As a technology matures, the focus tends to shift from qualitative achievements, such as who was the first individual or organization to achieve a certain goal, to more quantitative measurements, such as how much resources and expertise are needed to complete a single instance of a task, and how much environmental impact and risk of harm is generated. This is a necessary transition in order to scale up the technology from proofs of concept to mass adoption. For instance, in the early days of powered flight, the emphasis was on milestones such as the Wright brothers' first powered, controlled, heavier-than-air flight in 1903, or Lindbergh's first solo non-stop transatlantic flight in 1927. But it required the decades of boring but important and sustained development in jet aviation (as well as the attendant infrastructure and logistical support) from the 1950s to today to lower the cost of (say) transatlantic air travel while simultaneously improving safety standards to the point where it became both safe and affordable (albeit not particularly luxurious) on a regular basis for a middle-class individual in a developed country. In contrast, the Apollo programs famously led to the milestone of crewed missions to the Moon in 1969, but at prohibitive expense. Unlike the situation with aviation, there have not been significant advances in cost reduction; NASA's Artemis program, for instance, is estimated to require tens of billions of dollars to perform a single such mission (which, to be fair, involves heavier payloads and longer time periods than the Apollo missions). (Also, the future of this program may be in doubt due to significant budget cuts.) (1/3)