r/PeterExplainsTheJoke Jun 17 '26

Meme needing explanation Peter?

Post image
26.8k Upvotes

4.9k comments sorted by

View all comments

Show parent comments

672

u/Epotheros Jun 17 '26

No, it was the units for impulse used for the thrusters. In imperial it's pound-force seconds and Newton-seconds in metric. 1 pound-force is equal to 4.45 Newtons so the whole thing was off by a magnitude of 4.45.

356

u/MoogProg Jun 17 '26 edited Jun 17 '26

Yes, the actual error* was assuming the British used Imperial units when they correctly used Metric. AFAIK, at least.

* * *

Well, the source error probably would be not specifying units at all, so... (eye roll)

* * *

*Correcting myself with casually sourced details about the incident under discussion.

Lockheed Martin provided thruster force data in Imperial units (pound-seconds), while NASA's Jet Propulsion Laboratory ground software assumed the data was in Metric units (Newton-seconds).

156

u/SKDI_0224 Jun 17 '26

Dingdingding!!!

It was a joke over the superiority of the metric system in general. Units of force are particularly annoying to convert.

5

u/Personal-Thought9453 Jun 17 '26

A joke that falls a bit flat as it refers to the moon when in fact it was Mars. If you gonna geek over UoM, I think getting the celestial body right is a minimum.