Our world was forever changed on 5:30am, July 16, 1945 when in the sweltering morning heat of the New Mexican desert, the world's first atomic explosion was unleashed. The Trinity Test, at a yield of 21 Kilotons of TNT, was thousands of times more powerful than anything detonated by man up until that point in time. The immense heat turned the desert sand into a vaporous, green glass, which even today still litters the test site. Winds from the shock wave reached upwards of nine hundred miles per hour, and could be felt hundreds of miles away. Observers who had placed their hands over their eyes (atop their protective goggles) reported seeing the bonds in their hands and arms, as if looking at an x-ray. The fireball grew, massive in size, and the mushroom cloud rose to almost eight miles. For several minutes, no one said a word. There were no words to describe the act of taking a star, and placing it down on our Earth. 
Only a few weeks later, the cities of Hiroshima (Little Boy, 15 kilotons) and Nagasaki (Fatman, 21 kilotons) were leveled by this new weapon. People close to ground zero were vaporized, completely. Those further away were turned into carbonized ash figures, and others further away still were thrown hundreds of feet by the air blast. Firestorms swept across the cities, at hundreds of miles an hour. Later, it rained black fluid from the debris falling back down on the cities, highly radioactive water that looked more like motor oil than a clear liquid. Months after the blasts, those at the epicenters began falling mysteriously ill. Hair would fall out in clumps, they would vomit uncontrollably and their skin turned a sour shade of purple. They would soon die, casualties of the massive amounts of radiation the bombs gave off upon detonation. These were the first, and only casualties of nuclear weapons in a time of war.
And hopefully, the last.
But in times of desperation, such as the Human-Covenant War in the Halo franchise, all red lines are erased and once again, weapons too horrific to use are unleashed once more. Not against humans, but against an entirely new, alien threat. But to understand the UNSC's arsenal of nuclear payloads, we first have to understand how these weapons work and why the choice to use them is always a difficult one.
Nuclear weapons are basically taking a star, governed by the laws of physics and our universe, and placing it here on Earth. The same mechanisms that keep stars from collapsing (at least temporarily,) nuclear fusion, is also the same mechanisms that power a nuclear weapon. The first nuclear weapons used a process call "fission," where particles undergo a splitting action from a chain reaction and violently rip each other apart. Little Boy and Fat Man, used this type of process.
There are two ways to create a fission reaction, one is to slam two pieces of critical mass (usually a refined piece of Uranium 235) into each other. This releases the bonded atoms, and the fission process begins. The second, is implosion. Where a spherical piece of Plutonium 239 (refined) is compressed inwards by conventional explosives lenses, causing a chain reaction. The implosion method is infinitely more complex than the simple "slam" or gun-type method. These are simplistic atomic weapons, and the yield of these kinds of weapons cannot exceed more than 500 Kilotons, give or take.
But if you want to make a nuclear weapon, a "thermo-nuclear" weapon capable of reaching the Megaton range, you will need to harness the power of stars; fusion. Thermo-nuclear weapons are complex, and need several process' in order to reach a critical mass. The most widely used method is the ulman-teller design, and is a multi-stage design. These weapons use a fission bomb (Uranium), in order to fuse together atoms within a secondary package of plutonium. Furthermore, these can be boosted by the element tritium, making their chain reaction that much more sustainable. These two stages can also be multiplied many times to create a larger explosion. The largest bomb ever made, the Russian Tsar Bomba, was a three stage monster of 50 Megatons, but had a theoretical yield of 100 Megatons of TNT.
All modern nuclear weapons use this design, as it can vary the yield, is easily safeguarded and is incredibly destructive. For scale, a 1 Megaton nuclear weapon can vaporize an entire city. Countries now have sophisticated anti-missile defense systems, so most nuclear weapons are used in MIRV (multiple independent re-entry vehicle) assemblies. Where a missile releases several warheads from high orbit to rain down on multiple or singular targets.
There are hundreds of weapon designs in the world today, and thousands of warheads. Luckily, it seems that even though these weapons have guided politics for decades, no country is willing to use these weapons for fear of retaliation (mutually assured destruction) or because they are just too horrific to think about deploying.
But all that can change.
In the Halo franchise, the UNSC began using nuclear weapons on a large scale during the Covenant War. Either out of desperation, or because they were one of the only effective weapons against The Covenant. Several types were deployed during the war, from small demolition warheads, to planet cracking novas.
