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Mars is the fourth planet in the Sol System, and the third largest terrestrial planet. Since the Collapse, much of Mars has returned to the desolation that came before the Traveler. Like the rest of the planets in the system, the red planet is littered with ruins from the Golden Age. It is home to Rasputin. It is also a living consciousness, and one of the Nine.
A harsh and deadly environment, Mars is now a desert world frequently plagued by dust storms. The Cabal forces have a presence on the planet in the form of their Exclusion Zone, as do the Vex, who are at odds with the Cabal. An indelible sign of the Cabal presence on Mars is the moon of Phobos, which has had its orbit dramatically altered by Cabal planetary engineering; it now fills a significant part of the sky. Even more disturbing is the discovery of large "planet-cracking" munitions among the Cabal's already devastating arms. There is some degree of conflict as humanity tries to reclaim its former glory.
The Ancient Past
Long before the evolution of humanity, Mars and the other planets of the Sol System served as gravitational foci for interstellar streams of dark matter particles. When life evolved elsewhere in the System, the movements of lifeforms created perturbations in these looping streams, which caused the dark matter loops to "awaken" into consciousness. These nascent consciousnesses would one day become known to Humanity as the Nine.
With the coming of the Traveler, rain washed over Mars, and it was here that humans first encountered the spherical entity. Once, populating Mars had been nothing more than a dream for humanity, but after its terraforming, a thriving metropolis named Freehold came to dominate the skyline - a bastion of human life in the red dunes. The Clovis Bray corporation had a major presence in Freehold, in addition to setting up their own private facilities, such as one in the Hellas Basin which acted as a tourist attraction and a site for research into Exo and Warmind technology, as well as the location for the core of the Warmind Rasputin.
With the coming of the Darkness, nearly all of Freehold was "swept away" and the sand claimed what remained. Today, Freehold lies buried beneath a mountain of sand, and its once-soaring skyscrapers are only visible.
Mars would be subject to incursions from multiple alien races, being the Cabal, the Vex, and the Hive. The former two would find each other at odds in an attrition war in Meridian Bay, the area surrounding Freehold, with the Cabal vying to mine resources and study the Vex artifacts and structures in the area, which include the massive gate to the Black Garden. A Hive sect known as the Grasp of Nokris would attempt to invade the Hellas Basin, only to be frozen in ice by Rasputin's defensive SIBERIAN ENTROPY protocol for the years to come.
Mars was once ruled by the Awoken.
When the Red Legion arrived in Sol, breaking the Cabal-Vex stalemate in Meridian Bay was one of its priorities. The Vex are hard-pressed and have lost multiple gates, including the Black Garden gate. The whole of Meridian Bay is now under total Red Legion control.
With the awakening of the Traveler at the end of the Red War, the ice caps on Mars began to thaw, extending to the iced-over Hellas Basin. This would also thaw the invading Grasp of Nokris, prompting Rasputin's newly-awakened core intelligence to deorbit Warsats as a defensive measure, inadvertently attracting a defeated Red Legion looking to scavenge technology to strike back at the Guardians who denied their victory.
Arrival of the Pyramids
Two years later, a Pyramid would arrive on Mars, mirroring one of its counterparts which arrived on Io a month earlier. There was recently a signal that was coming from a device in the Clovis Bray Facility, Guardians went to investigate to find an individual's journal who's name is Helsom, Ana describes him as a Xenoarchaeologist who believed in possible contact with extrasolar species and humanity, she contemplated on if he ever found what he was looking for, he remained on Mars since the Collapse happened.
Several months after the arrival of the Black Fleet, they caused the planet along with Io, Titan, and Mercury to mysteriously disappear, just as the Traveler healed itself. Mars' two moons Phobos and Deimos, however, survived and orbit the maw of the void planet.
Shortly after the disappearances, Emperor Calus attempted to speak to the unknown Entity behind the gravitational anomaly of Darkness left where Mars used to be. He used Scorn wearing the Crown of Sorrow aboard a carrier to ultimately succeed, as they tumbled into the anomaly itself.
List of appearances