Posted on 05/02/2008 2:52:54 PM PDT by anymouse
Using data recovered from a damaged computer hard-drive that was aboard the ill-fated Space Shuttle Columbia in 2003, scientists have recently learned more about why the act of shaking a material can quickly transform it into something completely different.
One of the best examples of this phenomenon is ordinary ketchup. Shake the bottle and the semi-solid paste becomes a runny liquid. Food scientists do the shaking in a controlled way by putting ketchup (and other processed foods) into a rheometer (rheo, meaning "flow") to see how its viscosity -- the scientific word for stickiness -- decreases when shaken.
Robert Berg and his colleagues at the National Institute of Standards and Technology in Gaithersburg, MD., wanted to do more than measure viscosity. They wanted to know why the changes happen through "shear thinning," a phenomenon in which agitation enhances a force that cuts across weak attachments among atoms or molecules.
Understanding shear thinning is a big deal in the industrial world of processed foods, polymers, and paints. For instance, motor oil's viscosity can be degraded by the movement of engine parts, and the application of paint to a surface can be easy or hard depending on the manner of the brushstroke.
Zero gravity
To better understand the microscopic relation between viscosity and shear thinning, the NIST scientists looked at how the thinning works in an unusual fluid -- the gas xenon [used to power some space probes]. The trick is, xenon's own weight -- as light as it is -- still can compress the sample of the gas enough to throw off the delicate measurements that were needed.
To do a proper study, the experiment needed a zero-gravity environment. And so up it went in Columbia.
But Columbia's mission ended when insulation tiles on the leading edge of the left wing, damaged during launch, failed upon reentry. The craft burned up and disintegrated, killing the seven astronauts on board. Some of the data from the xenon experiment had been down-linked before the shuttle was destroyed, but the rest were stuck on the hard drive that fell to earth along with Columbia.
Fortunately, NASA's recovery team found the hard drive among the debris that was scattered for hundreds of miles across Texas and Louisiana. The data on the disk were retrieved by a company that specializes in recovering information from the kind of disk crashes that happen every day here on Earth.
The package in which the experiment itself took place was also found. It was at the heart of a series of concentric shells, the outermost of which had burned up. The cell containing the xenon atoms, however, was intact. None of the atoms had escaped.
Xenon, a loner
Xenon is one of those atoms that doesn't like to associate or react with other atoms. The researchers set up the Columbia experiment to look at how xenon behaves when, under exact conditions of pressure and temperature, it exists midway between two fluid states.
Why go to the trouble of getting xenon atoms into just the right pressure conditions? Xenon is a gas, whereas ketchup and most interesting fluids consist of liquids and pastes. The answer is that the shear thinning process becomes possible for even simple fluids like pressurized xenon at the special critical point. What is learned from the simple fluid might also apply to ketchup.
While in orbit aboard Columbia, the xenon was gently stirred by a fine mesh, a sort of tiny tennis racket. The experiment was a success. Stirring harder decreased the viscosity, confirming a decades-long theory about the relation between shear thinning and stirring. They published their results in a recent issue of Physical Review E.
Nobody knew - but they were damn well going to spend billions of dollars on it anyway.
Gee, I wish scientific urinalists would at least learn a little science before they report.
Until now, I was under the mistaken impression that viscosity meant thickness and rate of flow, not stickiness. I guess that 10W-40 viscosity motor oil I change to for summer driving is because it is stickier than the 10W-30 I use the rest of the year rather than because it holds its flow rate better.
From the article, how about when and why a motor oil fails? Or making a paint that sticks to a brush, but flows off during the application?
As an aside, I wish I had hard drives that were that durable.
What are you talking about?
I agree. Super Glue has a very low viscosity (flows like a stuck pig) but is very freeking sticky. The MSM loons are at it again.
We knew that, because when you shake a non-pouring upside-down bottle of ketchup, it suddenly comes out in a hurry, all over you.
Wow, if a hard drive’s data can still be recovered after being burned in re-entry, I guess that casts some doubt into whether one can really destroy a hard drive simply by taking a hammer to it, or shooting it with a gun. Incredible what can be done to recover data!
Great. Just what we need. Snooty atoms.
It wasn’t burned.
Ketchup ketchup in a bottle
None will pour and then a lot’ll
We spent billions on this?
What's your source?
Ogden Nash, or Burma-Shave?
If you consider that the drive was powered off with the read/write heads parked ,, all data successfully written before the breakup... the drive was cocooned inside lightweight metal boxes within boxes as the experiment was self contained.. The experiment box may have started at 14,000 mph but it would have slowed to whatever “terminal velocity” would be for that ,, maybe 200mph at impact... so depending on the orientation at impact you may have had a head crash at the “parked head” location or you may have had the heads skate across the disks without the air cushion you would have with a running drive... the main thing was the disk wasn’t rotating, any data lost would have been just a byte or two per track... more than likely the worst damage was to the disk controller card.. simply disassembling the drive and swapping the platters into another drive of the same model would probably recover nearly all the data.
She a poet,
who didn't know it...
But she found out
because her feet became,
LongFellows...
Is Tereeeeeza Heinz involved in this?
FMCDH(BITS)
I think they're just misunderstood.
That's good stuff to know.
FMCDH(BITS)
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