[TMWNN]

Shuttle missions began and ended with simple numeric designators (STS-1, STS-2 ... STS-135). In between was the above system, because of triskaidekaphobia. <https://en.wikipedia.org/wiki/List_of_Space_Shuttle_missions...>

[vikingerik]

To be fair, the previous history of American space missions numbered 13 did have a 100% rate of near-catastrophic failure...

[fragmede]

technically, sts-13 was a catastrophic failure, but they also technically renamed it.

[jjk166]

STS-13 was renamed to STS-41-C which was a reasonably routine mission.

[fragmede]

you're right, my mistake. I was thinking of a different mission by that particular shuttle

[mrexroad]

> “As a result of the changes in systems, flights under different numbering systems could have the same number with one having a letter appended, e.g. flight STS-51 (a mission carried out by Discovery in 1993) was many years after STS-51-A (Discovery's second flight in 1984).[6] It wasn't until STS-127 in 2009 where the flight numbering system returned to a standard and consistent order.”

Ouch, shortly after they get standardized and consistent flight numbers, the shuttle program gets cancelled. I guess computer science doesn’t have a monopoly over the difficulty of naming things.