NASA Sticking To Imperial Units For Shuttle Replacement 901
JerryQ sends in a story at New Scientist about the criticism NASA is taking for deciding to use Imperial units in the development of the Constellation program, their project to replace the space shuttle. "The sticking point is that Ares is a shuttle-derived design — it uses solid rocket boosters whose dimensions and technology are based on those currently strapped to either side of the shuttle's giant liquid fuel tank. And the shuttle's 30-year-old specifications, design drawings and software are rooted in pounds and feet rather than newtons and meters. ... NASA recently calculated that converting the relevant drawings, software and documentation to the 'International System' of units (SI) would cost a total of $370 million — almost half the cost of a 2009 shuttle launch, which costs a total of $759 million. 'We found the cost of converting to SI would exceed what we can afford,' says [NASA spokesman Grey Hautaluoma]."
Oh the Humanity! (Score:4, Funny)
Re: (Score:3, Insightful)
That *is* the lesson learned, and being followed.
There are other issues. A machine setup that can make a .5 inch bore to ten-thousandths of an inch precision, cannot necessarily be changed to make a 1.27cm bore with the same precision. Many of the machine tools used in aerospace are calibrated in SAE units, and the machines cannot be replaced economically, if at all -- lathes, milling machines, grinders etc., still in service since the 1960s or even 1940s, refit for CNC, still turning out high-precision w
Re:Oh the Humanity! (Score:5, Insightful)
Which is the difference between scientists and engineers.... Sometimes the right decision is to listen to the engineers and not the scientists.
The scientists have it easy. They work in theories and numbers. The engineers have to produce usable physical objects. They have to do so in an environment that had significantly established manufacturing infrastructure before the SI standard existed. The countries that have converted to SI are the countries that were late to the industrial revolution party. It is expensive and difficult to overcome a massive established base of equipment. And it's a self perpetuating problem, because you can't just replace individual tools and machines as they wear out. An individual replacement has to be compatible with the rest of your infrastructure.
Sigh all you like. Short of a massive cash investment (Many Trillions of Dollars), or all manufacturing leaving the US and UK for good, Imperial units will stay and be indifferent to the sighs of the "rest" of the world.
(Incidentally, this would have been a *great* thing to spend stimulus money on instead of government employee salaries and other stupid programs.)
Re:Oh the Humanity! (Score:5, Interesting)
Wonderful +1 Welcome to the real world
Also, SI conversion with stimulus $$ is one of the better ideas I've heard. It creates jobs (and ones that require at least basic education instead of just the ability to pour and smooth asphalt.) Hell, we could have even have offered basic training for people that would be involved in the more trivial but labor intensive efforts.
Mass conversion to SI requires some manual labor (switching road signs, etc), a lot of public awareness stuff, and a lot of Associate-level tech folks (and probably higher-level for review). You know who building a duck pond employs? 4 guys with heavy equipment (or 50 with shovels) and some ducks.
Re:Oh the Humanity! (Score:4, Funny)
Re:Oh the Humanity! (Score:4, Funny)
Re:Oh the Humanity! (Score:5, Funny)
Sure, you tried to look smart by using Latin phrases and failed to an epic degree?
Re:Oh the Humanity! (Score:5, Funny)
Re:Oh the Humanity! (Score:4, Funny)
The countries that have converted to SI are the countries that were late to the industrial revolution party.
What do you mean? EVERY country in the world uses the SI, except for the USA, Liberia and Burma.
Re:Oh the Humanity! (Score:5, Informative)
Re: (Score:3, Insightful)
Well, maybe because 200 grams of carrots would be two carrots and most people need higher amounts.
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Is that why Top Gear reviews all the cars in terms of miles per hour and horsepowers?
Re:Oh the Humanity! (Score:5, Funny)
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All of the other cars I've ever owned had engine capacities measured in liters too, but they were Japanese cars (even though two had the ostensibly American "Eagle" brand name...but in reality, they were Mitsubi
Re:Oh the Humanity! (Score:4, Funny)
At that point I was horribly confused.
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There are very, very few exceptions. Speeds are measured in miles per hour, but engine capacity is in litres. Beer still comes in pints but a standard spirit measure is 25ml. And anybody actually building something (whether it's hi-tech or a house) will be using metric.
Last I checked the houses being build around here: have all 16 inches (or 12 inches if you paid more or 24 inches if paid less) of space from center of the wall stud to next one, the house is so many feet by this many feet, the water heaters are 40, 50, 80 gallons. These were home build in the last 18 months.
Maybe in Europe metric is king. Not yet over here.
At least the schools are using metric for the science measurements. The university research programs are using metric. It is a start, all be it a slow o
Re:Oh the Humanity! (Score:5, Funny)
Next task for UK: driving on the right hand side.
