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The problem is with the "hours" part. Which, not accidentally, is not even part of the SI.





In the official BIPM brochure, hours are technically classified as "Non-SI units accepted for use with SI." This puts them in the same category as liters, hectares, tonnes, decibels, etc.

https://en.wikipedia.org/wiki/Non-SI_units_mentioned_in_the_...


I can read Wikipedia too. All the calculations are done in m, s, g, etc. if you want to dumb it down to the public you might as well go in miles per hour, leagues per day, etc., spaceflight is not the place where it is appropriate.

  >I can read Wikipedia too.
I'm proud of you?

Presumably you can also read the official BIPM SI Brochure. As mentioned, it will tell you the same thing:

https://www.bipm.org/documents/20126/41483022/SI-Brochure-9-...

  >if you want to dumb it down to the public you might as well go in miles per hour, leagues per day, etc., spaceflight is not the place where it is appropriate.
1. Quick, call the spaceflight units police.

2. When you ask the regular units police (BIPM), their official decision is that hours are "accepted."

I trust you can read the dictionary definition of "accepted" all on your own.


> spaceflight is not the place where it is appropriate.

But, a video stream meant for the public consumption is. SI are standardized for the context of calculations, not necessarily for human consumption, which happens to be why nobody gives the weather in degrees kelvin.


Their main target audience is still space geeks. Parts of broadcast will be shown in daily news bits on cnn and reuters, who will still translate the height to football fields, velocity to car speed, etc. Geeks will watch and re-watch it multiple times and fight over crazy theories online and it really helps if you can use normal units of measure.

Btw the rest of the world measure temperature in Celsius which is derived from Kelvin (by adding or subtracting the value of absolute zero in Celsius).


> Btw the rest of the world measure temperature in Celsius which is derived from Kelvin (by adding or subtracting the value of absolute zero in Celsius).

Yet, it's not SI, because it's for humans. The same could be said for using km/h. The rest of the world measured speed in km/h which is derived from m/s (multiplying by a constant).

They're presenting units that people are most familiar with, that most people see and experience, modulate with their foot, every day of their lives. The presentation is for humans, not calculators. The best way to make people interested is to make things relatable, and let the interested people do the trivial math they're so familiar with. It's good PR, and an example of why engineers shouldn't be involved with PR.


> if you want to dumb it down to the public you might as well go in miles per hour,

The blue origin launch this week used mph and feet of elevation, and I can definitively say that using modified SI is way way better than US customary


Well, at least they didn't do knots, that's progress I guess :)



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