NASA Still Can't Get That Metric Stuff Right (update)
NASA Announces Next Opportunity for CubeSat Space Missions
“CubeSats are a class of research spacecraft called nanosatellites. The cube-shaped satellites are approximately four inches long, have a volume of about one quart and weigh about 3 pounds.”
Keith’s note: Inches? Quarts? Pounds? What happened to the NASA policy directing the use metric units? Curiously, if you read the official CubeSat Design Specification Rev. 12, from California Polytechnic State University (an American educational institution) the specs are in metric units. So has [email protected] gotten yet another waiver to not use of metric units in their program? Or is this another PAO author being lazy? Then again, it was this confusion over units of measure that allowed Mars Climate Orbiter to make a surprise landing on Mars.
Assessment of NASA’s Use of the Metric System, G-00-021 (2001)
“Following the loss of the Mars Climate Observer, the NASA Office of Inspector General initiated a review of the Agency’s use of the metric system. By law and policy, the metric system is the preferred system of measurement within NASA. However, our review found that use of the metric system is inconsistent across the Agency. A waiver system, which was required by law and put into effect to track metric usage and encourage conversion, is no longer in use.”
NASA Still Can’t Get That Metric Stuff Right, earlier post
This is still America, where American is still spoken and standard American units are still used. If metricated units are so important to you, then start a blog called ESA Watch.
I did not know that there was actually a language called “American” or that there was an “American” system of units. That has to be the funniest thing posted on NASA Watch in a very long time – thanks!
You misread – not just “American units”, he meant “standard American units”
Keith, your MCO surprise landing jab was pretty funny itself tho. I’ve never heard it put this way before.
I would think both should be listed. That works for the propeller heads, and the common folk alike. Also it could be part of the NASA education mission to help people understand both measurement systems. I mean like a 24 oz, 1.5 pt, 710ml bottle of soda. 🙂
Yeah whatever.
When Myanmar and Liberia land rovers on Mars I’ll give a s&%/# Cowing.
What planet are you from? The entire rest of our world switched over to metric DECADES AGO by international agreement, not to mention sound logic. It is only Americans who, after all this time, still haven’t managed to handle it and insist on being frozen as science and technology fossils. Your comment speaks volumes about the inadequacies of the US public educational system (and don’t bother arguing that the US system is best; only Americans believe that.)
Steve to give you some more insight, when I was in elementary school in the late 60’s we were taught how to use the metric system and told that in a few years we would switch over. Obviously that never happened, but in science classes in high school and college it was virtually all metric. In fact I remember my high school physics teacher would occasionally give us a problem in lbs, feet etc. and we would all groan as we considered it punishment as it was so much harder to do equations that way.
So I think the problem is not with our educational system, it is cultural, not wanting to change. Sort of like we still can’t seem to shake those stupid pennies, I notice that you are finally getting rid of them in Canada.
When I go to Canada, UK, or Europe I switch to metric. When I went to Nepal I switched to metric. When I got my biology degrees in the 1980s, I used metric. But when I worked at NASA space station in the 1990s and tried to use metric I got yelled at.
Steve,
I absolutely agree that it’s a cultural resistance to change, but whether in the schools first or in the working world first, the change must happen and is long overdue. The US is its own worst enemy in situations like this.
Steve
Keith,
I was much luckier. When “the conversion” happened in the 70s (in Canada) I was working in a research lab for one of the big oil companies and they not only provided all of the reference materials we needed, I was given my own personal copy of a professionally prepared in-house text book on the use of metric and converting to it. I spent half an hour an evening with it for a couple of weeks and I was up to speed. In the lab everybody “switched over” during a one week period with almost no trouble. Perhaps if more people had been so well supported we wouldn’t still be discussing this decades later.
Steve
And the U.S. still spends money printing dollar bills with short life times instead of forcing a dollar coin on us…
Actually the US system is set by NIST, and defined with reference to metric units. PAO always uses imperial, and if they didn’t the US media would convert them anyway. http://en.wikipedia.org/wik…
Subject: NASA Engineering and Program/Project Management Policy
NPD 7120.4D
Effective Date: March 16, 2010
Expiration Date: March 16, 2015
i. Metric System of Measurement. It is NASA policy for all new programs and projects subject to NPR 7120.5 to use the International System of Units (commonly known as the Systeme Internationale (SI) or metric system of measurement) for design, development, and operations; in preference to customary U.S. measurement units, for all internal activities, related NASA procurements, grants, and business activities. Exceptions to this policy may be granted by the NASA Chief Engineer based on program/project recommendations by the responsible Mission Directorate Associate Administrator.
