering higher cancer rates. Also frequent travelers I think also opt out too.

In the 80's there was a computerized radiation therapy machine called the Therac-25 that overdosed at least 6 people with resultant deaths and serious injuries. The culprit was found to be bad software.

http://courses.cs.vt.edu/cs3604/lib/Therac_25/Therac_1.html

Asbestos was generally recognized as safe. The FDA approved, among other things, thiolidamide. I might not have a job, if it weren't for the fact that any sufficiently complex software has flaws.

I would like to trust them, but I am neither that stupid nor that naive. Regardless of the safety aspect, that is one indignity I plan to forego.

There was a study of police in relation to cancers from radar guns.

http://www.osha.gov/SLTC/radiofrequencyradiation/fnradpub.html

This group would include cockpit crews, anyone holding a government security clearance, anyone already a member of the Department of Homeland Security's Global Entry, Sentri, and Nexus, and anyone who applied and was accepted into a new Trusted Traveler program.

I worked on a SAC base (bomber base) in the late '80's. About half the base had a secret clearance. I wouldn't say I would worry about them, but that doesn't automatically make them the best either. Just saying.

"You'll notice that with your microwave on the shelf, the only variable is time, not really emitter power."

You can changed the power of the microwave. It takes pressing a few more buttons and generally there's no need to (I only do it when I need to melt butter), but you can definately turn the power down.

Now I know next to nothing about how microwave emitters work so there may be another mechanism at work.

Elle, on most microwave ovens, when you set the "power level", all it's really doing is cycling the beam on and off during cooking. You can usually see and hear this happening. Some high-end microwave ovens have true variable-power systems.

Rad, I figured the author was thinking about the Therac-25. Of course, that machine was designed to produce far higher radiation levels. The airport X-ray backscatter machines I'm sure aren't capable of producing anywhere near that power level. I read something last night that stated that the typical exposure is about 1/100 of the average chest X-ray, which means it's probably harmless for someone who flies a few times a year. Of course, the problem comes for frequent fliers and especially flight crews, who have to go through the scanner 4-5 times a week.

If the choice is getting exposed to radiation or getting felt up by some TSA pervert, guess I’ll pick the pervert every time.

1. Trusted Travelers, who have passed a background check and are issued a biometric ID card that proves (when they arrive at the security checkpoint) that they are the person who was cleared.

Oh, boy. That's a whole lot of trouble. Sure, they pass their background check now, but what about 5 years down the road? or a new jihadi recruit who doesn't have any red flags just yet? or the person approached with if you do this one thing for us, we won't kill your family.

Trusted Travelers == give us money and we'll let you breeze thru security.

The airport X-ray backscatter machines I'm sure

I'm glad that you are sure, would be nice if the government released the technical specs to non govrnment sources for indepndent varification

Thanks Cousin Dave. I appreciate the info.

The Rapiscan Backscatter imaging device is capable of creating photographic quality images of the body beneath clothing. The software is used strictly to distort "private" areas, NOT to set exposure levels for the device. William, as an alleged software developer, should know better.

The Rapiscan creates ionizing radiation at very low levels (0.05 uSv) equivalent to about 42 minutes of exposure to the ionizing radiation that surrounds us daily, or 4 minutes of normal air travel (more ionizing radiation exists at high altitudes), or 1/1,000th of a chest X-Ray.

The device has been studied extensively for the past 20 years by many independent agencies (including the American College of Radiology.) The fear over this thing is simply ungrounded and equivalent to the fear of electric blankets, cell phones, and high tension wires.

I'm sure this will do nothing to assuage the fears of the paranoid Luddites. The concern about this device should not be the technology, but rather the invasion of privacy.

The Therac-25 generated a beam with an energy of 25 million electron volts, and could focus this energy on a tiny area of the body. So there was a possibility of massive, lethal overdoses if anything went wrong.

By contrast, the Rapiscan, SmartCheck, and other brands of airport backscatter scanners have energies of 120 kV or less. This paper gives a maximum X-ray energy of 100 to 120 kV, with an average of 80 kV:

http://www.public.asu.edu/~atppr/images/RPD-Manuscript.pdf

For comparison, cathode ray tubes in color TVs generate energies of 30 kV or so. People are only in these things for a few seconds at a time. They just don't have the power to fry you. Like AllenS said, it's the fact that perverts in TSA uniforms will be able to see exactly what little girls look like under their clothes, and that the only alternative they offer is legalized sexual assault, that should really get people upset.

This is what you get for letting Political Correctness rule the day. We get all strung out attempting not to hurt anyone's feelings, meanwhile the killers are laughing their asses off watching America slip into a Police State. I don't need to prove in any way shape or form that I'm not a freakin' terrorist, it's bullshit! I resent our government resorting to this one size fits all, "we're keeping you safe" cock and bull story. When we allow policies that promote security over Liberty we no longer deserve the latter.

I don't need to prove in any way shape or form that I'm not a freakin' terrorist, it's bullshit! I resent our government resorting to this one size fits all, "we're keeping you safe" cock and bull story.

As if there was no downside to a half dozen panty bombers getting it right on the same day.

First - I agree with Martin and others who view this as primarily a privacy violation. However, I think there's something deeper and more sinister going on. The extended grope is clearly intended to get everyone to fall in line and do what the nice people in the uniforms tell you to do.

Be a good little sheep, and we'll leave you alone. For now. Make a ruckus, and we'll humiliate you in front of everyone.

@Skipper - the problem is they didn't start looking for panty bombers until one failed. After that, they won't try that again, they'll try something else we aren't looking for.

Again, we're looking for bombs, not bombers.

