Arkive was an ancient machine that was created to preserve the memory of an extinct race.
Arkive was roughly spherical and several hundred metres wide. It was originally made with rocket engines and solar sails, but both were badly damaged in its initial launch. Inside was an unknown power source, possibly a miniature black hole. The Arkive contained a matter replicator, intended to recreate its creators. It used this to create the Blue Dolls and Blue Soldiers. Its hull was made of a bernalium alloy. Arkive produced neutrinos to communicate. (PROSE: The Wheel of Ice)
Roughly 5 billion B.C., there was an unknown species. When a supernova from a nearby star threatened their planet, they planned to create the Arkive to preserve their history. Unfortunately, the supernova didn't react as expected and Arkive was badly damaged and thrown out of the system. It drifted through space for millions of years until it came to the gas cloud that would make up the Sol system. It formed the inside of Mnemosyne, a moon of Saturn.
Around 50 million B.C., the Arkive decided to try to save its creators by going back in time. In order to do this, the Arkive decided to attract the Silurians to help build a proper time machine. Two plans were used at once; an allohistorical lure would be sent back in time change the Silurian's history. This process would destroy much of Mnemosyne, which would attract the Silurians on Earth. Both plans failed; the Silurians were too busy preparing for the rogue planet to investigate Saturn and the lure ended up 50 million years before the Silurians evolved.
Luckily, the lure was fossilised and preserved until it was found during the excavation of the London railway in 1890. It was bought by Josephine Laws and passed through the generations until it reached Jo Laws. She was one of the people who decided to colonise the moons of Saturn. The Mnemosyne Cincture was created around Mnemosyne and the humans started mining for the bernalium that had seeped from Arkive's hull.
Arkive created the Blue Dolls to collect material to create a new time machine. The Blue Dolls came into conflict with the humans several times. Most of these efforts were coordinated by Florian Hart, who had a grudge against aliens. Despite the Doctor's best efforts, Arkive felt threatened and created the Blue Soldiers to kill all the humans. Once the fighting had died down, the Doctor tried to communicate again with Arkive again. Though he succeeded, he had to deal with Florian Hart again, who had set up a Z-Bomb to destroy the Arkive and the moon with it. Once it was disabled, the Doctor set up a plan to create a working time machine to send a message back to Arkive's creators. (PROSE: The Wheel of Ice)