in space: above and beyond
Commonly described by the marines as 'Chigs' (due to their similarity in outward appearance to the skin-burrowing insect known as a 'Chigger'), the alien invaders are humanoid form, bipedal, and apparently cold-blooded.
Examination of the alien corpses retrieved by the 58th squadron on Mars and from later engagements on Tellus, Bellerophon and Kazbek reveal their metabolism to be based on a chlorophyll/copper blood chemistry, noted by the green colouration of their internal body fluids. The rapid decay of the alien corpses after death also indicates a vastly different electrolytic balance. While they are capable of breathing an Earth-normal atmosphere, normal water has a highly corrosive and poisonous effect on them.
Their body armour and equipment appears to be made from complex spun ceramics, and commonly they utilise a curved metal blade for hand-to-hand fighting and multi-barrelled plasma rifles for longer range combat.
Several types of alien spacecraft have been observed; the most common is the two-man fighter, encountered in three-ship attack flights. Armed with a single plasma cannon, these ships are faster than the SA-43 Hammerhead and have a greater rate-of-ascent. Intelligence reports also suggest that a 'Red' version of this ship capable of skipping across high gravity fields also exists. The larger bombers have five crew members and are armed with long-range space-to-surface missiles. Of the larger capital ships encountered so far, observed types include landing-capable transports, motherships, orbital picket stations, and the so-called U378 Class D Destroyer. This latter ship is equipped with a high-powered microwave cannon for indirect attacks.
Recently decoded signals also indicate that a crash development programme for a new class of super-fighters is underway by the aliens. To date, what motivates the aliens remains unknown.