Sure there are a lot of vehicles, but the complexity can be managed by the following easy two-step process:
1. Today switch passenger cars to the right hand side
2. A week from now follow with the trucks too...
Re:mod parent +1 realistic (Score:4, Insightful)
Re:mod parent +1 realistic (Score:4, Insightful)
Except unit conversions are not the norm. When a grocery store manager orders potatoes, it doesn't really matter if he orders 200 10 pound bags (which is really tough to convert to 2,000 pounds) or if he orders 200 5 kilogram bags (which is really tough to convert to 1,000 kilograms).
Sure, sometimes someone has to get a calculator to figure out how many inches are in 200 feet (but hopefully not most people) before they figure out how many 1.65 inch pieces they can cut that 200 feet into, but the other guy is going to need a calculator (or some scratch paper, whatever) to figure out how many 4.191 cm pieces they can get from 60 meters anyway.
Re:mod parent +1 realistic (Score:4, Insightful)
How many ounces is that? Tons?
It's a stupid system which is held onto simply because it's what we're used to. (and yes, it's easy to google the answer, but I could give you the kilogram converstions faster then you could type it)
Re: (Score:3, Funny)
Damn right.
Consistently and accurately labeling numbers with their units is a lot more important than making sure that it is easy to convert between units and occasionally be able to quickly do math.
SI is certainly easier to work with, but the constant implication that this makes it hard to work in Imperial units is ridiculous. If someone has trouble with inches and feet, I'm not going to pay them to do any work on my rocket.
Re: (Score:3, Interesting)
Indeed!
1 gal = 4 qt = 8 pt = 16 c = 128 fl oz
:D
Re:mod parent +1 realistic (Score:4, Insightful)
both SI and Imperial units are pegged to arbitrary things. In the case of Imperial units it was some king's foot. In the case of SI it is the distance light travels in some amount of time. whatever.
That's beside the pont. Yes the SI units are pegged to arbitrary things but they are not arbitrarily pegged to *eachother*.
Converting from centimeters to kilometers requires dividing by 100,000. I can do that in my head.
Converting from miles to inches requires dividing by 63,360. I can't do that in my head.
Re:mod parent +1 realistic (Score:5, Interesting)
Actually "imperial" units [wikipedia.org] are pegged to SI units. Since July 1, 1959, the the inch, foot, yard, and mile have been defined on the basis of 1 yard = 0.9144 meters. The pound is defined as exactly 453.59237 grams.
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Yeah, that's very helpful.
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To paraphrase from a post above you:
"How many 4.19cm pieces of wood can you cut from a length of wood that is 6m long?"
I'll bet you can't do THAT in your head either and it's just as valid of a math example as your own that involves miles to inches.
In the real world both systems can be a real PITA but it's not the fault of the system. It's the fault of the real world where numbers aren't some exact multiple of your base system.
Re:mod parent +1 realistic (Score:5, Informative)
humans find it much easier to divide into halves than into tenths [...] Give me a gallon of liquid and a set of unmarked jugs and I'll probably have pretty darn close to 1 fl. oz. long before you can cut 1 L down to 1 mL.
a) Wow. Ok. Is that a problem you encounter frequently? This seems a bit artificial. :)
b) Yeah, I'll grant you that dividing something physically in half is easier. But while YOU might be able to pull a fluid ounce from a gallon using unmarked jugs, lets be honest most people would still really struggle with that.
c) Next, people like you and I who could solve this problem are also smart enough to realize that they don't have to physically divide into 10ths, but halves and fifths. So to cut 1L down to 1mL they need to divide by 1000... or 2x2x2x5x5x5. Fifths is harder than halves but not THAT hard.
d) Further its bit of an unfair problem. The SI problem is a 1000th cut, your imperial problem is considerably less. Its only a 128th cut. A closer problem (both in difficulty, and in the actual amounts of liquid involved would be: 4L to 50mL, which 2x2x2x2x5.
e) Further you are cherry picking imperial units. Tablespoon to Teaspoon is 3rds. Feet to inches is 12ths (2x2x3). Yards to feet is 3rds. And from yards to feet is 1760ths... and 1760 factors to 2x2x2x2x2x5x11. Yeah there's an 11 in that one. How many people do you know who are facile at 11ths? I suppose we could dig through rods and chains etc but I'd have to look up what those actually are...
f) decimal is easier for any serious work, where you have paper and calculators and computers instead of sets of unmarked jugs and cherry picked problems.
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Yes, it's an artificial example, but you're more likely to divide things in halves (or even thirds) than into fifths simply because it's easier. If I had to do fifths, I'd probably start with sixths (1/3 * 1/2) and estimate 1/5 to be slightly bigger.
My point was not that any dummy off the street could get 1 fl oz from 1 gal. My point was that any dummy off the street could successfully divide the liquid in half repeatedly if that's what you told him to do.
