what is essentially a continuous nuclear fission explosion, NSWRs would have both very high thrust and very high exhaust velocity, meaning that the rocket would be able to accelerate quickly as well as be extremely efficient in terms of propellant usage. The combination of high thrust and high specific impulse is a very rare trait in the rocket world. One design would generate 13 meganewtons of thrust at 66 km/s exhaust velocity (or 6,730 seconds ISP compared to ~4.5 km/s (450 s ISP) exhaust velocity for the best chemical rockets as of February 2023). The design and calculations discussed above are using 20 percent enriched uranium salts. However, it would be plausible to use another design which would be capable of achieving much higher exhaust velocities (4,725 km/s) and use a 30,000 tonne ice comet along with 7,500 tonnes of highly enriched uranium salts to propel a 300 tonne spacecraft up to 7.62% of the speed of light and potentially arrive at Alpha Centauri after a 60 year journey. "NSWRs share many of the features of Orion propulsion systems, except that NSWRs would generate continuous rather than pulsed thrust and may be workable on much smaller scales than the smallest feasible Orion designs (which are generally large, due to the requirements of the shock-absorber system and the minimum size of efficient nuclear explosives)." Limitations The propellant used in the initial design would contain a rather large amount of the relatively expensive isotope U, which would not be very cost effective. However, if the use of NSWR began to rise, it would be possible to replace this with the cheaper isotopes U or Pu in either fission breeder reactors or (much better) nuclear fusion–fission hybrid reactors. These other fissiles would have the right characteristics to serve nearly as well, at a relatively low cost. Another major limitation of the nuclear salt water rocket design by Robert Zubrin included the lack of a material to be used in the reaction chamber that could actually sustain such a reaction within a spacecraft. Zubrin claimed in his design that the apparatus was created so that the liquid flow rate or velocity was what mattered most in the process, not the material. Therefore, he argued that if the proper velocity was chosen for the liquid traveling through the reaction chamber, the site of maximum fission release could then be located at the end of the