Atrophos is Antei's largest moon and the location of the Grand Master's Royal Guard's primary training facility. Atrophos is often referred to as the 'Ascendent Moon' because of its status as Antei's first moon and the fact that it was originally Antei's only moon before its sister moon, Lyspair, was kicked into orbit as a result of the catastrophic proliferation of one of Antei's binary stars (approximately 4,000 years ago).
The Grand Master's Royal Guard currently maintains the only outpost on Atrophos. The GMRG facility consists of a landing pad, multiple barracks, a handful of administration buildings, and the Crucible Training Seminary where Guardsmen are conditioned both physically and mentally. The Crucible itself is comprised of 27 environmentally sealed cubes; each cube is its own unique combat arena and the Crucible's intent is to provide Guardsmen with the opportunity to practice combat in every conceivable environment.
The moon, Atrophos, was once a lush and verdant body populated by all variety of flora and fauna. However, now, like Antei, no life exists anywhere on Atrophos. No significant bodies of water exist anywhere on the moon. The surface of Atrophos is comprised primarily of silicates and sparse rock formations. Atrophos' atmosphere is comprised of nitrogen, carbon dioxide, and oxygen, with trace amounts of other gases. The high concentration of CO2 in the air makes breathing unassisted impossible on Atrophos and a breathing apparatus is required.
Atrophos is a very large moon (~6900km in diameter) and its geosphere is comprised mostly of dense metallic elements wrapped around a thick core of iron. As a result, Atrophos exhibits slightly higher gravity than most planets (1.1gs). This makes Atrophos ideal for physical training.
Excavations have recently begun on Atrophos in an attempt to discover the ancient ruins of the Krath Orrery. The orrery was rumored to contain Star-charts to all known Sith relic worlds and the recovery of these star-charts has become a priority of the Krath Order. Other ruins have also been unearthed on Atrophos: including the Palatial Estate of one unknown Grand Master. Several temples and monuments of unclear origin and function have also been uncovered; although nothing of dire significance has been found thus far. Despite this, the chronological importance of these sites cannot be denied by historians within the Krath Order.
In 35 ABY, the Fist of the Brotherhood, Fremoc Pepoi, made the decision to move the GMRG from Atrophos and into the newly constructed Spike on Antei itself. The Crucible has been abandoned since that time.