I think you just made my point. PAO is by definition not an “internal activity, related NASA procurements, grants, and business activities.” And if PAO is doing design, development and operations, NASA has bigger problems….
Give NASA PAO a call. See what they have to say.
NASA Policy does not dictate what is SOP in the science and engineering worlds. It should be the other way around, but NASA policy was years catching up.
Steve
“When I go to Canada, UK, or Europe I switch to metric. When I went to Nepal I switched to metric. When I got my biology degrees in the 1980s, I used metric. But when I worked at NASA space station in the 1990s and tried to use metric I got yelled at.”
You should have joined the Marines. Apparently US grunts can handle metric without difficulty, even while being shot at. As can every video-gamer who plays US military shooters.
But it’s all too hard for people interested in space.
Oh for cryin out loud, CubeSats are supposed to expand LEO
opportunities for a broad range of the American public, not just us propeller
heads.
Like it or not, most American non-engineering types think in imperial
units.
Give it a rest and whine about something more
important.
It would seem that the U.S. has a lot of company in not going metric – Myanmar and Liberia … Map. More information.
I agree fieldtrip. Even tho I am a propeller head (I like that term) I have a much better and instant feel for the imperial units than metric. It’s what I grew up with and it is second nature. If I was doing something like landing on the moon I’d want to use imperial units so I don’t have to mentally convert. I can measure a board in inches or centimeters and still cut it too short. The point being that they are both just numbers that relate to something, tho one easily divides by 10.
“most American non-engineering types ” are not the people who are going to be using CubeSats (science and engineering types are), so your argument is meaningless.
For cryin out loud, instead of your whining, why not live in the present instead of the past. Of source, if metric is for some reason simply too difficult for you guys to handle…
Steve
American? Do you mean American Standard English? Then you should say English. And there are no American measurements. The preferred measurement system, culturally, in the US are Imperial measurements, which come out of European empire standards – the defining weights for Imperial weights are kept in a vault in France.
Considering that the essential sustenance for a large part of American population is french fries, they don’t mind.
Fair enough, but we’ll have to work out a system subunits and aggregate units to supplement it. (how many Finger-Wipes in a KiloFry?) (Or is it milliFries to a DecaFry?)
teflaime,
Sorry, but there is actually a difference. The “English” language is spoken and spelled in England, whereas the US language is “American English.” There are many differences in spelling (some that may surprise you, like tyres instead of tires) and there are some non-colloquial differences in definitions as well. I’ve lived my whole life in Canada, where our “Canadian English” is in many cases a mixture (often British spelling and American definitions, but not always), so we all grow up here knowing (and grumbling about) the differences. It’s even reflected in business nomenclature, where a US company is Inc. (Incorporated), a British company is generally Ltd. (Limited Liability), but in Canada we can use either one interchangeably (and in fact both, since ABC Inc. and ABC Ltd. are two separate legal entities), but both terms mean exactly the same thing, as does LLC (Limited Liability Company).
So, there are actually different names for the different languages, and “English,” properly speaking, is spoken/spelled in England, not the US or Canada.
This whole metric vs. imperial units business is another matter, and anybody who received a science or engineering education (or just about any other education) anywhere outside of the US would just shake their heads at some of the comments made in this post.
Steve
I hesitate to bring this so off topic but the comments are getting amusing on this one so why not. I would consider English, American English, Canadian English as dialects of the same language (though according to the wikipedia page on dialects, there is no hard distinction between languages and dialects that can be made).
Yes we should be using metric. 🙂
I am from New England and spoke New English growing up.
Yep, more dialects. Wikipedia further distinguishes standard and non-standard dialects. Standard have “institutional support” (govts, schools, dictionaries, etc.). http://en.wikipedia.org/wik…
Keith,
And yet, no matter how long it survives, New English will never become Old English. Unfair discrimination!
Steve
US customary units are not the same as the pre-Metric English units. For example the US gallon is 3.78541 litres, while the UK gallon was 4.54609 litres.
