Mark I prototype exoskeleton
From Halopedia, the Halo wiki
The Mark I exoskeletons were the product of the UNSC Navy's first experiments with powered exoskeletons, some time before the initiation of Project: MJOLNIR. The exoskeleton allowed its wearer to run at up to 32 kilometres per hour, and lift a weight of up to 2 tonnes. They also featured shoulder mounts for heavy weapons, with self-targeting armatures. However, as a result of these, the prototypes consumed an enormous amount of energy, and as a result, had to either be physically connected to a generator, or use broadcast power, where energy would be wirelessly transmitted to the exoskeleton from a nearby generator. Neither option was practical for use on a battlefield, significantly limiting the usefulness of the design.
Ultimately, the Mark I exoskeletons became defunct. While some were scrapped, many of the remaining units saw use as dock loaders, and others still were put into storage. Dozens of suits were stored in an abandoned titanium mine on Reach that had been repurposed as a UNSC storage facility. It is likely that the later Mark III exoskeleton produced by the Office of Naval Intelligence was a successor to the Mark I prototype.
Catherine Halsey was aware of the Mark I prototypes during the SPARTAN-II program, but considered them antiques and stated that for Project: MJOLNIR, they had scrapped all previous attempts at a powered exoskeleton and designed from the ground up. Nevertheless, the Mark I prototypes still had a role to play in the SPARTAN-II program; after the candidates underwent augmentation, their instructors had to don Mark I exoskeletons during training exercises, for their own safety. These particular suits had been upgraded with modern motion detectors and IR sensors, and equipped with a 30mm minigun on the shoulder mount, loaded with stun rounds. These suits were further modified at the behest of John-117, to present more of a challenge to his squad during training exercises.
Many sources, including the 2009 edition and 2011 edition of the Halo Encyclopedia, conflate this Mark I prototype with MJOLNIR Mark I, with the Encyclopedia even ascribing the statistics given to this armour by Halo: The Fall of Reach to MJOLNIR Mark I instead. However, The Fall of Reach never identifies this exoskeleton as such, and has Halsey describe it as antique, suggesting that it originated long before the start of Project: MJOLNIR, which all sources agree was initiated in 2515. Thus, Halopedia chooses to treat them as separate entities until otherwise confirmed.
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