Mark I through III
Initiated in 2512, the UNSC Navy wanted their Marines to have better equipment in the field. The Mark I Prototype Exoskeleton was the first functional version of this armour. While the armour was bulky and unwieldy, and had an external power source, the wearer was able to lift over 2 metric tons (4,400 lb) and sprint at 32 kilometres per hour (20 mph) for an extended period of time. The Mark I contained a cutting edge on-board computer that could assist the wearer by transmitting tactical and communications information to the standard Neural Interface issued to a soldier, the suit however did not possess the ability to carry an AI. The armour could also be equipped with motion sensors, infrared scopes, and could be mounted with a 30mm mini-gun that fired on self-targeting armatures.
All the research and development of this Mark I Prototype was carried out at ONI Section Three, as the Office of Naval Intelligence had been tasked with the R&D. CASTLE Base was host to this highly secretive operation, which also hosted an office of Dr. Catherine Halsey and Colonel James Ackerson. CASTLE Base was not the host of the testing of these Prototypes, as this was done at the Damascus Testing Facility on Chi Ceti IV. A total of forty prototypes were created, but they never saw deployment on the battlefield. They would later be used in the training of the SPARTAN-II Program, as their augmentations would prove lethal to unaugmented trainers, even in training. As the mark I still required an external power-source, and was very bulky and unwieldy, the prototype was never put into service.
Not much is known about the Mark II Prototype, besides that it still required an external power source. Great care was taken to improve on the most common complaints about the Mark I, as Mark II was significantly slimmer and had greatly increased mobility. The researchers had also added a refractive coating, which would keep the person inside better protected from the heat and blast of a nearby explosion. Even though it was a big improvement on the Mark I, it was never used on the battlefield, mainly because of a lack of mobility because of the power-source.
Mark III tried to improve on Mark I's and II's biggest flaw, the external power-source. The Mark III instead had an accompanied immobile power source which would wirelessly transmit the power the suit needed over a large distance. This technique was also in use for the Orbital Defense Platforms which were deployed over important UNSC colonies. This design was quickly rejected for two reasons: first the armour still had a limited operational range as it had to remain within range of the bulky, immobile generator, and second, if the generator was to be knocked out it would result in the incapacitation of the suit and leave its user locked inside and helpless against enemy attacks.
In the end, all of the first three prototypes had one thing in common: They were impractical on the battlefield. If this issue was not overcome, there would be no change of having the super soldiers the Navy had envisioned.
Mjolnir Mark IV Powered Assault Armor
As Dr Catherine Halsey worked in the same facility as the birth of Mark I through III, she had some knowledge of what they had been trying to do. At this point, Catherine was working on her ORION Project, and saw the potential of combining these 'Spartans' of her with these exoskeletons. She decided to design and build the Mark IV Mjolnir Armour, which would be capable of taking full advantage of the physical capabilities of these 'Spartans'. It would take her many years before she was able to produce the armour she had envisioned, while the Orion Project had already progressed into the SPARTAN-II Program. The Spartan-IIs were already far superior than even a fully trained ODST, but her MJOLNIR armour would make them even better.
Catherine was able to come up with a radically re-designed version of the previous incarnations, an exoskeleton which provided unrivalled mobility while keeping the Spartans inside safe. While the previous prototypes consisted of only one material, the Mark IV existed of multiple, 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 armour'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 armoured 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 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 armour's movement and weapons and input from the on-board 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.
Sandwiched between the external armour and the internal padding is the most devastating weapon the suit carries: a layer of reactive metal liquid crystal. This layer amplifies force, doubling lifting capability and increasing reaction time by a factor of five. As the Spartan soldiers who wore the armour were already incredible in those regards, the exoskeleton, more akin to a suit of armour at this point, caused them to be nigh-invincible. The armour was mass-produced and would be in service for nearly 26 years. The Spartan-II John-117 was the last wielder of the Mark IV, as he was in the field when the Mark V armour was introduced.
Mjolnir Mark V Powered Assault Armor
While the Mark V was not in the field for long, lasting a little over a year, the armour was in production for about a decade. The Mark V was an improvement over the Mark IV in many ways, as data collected during the then-17 year service provided plenty of data for improvements. Hundreds of these improvements were minor, and would be hardly noticeable, while others changed either the look or the functionality in a major way; The two major changes set the Mark V apart from the Mark IV.
The first of these highly impactful changes was to the suit's crystalline layer, the part of the suit that enhanced the strength and reaction time of the Spartans. In the Mark V this crystal layer was split up into 2 parts, while one part enhanced the Spartans movements. the other part could become host to an AI. In order for the AI to have access to the Spartans' vital signs, the Neural implant had to be further upgraded. Without the armour, a SPARTAN's reaction time is charted at twenty milliseconds; with the Mark V, and an AI installed, the time translating thought into motion is rendered almost instantaneous.
