- “This is the prototype NOVA Bomb, nine fusion warheads encased in lithium triteride armor. When detonated, it compresses its fissionable material to neutron-star density, boosting the thermonuclear yield a hundredfold. I am Vice Admiral Danforth Whitcomb, temporarily in command of the UNSC military base Reach. To the Covenant uglies that might be listening, you have a few seconds to pray to your damned heathen gods. You all have a nice day in hell...”
The NOVA Bomb 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 a hundredfold. This gives the NOVA Bomb an unprecedented payload for its size. Its capability to destroy a planet has earned it the nickname the "Planet-Killer". It should be noted that on the one recorded event when a NOVA Bomb was detonated in the midst of a fleet close to the planet Joyous Exultation, it scorched one quarter of the planet's surface due to a high concentration of thermal energy inside the planet's atmosphere; it also shattered a nearby moon. Any further detailed analysis on the full power of this bomb has yet to be mentioned in the Halo series, but it is known that it is the most destructive weapon in the UNSC's arsenal.
The NOVA Bomb's explosive power is quickly depleted due to the lack of particles or atmosphere around it when detonated in space. This results in a much quicker release of energy, with the possibility of even further multiplying its damage to ships, planets, moons, and other celestial objects due to the lack of energy absorbing particles in space. However if detonated inside a planet's atmosphere, a portion of the total energy generated would be dispersed throughout the atmosphere. The density as well as composition of the atmosphere are the largest contributing factors when determining how much energy is dispersed. Even though the power of the NOVA Bomb is not mentioned in the book, a low end can be calculated:
Assumptions: the moon is 2 km, and the NOVA bomb is only 5,000 km away.
Calc: Apply the Inverse Squared Law: Source Energy / (4 * Pi * R2) the radius is the distance from the source to the range.
x/ (4 * 3.14195... * 5,0002) = 4 Megatons per square kilometer to fragment a 2 km moon which requires 8 Megatons to be fragmented.
x = 1.2 Petatons.
Some may find this yield hard to believe for a fusion device, but the stated effects to the planet and nearby moon require explosive power of this magnitude. Whitcomb does mention, however, that the lithium triteride cases are compressed to "neutron star density" during the detonation, implying that the warheads themselves boost a second, much larger fusion reaction.
In Halo: Ghosts of Onyx, the detonation of the NOVA bomb was noted to have caused "300-kilometer-per-hour winds" to sweep over Joyous Exaultation. Using data from nuclear testing calculated for ideal shock fronts, if Joyous Exaultation had atmospheric pressures and elemental composition similar to that of Earth, a 300 kph wind velocity corresponds to a peak overpressure of 6 psi (31.4 kpa) and a peak dynamic pressure of 0.85 psi (5.9 kpa)
For comparative purposes, using the formula of yield equivalence for nuclear weapons, EMt = n * Y ^ (2/3), where "EMt" is the equivalent yield, "n" is the number of warheads, and "Y" is the actual yield of each individual weapon in megatons, the NOVA bomb has a yield equivalence of:
"Little Boy" - bomb dropped on Hiroshima, Japan; Yield = ~15 kilotons
(1,200,000,000 Mt ^ (2/3)) / (.015 Mt ^ (2/3)) = 18,566,355
18,566,355 Hiroshima-style fission bombs
"Tsar Bomba" - largest nuclear weapon ever tested; Yield = ~50 megatons
(1,200,000,000 Mt ^ (2/3)) / (50 Mt ^ (2/3)) = 83,203
83,203 Tsar Bomba thermonuclear bombs.
Fireball diameter - 217 km
Blast radius - 6032 km
It was intended for the NOVA Bomb to be used in space against the Covenant Fleet during the Battle of Reach. In the novel Halo: First Strike, it was left on Reach and "repurposed" by Admiral Whitcomb. His reasoning was that "either the Covenant pack those bombs up and take them home for study, a possibility that I hope to God happens. A bomb like that could crack their homeworld in two. Or, the bombs stay here and they'll stop the Covenant on Reach..."
The only documented triggering of a NOVA Bomb occurred when it was accidentally detonated by a group of Huragok stationed on the Covenant Sublime Transcendence. Immediately after Kwassass, a fellow crew member, deciphered Admiral Whitcomb's message, the Huragok, through their curiosity and frenzied obsession, fixed the circuitry of the bomb, detonating it despite Kwassass's attempts to stop them. The Huragok completed the detonation timer's circuit, which promptly resulted in its activation. The resulting explosion occurred between a Covenant outpost planet Joyous Exultation and its moon, Malhiem, scorching half of the planet and shattering the moon. The resulting winds on Joyous Exultation flattened cities and spawned tidal waves. Radiation flooded the planet and killed everything living on it, penetrating the surface of the planet to its core. Every ship within the NOVA Bomb's range, save for those on the opposite side of the planet, boiled and vaporized in an instant. It is unknown what the Covenant did with the planet, but it is no longer capable of supporting life.
The NOVA Bomb explosion completely destroyed three-fifths of the fleet that was there, totaling over 300 ships. Eighteen Destroyers, two Cruisers, one Carrier and the Flagship Incorruptible escaped the NOVA Bomb explosion due to a Slipspace jump en masse just seconds prior to the explosion. Other ships arrived to reinforce the Incorruptible arrived from Joyous Exultation, suggesting that they escaped the bomb's detonation as a result of being positioned on the opposite side of the planet. The novel describes the explosion as though "a small star erupted between Joyous Exultation and its moon."
During the Battle of Installation 05, and the subsequent Quarantine of the Installation and High Charity, Cortana requested that UNSC HIGHCOM deploy a NOVA Bomb around Installation 05 and High Charity to stop the outbreak of the Flood and in order to destroy the Covenant Holy Capital.
However, this request was not granted likely due to the low number of nuclear warheads left and their need to protect the Inner colonies. High Charity was not bombed and later landed on Installation 00. It is also possible that this request was granted, but that High Charity went into Slipspace before the warhead could even be launched. However this last possibility is highly unlikely because a nuclear warhead is very easily spotted when transitioning from a Slipspace jump because of the massive amount of Cherenkov radiation that is emitted during the final transition. Cherenkov radiation is observed during a transition of fissile materials such as plutonium and uranium from Slipspace. Fusion requires both deuterium and tritium (or in the case of "dry" bombs lithium which produces tritium when bombarded by neutrons). These elements would not emit Cherenkov radiation and thus a pure fusion bomb would not be detected when exiting Slipspace, but NOVA Bombs are stated to be thermonuclear weapons and thus use fission at various steps to create the temperatures and pressures necessary to initiate fusion. It is also possible that there were few NOVA bombs because it was only a prototype, but a dangerous one at that.
- The NOVA Bomb was a bomb mentioned in the novel Starship Troopers, wherein it is described as "being able to split a planet in half." It is likely that this inspired the Halo Universe's own NOVA Bomb.
- Also, it has been mentioned in Andromeda Ascendent, the other famous Gene Roddenberry-created TV Show, as the titular ship carries the same kind of bombs, it is also likely that this inspired the Halo Universe's NOVA Bomb as well.
- While it was first used in Halo: Ghosts of Onyx, it was first mentioned in Halo: First Strike.