The odds were against the effort from the start. Frontier’s a 296-ton machine of roughly 60 million parts, each essential to operation, that initial estimates projected would require more power to run than a mid-sized U.S. city.

That machine had to be not only built but assembled, booted up, tuned, primed and finally proven to perform.

“Given all the obstacles and events that stood in our way, you can look at the probability and show mathematically this success story should not have happened and a machine as complicated as Frontier should not work,” said Thomas Zacharia, now retired, who led development of ORNL’s supercomputing capability and served as the lab’s director during the launch of Frontier and its predecessor, Summit.