This is rude, but I'd like to reply a comment you deleted in a separate thread. "why didn't they have a hot-spare" They do! Flight spares are complete, flight-

This is rude, but I'd like to reply a comment you deleted in a separate thread. "why didn't they have a hot-spare" They do! Flight spares are complete, flight-rated copies of spacecraft built for exactly this contingency: https://en.wikipedia.org/wiki/Flight_spare https://en.wikipedia.org/wiki/Flight_spare After launch the flight spares are used for terrain testing and troubleshooting. (The "mars yard" has flight spares for Curiosity and Perseverance https://www-robotics.jpl.nasa.gov/how-we-do-it/facilities/marsyard-iii/ https://www-robotics.jpl.nasa.gov/how-we-do-it/facilities/ma... which were used to test some wheels to destruction after Curiosity started showing some wear https://www.planetary.org/articles/08190630-curiosity-wheel-damage https://www.planetary.org/articles/08190630-curiosity-wheel-... ) The blog post lays it on a bit thick with the $500 million number and the "launch only two weeks away" given that the article itself is illustrated with a photo of the Sojourner flight spare. Spirit had the SSTB1 test rover. If he had actually blown out the entire electrical system, they could have launched it instead. Swapping out the entire vehicle right before launch would have been an awful job, but it's not flat out impossible.