I'd forgotten just how darn tiny 1 mL is. Give me 10
Re:mod parent +1 realistic (Score:5, Insightful)
The problem with imperial is not what it is based upon (actually, these days the US units are all defined by reference to the SI units anyway - since 1959 an inch is defined as 2.54 cm - see http://en.wikipedia.org/wiki/Inch [wikipedia.org] ) the problem with the imperial system is the arbitrariness and inconsistency of the relationships between the units. The SI system has a consistent relationship between all of the units, and a consistent naming system and a consistent abbreviation system. In the imperial system, the relationships between units are not only arbitrary, but they are also inconsistent, there are multiple uses of the same word (ounces for example) used to describe different measurements (weight as well as volume) or dry vs liquid volumes.
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In other words, it only takes a generation for your argument to no longer be valid.
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It's easy to pull up a keyboard and get on your high horse.
It's even easier when you're wrong.
SI units were established as an international standard in 1960. That's 139 years after Napoleon died, in case you don't feel like doing the math. Before that, they were just yet another system of units like all the other random systems.
The "fucking excuse" for building the shuttle using any other system is that they sourced parts from thousands of small machine shops throughout the country. Those shops were not too
If you give up the inch, they'll take the mile (Score:5, Insightful)
You know, a lot of Europeans probably think that U.S. reluctance to embrace the metric system is just another example of our arrogance. But a lot of Americans (like me) are genuinely interested in adopting this system. We even passed a law [wikipedia.org] in 1975 trying to mandate it.
The real problem is that it is surprisingly hard to embrace a new system of measurement when you've spent your entire life thinking in different terms. Try as I might, I still can't picture a kilometer without converting it to a mile first, and still can't picture a centimeter without converting it to inches. The meter is a lot easier because it's pretty analogous to the yard. I think maybe your brain gets locked into a certain measurement pattern pretty early in life and it's very difficult to get out of it, even though many of us would happily embrace it. I'm still trying to think more in metric, but it requires a surprising amount mental effort to do so.
It's not that Americans are really all that arrogant or stubborn about the imperial system. We've actually been trying to embrace the metric system [wikipedia.org] for some time.
Re:If you give up the inch, they'll take the mile (Score:5, Informative)
I don't buy it
I lived in guilders all my life, and the first couple years in Eurotime I could only "imagine" a price by converting back to guilders and thinking whether the price sounded right. Now, I can only "imagine" a guilders price by converting it to euros
I've lived in the UK and US for 1.5 and .5 years, respectively, and I started thinking natively in most units pretty quickly, esp. inches and miles, and of course pints in the UK. Some units are more difficult, either because they have an offset as well as a scale difference (fahrenheit) or because they just don't make any sense (a 22 fluid ounces drink?? gimme a pint, damnit!)
I think the UK is busy converting mostly to metric system, so maybe some UKians can chime in with their experience?
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We have some people called the Metric Martyrs who think metric units are some unnecessary EU interference in our affairs.
It gets confusing at times when for example the distance you drive in a car is measured in miles, fuel for it is sold in litres, and fuel efficiency is either miles per gallon or litres per 100km. We really need a miles per litre measure, but I guess that isn't going to happen.
The same law that prevents the Metric Martyrs from selling their vegetables in pounds and ounces also prevents p
Re:If you give up the inch, they'll take the mile (Score:4, Insightful)
Re:If you give up the inch, they'll take the mile (Score:5, Informative)
I think the UK is busy converting mostly to metric system, so maybe some UKians can chime in with their experience?
Unfortunately, not really. All street signs still measure distance in miles, and eighths of miles, and the like, and half the population think that the metric system is (like the euro) just another damn frenchie scheme to undermine our sovereignty. We have a long history (this [wikipedia.org], for instance) of coming up with crazy conspiricies to demonstrate why the imperial system is our God-given right, and why the French would like nothing better than to force their evil organised system of measurement upon us.
Meanwhile, for at least a couple of decades now, kids grow up being taught nothing but metric, and wonder why the grown ups still insist on using imperial, and what on earth a fluid ounce actually is. Cos everyone seems to use it, but I don't think anyone under 25 has actually been taught it.
Re:If you give up the inch, they'll take the mile (Score:5, Informative)
I'm from the UK, and my mental image of measurements is fucked.
I know how much a pint is. I know how much 1kg is, but I don't know how much is 1 pound in weight. I know how tall I am in feet and inches, but not in meters.
All because we use metric for some reasons, and we are still stuck in imperial for others. My milk comes in bottles that are labelled 568ml although *everyone* refers to it as a pint, obviously our alcoholic drinks come in pints and half pints. Our speed limits are measured in miles per hour, yet we used to run the 100 meters at school. My height has always been given to me in feet and inches (while growing up by my parents) and if you speak to pretty much anyone they will also give their height in feet and inches, yet if I go to the doctor, they want me to know how high in meters. If you go under a low bridge, the height is given in feet.
