Nuclear weapon

''Note: This page contains the definition and history of nuclear weapons. For a list of nuclear weapons used in the Halo Universe, see Nuke.''

History
A Nuclear Weapon is employed as a weapon of mass-destruction created in the middle 20th century by physicists and scientists on Earth. A nuclear weapon derives its destructive force from nuclear reactions of fusion or fission. As a result, even a nuclear weapon with a small yield is significantly more powerful than the largest conventional explosives, and a single weapon is capable of destroying an entire city.

The first nuclear weapon (and later, more nuclear arms) was created by the United States with help from an international team, including many displaced scientists from central Europe, which included Germany, with assistance from the United Kingdom and Canada during World War II as part of the top-secret "Manhattan Project". While the first weapons were developed primarily out of fear that Nazi Germany would develop them first, they were eventually used against the Japanese cities of Hiroshima and Nagasaki. The first test was conducted on July 16, 1945 at a site near Alamogordo, New Mexico. The Soviet Union developed and tested their first nuclear weapon in 1949, based partially on information obtained from Soviet espionage in the United States. Both the U.S. and USSR would go on to develop weapons powered by nuclear fusion (hydrogen bombs) by the mid-1950s. With the invention of reliable rocketry during the 1960s, it became possible for nuclear weapons to be delivered anywhere in the world on a very short notice, and the two Cold War superpowers adopted a strategy of deterrence to maintain a shaky peace.

World War II
During World War II, two major nuclear detonations took place on Earth on the territory of the former Empire of Japan, in the cities of Nagasaki and Hiroshima. The detonations were made by the United States of America, and they represented the decisive strike in the fall of the Axis Powers.

Nuclear Warfare
Nuclear warfare strategy is a way for either fighting or avoiding a nuclear war. The policy of trying to ward off a potential attack by a nuclear weapon from another country by threatening nuclear retaliation is known as the strategy of nuclear deterrence. The goal in deterrence is to always maintain a second strike status (the ability of a country to respond to a nuclear attack with one of its own) and potentially to strive for first strike status (the ability to completely destroy an enemy's nuclear forces before they could retaliate). During the Cold War on Earth, policy and military theorists in nuclear-enabled countries worked out models of what sorts of policies could prevent one from ever being attacked by a nuclear weapon.

Nuclear Explosion
A nuclear detonation has the explosive power to destroy an entire city and well into its outskirts. A nuclear warhead often represents a "Drastic measure" taken by a certain military force, including the UNSC in defeating an enemy force or avoiding its own destruction by means of mass-destruction. In this case, the UNSC used nuclear warheads against the Covenant in a First Strike.

Hiroshima
Hiroshima was the primary target of the first nuclear bombing mission on August 6, with Kokura and Nagasaki being alternative targets. August 6 was chosen because there had previously been clouds over the target. The bombing of Hiroshima was the first case of nuclear detonation in Human history.

Nagasaki
On the morning of August 9, 1945, the second nuclear detonation of World War II took place in Japan in the city of Nagasaki by the United States of America which marked the end of the war between Japan and the Allies.

Nuclear Aftermath
The energy released from a nuclear weapon detonated in the troposphere can be divided into four basic categories:


 * Blast—40-50% of total energy
 * Thermal radiation—30-50% of total energy
 * Ionizing radiation—5% of total energy
 * Residual radiation—5-10% of total energy

However, depending on the design of the weapon and the environment in which it is detonated the energy distributed to these categories can be increased or decreased to the point of nullification. The blast effect is created by immense amounts of energy, spanning the electromagnetic spectrum, with the surroundings. Locations such as submarine, surface, airburst, or exo-atmospheric determine how much energy is produced as blast and how much as radiation. In general, denser mediums around the bomb, like water, absorb more energy, and create more powerful shockwaves while at the same time limiting the area of its effect.

The dominant effects of a nuclear weapon where people are likely to be affected (blast and thermal radiation) are identical physical damage mechanisms to conventional explosives. However the energy produced by a nuclear explosive is millions of times more powerful per gram and the temperatures reached are briefly in the tens of millions of degrees.

Energy from a nuclear explosive is initially released in several forms of penetrating radiation. When there is a surrounding material such as air, rock, or water, this radiation interacts with and rapidly heats it to an equilibrium temperature. Causing vaporization of surrounding material resulting in its rapid expansion. Kinetic energy created by this expansion contributes to the formation of a shockwave. When a nuclear detonation occurs in air near sea level, much of the released energy interacts with the atmosphere and creates a shockwave which expands spherically from the hypocenter. Intense thermal radiation at the hypocenter forms a fireball and if the burst is low enough, its often associated mushroom cloud. In a burst at high altitudes, where the air density is low, more energy is released as ionizing gamma radiation and x-rays than an atmosphere displacing shockwave.

Cold War
The Cold War on Earth saw increased tensions and fear of Nuclear War sparking between the United States of America and the Soviet Union. The two countries and their respective spheres of influence found themselves on constant alert of nuclear launch and nuclear war. During this period the humanity tested the most powerful device, one of the most know the Tsar Bomba.

Nuclear Weapons In Halo
Various nuclear weapons have been used in the Haloverse launched by the UNSC against the Covenant forces.

Fury Tactical Nuclear Warhead
During the attack on Reach, Spartans Frederic-104, Kelly-087, and Joshua-029(AKA Alpha Team) destroyed a Covenant Cruiser by capturing a trio of Banshees and throwing a Tactical Nuke into its grav-lift.

Shiva-class Nuclear Missile
It is a ship-mounted thermonuclear missile, outfitted with varying pay load, missile thermonuclear warhead assumable to be anywhere from 20 to 80 Megatons yield depending on its type (most of missiles utilize UNSC standard 30-megaton HAVOK thermonuclear warhead).

FENRIS Nuclear Warhead
FENRIS Nuclear Warheads are retired low-yield thermonuclear devices that the UNSC once used. They were replaced by more powerful warheads. However, recent actions had depleted the UNSC nuclear stockpile and these retired warheads, slated for conversion into peaceful purposes, were the only bombs they had left.

NOVA Bomb
First mentioned in Halo: First Strike, the NOVA is a special device that uses nine fusion warheads in a ring formation. Once detonation occurs, the lithium-triteride fusion cores combine together and the resulting blast is multiplied one hundred-fold. Nick-named "planet-killers," these have enough explosive power to destroy an entire planet.

HORNET Mines
HORNET Mines are a type of heavy ordinance used by the UNSC. HORNET Mines are nuclear devices capable of considerable stealth and are kept aboard some UNSC prowlers, such as the Dusk.

HAVOK Nuclear Warheads
The HAVOK thermonuclear warhead is mainly used in missiles fired by UNSC Bombers or Cruisers. However, an alternate use is to simply place the warhead on a ground target and detonate it with a remote. Its yield is thirty megatons

Related Articles

 * The Fury Tactical Nuclear Warhead
 * The Shiva-class Nuclear Missile
 * The FENRIS Nuclear Warhead
 * The NOVA Bomb
 * HORNET Mines
 * HAVOK Nuclear Warheads