In April 1941, the National Defense Research Committee (NDRC) asked Arthur Compton, a Nobel-Prize-winning physics professor at the University of Chicago, to report on the uranium program. His report, submitted in May 1941, foresaw the prospects of developing radiological weapons, nuclear propulsion for ships, and nuclear weapons using uranium-235 or the recently discovered plutonium. In October he wrote another report on the practicality of an atomic bomb. Niels Bohr and John Wheeler had theorized that heavy isotopes with even atomic numbers and odd number of neutrons were fissile. If so, then plutonium-239 was likely to be.