Alaxxes Nebula

The Alaxxes Nebula is a region of space located in the Segmentum Solar. This stellar phenomenon is regarded as an impassable shipping hazard as it is composed of large clouds of dust and hydrogen ice fields that are extremely corrosive to vessels and make stellar communication nearly impossible. This region was the sight of the Battle of the Alaxxes Nebula, an engagement that took place between the bulk of the Space Wolves fleet and the bulk of the Traitor Alpha Legion in 007.M31, during the early years of the Horus Heresy.

History
First entered onto Carta Imperialis charts by the 6th Imperial Expeditionary Fleet in 817.M30, the Alaxxes Nebula was initially regarded as nothing more than an impassable shipping hazard. The danger it presents lies in its unique chemical composition -- highly corrosive ammoniac compounds combined with vast clouds of dust and hydrogen ice move in an ever-shifting labyrinth, shot through with passages many hundreds of kilometres wide. These clouds can overload the void shields of even the largest Imperial warships, leaving their adamantium hides exposed to rapid environmental degradation. Vessels straying into the outer edges of the nebula will suffer catastrophic hull breaches in under an hour, while ships tumbling out of control in the deep core can be lost within minutes. In addition to these physical dangers, the nebula is known to baffle sensors and limit vox communication. Ghost returns and false readings make mapping the interior difficult by any means other than physically traversing the clear passages, and such data is often outdated within a few years due to the natural shifting movement of the clouds.