New York Times: In 1949 scientists at the Naval Research Laboratory in Washington, DC, determined that the Soviet Union had succeeded in testing its first atomic bomb. They did so by measuring the gamma radiation emitted by rainwater collected in a barrel on an NRL roof. According to a report by the National Research Council, the US is at risk of losing the specialized knowledge needed to perform such feats of nuclear forensics. The New York Times‘s William Broad reports that the US government has recognized the problem and is taking measures to address it.