Nuclear weapons delivery
The bombs that destroyed Hiroshima and Nagasaki in 1945 (with TNT equivalents between 15 and 22 kilotons) were weaker than many of today's tactical weapons, yet they achieved the desired effect when used strategically.
Gravity bombs are designed to be dropped from planes, which requires that the weapon be able to withstand vibrations and changes in air temperature and pressure during the course of a flight.
US nuclear weapons that met these criteria are designated by the letter "B" followed, without a hyphen, by the sequential number of the "physics package" it contains.
Various air-dropping techniques exist, including toss bombing, parachute-retarded delivery, and laydown modes, intended to give the dropping aircraft time to escape the ensuing blast.
The earliest gravity nuclear bombs (Little Boy and Fat Man) of the United States could only be carried, during the era of their creation, by the special Silverplate limited production (65 airframes by 1947) version of the B-29 Superfortress.
Air- or Ground-launched nuclear-armed cruise missiles (sometimes even nuclear-powered) were considered by both sides early in the Cold War, but both concluded that it was impractical with the technology of the time.
Later on in the Cold War both disciplines had advanced far enough that it was feasible to create both reliable long-ranged cruise missiles and the strategic bombers able to launch them.
In 2018, the first operational nuclear-powered strategic cruise missile, the SSC-X-9 "Skyfall" (9М730 Буревестник) was revealed by Russian President Vladimir Putin.
Also, the eventual Soviet Fractional Orbital Bombardment System (FOBS) that served a similar purpose—it was just deliberately designed to deorbit before completing a full circle—was phased out in January 1983 in compliance with the SALT II treaty.
Since the 1970s modern ballistic weapons have seen the development of far more accurate targeting technologies, particularly due to improvements in inertial guidance systems.
This set the stage for smaller warheads in the hundreds-of-kilotons-range yield, and consequently for ICBMs having multiple independently targetable reentry vehicles (MIRV).
The Americans responded with the first "modern design" of ballistic missile subs; the George Washington-class, which launched the Polaris SLBM.
These maneuverable devices threaten to obsolate current forms of ABM defences, thus various nascent and established nuclear powers are racing to field examples of such systems.
The United States have largely taken nuclear air-defense weapons out of service with the fall of the Soviet Union in the early 1990s.
Similarly in the Soviet Union it was the R-7 ICBM/launch vehicle that placed the first artificial satellite in space, Sputnik, on 4 October 1957, and the first human spaceflight in history was accomplished on a derivative of the R-7, the Vostok, on 12 April 1961, by cosmonaut Yuri Gagarin.
The Soviet Union's first fully operational weather satellite, the Meteor 1 was launched on 26 March 1969 on the Vostok rocket,[citation needed] a derivative of the R-7 ICBM.
WD-40 was first used by Convair to protect the outer skin, and more importantly, the paper thin "balloon tanks" of the Atlas missile from rust and corrosion.
In 1953, Dr. S. Donald Stookey of the Corning Research and Development Division invented Pyroceram, a white glass-ceramic material capable of withstanding a thermal shock (sudden temperature change) of up to 450 °C (840 °F).
[13] Precise navigation would enable United States submarines to get an accurate fix of their positions before they launched their SLBMs, this spurred development of triangulation methods that ultimately culminated in GPS.
During a Labor Day weekend in 1973, a meeting of about twelve military officers at the Pentagon discussed the creation of a Defense Navigation Satellite System (DNSS).
[16] During the development of the submarine-launched Polaris missile, a requirement to accurately know the submarine's location was needed to ensure a high circular error probable warhead target accuracy.
In 1967, the US Navy developed the Timation satellite that proved the ability to place accurate clocks in space, a technology required by the latter Global Positioning System.
That same year, the concept was pursued as Project 621B, which had "many of the attributes that you now see in GPS"[25] and promised increased accuracy for Air Force bombers as well as ICBMs.
The Navy Research Laboratory continued advancements with their Timation (Time Navigation) satellites, first launched in 1967, and with the third one in 1974 carrying the first atomic clock into orbit.