Fury MFDD (Medium Fusion Destructive Device)
As far as nuclear weapons go for the UNSC, the Fury MFDD is fairly compact. But don't let the size fool you, the Fury is about (give or take) the same 12-15 Kiloton yield as the Little Boy device that destroyed the city of Hiroshima. The closest analogous we have in our own history is the M-29 Davy Crockett Weapon System, which functioned as a small nuclear grenade launched from a reconciles rifle. The design was not stable, or intelligent. As soldiers who launched the sub-Kiloton yeild nuclear weapon would inevitably be within the range of fallout. The idea was that a pair of artillery officers would fire the weapon at on-coming soldiers or tanks, then run the other way...So, not very practical or safe.
The Fury, however, saw far and wide use during the war as it was both practical and portable. While we don't exactly know the "safe" way to deploy a Fury, we can assume a group of soldiers would sneak behind enemy lines and plant the device, then extract, detonating from afar. Alternatively, Spartans or ODSTs could sneak aboard a Covenant ship and plant the device, then extract. The device has a touch screen, similar possibly to our own PAL (Permissive Action Link) system, in order to authorize and set the yeild/detonation characteristics.
However, the Fury has been used in more desperate applications. A Fury was used by Noble Team to destroy a CCS-class battlecruiser during the Battle of Fumirole, with Spartan Thom staying aboard the ship when the device detonated. The explosion, again the same relative size of Little Boy at 12-15 Kilotons, completely destroyed the ship from the inside out.
The Fury is a jack of all trades nuclear weapon, used throughout the war for various actions and engagements.
HAVOK Tactical Nuclear Weapon
There's very little that is "tactical" about the HAVOK and the more correct term would be to describe it as a strategic nuclear weapon. Tactical nuclear weapons are low yeild weapons, meant to be used on the battlefield, or to deny an area to the enemy. Strategic weapons, however, are usually multi-Megaton large warheads that are meant to completely destroy a city, base or infrastructure of the enemy. In that sense, the HAVOK, functions more as a strategic nuclear weapon than a tactical one. The fireball from a HAVOK would be two miles wide and completely vaporize an area of around three miles. The largest United States Nuclear test was 15 Megatons, Castle Bravo. Half the yeild of the HAVOK, but it completely vaporized the entire portion of the atoll it was detonated on and has left a two mile wide crater in the seabed that is still visible today. A HAVOK device would be twice as devastating as the Bravo test, and would cause considerable damage for miles.
At 30 Megaton, the HAVOK is one of the largest nuclear weapons in the UNSC arsenal. It can be fitted to a number of delivery systems, such as a missile to be carried by fighter, bomber or ship. It can also be deployed as a 30 Megaton mine, to be laid in an asteroid field or the blackness of space until it is triggered by proximity or remotely. These mines, are known as HORNET mines, and can cause considerable damage to smaller Covenant cruisers and other ships. HORNET mines are carried primarily by Prowlers and have been used in brilliant fashion against Covenant ships, while the missile variants are carried by a large number of craft and used as brute force payloads.
The HAVOK has the unique distinction of being one of the larger nuclear weapons that can be detached from its delivery system and used as an independent payload. We saw John-117 do this in Halo 4, using a HAVOK against the Didact's flagship, Mantle's Approach. An independent HAVOK is armed by twisting the warhead's top panel housing, which then "pops" up. To detonate the warhead, one simply only needs to press down on the head. This type of application is only used in desperate situations, as the user and everyone in a few miles radius would be instantly vaporized.
HAVOKS saw wide use during the Covenant War, being deployed as strategic weapons, either destroying cities that were under Covenant control (Such as the Battle of Sigma Octanus IV) or as shipboard payloads to be used against enemy craft.
The HAVOK device is utterly devastating, and only used in the most dire of circumstances. Which during the Covenant war, unfortunately, were many.
Shiva/Hyperion Class Nuclear Missile
The Shiva and updated version (post Covenant war) Hyperion thermo-nuclear space ready missile is the primary nuclear armament aboard UNSC sharships. While the exact yeild of these missiles is unknown, they are at least two-staged fission/fusion weapons, so it can be assumed their yeild reaches upwards of 30 Megatons to 50 Megatons. The real world analogous would be the United States Titan and the USSR SS-18 "Satan" missiles which carried several multi-megaton nuclear payloads. These missiles were intercontinental ballistic missiles, capable of flying into high orbit, then raining down their independent re-entree vehicles back down on their targets. As strategic weapons, these were (along with their submarine variants) the most powerful weapons ever fielded by a nation. Each warhead could vaporize an entire city, and then some. Couple that with the fact each missile carried sometimes up to twelve of these 10 Megaton warheads, you can see why they hold the position they do.
