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Starship Flight 7

(www.spacex.com)
678 points chinathrow | 2 comments | 16 Jan 25 21:25 UTC | HN request time: 0s | source
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drillsteps5 ◴[17 Jan 25 16:05 UTC] No.42739270[source]▶
Can someone please please PLEASE tell SpaceX PR/Streaming team that the speed (per SI system) is measured in meters per second, not kilometers per hour? The speed of sound is approx 300 m/s, orbital velocity is approx 8,0000 m/s (depending on altitude), free fall acceleration on Earth is 9.81m/s, 1.63m/s on the Moon, the speed of light is apporx 300,000,000 m/s, people learn these numbers in middle school. It's not 1000 km/h, or 28,000 km/h, it just looks so weird.

Edit: ok, acceleration is meters per second per second, but my point stands.

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xhkkffbf ◴[17 Jan 25 16:13 UTC] No.42739416[source]▶
I understand the appeal of using the same combinations everywhere, but I thought the great thing about the metric system was that it was easy to convert. So 8000 m/s is 8 km/s.
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drillsteps5 ◴[17 Jan 25 16:26 UTC] No.42739694[source]▶
The problem is with the "hours" part. Which, not accidentally, is not even part of the SI.
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schiffern ◴[17 Jan 25 17:10 UTC] No.42740504[source]▶
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_...

replies(1): >>42740624 #
drillsteps5 ◴[17 Jan 25 17:17 UTC] No.42740624[source]▶
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.
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nomel ◴[17 Jan 25 22:05 UTC] No.42743780[source]▶
> 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.

replies(1): >>42750628 #
1. drillsteps5 ◴[18 Jan 25 19:14 UTC] No.42750628[source]▶
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).

replies(1): >>42784487 #
2. nomel ◴[21 Jan 25 19:52 UTC] No.42784487[source]▶
> 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.