M723 Kangaroo

The M723 infantry support vehicle, nicknamed the Kangaroo or simply the Roo, is an infantry fighting vehicle in service of the UNSC Marine Corps.

Role
As the more aggressive counterpart to armored personnel carriers such as the M650 Mastodon, the M723 Kangaroo is envisioned as a vital supporting pillar of UNSC Marine assaults. They are used as transports, carrying up to two fireteams as close to the battle as possible, often using their superior speed to evade enemy barrages. They then complement Marines by directly targeting fortified emplacements and attack craft that would normally be able to cut them down, and creating openings with suppressive fire. Once the initial advance has been successful, Kangaroos transition into full-fledged infantry support assets, where their impressive countermeasures, scanning systems, and most of all their secure communications array keeps team leaders connected to the Battlenet.

Outside of this, Kangaroos are also used as escorts for convoys, where it is feared that the much lighter Warthog is insufficient for protection, yet speed is still required. They may be used as transports themselves, but the limited interior space compared to existing vehicles does not make it useful in this role. However, their advanced mapping suite, communications array, and high speed meant that they enjoyed use as a heavy scout in occupied regions.

Development
The vehicle that would become the M723 Kangaroo was not originally developed for the UNSC, and indeed, it almost missed out on service in that organization. It was originally designed for the small Private Military Corporation known as the Grey Guard, whose lack of Pelican dropships meant that they could not use traditional surplus APCs such as the Bison. As a result, they negotiated with the Garrido Compañía de Motor (GCM) on Midvale for a specialized fighting vehicle that was compact and well-armed for its size, better protected than the Warthog but light enough to be carried on the commercial fliers the Guard employed.

Armament
The primary armament of the M723 Kangaroo lies in four M101 smoothbore autocannons, mounted on a large turret at the rear of the vehicle. These fire the 45x270mm shells, which are well-suited to defeating the armor of light fortifications and medium vehicles, and are absolutely devastating against any infantry target unfortunate enough to be hit. Each gun is able to fire 32 rounds per minute, for a total barrage of 128 across all four cannons. The turret is on an elevating platform, which allows it to be sunk somewhat deeper into the vehicle to decrease its target profile while moving, and extend the turret's traverse from 10 degrees to 45 degrees escalating. Although disembarking is possible while the turret is lowered, the low ceiling clearance makes this an uncomfortable affair.

The 45x270mm is an evolution of the 40x180mm shell, and exhibits much higher velocity, greater destructive power, and further range over its smaller predecessor. Originally designed for anti-aircraft duties, it has instead seen far greater adoption among ground forces. The autoloader in the Kangaroo's turret is able to easily change between multiple ammunition types with little issues, so while High Explosive, Anti-Tank (HEAT) is preferred by most operators, it is not uncommon to see it accelerating a variety of Armor-Piercing, Fin Stabilizing, Discarding Sabots (APFSDS), High Velocity Armor-Piecing (HVAP), or High Explosive AirBurst (HEAB) shells. In spite of its superior performance, the 45mm remains fairly obscure, so much of the M101's ammunition also includes subcaliber 40mm rounds that are fitted with a larger casing.

To protect it against infantry, as well as offer further suppressive fire capabilities, two pintle turret hardpoints are fitted on each side of the Kangaroo. These are open-seated positions, similar to that on the M808C Scorpion, and what weapons are fitted are strongly informed by mission requirements. Most commonly, the M247H machine gun is typically fitted, which is chambered for 12.7mm .50 cal rounds and is used for anti-infantry defense. Another common choice is the M460 automatic grenade launcher, which fires 40mm timed or trigger-linked explosives at aggressors. Although primarily intended for use against vehicles and as indirect fire support, the M460's grenades can release a strong EMP that can significantly damage shields or temporarily cut power to generators and vehicles. A hybrid combination of both weapons is not uncommon, but only the grenade launcher is able to fire at both sides of the Kangaroo.

In some variants, the Marines carried aboard may have access to armored gunports, which allows them to use their firearms to directly complement the Kangaroo's firepower. However, this is not a universal upgrade, as the gaps makes the vehicle's armor more likely to crack and break apart. In addition, it also makes them vulnerable to chemical weapons.

Defenses and Countermeasures
To protect it from incoming fire, the M723 Kangaroo is plated with between 8 and 17mm of composite plating, which mixes titanium alloy with graphene-ceramic plates to keep the armor strong without making it brittle. Some plates, such as the armor skirting, have hydraulic supports to better absorb, ricochet, and defeat kinetic penetrators. Although not always fitted, Valiant non-explosive reactive armor is sometimes fitted to the sides and front of the vehicle to protect it from anti-tank weapons.