The second major change to the armour was the energy shielding system, which was reverse-engineered from captured Kig-Yar shields. These shields would be able to deflect or repel incoming objects of bolts of energy. As the shielding is covering the entire body, several well-aimed shots from close-up would be enough for the shield to dissipate, and leave the Spartan vulnerable. The automatic shield-recharging system can only function if the suit is not deflecting/repelling incoming gunfire, so the wielder should remain completely out of fighting for a few seconds to recharge the shield.
The first Spartans to receive the Mark V armour would be the Spartan-IIs and IIIs that made up the top-secret Noble Team. Although never confirmed, it is assumed that Noble Team received a prototype version of the armour, as their armour lacked the function of embedding an AI construct in their gel layer.
On 29 August 2552, John-117 was the first Spartan to test the finalised Mjolnir Mark V with a Smart AI implemented within the armour during a live-fire combat scenario. His test was to ring a bell after traversing through a dangerous obstacle course. This course involved ten fully armed ODST's, a field of Lotus anti-tank mines, three automated 30mm chain guns, a forest of wooden poles, and an unexpected aerial assault from an AV-19 SkyHawk aircraft intending to kill him utilizing its four 50mm cannons and Scorpion Anti-Tank Missiles. This test showed that on-board AI's could exponentially improve the armour's reaction times. This was exemplified by John-117, who was able to deflect a speeding anti-tank missile with a lightning-fast melee strike, a feat of unprecedented speed and reaction time; made possible by John's accelerated neural synthesis with his Mjolnir armour by the AI Cortana.
Mjolnir Mark VI Powered Assault Armor
When the Mark V armour was decommissioned, it was replaced Mjolnir Mark VI armour. This armour had been in development for many years as well, but was started by a separate team situated in Hiroshima, Japan. This team was planning to add functionalities to the already released Mark V, naming their armour Mjolnir: Black. This armour would be issued exclusively to Team Black, who gave many suggestions which would later be implemented in the Mark VI.
One of these changes was to the radar, as the radar could not take altitude into account. This made tracking very difficult in a vertical structure very difficult. The internal biofoam injectors were also prone to malfunction, and set broken bones in a wrong shape before immobilising it. This would cause the limb to heal wrong if left in that position.
These changes, together with many more, where introduced in the Mark VI system. The bodysuit that the Spartans wore underneath their Mjolnir armour was upgraded to a more resisting form of protection, and provided much more protection from incoming gunfire or melee attacks. As the main problem with the Mark V was the duration and reliability of the energy shield, the Mark VI had now a much larger capacity which would recharge much quicker. The armour was also more streamlined, and provided enemy attackers with fewer 'handholds' to grab the Spartan with. Unlike the Mjolnir: Black's internal biofoam injectors, the Mark VI were sufficiently improved that mishaps were very rare.
Mjolnir Mark VII Powered Assault Armor
The Mark VII Mjolnir Powered Assault Armour is (so far) the last variant of the armour envisioned. While it was created by Dr. Catherine Halsey, but was still in prototype phase in 2553, and there was only 1 known wielder of the armour, Naomi-010.
There is very little known about the armour, but is was known to be more expensive than a GA-TL1 Longsword-class Interceptor. The armour was designed to be able to transform and upgrade itself passively, while the wearer is in cryo-sleep.
Mjolnir Powered Assault Armor [GEN2]
Dr Halsey had been discredited and disbanded from ONI after the truth behind the SPARTAN-II Program came out, she was marked for execution, but was able to avoid that fate. In her absence, Materials Group, the company which had helped her with the previous Mjolnir variants, had been tasked in designing a completely new Mjolnir system. It is produced by dozens of manufacturers, both private and militarized. Aesthetically, the second generation of Mjolnir Armor differs from first generation most noticeably in regards to its streamlined edges, pronounced power pack design and increased customization options. This causes most Spartans to have a distinct look, as they have a wide variety of elements to choose from to implement.
Unlike the previous instalments of Mjolnir Armor, the ceramic-metallic alloy that composes the main armour plates is much more versatile, and can be attached to the metal-alloy under-suit within a matter of seconds (as opposed to the original MK. IV armour, which took Spartan-IIs several hours and a team of technicians to don). One of the most drastic physical changes between GEN2 and GEN1 Mjolnir Armor is the under-suit. It seems that Spartan-IV personnel wear part of their under-suit at all times so they can be readied for battle more quickly. GEN2 armour boasts a more streamlined and form-fitting metal-alloy under-suit with the sheathing of the neck now extending until just under the jaw. Whether this design modification was implemented in regards to pressurizing the suit in vacuum is unknown. The outermost layer of the under-suit has also been modified, now resembling a layer of scales.
The GEN2 Mjolnir armour also has a few differences which help the Spartan in the field. The GEN2 armour is much stronger, faster and lighter than its predecessors, with increased functionality of the radar system. While in previous Mjolnir armour the radar would display simple coloured dots, the GEN2 radar shows the outline of the object in-range. This provides a significantly improvement for the Spartans, as a Wraith requires a different way of taking down than a Ghost or Phaeton.
It is of course impossible to talk about all the armour configurations that were and are possible, each serves its own function and benefits the wielder. This article has been talking about the default configuration of that particular version of the Mjolnir armour, unless otherwise specified.