This question still plagues the scientific community. The Kharaa began appearing on ships and bases throughout the Ariadne Arm a decade ago, slaughtering everyone on board. In almost every case the ship then wandered off course, and either destroyed itself by slipping into some gravity well (usually a planet or sun), or was tracked down and destroyed by the owners of the craft. Life support on bases and ships usually fails soon after the Kharaa take over, so even without military response, they don't last very long. But without more detailed knowledge about them, we will never learn how to prevent them from appearing on our ships in the first place. Every successful team returns with valuable information. And our fragile economy cannot afford to loose all those ships and bases. There is also the danger that a fallen ship will automatically dock at a major city-base, or land on an Earth-compatible planet. Lord help us if this happens – we have seen what they do with the limited resources on ships … and can only imagine an entire planet of Kharaa. Thankfully, the Ariadne Arm is a frontier sector, and there are few large habitations. So far, there have been no incidents involving more than a crew of civilians.

The terminology for the aliens is still being developed. At the moment, we refer to the aliens, and their whole system of bacteria, lifeforms and growths, as the "Kharaa"; and the pre hive-stage presence as the "bacterium". The first TSA encounter with the aliens occurred aboard the Mongol's Sanjii mining facility. The tattered voice comm logs they extracted from the command network had one word that stood out, used again and again – "Kharaa!" "Kharaa!" Later, it was understood that this means "Watch out!" in Mongolian. By then, it had stuck.

The relatively obscure field of exo-biology has flourished since the beginning of the conflict, attracting many of the best and brightest from biology, chemistry and even paleontology and sociology. And while we have made huge strides (as you will read in the pages to follow), we are a long way off from a true understanding of these prolific and dangerous creatures. The information in this manual is that small amount we are confident enough in to tell you as you head in to combat.