When I go swimming the pool is in meters, when referring to medium distances anyone aged over 40 refers to yards, everyone below that refers to meters, at larger distances it's rare for anyone to use kilometers. Anyone over 40ish only understands Fahrenheit, everyone below uses degrees centigrade.
Generally speaking things are moving to metric (thankfully) but it will take many many years for imperial to die here currently we are in one big measurement mess and we will be for some time, especially as every traffic sign is in imperial.
Re: (Score:3, Interesting)
I think the UK is busy converting mostly to metric system, so maybe some UKians can chime in with their experience?
Almost everything now metric. Exceptions are for beer and milk (pints, though milk is also sold in metric units; total muddle), spirits (fractions of a gill) and road distances (miles). Next to nobody uses imperial weight measures any more.
Beer and spirits are imperial because it would take a major piece of legislation to change. (English law is very very strict there, and pints and gills do have precise metric definitions these days...)
Re: (Score:3, Insightful)
Beer is imperial because it would take a major piece of legislation to change.
It would take a tiny piece of legislation to change it (and the rest of them). But the Daily Mail wouldn't like it, so it hasn't happened yet.
Re:If you give up the inch, they'll take the mile (Score:4, Interesting)
No it's not. I've was born and raised in France, moved in the US at 23, 4 years ago. The only unit I'm still uncomfortable with is F (also one of the stupidest) I have no problem thinking in inches, miles, gallons, ounces without converting.
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Fahrenheit is one of the few units I prefer over the metric counterpart. At least when talking about weather or indoor climate.
When expressed as an integer (temperature frequently is when talking about weather), Fahrenheit is a more precise unit.
Re:If you give up the inch, they'll take the mile (Score:5, Insightful)
Fahrenheit is a wonderfully human temperature scale. Over 100 is Way Too Damn Hot, and under 0 is Way Too Damn Cold. I like that.
Re:If you give up the inch, they'll take the mile (Score:4, Funny)
What's so special about 100? Oh, a decimal number... The irony is delicious.
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Yeah... stupid arbitrary decimal system.
Speaking of base systems... US fluid units: perfect for computer nerds!
1 gal = 100 qt
1 qt = 10 pt
1 pt = 10 c
1 c = 1000 fl oz
So, 1 gal = 10000000 fl oz... one unsigned byte holds almost 2 gallons!
Bonus points if you learn to cook... chicks dig guys who can cook, right? Who knows, they might even be so impressed by your cooking abilities that they won't roll their eyes at you when you try to tell them how nice the binary system would be for measuring liquids...
Re:If you give up the inch, they'll take the mile (Score:4, Insightful)
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You have a "useful" Celsius range of about -15 to 40.
You never cook or bathe? Ew!
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Re:If you give up the inch, they'll take the mile (Score:4, Funny)
nothing different from celsius. Over 100 Celsius is way too damn hot, and under 0 is way too damn cold.
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Fahrenheit is a more precise unit
Why? Is there a limit to the number of decimal places you're allowed to use where you're from? The limit to precision isn't due to the units used, it's due to the tool used to measure the temp.
When expressed as an integer (temperature frequently is when talking about weather), Fahrenheit is a more precise unit.
It really helps if you read the first part of a sentence before bitching about the second part.
Re:If you give up the inch, they'll take the mile (Score:5, Insightful)
It would be relevant, but most of the time when people mention a temperature it's inaccurate anyway.
Consumer grade thermometers are generally out by a degree or 2 Celsius. Your local weather report is probably more accurate, but only where the temperature is actually taken.
Using Fahrenheit is more precise, it isn't more accurate.
Re:If you give up the inch, they'll take the mile (Score:5, Insightful)
The real problem is that it is surprisingly hard to embrace a new system of measurement when you've spent your entire life thinking in different terms.
Yes. Thats why the Canadians haven't been able to do it either. Or the Irish. Not Australia and New Zealand either. Or India.
Oh wait, they *have* all done it. So how come they can, but for the US it's just too hard?
Re:If you give up the inch, they'll take the mile (Score:4, Insightful)
Oh wait, they *have* all done it. So how come they can, but for the US it's just too hard?
No, I think it's because too few people care, so politicians don't care...and it never gets done. Simple as that.
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Some things are deeply ingrained. In Canada, the building industry is still imperial, and people generally talk about their weight in pounds (not stones and pounds like the UK). Australia seems to have converted more thoroughly, although I could talk to older people in imperial.
