Mars Defence Perimeter
From FEInfobase
The Mars Defence Perimeter was a grouping of defensive vessels and emplacements strategically placed about the Sol system approximately 230m kilometres out from the Sun. The MDP is co-ordinated from the surface of Mars and has historically formed an intergral part of the Sol System's defence.
History
The MDP has been in operation at least since the mid-24th century. By the sixties however, the force was falling behind technological advances. The lack of an apparent direct threat to the Sol System (or more specifically, Earth), meant that the planetary defences and fighters were no longer effective enough to securely guard the inner system. This was made obvious in 2367 when a solitary Borg Cube brushed through the fighters sent to engage it, taking them out with a single shot to each craft.
Following the Borg incursion, the MDP was upgraded however still lagged behind other planetary defence systems employed by hostile species such as the Romulans and Cardassians. It was not until the aftermath of the Breen attack on San Francisco in 2375 that the defence of the Inner Sol worlds became of paramount importance to Starfleet.
Utilising Cardassian technology obtained in the Chin'toka system, Starfleet began to create a large web of 'orbital' defence platforms that could be deployed near a planet or in deep space if need be. Like the Cardassian design, the platforms were powered by an external source, however the Federation grid was designed to function using a series of generators, with a number of back-up generators ready should the primary ones be knocked out. In addition to this grid, the ancient fighters were replaced by new state-of-the-art Eagle fighters, and were later supplemented by the versatile Valkyrie Class fighter. Mars itself was the recipient of large ASA or Anti-Starship Artillery placements, positioned to defend the MDP's Combat Information Centre. As well as this, available Starships were assigned to the force and regularly patrolled the outer borders of the Sol System. The heavy weaponry being deployed throughout the system led to some commentators dubbing it, "Fortress Sol," though the term was never officially employed by Starfleet.
In 2398, what remained of the MDP following the war was nearly completely wiped out by the Borg in the Battle of Sol. The MDP has not been officially re-juvinated by Starfleet Command but has largely been replaced in its role by the new First Fleet. Specific to the Red Planet, a number of Starfighter squadrons are now based in the Martian desert and support ships such as the USS Thunderchild are regularly in orbit.