PA-3 PASGT (Personal Armor System for Ground Troops) - The PASGT program was initiated in 1999 after XCOM learned to reproduce alien alloys. Soldier mortality in the field was high during this period, and normal military grade armor was ineffective in the face of alien firepower. The decision was made to go forward and develop a next generation armor for the soldier using alien alloys and the most advanced technology. This was the Personal Armor System Exotic Alloy (PASEA) program, which yielded the PA-1 (the first use of alien alloy plates in standard armor) and PA-2 (first armor designed from the ground up to use alien alloys).
The PA-3 PASGT program began in March of 2000, and called for at least a 25% increase in protection against kinetic/explosive and plasma weapons with a maximum 10% increase in overall weight over the PA-2. Work began in earnest and the first models were field tested in May of that year. The trials were a resounding success and UNETCO Command approved the replacement of the PA-2 with the PA-3.
The PASGT armor is composed of four major layers that provide extensive protection against shrapnel and projectiles as well as protection against charged-particle plasma weaponry. The first layer is a skin-tight, spongy sensor and environmental layer that keeps track (through embedded sensors) of the soldier's physical status, heartbeat, injuries and temperature. Embedded on the outside of this layer are small coolant tubes that aid in regulating the soldier's body temperature. The next layer is composed of a non-permeable rubber-analogue that makes the suit completely environmental and is also the layer responsible for power channeling as it is embedded with hundreds of feet of fiber-optic and copper power line to connect the various armor systems together.
The third layer is a complex fiber-mesh weave of conductors and coolant fluids, to provide additional protection from intense heat (such as that from an alien plasma weapon). This layer is also composed of a special areogel that, when exposed to air, will flow into the breach and harden on contact. This layer allows the armor to absorb all but the most severe impact and explosive attacks while keeping the user protected from plasma. It also acts as a self-sealant in case of attacks that get through the final, outer ballistic layer.
This last layer is comprised of reinforced .22-inch thick alien alloys plates that can defeat large caliber projectiles and survive exposure to extreme heat without radiating it back into the third layer. This layer is attached to the suit in sections as it is the most frequently penetrated layer and therefore is most commonly replaced instead of repaired.
Sensor systems built into the third layer of the armor include a laser-sensor (blares an audio warning to the soldier when he/she is lased by any known targeting laser), a proximity sensor, radar-warning indicator, limited radiation shielding and detection, and a missile warning sensor that notifies the soldier of missiles or other 'hot' objects are being launched (basically an IR device, note that this does not work on Blaster Bomb projectiles which use gravity waves to move). The object here is obviously to give the XCOM soldier in the field as much availability of information as possible, regardless of the particular threat in his or her area. This is particularly true when coupled with prerequisite Combat Helmet HUD systems and goggles.
A faceplate is also available for the PASGT to provide full NBC protection. The armor is unisex, but can be personalized, and comes in a Full Body Armor and Light Body Armor (or "scout") configuration.