Stealth ablative coating
From Halopedia, the Halo wiki
Stealth ablative coating is a specialized spacecraft hull material of human origin.
Black in color, the stealth ablative coating serves to refract both UNSC radar and Covenant sensors, making the ship invisible to radar, similar to the way active camouflage cloaks something from eyesight. However, the coating also doubles as a visual cloak, enabled by the ship's texture buffers.
The coating must be maintained perfectly or it will return radar signals. This necessitates constant maintenance on the entire coating. Therefore, virtually all UNSC prowlers have relatively small surface areas, so that less has to be maintained. An exception to this is the UNSC Point of No Return, which is a prowler the size of a UNSC destroyer. Stealth ablative coating can also be found on Long Range Stealth Orbital Insertion Pods.
By early 2557, stealth ablative coatings had begun to see applications outside the UNSC. Ace of Spades, a Mariner-class transport ship captained by Rion Forge, was equipped with such a coating along with other stealth technologies.
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