by the explosion. A scientist in Andre Sakharov's theoretical lab recalled the test in a collective book of memoirs. He witnessed the RDS-37 test from a viewing station away from the hypocenter. As the countdown reached zero, the first impression he had "was of almost intolerable heat, as if [his head] had been placed into an open oven for several seconds." The shock wave of dust and debris caused by the explosion could be seen and heard approaching and reached the viewing station roughly ninety seconds after the thermonuclear detonation. All viewers were forced to fall down on their faces with their feet pointed toward the explosion to help avoid injury from flying debris. After the shock wave passed, all the viewers stood up and started cheering their success, the Soviet Union became the first to successfully air deliver a two-stage thermonuclear weapon. The measured energy yield of the device was equivalent to that of 1.6 megatons of TNT. After the testing of the RDS-37, the commission noted three things during the meeting on 24 November 1955, "the design of the hydrogen bomb, based on a novel principle, has been successfully tested; it is necessary to continue detailed studies of the processes proceeding in explosions of bombs of this type; further development of hydrogen bombs should be conducted on the basis of a broad application of the principles chosen as the foundation of the RDS-37 bomb". The successful testing of the RDS-37 made it possible to start large-scale development of thermonuclear weapons. The charge of the RDS-37 became the prototype for all of the following two-stage thermonuclear devices in the USSR. The device was deliberately detonated high in the air to avoid local fallout. The height of burst was above the ground. Delivery method The weapon was air-dropped at Semipalatinsk Test Site, Kazakhstan, making it the first air-dropped two-stage thermonuclear test. It was the largest detonation ever carried out at the Semipalatinsk test site. The RDS-6s device (Joe-4) test in 1953 had one-stage design, and was not scalable into the megaton yield range. The RDS-37 was dropped from a Tupolev Tu-16 bomber and was used most through the late 1950s and 1960s. After a while the Soviet Union felt as if the 2.9-megaton thermonuclear bomb was excessive for some missions, so the less powerful RP-30 and RP-32 200-kiloton bombs were ready for some missions. It would take the United States