Tsar Bomba, whose test on October 30, 1961, still remains the most powerful man-made explosion in history, was designed by Russian physicists including Andrei Sakharov. Sakharov later became an outspoken critic of nuclear testing, with his work earning him 1975 Nobel Peace Prize. The hydrogen bomb released energy nearly 1,500 times the combined yield of Hiroshima and Nagasaki atomic bombs.