The explanation, I suspect, is pleasantly mundane: both budgets float on the same rising tide of American GDP. When the economy grows, more money sloshes into almost every institutional bucket simultaneously—the government gets fatter, professional sports get fatter, and both become fatter in remarkably similar ways. Consider that in 2005, the average NFL player earned about 1.4 million dollars, while NASA's budget hovered near 16 billion; by 2023, those figures had both roughly doubled, which is to say they moved together the way two swimmers caught in the same current move together, not because they're coordinating but because the current is doing the moving. Add inflation, add the fact that both organizations compete for attention and funding in an economy that was, on net, getting wealthier (with exceptions noted), and the correlation stops being mysterious and becomes almost inevitable.