Therefore you should never say “English units” in the US, it’s unnecessarily confusing.
[There are also slight differences between the “International Foot” and “US Survey Foot”, which many US states still require for land surveys.]
Actually, the foot and the pound agree with Imperial. The US gallon, bushel and ton are different than Imperial (and multiples and submultiples). (The US gallon and bushel predate 1824 Imperial, and we never used the stone, so we have a different hundredweight and ton.)
I was LMAO at the idea of Imperial weight standards being kept in France. However, the legal definition of the pound is currently 0.453 592¡37 kg, and the master kilogram is kept in France, so technically, you are correct. (We have no primary Customary standards, only declared fractions of metric standards.)
I can’t speak for ARC PR, but it’s very common practice in the land of scientific outreach to use units of measurement which are commonly and easily understood by your target audience. In this case, the USA is a majority imperial audience (sad as that is).
Neil Degrasse Tyson explains it very nicely here: http://youtu.be/5OZ3B4WRSHk
There’s plenty of great stuff to criticize NASA about, but this is a little nit-picky and has very valid reasons behind it.
Matt,
I would agree completely with you IF each point was qualified by saying, “in the United States,” but only if you make that qualification. Outside of the US, your target audience is not going to have imperial units as “commonly and easily understood.”
Having said that, I would add that I don’t see “scientific outreach” as relevant to this situation, where is it a communication between scientific users and scientific facilities providers, which should clearly be in appropriate engineering terms and units.
Steve
Steve, you’re absolutely correct. I had meant to clearly state but instead only implied that NASA’s perceived target audience are the USA. While we’re all about international cooperation and collaboration, it’s the US taxpayers who pay the bills and they’re #1 in terms of who we need to get our message out to.
Everyone knows that American newspaper readers only understand measurements in units of football fields. The CubeSats are about 1/900th of a football field long (sans end zones.)
HortonsEgg,
So, are CubeSat dimensions expressed plus and minus center field? And what do we call the CubeSat third dimension in football field units? You may be onto something here!
Steve
Well, at least they aren’t using cubits, flagons, bauds, and Smoots.
( Look up smoot. It’s a doozie. It’s a unit of length equivalent to 5 ft. 7 inches, but how that came to be is pure Ivy League college intellectualism at it’s finest , determining accurately that it is 364.4 smoots from Boston to Cambridge via the Harvard bridge , plus or minus a smidgen)
Wow. I am 1.0 smoots tall. Who knew.
Keith,
I’m jealous. I’ve been constrained to subsmoot stature my whole life (and getting shorter daily).
Steve
Australia has been metric since 1975 yet I still think of myself as 5′ 6″ tall and think of fuel consumption in terms of miles per gallon.
Eighteen-year-old GIs with high school diplomas have no trouble calling in 155mm rounds 300 meters from their position. Commissioned officer pilots with college degrees need a duplicate set of maps in miles and feet. The principal argument (by managers) for the use of Imperial units in aviation is said to be that in an emergency pilots would revert to the units that they are most familiar with. Yet it there is a single objective study supporting this assertion I cannot find it. In my experience pilots (and other professionals) will respond to emergencies according to their current training. Moreover, the majority of pilots the world over grew up in countries where the metric system is more familiar.
In reality only a few countries fly by metric units (Cuba is one) but most glass cockpit systems can easily switch from imperial to metric “on the fly”, and the pilots I have discussed this with do not find it a problem. Mental workload with metrics is somewhat lower which improves safety.
In the early years of Station planning I submitted a CR to make metric standard in the program. My CR was ignored but someone more important submitted a similar CR that nearly was accepted, only to be rejected on the grounds of cost (before any metal was cut).
Despite the obvious superiority of metric it isn’t perfect. I think the decision to shift from bars to pascals (both metric units, but bar much more intuitive as it is almost exactly one atmosphere) was ill-advised.
“I think the decision to shift from bars to pascals was ill-advised.”
Pascals is okay, but using hectapascals (chosen to match millibars) instead of kilopascals was stupid. Likewise hectares, to mimic acres. Better to just use square metres. (Likewise most deca- deci- hecta- units. We can’t understand numbers with tens and hundreds? Blocks of a thousand seems to be the natural grouping most people use. Dividing it further just makes it less useful, IMO.)
