A powered exoskeleton is a mobile machine consisting primarily of a skeleton-like framework worn by a person and a power supply that supplies at least part of the activation energy for limb movement.
Powered exoskeletons are designed to physically assist and, in many cases, protect the wearer. They may be designed to assist and protect soldiers and construction workers, or to allow people to survive in other dangerous environments. A wide medical market exists for powered exoskeletons to provide mobility assistance for aged and infirm people. Other possibilities include rescue work, such as in collapsed buildings, in which the device might allow a rescue worker to lift heavy debris, while simultaneously protecting him from falling rubble.
The MJOLNIR Powered Assault Armor designed by Dr. Catherine Halsey is the most sophisticated UNSC powered armor project so far. As one of its main strengths, the MJOLNIR system eschews traditional mechanized joints in favor of a strength-enhancing layer of electroactive liquid crystal and provides a cybernetic link which boosts the wearer's reactions by a factor of five. While it is the most successful UNSC powered armor project, MJOLNIR is by no means the only effort to physically augment soldiers in combat. The HRUNTING Mark III (B) Exoskeleton and the HRUNTING/YGGDRASIL Mark I were exoskeleton systems derived from the earlier prototypes from the exoskeleton program which predated MJOLNIR. Large-scale powered exoskeletons became more common in the years following the Human-Covenant War, with at least one model, the Mantis, seeing battlefield use.
The Semi-Powered Infiltration armor predominantly used by the Spartan-III supersoldiers provides modest physical enhancement as well as a rudimentary active camouflage by means of photoreactive panels, allowing covert operations in enemy territory. RKD, an Earth think-tank, created Project HAYABUSA concurrently with MJOLNIR and while the two were developed separately, they share many characteristics, and are interchangeable to a degree.
In 2558, Michael Crespo wore an older suit of ODST armor from the early Human-Covenant war, which apparently had an exoskeleton installed in it. It was noted to be significantly less capable than MJOLNIR Powered Assault Armor.
The Forerunners' personal armor offered powered support to some extent. For combat use, they also developed armor suits known as combat skins, using a class system based on numbers, on which the MJOLNIR Mark V and Mark VI would be rated Class 2.
Known powered exoskeletons
There are form fitting exoskeleton suits that act as armor, and there are larger exoskeletons that act as vehicles.
- Personal armor - Body-assist armor worn by virtually all Forerunners in everyday life
- Combat skin - Armor worn by Forerunners in battle
- Hayabusa Powered Assault Armor - A UNSC powered armor system similar to the MJOLNIR armor
- MJOLNIR Powered Assault Armor - The performance-enhancing body armor first used by the SPARTAN-IIs and later by all Spartans
- Mark I, Mark II, and Mark III powered exoskeletons - The powered exoskeletons that predated MJOLNIR; later retooled by the HRUNTING and YGGDRASIL programs
- Mark IV - First proper iteration of MJOLNIR; issued in at least three distinct generations
- Mark V - Introduced energy shields and artificial intelligence housing; fielded in two versions
- Mark VI - Introduced automated biofoam injectors
- Mark VII - Last of GEN1. Only known use is by Naomi-010
- GEN2 - A broad array of suits developed after the Human-Covenant War
- Semi-Powered Infiltration armor - The armor used by most SPARTAN-IIIs
- Nightfall armor - A suit of powered armor used by ONI operatives on missions in hazardous environments
- Sangheili harness - The suits of armor worn by Sangheili in combat have exoskeleton properties
- Cargo walker
- HRUNTING and YGGDRASIL
- HRUNTING Mark III (B) Exoskeleton - Also known as the Cyclops; a large exoskeleton mainly designed for non-combat tasks, such as construction and dock work
- HRUNTING/YGGDRASIL Mark I Armor Defense System - An advanced development of the pre-MJOLNIR exoskeleton system
- HRUNTING/YGGDRASIL Mark II (D) armor system - A very large armored fighting vehicle akin to the later Mark IX "Mantis"
- HRUNTING/YGGDRASIL Mark IX Armor Defense System - A powered exoskeleton/armored fighting vehicle used by the UNSC Marine Corps after the Human-Covenant War
- Munitions loader
- Skyfire Exosuit
- Goblin - A bipedal battlesuit of Unggoy design
An exoskeleton piloted by Decimus.