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Ablative armour is armor which prevents damage through the process of ablation, the removal of material from the surface of an object by vaporization, chipping, or other erosive processes. In contemporary spacecraft, ablative plating is most frequently seen as an ablative heat shield for a vehicle that must enter atmosphere from orbit, such as on nuclear warheads, or space vehicles like the Mars Pathfinder probe. The idea is also commonly encountered in science fiction.
Ablative armour is distinct from the concept of reactive armour which is actually in common use in modern armoured vehicles.
Space colonies and ships of the future will almost certainly require a type of ablative armour to withstand space radiation and heat. When traveling at higher speeds the momentum of the particles the ships will encounter will be large, and require more protection.
Uses in fiction
Ablative hull armor appears frequently in the Star Trek universe. Having been introduced in the year 2371, it features on starships including the USS Defiant, USS Prometheus, and an upgraded USS Voyager.
The Star Trek: Deep Space Nine Technical Manual explains that ablative armor works in two stages: When the shields are hit by an energy or particle weapon, thermal energy from the ship is dissipated across the hull. The boil-off rate creates a particle cloud that is dense enough to disperse the incoming beam's energy.
Regenerative ablative armor is powered armor that can restore the ablated material.
In the Universal Century time line of the Gundam series, ablative coatings are used to minimize the effect of beam weapons, called beam resistive coating and a later improved version, Anti-beam coating.
In the Cosmic Era time line, the ablative armor concept is applied in similar capacity to the anti-beam coating and laminated armor technologies utilised by mobile suits as a form of protection against beam and laser weaponry. Selected spacecraft are also able to deploy ablative gel for high-velocity atmospheric reentries.
In the Anno Domini time line, the Earth's three space elevators are covered by ablative armor plates to protect their structures from damage. When one of the elevators is partially destroyed, purging these plates require the technical crew to jettison the counterweight at the orbital end in order to avoid the now-unbalanced elevator's complete collapse.
In the online game EVE-Online, ablative armor plating is utilized as a secondary defensive layer that protects the relatively fragile internal systems. Depending on the ship's loadout configuration, a ship can continuously repair incoming damage on the armor, fit additional armor plates to sustain large amounts of damage in the short term, or remotely repair friendly ships' armor using specialized modules. The rate at which the armor gets depleted depends on the types of damage incurred to the armor and the armor's resistance value against each particular type of damage.
Armor plating is usually considered strong against electromagnetic(EM) and thermal damage, and weak against kinetic energy penetrators and bombardment of subatomic particles (explosive), although a few exceptions exist.
In the console and PC game Mass Effect there are several variants of armor for all species referred to as ablative.
In the tabletop RPG Inquisitor, ablative armour may be layered on top of other armour. If the ablative armour is struck, it is destroyed (after the damage caused by the attack is reduced accordingly). Ablative armour may have additional properties such as added resistance to heat- or laser-based weaponry; if special ablative armour is destroyed, it loses those additional properties. Unlike other types of armour in-game, ablative armour is quite cheap to purchase (since it is so easily destroyed).
In Battle Pirates, ablative armour is used to increase resistance to explosive damage on a ship.