I understand the desire to provide imperial units for those used to that convention. Why doesn’t PAO state the metric unit first and provide the imperial conversion in brackets following? This is what was done in “Wings on Orbit”.
Exactly.
I dunno… I do engineering in both unit systems. Obviously the metric system makes more sense, but for a *public* relation communication, I don’t see the harm.
And for the record, the MCO mishap didn’t happen because they used the wrong units. It happened because of a communication error between people.
It could just as easily have been an issue of clockwise vs. counterclockwise, voltage measured against the wrong reference ground, “X-axis” defined relative to the sub-assembly instead of the super-assembly, or just a typo.
A million components, a million chances for errors, and they missed one.
Calling it “incredibly stupid” as you often do, and bringing it up in contexts such as this only reflects back on you.
“Calling it “incredibly stupid” as you often do, and bringing it up in contexts such as this only reflects back on you.”
meekGee,
I can’t agree. Whatever we call it, it takes only one such incident to cost lives, so from that perspective, I would say that the issue can’t be overstated. I think it’s the ratio of words to constructive words that needs more attention.
Steve
Steve – Which issue can’t be overstated – usage of metric, or MCO’s failure?
meekGee,
I meant the use of metric units in science and engineering (or the use of any other engineering practices for that matter). And NASA’s use of waivers (or any science or engineering entity using waivers) to get around something that they find inconvenient or harder to do I consider to be an abuse of the waiver system. With some issues, standard practice is acceptable (such as best commercial practice for QA sampling by contract), but the use of metric is not in that category. There are many NASA/contractor and even NASA/NASA cases of failures and disasters because of mismatched units which should never have happened. Air Traffic Controllers the whole world over speak a single language on the job, by international agreement, for very good and obvious reasons, despite the language that any given airport’s people might find convenient or easiest. The same logic applies to the use of metric units.
I grew up with imperial units and had to learn to use metric as an adult, and it wasn’t particularly difficult. I have worked with various kinds of engineers, technicians and scientists from many countries over the years, and it’s been my experience that only Americans have a problem with this and make an issue of it, and continue to do so after decades of this same argument. It is, unfortunately, just one example of how Americans seem to think that they can play by their own rules without consequences, despite what the rest of the world thinks. And yet we keep having problems. Many have argued that Americans should be able to do whatever they want within their own borders, and, in fact, America has made no treaty commitments to use metric (unlike the rest of the world), but these factors while legally true, completely fly in the face of logic and common sense, and completely ignore that fact that US federal agencies (including NASA) all have their own official recommendations and policies in place stating that metric is the preferred system should be used whenever and wherever possible. If US agencies and companies want to participate and complete in the world marketplace, then people are going to have to make the effort to comply with international standards and practices and lose the antiquated provincial attitude — or continue to lose ground to other nations. That last is just my opinion, of course, but readily observable economic trends appear to support it.
Steve
Maybe. I like metric better too. I recently ran into the unit of Acre-Foot (as in water storage capacity in civil engineering) and almost has a heart attack from the fit of laughter that ensued – what a bastardized unit…
But at the end of the day, if you’re going to do calculations, convert to metric, no big deal – it’s just one of these aspects in which life is not ideal..
How’s about angle measurements, btw – do you work 100% in Radians (since this is the “natural” unit that does not require conversion constants inside equations) or do you sin (<– pun) and think in degrees every so often?
We use 360 degrees because the ancient Babylonians used base 60 and divided a circle by first inscribing a hexagon, which they could easily construct, and then dividing each side into 60 segments. Talk about sticking to a tradition.
My opinion is that if NASA insisted on metric only within a week people would stop complaining.
Exactly my point – degrees are just an arbitrary system that doesn’t jive with anything, but we feel more comfortable with it for casual use. When you get down to doing math, convert it to radians and don’t worry about it until it’s time to figure out what the result means…
So give those “imperials” a break…
The SAE (which is metric) recommends the cubic dekameter (dam³) for water storage and irrigation in place of the acre-foot, in their metric practice guide.
(1 acre-foot = 1.2335 dam³ approx)
For calculation, it is easy to convert to cubic meters by moving decimals whereas the acre-foot involves knowing at least two common conversions.
What’s the worst that can happen?
NASA runs into another planet and counts it as a “landing” on their big scorecard.
