Today in 1949, the Soviet Union tested its first atomic bomb in Semipalatinsk, Kazakhstan. The 22-kiloton RDS-1 device—codenamed Joe-1 by the United States—was essentially a copy of the first plutonium-fueled implosion-type atomic bomb (the “Gadget”) the United States tested on July 16, 1945.
So close to the reverse of the Connecticut commemorative 25-cent coin.
Although the Soviet Union had crucial information from spies inside the Manhattan Project and the Smyth Report about the device’s design and the industrial processes the United States used to make its components, it still took more than 48 months to build and test it—versus 35 months for the US.
Here is a restored official (silent) footage from @atomcentral.bsky.social of that momentous nuclear test:
And here is a 32-minute formerly secret official documentary (with English subtitles) prepared for Soviet leader Joseph Stalin about the extensive preparations for and execution of that first atomic weapon test, along with a detailed report about the results.
Radioactive debris from this test was detected in early September by US Air Force WB-29 reconnaissance aircraft and a US Navy program to collect and analyze fallout in rainwater. Once traced back to its source—see next link for how that happened—President Truman announced the test on September 23.
[Source: “Finding the Site of the First Soviet Nuclear Test in 1949,” by former U.S. Weather Bureau meteorologist Lester Machta in the Bulletin of the American Meteorological Society (1992)]. journals.ametsoc.org/view/journal...
President Truman was initially not certain he wanted to publicly announce the Soviet nuclear test, worrying that doing so would have serious diplomatic and economic repercussions. When he finally did, however, he did not say it was an atomic bomb test, only that “an atomic explosion occurred.”
Today is also the 34th anniversary of the closure of the Semipalatinsk Test Site—aka the Polygon—and the 16th International Day Against Nuclear Tests, established by the United Nations in 2009 at the urging of Kazakhstan and other states to commemorate that milestone.