Inches and feet are units of a nice sized. Most things can be expressed as a whole unit, and when working precisely, they're easy to sub-divide (1/2, 1/4, 1/8, 1/16, etc). Try quartering a cm - you end up with fractions of mm. C
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Try quartering a cm - you end up with fractions of mm. Cm and m seem to be constantly odd numbers or funny fractions.
A question of POV. I have a couple of wrenches whose sizes are written in SI and imperial units, and I really find 5/16'' more odd than 8 mm.
Americans seem particularly resistant to change. It will take a government with a lot of will to make such a change. A good starting place would be if the government mandated everything it does is metric.
I think it worked in Germany by outlawing old units. You were forced to sell your stuff in kg instead of pounds etc.
It also helped a lot that Germany was a conglomerate of various kingdoms, each of which had different units. On markets near the border between, say, Prussia and Hanover people were sick of converting the Prussian ell (pound, mile etc) into their Hanoveri
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Most Americans cant picture a mile. picturing a kilometer is easy, it's very close to 7 city blocks.
Or for you suburbians the distance from abercrombie to starbucks.
It's easy if you simply use it. Problem is ask any of your co-workers how big an inch is and most will be very wrong.
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Countries have changed, with varying success. You can do it if you want to.
Canada sort of changed, but has slipped back a bit. However, our road signs are in kilometers, our weather forecasts are in degrees Celsius, we sell liquids by the litre, and few people under the age of 50 have any issue with this. I was in elementary school when we changed our weather forecasts (I'm 47), and I find U.S. weather forecasts and road signs and such meaningless unless I translate them to proper units.
While the price
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Engineers in the U.S. are trained in both, but the emphasis is generally on metric. Which system you actually use is dependent on where you work, as some shops are metric, some use the standard system. In my experience, metric is becoming more common as it was uncommon to find metric fasteners on equipment 20 years ago; now it's uncommon to find standard ones.
Medicine in the U.S. is almost completely metric internally. Even though your doc may tell you your kid is 44 pounds, they write "20 kg" in the charts
Let's all help the guys over at NASA (Score:4, Funny)
1 foot = 0.3048 meters
There you go, NASA. That one's for free.
Conversion is Exact (Score:5, Informative)
Just get it over with already (Score:4, Funny)
The sticking point is that Ares is a shuttle-derived design â" it uses solid rocket boosters whose dimensions and technology are based on those currently strapped to either side of the shuttle's giant liquid fuel tank. And the shuttle's 30-year-old specifications, design drawings and software are rooted in pounds and feet rather than newtons and meters.
And in 20 years, that'll be the same excuse given for building Ares's replacement with imperial units.
Horses Asses (Score:5, Interesting)
Re:Horses Asses (Score:5, Funny)
Why is my mailbox full of unfunny spam?
Because a bunch of horses' asses keep hitting the Forward button.
Re:Horses Asses (Score:5, Informative)
Claim: The United States standard railroad gauge derives from the original specification for an Imperial Roman war chariot.
Status: False
Re:Horses Asses (Score:5, Interesting)
That must be one of the weakest "false" results I've seen on Snopes. As it says itself:
Origins: This is one of those items that although wrong in many of its details isn't exactly false in an overall sense and is perhaps more fairly labeled as "True, but for trivial and unremarkable reasons."
In fact, it collaborates that the English railway was made in the same size as double-horse carriages, that the US share that width because they shared tools and that it's the dominant standard today since the northern US won the civil war. It's a bit of a stretch that double horse carriages were popular only because the romans did it, but they certainly did do it first and built a massive network of them.
Finally, on the space shuttle thing snopes is just being silly. The largest carriage in the table listed by snopes is 9-10 feet. According to wikipedia the shuttle boosters are a little over 12 feet. So while the part about being "slightly wider than the track" is a liberal description, it's certainly possible they couldn't be built bigger because the tunnels aren't bigger.
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I live in Rural Idaho, Cow tipping is a lot like snipe hunting.
We would take gullible kids out to a farm in the middle of the night. They would try to sneak up on a cow and tip it. It would either move or not tip, and then move. We would convince them that their shoes were making too much noise.
After they gave up their shoes, we would hop in the car and leave them in the middle of a pasture, barefoot, in the middle of the night, miles from home.
That is what cow tipping is really about.
Re:Snopes is often wrong. (Score:4, Funny)
I grew up in rural Canada, and can assure you that you can, indeed, tip a cow. Certain breeds are more difficult to sneak up on and others wake up before they hit ground, but it is certainly not difficult once someone has shown you how. If you really are from a farm and have never done it or even seen it done, I suggest you visit us up north and we'll take you out one night and show you the finer points.
$370 million? (Score:3, Interesting)
Re:$370 million? (Score:4, Insightful)
You make it sound so simple...when, in fact, this is quite literally rocket science here.
