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Disasters Caused By Measurement Mismatches: UL?

Nosmo King

I'm not a cat
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Was it an UL or do i remember one deep space/mars mission waa fubar because the Europeans and US were both working on it together and the US was using imperial measurements and Europe metric?
 
Was it an UL or do i remember one deep space/mars mission waa fubar because the Europeans and US were both working on it together and the US was using imperial measurements and Europe metric?

I suspect you're referring to the 1999 loss of the Mars Climate Orbiter. There was no European involvement. The cause related to software employed for mission monitoring back on earth. NASA specifications called for certain performance data to be generated and processed in metric units, but a contractor's software package was forwarding data in US customary / imperial units.

https://en.wikipedia.org/wiki/Mars_Climate_Orbiter
 
I suspect you're referring to the 1999 loss of the Mars Climate Orbiter. There was no European involvement. The cause related to software employed for mission monitoring back on earth. NASA specifications called for certain performance data to be generated and processed in metric units, but a contractor's software package was forwarding data in US customary / imperial units.

https://en.wikipedia.org/wiki/Mars_Climate_Orbiter
Wasn't the mixup between metric and Imperial on the Hubble telescope?
 
Wasn't the mixup between metric and Imperial on the Hubble telescope?

If you're referring to Hubble's initial problems preventing it from precisely focusing - no. That problem was caused by an incorrectly ground mirror and a series of mistakes in evaluating the mirror prior to installation and launch - none of which were attributed to any mismatch or conversion errors between metric and imperial units.
 
I've always been amazed at the precision (albeit slightly inaccurate precision) that the Hubble mirror was manufactured to - not because I doubted it could be done, but because it was correctly expected to survive the stresses of being launched by rocket.
 
Not measurement but a hyphen....

On July 22, 1962, at 9:20 PM, the Mariner I sat idly on its platform, ready to make history. After investing years of construction, calculation, and funding, NASA had high hopes that its rocket would successfully conduct a flyby survey of Venus, thus shifting the Space Race’s momentum back to the home front. In every way, it was poised to set a space travel precedent.
But when the rocket embarked, it was clear there’d be no cause for celebration: less than 5 minutes into flight, Mariner I exploded, setting back the U.S. government $80 million ($630 million in 2014 dollars). The root cause for this disaster? A lone omitted hyphen, somewhere deep in hand-transcribed mathematical code.

https://priceonomics.com/the-typo-that-destroyed-a-space-shuttle/
 
ARIANE 5 ROCKET SELF-DESTRUCTS

The mistake: An old piece of software code couldn’t store an unexpectedly large integer, triggering a self-destruct.

Estimated cost: $370-500 million

What happened: The European Space Agency’s Ariane 5 rocket was designed to vault Europe to the head of space exploration and industry, though its guidance system was running some of the same computer code as its older and slower sibling, Ariane 4. At 36.7 seconds into the launch, the guidance computer routinely attempted to convert the sideways velocity of the rocket from a 64-bit “floating point” format to 16-bit “signed integer” format. But in this case—with Ariane 5’s faster rocket—the velocity conversion generated a number that was too big to be represented by a 16-bit signed integer (which can only store values up to 32,767.) The nozzles of two solid rocket boosters and an engine suddenly swung out of position, nearly detaching the boosters from the body of the rocket, triggering a self-destruct mechanism; the rocket disintegrated 39 seconds into its maiden flight, destroying several extremely expensive satellites.

Ordinarily, “when a program converts data from one form to another, the conversions are protected by extra lines of code that watch for errors and recover gracefully,” science historian James Gleick wrote in the New York Times. “Indeed, many of the data conversions in the guidance system’s programming included such protection. But in this case, the programmers had decided that this particular velocity figure would never be large enough to cause trouble. After all, it never had been before. Unluckily, Ariane 5 was a faster rocket than Ariane 4.”

https://www.worldsciencefestival.com/2014/11/six-tiny-scientific-mistakes-created-huge-disasters/
 
The story of the Gimli Glider fits in here, though I suppose strictly speaking it was a near disaster. It's a famous story of an airliner running out of fuel mid-flight, in large part because of confusion over how much fuel was needed, and how much was in the plane's tanks because of a recent change in the units used. This fellow does a brilliant job of explaining a very complex "perfect storm" of mistakes, incorrect assumptions, technical failures, and happenstance. Fortunately, the captain was a highly experienced glider pilot. I really like this YT channel. Some fascinating stuff there, very well presented.

 
It obviously didn't cause a disaster, but I once saw a bit of The Apprentice, and one of the tasks was to get a flag printed. One of the teams didn't understand 'feet' (the flag was supposed to be 6'x4', IIRC), so had their flag made in cms.

The team's faces on being given this teeny, tiny flag by the printer was honestly one of the funniest things I've ever seen :chuckle:

I also don't watch The Apprentice normally (I think I must have been waiting for the next programme), so I was very lucky to catch it, it made my day!
 
There was also a news story last week, where someone was offered the vaccine as their BMI was quite extreme. That turned out to be due to his height having been listed as 6 cm instead of 6 feet.

Then there is the world's littlest skyscraper, but that was more of a scam.
 
It's a little bit like all those times I thought I was ordering kilos of bananas and would order 1 and receive one single banana because it was (unlike all the other fruit) sold in units rather than kilos.
 
Another famous one.

A few years ago I heard a story from Sharon Osbourne concerning Black Sabbath (at a time Ozzy wasn't in the band). In an amazing coincidence, at about the same time This is Spinal Tap was being made, they had a "life size" Stonehenge set piece constructed for a tour. It wound up being too big to get into many of the venues. (There was some speculation that someone mixed up feet and meters.)
 
A modern variation of this trope is the case of Robin Rigg windfarm, where a decimal point error appeared in the international standard for an element of the turbines' construction, meaning that they started to fall to bits after a couple of years.
 
Whether you use metric or Imperial/US (the US system is not exactly the same as Imperial), it's the humans that cause the errors, not the system :)

I personally prefer Imperial for everyday things - it's easier to approximate. And for the same reason I prefer proper fractions to decimals. The maths are more fun as well :cool:

There is nothing inherently superior or 'more scientific' about metric. It's just fashionable. It's good at some things, bad at others.

Given we are in the computer age, the fact that the metric system is in powers of 10 is no longer an advantage - in fact it's a direct cause of inaccuracy in everyday computer systems. I'm glad to say now I'm retired I no longer have the 'excitement' of tracing errors as one translates and / or rounds fractions from decimal to hex to binary and back again. (And I'm oversimplifying!)
 
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