Brian, I have to say that the TSA's smug, prissy public statements about this issue are going a long way towards proving your point.

The Therac-25 was a complex electromechanical system. They actually *miswired* the thing to attempt to reproduce the problem.

The Therac-25 was also 25 years ago. If the software developers of the scattering machines don't color *all* the squares, they haven't done their job properly. There should also be very reliable audit capability in the machines.

Martin, voltage, no matter how many millions, is not a measure of exposure to radiation. Please fix your units / produce the equivalence developed by the device you're citing.

You'll be looking for "rad", in terms of ergs deposited per gram of body tissue, when you get to the final effect. Something like that.

I believe that the primary concerns with the use of these devices is on privacy, but I'd also like to throw out some concerns with the health issue side.

I've spent the last few years recovering - and I've had more than the usual amounts of x-rays, CT scans, and MRIs. To top it off, my job places me in areas of NORM and TENORM exposure. http://en.wikipedia.org/wiki/Naturally_occurring_radioactive_material
The flight scanners add yet another variable to my cumulative radiation exposure. I really try to limit my point exposures whenever I can, which unfortunately leaves the grope option for flights.
I sincerely doubt that the TSA person at a security checkpoint would care about my reasons for an 'opt out.' I'd just be thought of as another inconvenience in their work day.

@Skipper - the problem is they didn't start looking for panty bombers until one failed. After that, they won't try that again, they'll try something else we aren't looking for.

Again, we're looking for bombs, not bombers.

And the point of the Rapiscan is?

It seems the one great contribution of Islam is inventive immolation.

It seems that the combination of X-ray machines and body scanners will make it extremely difficult to use the huge number of passengers as cover to get any meaningful amount of explosives on an airplane.

I don't care to think about the consequences of neolithic nitwits bringing down a half dozen airplanes on the same day.

My apologies. Each "kV" in my previous comment should be "keV", referring to X-ray energies, not voltages. Pages 12 - 14 of the pdf I linked go through the calculation of radiation dose (energy deposited per unit mass) for backscatter scanners, and provide a table showing how energy absorbed & absorption coefficients vary with x-ray energy for muscle.

Skipper: "It seems that the combination of X-ray machines and body scanners will make it extremely difficult to use the huge number of passengers as cover to get any meaningful amount of explosives on an airplane."

Not at all. I can think of a number of ways it could be done. For instance, what if the clothing itself was the explosive? Have you ever heard of nitrocelluose? The TSA's technological approach is all wrong. Their scanners are still looking for edged weapons! They're several tactical generations behind. What they need to be developing and using is explosive scanners/sniffers.

"It seems that the combination of X-ray machines and body scanners will make it extremely difficult to use the huge number of passengers as cover to get any meaningful amount of explosives on an airplane."

They wouldn't be able to detect the panty bomber and certainly not if a suspect had stuffed the explosives up in themselves (neither would the groping). If they were really worried about explosives they'd be walking bomb dogs up and down the line. No tech can beat a dog's nose.

This is just so much performance art, and now it's starting to piss people off.

Cousin Dave:

What they need to be developing and using is explosive scanners/sniffers.

As Elle said, they've already been invented, and quite well. They're called Dogs.

The dog is pretty much a smelling machine on feet. They can discern even the faintest whiff of something in a cloud of other smells.

Plus, when a dog smells your crotch, you can be sure they aren't doing it to humiliate you or to get their jollies.

Not only that, people LOVE sniffer dogs! For instance, Roscoe the Bed Bug Beagle is a star in New York, with his own Facebook page & website:

http://www.roscoethebedbugdog.com/

Just the sight of him inspires people with confidence that their bed bug problems are on their way to being solved. Nobody loves being exposed to radiation, or having their granny get groped by bumbling fools, or having their kids star in a peep show. Well-trained sniffer dogs with skilled handlers going up & down the line of waiting passengers would send exactly the message you'd think the TSA would want to send - we're on guard, we're looking out for you. They're deliberately sending a very different message.

"Plus, when a dog smells your crotch, you can be sure they aren't doing it to humiliate you or to get their jollies."

That doesn't happen until they start to hump your leg.

"That doesn't happen until they start to hump your leg."

I guess that's still better than having a TSA employee hump your leg...

Not at all. I can think of a number of ways it could be done. For instance, what if the clothing itself was the explosive? Have you ever heard of nitrocelluose?

Yes, I have. And, SFAIK, nitrocellulose in the form of clothing will burn, but not explode.

They wouldn't be able to detect the panty bomber and certainly not if a suspect had stuffed the explosives up in themselves (neither would the groping).

Nor would the dogs.

SFAIK, again, explosives with enough yield to come in both a small package and have sufficient punch to threaten an airplane require a non-trivial means of ignition.

Which a rapiscan type machine can see.

http://www.youtube.com/watch?v=eCk0lYB_8c0

And that is just a few grams
1 ounce = 28.3 grams

Not sure how much ceasium is just laying around but given the TSA doesnt bother to open the 1 quart bag if none of the bottles are over four ounces, but it seems to me you could easily get a pound on board a plane.

Now it might no be enough to blow the plane out of the sky - but it would cause every plane in america to be grounded while the feds tried to figure out what was going on

http://www.youtube.com/watch?v=eCk0lYB_8c0

And that is just a few grams
1 ounce = 28.3 grams

Not sure how much ceasium is just laying around but given the TSA doesnt bother to open the 1 quart bag if none of the bottles are over four ounces, but it seems to me you could easily get a pound on board a plane.

Now it might no be enough to blow the plane out of the sky - but it would cause every plane in america to be grounded while the feds tried to figure out what was going on