MJOLNIR Powered Assault Armor Mk. IV

Created alongside the SPARTAN-II Program, the MJOLNIR Mark IV Armor was a radical redesign to previous powered exoskeletons, streamlining their design into a practical purpose for use in the field. The brainchild of Dr. Catherine Halsey, the Mark IV represented her vision of creating a powered exoskeleton capable of taking full advantage of the physical capabilities of a SPARTAN-II. The MJOLNIR battlesuit is constructed in overlapping layers. It is a sealed system, capable of extravehicular activity or operations in toxic atmosphere and vacuum. It is hardened against EMP and radiation, and has filters that are completely effective at removing toxins and bacteria from local atmosphere.

The armor's shell is composed of a multilayer alloy of remarkable strength which has been augmented with a refractive coating capable of dispersing a limited amount of Covenant energy weapon strikes. The suit contains a gel-filled layer underneath a thick black armored bodysuit. The gel layer regulates temperature and can reactively change its density in a few seconds. The inner skinsuit is made of a moisture-absorbing synthetic material linked to an environmental control computer and the occupant's SPARTAN-issue Command Neural Interface. An upgrade to the standard Neural Interface is issued to all high-ranking officers; another modified version of the neural lace is issued to all SPARTAN-IIs in the UNSC as well. This network translates electrochemical signals to digital code and routes them through an interface connection at the rear of the skull.

Through this interface, the user's thoughts command the armor's movement and weapons and input from the onboard sensors comes directly to the user's mind. The synthesis of machine and mind is so fast that it is almost impossible to chart the reaction time. Unfortunately, the system is so reactive that normal human beings cannot use the suit without injuring or even killing themselves. Only humans who have undergone carbide ceramic ossification, a bone-strengthening treatment from the SPARTAN-II augmentation program, have been shown to safely operate the suit.

Sandwiched between the external armor and the internal padding is the most devastating weapon the suit carries: a layer of reactive metal liquid crystal. Woven by molecular tools into a superdense layer, this layer is amorphous, yet it amplifies force, doubling lifting capability and increasing reaction time by a factor of five.[3] Such technology did not exist when work began on the Mark I prototypes.

Because of these advancements, the design is more akin to an actual suit of armor, as opposed to a powered exoskeleton; the user moves the suit, and in return the suit moves the user. This allows for an incredibly compact design when compared to other combat systems. The armor contains numerous features including an integrated computer system which continuously monitors weapons, biological functions, and a "smart" motion-sensing radar. The suit also contains a built-in oxygen re-breather system that can provide air for up to ninety minutes. The suit's helmet also features imaging and video recording, and thermal sensors among other features.

In its final phase the MJOLNIR battle suit weighs nearly half of a metric ton,  or 1000 lbs, and when in use, is a fully neural-linked system and was the most advanced piece of tactical military hardware in human hands at the time of its inception.