Tom&Shelly
Senior Citizen Member
LOL!That'd be 328 yards, for people from the only nation that has landed on the moon.
Got me thinking--I worked on space related systems for more than half of my career, and don't remember ever using yards. (Seems like something British naval gunners would use, mostly in the Great War.)
I have rarely used nautical miles (I think that's sea miles, or something, in the former British Empire) and statute miles, the latter mostly for the sake of certain managers who we assumed couldn't think in kilometers. I've used feet, mostly for aircraft-space communications systems, as we describe aircraft altitude that way in the states. I've even used kilo-feet, though some managers called me out for mixing measurement systems.
I've converted pounds into various units of force, or was that mass? Not British currency, even when I lived there... (0 dollars = 0 pounds = 0 Pints of Guiness, no matter the conversion rate.)
I usually converted degrees centigrade to kelvin (not "degrees kelvin") (and not Celsius, though I'm slowly losing that one, even in the engineering world). Probably had to convert from Fahrenheit once in a while, though I don't remember when we used that in space systems. (Subtract 32 and halve the number, which is good enough within the range of human habitability, though you lose half of your resolution, which is why the US weather service resisted it for so long.)
Optical engineers love to use inches for the diameter of their lenses with focal lengths in meters (cm, mm, etc.).
Most angles are reported in radians, unless you're an astronomer or talking about positions on (or above) Earth and use degrees and decimals, or minutes and seconds (not the units of time).
Heat is fun, because sometimes we use calories or even BTU. Then there's pressure with Torr, standard atmospheres, or mm (or micro-meters) of mercury. (That's that drippy metal stuff, not the NASA space program, or the planet, both of which are spelled with a capital M.)
Oh, of course, we spec'd wire and sheet metal in gauge, and probably did a bunch of other silly things like that, that I'm forgetting. And our communications link budgets were kept in deci-Bels (dB )--a logarithmic unit--for such sound engineering reasons I've written essays explaining it to my less enlightened scientific brethren. (Really!)
Time is funny in space, as it's--well--relative, since the spacecraft are moving really fast with respect to each other (and us). Time slows down on-board spacecraft, but not nearly as quickly as it does in space related programmatics (as in the things program managers mis-manage). Space related programs (Apollo, the Shuttle, etc.) have timelines measured in years (about pi times 10^7 seconds), and are also relative which explains why milestones always slip to the right. (Has something to do with dollars and the conversion rate to pints of Guiness, and politicians, but I never was good at program management.)
Then, within the "metric system", we usually use MKS but might use cgs. (An erg is 10^-7 Joules for those keeping score.)
Anyway, the metric system is a fine thing, but, in the space engineering world, not quite the panacea of easy in-head computing as often advertised to the general public. When I wrote computer programs, I'd usually include about a half a page of in-line conversion functions, all validated and verified, of course. Really, we could have done the calibrations in any units, and actually often used "normalized units" where my favorite normalization was to furlongs/fortnight = 1.66309524 x 10^-4 mps, or approximately fifteen micro-meters per second. Usually good enough for engineering purposes, especially for government work.
Tom
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