The biggest breakthrough might not be in technology, but in policy. Nuclear propulsion has offered high-Isp and high-thrust together in the same engine since t

The biggest breakthrough might not be in technology, but in policy. Nuclear propulsion has offered high-Isp and high-thrust together in the same engine since the 60s[1], but for various reasons it hasn't flown. With the right safety precautions, public perception, legal changes, and luck, this could be the "breakthrough" you're looking for. [1] https://en.wikipedia.org/wiki/NERVA https://en.wikipedia.org/wiki/NERVA