errors in The Ultimate Tone by K. O'Connor

[MarkusBass]

Why the US doesn't like the Metric System:

[MarkusBass]

Explanation why Americans don't use Metric System:

[Enzo]

The Mars thing was stupidity, pure and simple. They could as easily misplaced a decimal point in an all metric system. I don't use it as an example for that reason. Any auto mechanic is aware of both systems, we electronics techs also are quite familiar with this. I know there will be no 6-32 screws in my Yamaha amp, and that Deluxe Reverb will have no M5 screws. 12" speakers are the same size when they come from the metric world. There was zero excuse for the Mars flap.

The USA is not officially on the metric system, but we have no trouble doing commerce in the metric world. We can just as easily make 2.54mm things as we can 1/4" things. And we do. Should we? Of course. But it isn't live or die.


I gave up listening to the historical perspective guy. Yes change is hard, but should we continue to use typewriters and dial phones? Should we watch VCRs instead of live streaming?

[Mike Sulzer]

The Mars thing was stupidity, pure and simple. They could as easily misplaced a decimal point in an all metric system.

Well, maybe not. When you pass numbers between different software programs, you do not lose decimal points. But you do have to be aware of different systems of units and convert as necessary.

[MarkusBass]

And the thread started from some mysterious errors in The Ultimate Tone by K. O'Connor (which finally appeared not to be an error). Now we are discussing Metric System in the US and failure of NASA satellite

[Enzo]

Mike, the software may not lose a decimal point, but it was the human engineers that can and do. A guy who has a lapse about metric versus imperial could just as easily have sloppily written a wrong decimal point in an equation. Or invert two digits, the decimal point was just an example. Whatever system you use is not a guarantee of no mistakes.

[MarkusBass]

Mike, the software may not lose a decimal point, but it was the human engineers that can and do. A guy who has a lapse about metric versus imperial could just as easily have sloppily written a wrong decimal point in an equation. Or invert two digits, the decimal point was just an example. Whatever system you use is not a guarantee of no mistakes.

Of course, any mistake is possible. But in case of Mars Climate Orbiter it was different. There was no mistake with decimal point - the values were not entered by anyone - they were measured by spacecraft equipment in meters. Also, no digits were inverted. One piece of software calculated a value used to determine a new orbit (and did it correctly - but in SI units), and some other part of the software interpreted this correct value in Imperial units. It's quite well described on Wikipedia:
>>>>>>>>>>>>>>>>>
On September 23, 1999, communication with the spacecraft was lost as the spacecraft went into orbital insertion, due to ground-based computer software which produced output in non-SI units of pound (force)-seconds (lbf·s) instead of the SI units of newton-seconds (N·s) specified in the contract between NASA and Lockheed. The spacecraft encountered Mars on a trajectory that brought it too close to the planet, causing it to pass through the upper atmosphere and disintegrate.
>>>>>>>>>>>>>>>>>
So NASA required on the contract SI units and the contractor (Lockheed) wrote their software in Imperial units. This must have cost them a fortune. Luckily, there were no astronauts in the spacecraft.
Of course, this does not prove anything. It's just an information for people who are curious what happened to the orbiter and why.

Mark

[Enzo]

The mistake was made when people assumed there would be no questions about the two separately engineered sub-systems interfacing. Human error. Who OK'd the combined system for launch without running a complete diagnostic through it?

[bob p]

Mike, the software may not lose a decimal point, but it was the human engineers that can and do. A guy who has a lapse about metric versus imperial could just as easily have sloppily written a wrong decimal point in an equation. Or invert two digits, the decimal point was just an example. Whatever system you use is not a guarantee of no mistakes.

Garbage In, Garbage Out.

In this video, they asked the builder to build an 18-foot Stonehenge, and wrote the abbreviation (18") using double quotation marks on the blueprint (napkin) instead of a single quotation mark (18').

Sometimes it sucks when you get exactly what you ask for.

[bob p]

The mistake was made when people assumed there would be no questions about the two separately engineered sub-systems interfacing. Human error. Who OK'd the combined system for launch without running a complete diagnostic through it?

Good question. Astronauts spend months doing flight simulations with the actual software that will be used before the real launch, to eliminate the possibility of these types of errors. It sounds like NASA didn't do such complete testing with the Mars orbiter software when they received it from the vendor.

[g1]

Another example that happened around the time of metric conversion here. Good thing the pilot had glider experience. (Boeing 767)
Again human error, but all the extra conversion probably helped increase the likelihood of error.
https://en.wikipedia.org/wiki/Gimli_Glider

[Mick Bailey]

Thirty years ago only scientists knew what Tera stood for, though it has been an official SI prefix since 1960. It was such a huge unit that nobody would ever encounter it in ordinary life. Nowadays, we all know about terabyte hard drives, and there is nothing even remotely exotic about one. Amazing!

-Gnobuddy

Tera is a base-10 unit, hence the introduction of the more accurate Tebi (and similar for other units) to describe base-2 magnitudes.

[rjb]

So NASA required on the contract SI units and the contractor (Lockheed) wrote their software in Imperial units.

This still boggles my mind.

At that time, I was working for a small company that designed and installed electronic systems at Cape Canaveral and Vandenberg AFBs. The contract requirements were spelled out in minute detail. We had to explain how we were going to fufill each line item, in compliance with all the referenced mil specs, or else take an exception to the requirement. Just to make sure contractors read every word (at least, I hope that's why), some specs such as MIL-C-44072C were listed in the contract.
https://nsarchive.files.wordpress.co...l-c-44072c.pdf

For each of our engineers, the AF had about a dozen guys reviewing our documentation (I do remember one AH insisting we were in breach of contract for not providing a dimensioned drawing or photo of the operating system.... but I digress.) I can't even recall how many stages of design review meetings were held.

Anyways, I still can't fathom how no one noticed such an obvious deviation from the contract requirements.

-rb

[Mike Sulzer]

Anyways, I still can't fathom how no one noticed such an obvious deviation from the contract requirements.

-rb

Drowned in details, missed the boat.

[J M Fahey]

I vaguely remember a similar problem over India, two planes collided in mid air because apparently one of the pilots had been trained on a Metric Russian plane and that day was flying a US scales Boeing or viceversa , not that he "did not know the difference" , but on an emergency he instintively "thought in the wrong units" and crashed.

Not surprising, Foreigners (think Mexican, Chinese, whatever) tend to curse in native tongue when a thumb gets hammer crushed even if in USA and surrounded by native English speakers, in emergencies you donīt *think* much (no time to), but react on instinct.