So because there is an article that describes the Cubesats in terms that an American reader can easily understand that means NASA is violating policy? It is just an article!! Read the design spec. It is clearly in METRIC. Duh.
Yet the article has the headline:
“NASA Announces Next Opportunity for CubeSat Space Missions”
and has the opening sentence:
“WASHINGTON — NASA is seeking proposals for small satellite payloads to fly on rockets planned to launch between 2013 and 2016.”
If they are seeking proposals, does it make sense to misinform potential proposers on the requirements or to fail to refer to the detailed specs? The mechanical tolerances are pretty tight, mostly ±0.1 mm. If you design with casual approximations, or even fairly detailed conversions, you are unlikely to meet spec or make the mission.
If the PR is ONLY for people who WON’T be making proposals, I suppose they can use cubits or smoots, but does anyone care about the information? It seems to me it is oriented towards prospective proposers. Maybe I’m reading too much into it.
The 100.0 ± 0.1 mm spec becomes 3.9331″ – 3.9409″ if you insist on converting and “about 4 inches” doesn’t begin to prepare you for what you have to meet. (Above conversions rounded “specward.”)
It’s been a while since I have dealt directly with procuring machined parts, but at the time one of the issues was the machine shops themselves. Most were set up to use imperial units only and flat out would not accept drawings using metric measurements. Been out of that particular game for a while so I don’t know if that situation still holds true, but it could be a factor.
WOW comments all over the board.
I will clear up two of the concepts being discussed here. When Mars 98 orbiter hit the Mars atmosphere by accident it was due to numerous things.
1- the algorithim for calculating the “small forces” onboard the spacecraft was outputting the forces in foot-pounds when on the ground they were interpreting it as Newton-Meters
This would normally have not made any difference except that:
2 – The JPL Navigation team decided that IF they used this information they would have a tighter navigation solution (to my knowledge the small forces data had never bee included in the navigation solution prior to this mission).
3 – The equation that provided the small forces data from the spacecraft software was provided by the thruster manufacturer and given directly to Lockheed Martin BY JPL. and they were told to use it as-is (standard units).
4 – There WAS a discrepancy in the navigation solution as the orbiter apporached Mars, but was only pointed out by a “newbie” that was pretty much told to sit down & shut up.
5 – The NAV team was being a bit of a “cowboy” in targeting closest approach because the closer to Mars you start the insertion burn, the more fuel you have left when you come out the other side.
6- Since JPL/LMA changed the design of the spacecraft between Mars Global Surveyor to 98 Orbiter, the reaction wheel desaturation burns were ~10X more frequent between Earth & Mars for Mars 98 than for MGS ( MGS had symmetrical solar arrays while Mars 98 had a single large array NOT centered on the solar pressure COM).
So it was multiple mistakes made by at least three different entities that all pointed fingers at each other after the mishap.
(I was in the LMA control room when the orbiter was supposed to come out of radio blackout).
Then there was the fistfight that brokeout in the failure review board as a result of all of the above…..;-)
I was very glad to see that there are people that expose NASA foolishness and waste of allocated resources.
I do see harm in their articles continuing to use
obsolete USC especially those that don’t include the original metric. The Constellation project was canceled
because NASA insisted on using obsolete units.
I still feel the need to express measurements in
obsolete units in NASA publications is poor judgment for a number of reasons.
First it makes NASA look out of date. Second, it gives the illusion projects are
still being designed and built using obsolete units and gives a false indication that obsolete units are
still acceptable, third and most important is that those citizens interested
enough in what NASA is doing are most likely knowledgeable in metric units that
they don’t need a dumbing down. Those who don’t understand metric or pretend
not to most likely have no interest in NASA projects. So who is NASA really
catering too?
All NASA needs to do is simply publish a policy
insisting it will henceforth use only SI units in all of its new releases and
publications. Those who prefer obsolete units can make their own conversions
but without NASA’s blessing. Let the burden of conversion fall on the user.
The reason there is no motivation to metricate in
the US is the obsolete users are pampered and someone converts for them. If the
pampering were to stop and they had to do the converting themselves they might
realize they are as obsolete as the units they cling too and may see it as time
for a change.
People cling to the old not because of resistance
to change but because someone pampers them. Stop the pampering and change will
come.