For its size, the Kangaroo is considered best-in-class in terms of active countermeasures, at least for its size range. A pair of countermeasure dispensers are fitted, which launch flares, smoke canisters, and anti-munition missiles to draw off incoming missiles and hostile fire. This is bolstered by an onboard multispectrum dazzler array, which can be directed to either blind unprotected men (for permanent or temporary duration), or confuse guided missiles used against it. A sizable communications jamming array is fitted to hinder enemy coordination, which when linked to a larger communications dish, allows UNSC troops to punch through battlefield interference and continue to operate cohesively. The external ammunition dumps can even be used for carrying drones for self-defense purposes, although at the time of its introduction, the UNSC had few compatible models to use it with. Passive defense systems include the standard anti-mine suite, which can detect buried explosives in a small radius around the vehicle. A sensibly-organized EMP shield is integrated within the hull of the Kangaroo, which protects the delicate electronics within.

Crew and complement
Under ideal conditions, the Kangaroo is designed with a team of five in mind: one driver, three gunners, and the commander. The driver sits directly in front of the main gunner in the cockpit, which is offset to help alleviate the issues involved in transitioning from other tanks and vehicles. These seats extend back to allow for easy access. The commander is given their own station on the right side, and has access to all countermeasure arrays and optical cameras needed to coordinate the crew. While a single serviceperson with a neural interface is capable of piloting, firing the autocannons, and use the defensive systems on their own, a larger crew means that repairs can be conducted in a much shorter span of time. However, during the Human-Covenant War, the risk of losing so many people when one of these vehicles are destroyed meant that this advantage is often disregarded.

For transportation, two padded bench seats line the sides of the Kangaroo's interior, each of which has space for three UNSC Marines each. Another four are recommended to stand, which gives them a recommended complement of ten UNSC Marines. It is possible for fourteen or even fifteen troopers to be carried, although doing this makes it difficult to disembark in a timely manner. There are two doors on each side that slide open forwards to allow them to exit, although the much larger rear door is typically used. There are weapons and ammunition racks near the front of the Kangaroo, and the seats cover storage spaces. In emergency situations, these can be retooled as hospital beds for wounded.

Drivetrain
The Kangaroo is one of a growing number of vehicles fitted with a 6x6 suspension system, with each pair of wheels being able to turn independently of the others to reduce its turning radius. Furthermore, each wheel is able to pivot independently, to more easily climb travel over difficult terrain. The tires themselves are made out of a solid carbon nanotube webbing all through it, and the lack of need of an inflatable gas ensures that so long as the nanotube supports remain, punctures will not affect its ability to roll. The large tires are intended to be used with high-traction treading to resist getting stuck in off-road environments, although much lighter equivalents used for operation on roads are also available.

Two Traxus 99S heavy-duty motors provide power for movement. Normally, their design specifications only allows them to accelerate a vehicle as heavy as the Kangaroo up to just under 75 kilometres per hour, however, a third shaft connected up to a Dormant PU44R electric motor can overcharge this up to almost 100 kilometers per hour (62 mph) on a straight flat road. This can only be done for a short time, however, as the battery is rapidly depleted and requires charging from the hydrogen-powered 99S motors. While pure gas is recommended, as per UNSC recommendations, a sophisticated water electrolysis machine with suitable filtration is fitted, ensuring that the crew can use any water source as a potential fuel source if needed. If working in a toxic atmosphere, then the Oxygen is recycled to refill the air tanks.

Electronics
The M723 Kangaroo is an integral part of Marine communications, with a wide suite of options available to both team leaders and the regular grunt. All models are outfitted with a large Mark 47 ground-to-orbit communications dish, a high-traffic device that in theory keeps the fighting vehicle connected to the UNSC Battle Network. This is paired with a series of encrypted short-ranged receivers and transceivers suitable only for secure short-range chatter, meaning that unless the Kangaroo is destroyed, any UNSC Marine can talk securely with their peers. This also rigs a false-chatter system to further dissuade attempts at decryption by feeding incorrect information to the enemy, fed by a dedicated program.

For sensors, there is no short supply there either. A pair of portable RADAR arrays constantly sweep the area around the vehicle for hostiles and friendly locations, while electro-periscopes gives the crew visual contact of the Kangaroo's blind-spots. There are stats used for furthering weather predictions, with humidity, wind speed and direction, time, and even the location of any orbiting moons being factored into its internal computer. A mapping suite is also built into the Kangaroo, which can use data retrieved from orbital satellites, any nearby drones, or Marine combat visors to create a detailed topography of the nearby areas. This can be edited by any officer with the appropriate clearance, so objectives, areas of interest, and identified obstacles and fortifications can be readily marked at any time.

The driver and gunner all have access to the standard heads-up display used by UNSC armored vehicles. A cursory view would see icons of UNSC troops (via their Infantry Friend-or-Foe tags), the projected firing arc of the Kangaroo's weapons, incoming weapons alerts, and detected sources of jamming. Although appearing cluttered to the untrained eye, it works seamlessly with their neural implants to organize the information when the operators desire it.

M724 Tactical Command Vehicle
The M724 Tactical command vehicle is a modified version of the Kangaroo, in which most of the space used for transporting Marines is taken up by a command station manned by one or two officers. A much more reliable communications suite is fitted, which can accommodate more traffic and employ superior encryption to the base model.