PIONEER-class Mjolnir

PIONEER-class Mjolnir is a variant of the MJOLNIR Powered Assault Armor [GEN2] manufactured by Acheron Security.

Specifications
The PIONEER helmet features passive, redundant environmental scanners whose the sensor fidelity and high-bandwidth storage capacity make it ideal for detailed environment scans used in War Games and intelligence analysis scene reconstructions. The helmet also has a duel-locked rebreather (YV-65) leveraged in hostile environments. It also features a twin-plated visual sensor for increased range of spectrum. The suit also has PNR-S7 split-convex pauldrons.

Development history
As a result of the UEG's pioneer initiative in order to claim new territories for colonization, Acheron Security set aside a budget and design team specifically for such endeavors, and within months Pioneer was presented. The suit was eventually put into full production and tested at the Acheron Trauma Sim.

It is intended primarily for reconnaissance operations in unknown or hostile environments, and was constructed to endure the rigors of a potentially hostile, alien environment, and to optimize overall performance through inhibitor mitigation. It also pairs advanced environmental sensors with Acheron's latest threat detection systems.

Usage
Pioneer-class armor is equipped by Spartans providing protection to ONI expeditionary groups.

The armor's first, and most notable, usage was during the first highly-classified exploration efforts of Installation 03 by Ivanoff Station's research deployments. Since then the Pioneer variant has been used in assisting in the security and protection of over two dozen field teams and science detachments. Pioneer suits have also been used to protect science teams on colonies and even to protect planetary engineering rigs.

Halo 3 MCC
In the Halo: the Master Chief Collection version of Halo 3, the Pioneer variant was added as part of Season 5 content. With the updated Halo 3 armor customization options, the players can now fit their Spartan with Pioneer helmet, chest, shoulders, forearms and legs. The description of the armor pieces are the same for every set.
 * Unlock: Unknown
 * Description: Acheron Security hopes that ANVIL testing will prove out improvements made after the suit's use on Installation 03.

Halo 4
Available skins: Adept (ADPT) Default unlock: Achieve Spartan Rank PR-4. Adept unlock: Achieve Spartan Rank PR-9.
 * Description: Used by security escort during the first exploration efforts on Installation 03.

Halo 5: Guardians
Unlock: Uncommon REQ card
 * Helmet description: The sensor fidelity and high-bandwidth storage capacity in the PIONEER helmet makes it ideal for detailed environment scans used in War Games and intelligence analysis scene reconstructions.
 * Body description: The PIONEER is a reconnaissance and combat expedition Mjolnir variant, pairing advanced environmental sensors with Acheron's latest threat detection systems.

In Halo 5: Guardians due to the "Body" having a predefined customisation this armor set permanently has the following parts from Halo 4:
 * Body: Pioneer
 * Shoulders: Pioneer
 * Forearms: Contoured
 * Legs: Contoured

List of appearances

 * Halo 3
 * Halo 4
 * Halo 5: Guardians