What is the ‘Manhattan Project’?

Question

UnlockIAS · Accepted Answer

Correct — A, A research and development undertaking that produced the first nuclear weapons. The Manhattan Project ran from 1942 to 1946, led by the United States in collaboration with the United Kingdom and Canada. Major General Leslie Groves of the US Army Corps of Engineers directed it; J. Robert Oppenheimer directed the Los Alamos Laboratory (Project Y) in New Mexico, where the weapons were designed. The name is an accident of address, not a description: the Army programme was designated the Manhattan District because its first headquarters were in Manhattan, New York, and that designation replaced the earlier codename 'Development of Substitute Materials'. The district was constituted on 13 August 1942 and disbanded on 15 August 1947, the civilian Atomic Energy Commission having taken over in January 1947. Its roots are older still — the discovery of fission by Otto Hahn and Fritz Strassmann in 1938, explained by Lise Meitner and Otto Frisch; the Einstein–Szilard letter of August 1939 warning Roosevelt of 'extremely powerful bombs of a new type'; the Frisch–Peierls memorandum of March 1940 and Britain's MAUD Committee, whose Tube Alloys programme the Americans absorbed after the Quebec Agreement of August 1943. The scale was industrial: about 130,000 workers at peak and nearly US$2 billion spent, with more than 80 per cent of that going into fissile-material plants — enriched uranium at the Clinton Engineer Works in Tennessee (Oak Ridge) and plutonium in the world's first industrial-scale reactors at Hanford, Washington. Two designs resulted: Little Boy, an enriched-uranium gun-type weapon, and Fat Man, a plutonium implosion weapon. The first nuclear device ever detonated was the Trinity 'gadget', fired at 05:30 on 16 July 1945 in the New Mexico desert with a yield of about 20 kilotons of TNT.

Why the other options are wrong — (b) Plausible only because of the borough. Manhattan genuinely is the centre of the world art trade — both Christie's and Sotheby's hold their New York sales there — so a candidate who knows the place but not the programme can be nudged towards this. But no auction has ever been called 'the Manhattan Project'; the phrase is a Second World War military designation for the Manhattan Engineer District of the US Army Corps of Engineers, and it belongs to weapons research, not to the art market.  (c) The closest thing to a genuine trap, because 'Manhattan' is a borough of New York City and in American usage a 'project' in a city usually does mean construction. The inversion is the point: the district was named after where its offices first sat, not after anything it built there. Its actual construction was deliberately far away and deliberately remote — Oak Ridge in Tennessee, Hanford in Washington and Los Alamos in New Mexico, all chosen for isolation and secrecy.  (d) There is no theme park of this name anywhere, and the option exists only to absorb a blind guess. Manhattan's famous sites are Central Park, Times Square, the Empire State Building and the September 11 Memorial at Ground Zero — a list with no amusement park on it. If a candidate is guessing between four options, this is the one that should go first, because it makes no claim that could survive even a moment's thought about wartime terminology.

Concept: The physics the project had to industrialise is simple to state and brutal to build. Uranium-235 and plutonium-239 are fissile: struck by a neutron they split, releasing energy and more neutrons, and above a critical mass the reaction sustains itself. A reactor holds that reaction steady with moderators and control rods; a weapon forces it to run away in microseconds. There were two routes to the fissile core and the project took both. One was isotope separation, because natural uranium is only about 0.72 per cent U-235 and the rest is U-238 — hence the vast gaseous-diffusion, electromagnetic and thermal-diffusion plants at Oak Ridge. The other was breeding plutonium-239 from U-238 inside reactors, which is what Hanford was built for, after Enrico Fermi's team at the University of Chicago's Metallurgical Laboratory achieved the first artificial self-sustaining chain reaction in Chicago Pile-1 on 2 December 1942. The two materials then forced two different weapon designs: uranium could be assembled by firing one subcritical piece into another (the gun method used in Little Boy), but reactor plutonium carries enough plutonium-240, which fissions spontaneously, to pre-detonate a gun weapon — so Fat Man had to be an implosion device, compressing a plutonium sphere with shaped explosive lenses.

State PCS 2023 Q14 — Science & Technology PYQ with Answer

State PCS 2023 Q14 — Science & Technology PYQ with Answer