One of the common stories here is people needing to rewrite an entire project because of a new language fad. The old project worked. Rewriting it first means you have to replicate the old project and then deal with new bugs while the old project had all the bugs mostly ironed out.
Why do we insist NASA to reinvent the wheel when we're so against it in our own profession?
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I'm sorry, it really sounded like you just called the metric system a "new language fad". Seriously?
Look, it's not about saving money now, it's about the future. They've already lost a multi-million dollar project because they haven't gone metric yet, and a similar mistake in the future is not unlikely.
Much of the production for space parts occurs outside of the US, where they use what? Metric. What kind of overhead do you think they charge to supply imperial equipment as well as the metric that they su
Re:$370 million? (Score:5, Insightful)
It's not like they're building anything new or buying raw materials; they just need someone to re-draw plans with new measurements in a different system.
Frankly, and without trying to be insulting, you're so ignorant of what the issue is that it's laughable that you even have an opinion on it.
This isn't a matter of trivia, where we are worried if plans are marked in inches or mm. Change to metric, now every bolt must be metric pitch thread, every nut must be changed to accomodate. Every calculation of mass and structural integrity has to be reexamined and recalculated for new components. You don't just magically say "ok, our 3/8" bolts are now to be called 9.525mm bolts" and call it a day.
Re:$370 million? (Score:4, Insightful)
And once the drawings are re-drawn, you have to verify the individual drawings. Then you have to verify the interfaces to make sure that vendor 'A' didn't round his tolerances in a direction that means his part will no longer properly mate with a part from vendor 'B'. Then you have to withdraw the old drawings from service and replace them with the new in an orderly fashion. Somewhere along the way you also have to not only update the references between drawings, but also the hundreds of thousands of pages of documentation, specifications, etc... that reference these drawings.
The individual steps are bone simple - but there are a lot of individual steps and they interact in various complicated ways.
An additional problem is that all this has to be done while those drawings, specifications, etc... etc... are in daily use at facilities scattered across the country, which means you have a fairly difficult problem not only in making these changes - but in ensuring everybody is 'on the same page'...
Re:$370 million? (Score:5, Insightful)
If they paid their engineers $150,000/year, they could hire almost 2500 engineers for a year-long project.
Or, pay 10 engineers to make sure that the adapter between the (imperial) boosters and (metric) Ares is properly sized and be done with it. If you're pulling a boat behind a truck, you don't care if the truck engine's bolts are metric and the boat's are imperial because they don't have anything to do with each other. As long as the hitch pieces are compatible, you're golden.
Re:$370 million? (Score:5, Insightful)
Please advise us on how you're going to train every machinist, and QC agent, just to name two job categories on how to measure 30.22mm with calipers that are intended to measure in Imperial? If they can't do this, do it reliably, and do it accurately then you're going to have some funny fitting parts on those Ares.
That is just one very simple example in two very limited job categories where changing from SI to Metric would introduce horrible, and potentially disastrous, difficulties.
obligatory simpsons quote (Score:4, Funny)
Abe Simpson: The metric system is the tool of the devil! My car gets forty rods to the hogshead and that's the way I likes it.
Space programs rarely have the choice (Score:3, Informative)
I can definitely see their point, because (Score:5, Insightful)
the issue isn't just one of redoing the drawings along with the various checks and cross checks to make certain the units were converted properly. I'm sure they could that, but the resulting set of new drawings would be extremely prone to encouraging mistakes. As a minor example. Let's assume that on one piece they currently have a dimension of 12 inches +/- 0.01 inches. So they convert this dimension to metric giving a new value of 30.48 cm +/- 0.025 cm. Excuse me?!?!? That's a rather odd and strange dimensional target to hand off to the machinest. And you'll be getting these rather strange dimensions for everything on the original design. Frankly using the metric measurements would make that rocket utterly hell to construct. So the "proper" solution would be to use the original design and then stretch/shrink various dimensions in order to make the dimensions "rounder" and easier to manufacture. But upon doing that, they have effectively come up with a new design that has to be recertified.
Re: (Score:3, Insightful)
>"Let's assume that on one piece they currently have a dimension of 12 inches +/- 0.01 inches. So they convert this dimension to metric giving a new value of 30.48 cm +/- 0.025 cm.... using the metric measurements would make that rocket utterly hell to construct."
If the part needs to be that certain length and tolerance, it will be, end of story.
There's no inaccuracy and it will be machined like so.
I doubt every part on the Japanese rockets is EXACTLY in 1mm increments.
The biggest payoff is in all the NO
Why not use slave labor? (Score:3, Insightful)
I'll do it! (Score:3, Funny)
For an extra $30 Million, I'll even make sure it's accurate!
Find something better to complain about (Score:5, Insightful)
Metric (Score:4, Insightful)
It never ceases to amaze me the resistance to going to metric here in the states for measurements but no one bats an eyelash at the fact our money is basically metric (base 10).
