Limitations
The vessel's exhaust would contain radioactive isotopes, but these would be rapidly dispersed after travelling only a short distance; the exhaust would also be travelling at high speed (in Zubrin's scenario, faster than Solar escape velocity, allowing it to eventually leave the Solar System). This is however, little use on the surface of a planet, where a NSWR would eject massive quantities of superheated steam, still containing fissioning nuclear salts. Terrestrial testing might be subject to reasonable objections; as one physicist wrote, "Writing the environmental impact statement for such tests might present an interesting problem ..." It is also not certain that fission in a NSWR could be controlled: "Whether fast criticality can be controlled in a rocket engine remains an open question.".
Read more about this topic: Nuclear Salt-water Rocket
Famous quotes containing the word limitations:
“The only rules comedy can tolerate are those of taste, and the only limitations those of libel.”
—James Thurber (1894–1961)
“No man could bring himself to reveal his true character, and, above all, his true limitations as a citizen and a Christian, his true meannesses, his true imbecilities, to his friends, or even to his wife. Honest autobiography is therefore a contradiction in terms: the moment a man considers himself, even in petto, he tries to gild and fresco himself.”
—H.L. (Henry Lewis)
“... art transcends its limitations only by staying within them.”
—Flannery O’Connor (1925–1964)