The Shiva missiles in Halo, however, are not ground launched but instead launched from starships, or flown in by bomber aircraft (piloted or remotely.) The Shiva variant is strong enough to obliterate most small Covenant ships, and completely destroy the shields of larger ships. They are, however, ineffective against Covenant capital ships.
The updated Hyperion variant, was carried aboard frigates, carriers and cruisers. The Hyperion is powerful enough to destroy an unsheilded Covenant cruiser, but like the Shiva not powerful enough to destroy larger Covenant vessels with active shielding.
Shiva and Hyperion missiles are often used in conjunction with other attacks, followed up with non-nuclear payloads such as Archer missiles. This tactic is an effective one-two punch, while the nuclear missiles destroys the shielding, the non-nuclear missiles destroy the ship's structure.
By far the most destructive weapon ever fielded by the UNSC was the NOVA bomb. The NOVA is a cluster of nine nuclear fusion warheads encased in a lithium triteride case. When the warheads are activated, the lithium triteride shell focuses the blast in upon itself, multiplying the destructive power by a hundred times. This gives the NOVA Bomb an unprecedented payload for its size. While in reality mutli-staged nuclear weapons can be as large as the material used in the fission/fusion process, the NOVA bomb is entirely fictional. Tritium is actually used as a boosting agent for nuclear weapons in modern times, ramping up the fusion process by way of adding more mass to the critical reaction. However, tritium is not stable enough to force heavier elements to fuse. The NOVA bomb's casing is also made of a fictional element triteride, so perhaps that has properties in which can fuse heavier elements as the bomb design suggests.
That being said, the NOVA is a weapon worthy of the nickname, "planet killer." When the Covenant found a prototype bomb on Reach, they took it back to their fleet for analysis. Little did they know, this was a planned trap by Admiral Whitcomb, who was planning on them either detonating it on Reach, or in within their homeworld. When the bomb went off, it caused a fireball the size of a small moon, completely shattering the planet Joyous Exultation's moon. The planet itself, facing the explosion, was vaporized and the other side experienced thousand mile hours winds and giant tsunami's. The entire orbiting fleet was turned into vapor gas. The final death toll was possibly in the millions. This gives the NOVA bomb, and by proxy Whitcomb, the highest casualty rate caused by a single device/person in the entire Covenant war.
While the yeild in not known, a nuclear explosion of this size would have to be along the lines of 1.2GT (Gigatons = 100,000,000,000 tons of TNT.)
No known device has since been used in the Halo universe by any faction.
The MJOLNIR Powered Assault Armor worn by the Spartans is sealed from chemical, biological and of course nuclear threats. That being said, some armor attachments and visor variants are specifically tailored to nuclear threats. One such technology is the "Daybreak" visor variant. The reflective coating on the Daybreak VISR (or visor) is specifically designed to mitigate damage to sensitive optics in the case of viewing atmospheric nuclear detonations.
This technology would be especially important when looking directly at a nuclear blast, as the light, heat and pressure would either blind, or outright kill the operator due to exposure. The visor is probably coated with both translucent lead lining and possibly white ceramic layers to absorb the intense heat and light. Albedo is important in this respect, and lighter colored coatings make all the difference. That is why the visor is of yellow hue, as yellow is great at absorbing and reflecting UV rays and heat.
Thank you to Spartan "Synth Samurai" for modeling the visor!
Now that we have taken a look at the nuclear payloads within the Halo universe, hopefully you have gained more understanding about these devastating and last resort weapons.
A Halo fan since the beginning, 2001. Also a games industry consultant, writer, and educator. These are my thoughts, praise and advice concerning the past, present and future narrative of the Halo franchise.
Halo, all assets within, characters and merchandise are property of the Microsoft Corporation and is developed by its subsidiary 343 Industries.
I do not own, claim to own or retain any rights to the Halo franchise. This is a fan based work, and is strictly non-profit.
All other images, articles linked, materials and franchises that are not strictly specified as my own are property of their respective owners.
A More Complete Look At The Halo Franchise
Written, Researched, Produced And Published By Halo-Nation member "Synth Samurai"
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