It is in fact soo damn easy that we can instinctively give somone a $5 and a penny for something that costs $4.01 so we can get back a dollar rather then 3 quarters 2 dimes and 4 pennies....
Boo metric it's too damn easy to use! Forget cutting a board 1.46 meters in half. it's too damn hard to cut it .73 meters! Better yet that 3 5/8th inch board needs to be cut in half so we need umm... err... need some scratch paper here....
Not ****IMPERIAL**** NOT!!! (Score:3, Informative)
Somehow the idea that U.S. units are called "Imperial" units has taken root. That term only applies to a system used in the British Empire/Commonwealth (hence the name) before they went metric. The U.S system is "English units" (because it's based on units that were widely used in England at the time of American independence) or "U.S. Customary Units." The two systems are very close (length and weight are the same) but not identical (volume units are quite different, even thought the names are the same).
In most other contexts, I'd just say, "OK, sloppy usage eventually becomes the standard, like 'broadband' instead of 'high-bitrate'. Been happening since language was invented, not going to change."
But in this case you have terms that are defined in standards. And miscommunication can cause much wackiness. For example, suppose I need 10 gallons of something. The nearest store is just across the border in Canada, and they're metric, so I use Google to convert units [google.com] and come up with 45.5 liters. Nice and simple, right?
Wrong. I only needed a little less than 38 liters [google.com]. The U.S. gallon is 20% smaller!
OK, this particular example is kind of artificial, because most people would just say "gallon" and Google assumes that "gallon" means "U.S. gallon". Still, you need to be careful with this stuff. Like, suppose you're putting fuel in an airplane [wikipedia.org]!
Of course, all this extra confusion is yet another reason for the U.S. to go metric. I work for for a computer manufacturer that not only sells widely in metric countries, our actual production is outsourced to companies that are mostly in metric countries. Does this cause headaches? You bet!
My ignorance is cause for surprise. (Score:3, Informative)
France first adopted the Metric System in 1791 (according to Wikipedia). Let me repeat that... 1791.
The first public, commercial, industrial use of the Metric System in America was Coca-Cola; Coca-Cola bottles have always displayed their volume in metrics, and they have been around since 1886. Let me repeat that... 1886.
First shuttle flight was in 1977.
Now here's the surprise on my part. For as long as I have been alive, all science and math text always focused on the metric system. Aside from off-tasks in grade school of converting Celsius to Farhenheit(sp?) or inches to centimeter... gallons to liters... everything has always been in metrics. Growing up, the total icon of science and math has been primarily NASA. It is very hard to for me to conceive, that given the adoption of the metric system in acadamia and almost exclusive to intellectuals and professionals... that NASA has for so long, and so widespread throughout any of their projects, adopted anything other than the metric system. Had this article not been published, I would have refuted any claim that NASA didn't use the metric system. All I can say in 2009 is "wow".
Imperial System != US Customary (Score:4, Informative)
The Imperial System of measurements is not the same as the customary measurements used in the United States. The legal arbiter of measurements in the United States is the National Institute of Standards and Technology. Apendixes B [PDF] [nist.gov] and C [PDF] [nist.gov] to their Handbook 44 provide a good overview of the structure of the respective standards and their relationship to SI (the science based International System, which was based on the Metric System).
The word system seems misleading when applied to US customary measures. For example:
Does this make a difference? From one viewpoint, no, when do you ever need to keep something accurate within 2 mm over a mile? From another, yes, repeated iterations of computations based on incorrect conversions can produce just plain gibberish. Another bit of measurement chaos to keep in mind:
We also must remember that NASA has proven itself incapable of managing the different systems of measurement before. Ten years ago NASA crashed a Mars bound probe [newscientist.com] because of botched conversions from customary to SI units. You would think that having paid $125 million for that lesson, they would want to avoid a recurrence. But, I suppose that they are from the government and they do not have to care.
Obligatory xkcd reference (Score:4, Funny)
Seeing the discussion here, I wonder why nobody has brought this up yet:
http://xkcd.com/526/ [xkcd.com]
Re:really? (Score:5, Informative)
I work for an engineering company, and unit conversions are not a trivial operation. All of our drawings are created in autocad, and after several years it becomes difficult if not impossible to find the original file. As such, converting achieved documents requires recreating the document entirely from scratch. We also use a fairly vigorous quality control system that requires 3 engineers to check every document change, verify the calculation, and repeat the calculation using a different method to ensure that no mistakes were made.
We recently acquired an older project where we needed to simply change the title block on each page, and this process took roughly 5000 hours. For something on the scale of the space shuttle, 370 million isn't unheard of.
