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NASA Will Go Metric On the Moon
An anonymous reader writes "Space.com is reporting that NASA has decided to use the metric system for its new lunar missions. NASA hopes that metrication will allow easier international participation and safer missions. The loss of the Mars Climate Orbiter was blamed on an error converting between English units and metric units. 'When we made the announcement at the meeting, the reps for the other space agencies all gave a little cheer,' said a NASA official."
Now if only American car companies will budge that extra 17/32" and finish going metric rather than forcing me to have 2 sets of tools for one car. Then I can "Compare Prices on Physics and Engineering" here at /.
This is a necessary, but difficult transition. Yes, difficult. Maybe it's pretty easy for the programmers, but for the mechanical guys out there (like myself), this introduces a huge relearning phase. Say, for example, I need some sheet metal to function as a structural piece. I can be pretty confident that my initial guess will be pretty close to the final thickness value if specified in imperial units. I also know what's typically readily available from suppliers (eg: 1/4" is far more common than 15/64"). Not only must I do a conversion from my ingrained inch units into "foreign" metric, but I must also look up which sizes are common.
With time, I would be just as good with metric as with imperial units. And I want to change to metric for its obvious advantages. It's just that my design confidence and productivity would falter through the transition. I'm quite sure I'm not alone on this.
IWARS.
People, in general, disappoint me. Politicians even more so.
Using the metric or imperial system would not matter one bit if all you're measuring is distance or volume. But as soon as you start converting distance into volume (quick question: how many cubic inches in a pint?), or thrust into velocity (quick: you apply a one-pound force to a one-pound object for one second. What's the resulting speed, measured in mph?), or torque into power, or energy into force or power, the beauty of the SI (metric) system really stands out. In the imperial system, the only way to get these calculations right is to insert all sorts of wacky numbers. Which you need to remember with potentially infinite precision.
Try this beauty: 1 Nm (Newton-meter) equals 1 J (Joule) equals 1 Ws (Watt-second). In the imperial system you'd have to insert all sorts of wacky numbers to go from pount-feet to calories to, strangely enough, Watt-seconds again. (Electricity, even in the US, is always measured in metric.)
Or more practical: Ever tried to convert the torque that your car engine delivers (measured in pound-feet) at a certain rpm (rounds per minute) to the horsepower (hp) that it delivers? In SI, it's a simple multiplication: Power (measured in W, or more commonly kW) = 2 * pi * torque (measured in Nm) * rotation speed (measured in 1/s). No wacky, imprecise numbers. Just 2 * pi due to the rotation and that's it.
The SI system and all the calculations you do with them are completely void of wacky numbers, with only a few exceptions:
- 2 times pi for anything that involves rotation.
- Natures constants like c (lightspeed), g (gravitational accelleration), e (elementry electric charge) and a few others, about half an A4 page full of them.
- Natural properties (like density) of materials that you use.
Since NASA does *a lot* of these calculations (how much force do you need to accelerate/decelerate the lunar lander, what's the effect of gravity?) I can understand why they switch to metric.