Worcester

I was recently reading how Satellites can detect certain chemicals such as water or oxygen on planets millions of miles away.

I does make you wonder why airport security can not distinguish between water and dangerous or explosive chemicals? While so much effort is put into looking for harmless items is there a danger of missing more dangerous items.

BStrauss3

Because the detection is based on absorbtion and/or light reflection from open water. The water in your luggage is within a sealed container and doesn't reflect light.


Every star emits a distinct spectrum with the peaks based on the abundance of different elements within the star. When that light passes through a planet's atmosphere, certain frequencies of that light is absorbed by the water vapor and so the light of the star changes.

rolling_stone

They can, watch when a family comes in with baby bottles containing milk and they put the bottle in a machine that determines if it is safe or not. The problem is that it has to be a clear container and...you think the line is long now, think how long it would be if they had to do a water check with nearly every single person in line.

FlyingHoustonian

That's ok, in 1969 Astronauts on the moon could talk to Houston and vice-versa fairly clearly yet with Wind Tele I cannot hear clearly on my mobile half-way across Catania. American Telephone and Telegraph is not much better stateside

(yes I know they are different bands, just having a laugh...)

spd476

They wouldn't need to check everyone. They could only test liquids they think are suspicious along with other random tests. It would be like when the WTMD randomly alarms and that triggers a bag swab.

Loren Pechtel

They can detect exposed water where it's spectral lines can be seen. That's a very different issue than figuring out what's inside a closed container.

lupine

I'm thinking they'd have more luck hiring old grannies with dowsing switches.

FliesWay2Much

Just look at all this water that our weather satellites detect in the earth's atmosphere every single second!



The TSA has a hard time detecting all of this water because it's constantly moving!

Water on the move all over America!!!

SeriouslyLost

Airport security can distinguish between them if they want. The tech exists, and has done for at least a decade or so. As for the second question, no, there is no danger of the type claimed judging by how ineffective security generally is and the lack of planes falling out of the sky.

KRSW

I'm still wondering why TSA is still around and is even worse than when it began. They've stopped ZERO terrorists and have cost billions, not to mention the billions (trillions?) of dollars of avoided travel because of the B.S. It certainly has reduced the amount I and my coworkers have traveled.

mikeef

Because nobody who counts has any incentive to see them go. Congress will never dump them, no matter how ineffective they are, because nobody wants to be the one who voted to rid the world of the TSA and then see a terrorist attack the next day. The airlines have a similar problem-they don't want to be seen as being "soft on terrorism" because no CEO wants to end up in front of Congress and hear, "You told us to get rid of the TSA and we did. Now looked what happened! How much in profits did you generate last year?" The media is bought and paid for. The TSA itself loves the funding and power it gets. It does not exist to provide security. That is incidental. It exists for the single purpose of self-perpetuation.

Mike

dstrahm

What I heard years ago when they first started the policy was that it was to prevent people from bringing clear weapon items on board. It was felt that a number of glass or clear plastic sharp objects could be contained in the water and escape detection under examination. It sounded plausible at the time, but somewhat misguided since you would be able to conceal similar items inside clothing anyway.

STBCypriot

That's a new one. I was under the impression the issue was that separate components of an explosive solution could be brought on the plane and subsequently mixed to cause an explosion and TSA figured (I would have like to see those calculations) that limiting the quantities of liquids to 100mL in a 1 qt bag would not be sufficient to cause any damage.

roberino

The issue is not detecting water per se, but detecting things that are not water, and there are two problems with that.

Firstly, while there might be a spectroscopic library for explosives, drugs and other banned substances it is not exhaustive and it may be interfered with by innocuous substances.

Secondly, liquids are enclosed in a polycarbonate container (usually) and that has a spectrum of its own that would overpower the spectrum of its contents to a certain degree, while simultaneously shielding the contents from the excitation source needed to make spectroscopy work under those circumstances.