NASA (US) Space Shuttle "Endeavour"

Why is the name of this shuttle, designed and operated by the US space agency NASA, spelled the British way “Endeavour”, instead of “Endeavor”?

Because it’s named after much older ships named that way.

A starting point, from the pertinent Wikipedia article:

“Endeavour was named through a national competition involving students in elementary and secondary schools. The orbiter is named after HM Bark Endeavour, the ship commanded by 18th century explorer James Cook; the name also honored Endeavour, the Command Module of Apollo 15. This is why the name is spelled in the British English manner, rather than the American English spelling of “Endeavor.” This has caused confusion, most notably when NASA themselves misspelled a sign on the launch pad in 2007.”

Of course, no one explained this to the NASA sign-making shop.

ETA: Should’ve finished reading the post before mine. Carry on…