Re:really? (Score:4, Insightful)
after several years it becomes difficult if not impossible to find the original file...We also use a fairly vigorous quality control system
How do you keep quality on your products, but not even keep your original documentation files? What happens if there is a change?
our drawings are created in autocad... unit conversions are not a trivial operation
The engineering team where I work uses Solidworks, and there are macros to do the conversions. Of course, those macros only work on the original files, not the printed documents... :-) So that brings us back to having lost the files...
Re: (Score:3, Informative)
Re:really? (Score:4, Insightful)
There's a VERY good reason to re-use the SRB's, they are a well tested design with the flaws worked out and the real operating parameters known.
We would be remiss if we did not note that the engineering kinks of the SRBs have been ironed out, by that they killed seven people in the process.
Re:really? (Score:5, Insightful)
Next time you should replace 4999 of those hours with a simple BASH script.
The original files were not available. What shell do you use that compiles to paper?
Re: (Score:3, Funny)
Next time you should replace 4999 of those hours with a simple BASH script.
The original files were not available. What shell do you use that compiles to paper?
lpr
Re:really? (Score:5, Informative)
You don't seem to understand, even a little. These numbers are on a piece of paper that no longer exists on a computer. Not even the most advanced computer script in the world can adjust paper. So okay, I understand part of your point, put it into the computer first, and then run the script. These documents are crawling with numbers. Line numbers, electrical classifications, instrument identifiers. Even if I had a script to manage the process, you then have the problem of units. I'm not doing 5000 ft to meter conversions. We have lengths (using both ft, in, ',and "), weights, volumes, temperatures, powers (hp, MMBtu/hr, kW, MW) and so forth. Even if you could have a script smart enough to check for units, how would it tell the difference between a temperature and a temperature change? If I have a heat exchanger with a temperature change of 50ÂF, the correct metric temperature change is 27.8ÂC. If you got 10ÂC, you used the wrong method. The sheer amount of back checking I would have to do to make sure a rogue script didn't destroy my drawings would be insane.
This is not a simple database you're playing with.
Re: (Score:3, Informative)
I know exactly what you are talking about. We had 2000 logic diagrams to change once, and we used a script to do it in AutoCAD. Took the farm 3 hours to do, but it took us 4 weeks to check over. It's even worse when the drawings didn't come from your department, or (god help us) an outside source. We got drawings from a sister company once that were not to scale, and the title blocks were scaled by hand to 'look' right. Half of them don't even use the same blocks either, so when you write the script it
Re: (Score:3, Insightful)
You scan the entire document in, OCR for text, and try to perform an automatic conversion. Then people go through where they see a graphic of the original scanned text and the OCR'd text. For each one the person selects it is correct, or adds the correction. I've known people that do this for a living, and this was cutting edge methodology 15 years ago. Now it is pretty standard.
The alternative method is to detect the text, but not OCR it. Force the user to enter the text themselves. In either case, y
Re: (Score:3, Insightful)
I prefer imperial units for lots of everyday tasks like cooking. Imperial units are much closer to a binary-based system, which is very convenient for human beings. Two cups in a pint. Two pints in a quart. An ounce of water weighs about an ounce. A pint of w
Re:Do we really need metric? (Score:4, Insightful)
And a liter of water weight exactly a kg. There are exactly 1,000 meters in a kilometer. And there's exactly a year in a light year.
Wait ... one of those is wrong.
Re:Now I know what NASA stands for... (Score:4, Insightful)
Yes...stored in electronic form. That's right. Wait, remind me again, what file format did Autocad use in the 1960s? 1970s? 1980s? Was it DWG back then?
Plus we're not building another shuttle. We're going back to the days of Apollo, with a capsule^Wspacecraft on top of a rocket. Apparently, though, they found that they can utilize the SRB design for part of the new project. (The big white rockets that get reused after launches.) The SRBs date from the start of the Shuttle era which...erm, yeah. 1970s.
So here we have a rocket booster already designed that works like a champion. The blueprints are all done. They work. They're reusable. They've been fieldtested over 100 times.
And you want to redesign them essentially from scratch? As many coders here want to say to their bosses when upper eschelon wants to recode an application in the new flavor of the month language: if it is not broken, do not fix it.
Re: (Score:3, Insightful)
Exactly. And that's a flaw that's been fixed.
How many flaws will be introduced if they have to be redesigned from scratch?
Re:There is hidden utility in imperial we overlook (Score:4, Insightful)
If you're dividing meters into centimeters, you can really only talk about tenths, hundreds, etc. If you're dividing yards into feet and inches, or pounds into ounces, etc. you have thirds, 16ths, 12ths, and all kinds of other useful fractions to use to think about the divisions.
And that would be an advantage for the imperial system? Really? Having to keep in mind always different fractions, instead of just 1000 (as in kilo, mega, giga... and milli, micro, nano, pico...)?