For one, nuclear pulse rockets violate several international treaties. Fission fragment rockets, while the performance is impressive on paper, have yet to be de

For one, nuclear pulse rockets violate several international treaties. Fission fragment rockets, while the performance is impressive on paper, have yet to be demonstrated in the lab. Nuclear thermal propulsion has been demonstrated on Earth[0] and Nuclear electric propulsion has been flight proven[1]. NASA had a serious effort to develop and flight prove a high power(200 KWe) nuclear reactor[2]. This would have been used to power the Jupiter Icy Moons Orbiter[3] which would have explored Europa, Ganymeade, Callisto, and Io if things were favorable. The reactor enabled high power electric propulsion, high bandwidth communication(10Mbit/s), and even a full scale ice penetrating radar. This much power is hard to come by as far out as Jupiter. The entire effort lasted about two years before it got canceled because NASA needed to free up money for the (now canceled) Constellation Program. The thing I would like to emphasize here is that this was a serious effort with money on the table and a mission in place. The nuclear propulsion work NASA is currently working on is either a concept study, that is just investigating whether an idea can work at all, or not very well funded. The issue is getting the funding to develop the hardware and actually following through [0]https://en.wikipedia.org/wiki/NERVA https://en.wikipedia.org/wiki/NERVA [1]https://en.wikipedia.org/wiki/Kosmos_1867 https://en.wikipedia.org/wiki/Kosmos_1867 [2]https://en.wikipedia.org/wiki/Project_Prometheus https://en.wikipedia.org/wiki/Project_Prometheus [3]https://en.wikipedia.org/wiki/Jupiter_Icy_Moons_Orbiter https://en.wikipedia.org/wiki/Jupiter_Icy_Moons_Orbiter