This isn't technology, but the supernova of 1987 [0] confirmed our understanding of supernova physics, and gave us useful bounds on the mass of the neutrino. Ev

This isn't technology, but the supernova of 1987 [0] confirmed our understanding of supernova physics, and gave us useful bounds on the mass of the neutrino. Even today, it gives stringent constraints on new hypothetical particles, which would have changed how the supernova played out. Unfortunately, we might have to wait decades to centuries for the next one. 0: https://en.wikipedia.org/wiki/SN_1987A https://en.wikipedia.org/wiki/SN_1987A