Rita is a Lantean from the Pegasus galaxy who traveled to Earth during the evacuation of Atlantis more than 10,000 years ago.  While much of her equipment was, by necessity, left behind in Atlantis, she sought to continue her work in the Milky Way.

She traveled from Earth to a number of suitable worlds, but eventually decided to set up her operations on a planet without a Stargate, hoping to avoid the attention of the other Lanteans and the Goa’uld.  She was, against the laws of the Council, continuing to experiment with human DNA, seeking to create perfect, obedient soldiers.  While her intentions might have been pure in the beginning, perhaps finding a way to combat the Wraith on land or retake Earth from Ra and the Goa’uld, after several years in isolation her purpose became twisted and corrupt.  Soon, she had created a powerful and loyal creature called Goldar as well as a race of nearly mindless soldiers called Putties.  She had stolen a Goa’uld ship to reach the gateless planet, and after she created her Putties, she loaded her equipment onto the ship and, with an upgraded hyperdrive engine, the ship set out for Earth.

However,  another Lantean, named Zordon, was in orbit around Earth in a modified ship of his own when Rita dropped out of hyperspace.  After a brief exchange, Rita fired on Zordon’s ship.  Zordon (who had known Rita before the evacuation of Atlantis) expected the attack, and was able to activate a device aboard his ship moments after Rita fired.  As the energy field from Zordon’s device hit Rita’s  ship, her modified hyperdrive, with Goa’uld safety measures overridden to allow for the upgrades to take effect, overloaded and a blast of energy rocked both ships.  Rita, Goldar, and the army of Putties were thrown into a small hyperspace window connected modified drive aboard her ship, while Zordon, due to his proximity to his device, was actually trapped in a subspace.

While Zordon’s android assistant, unaffected by the energy field, crash-landed on Earth,  Rita’s ship was caught in the Moon’s gravitational pull and crashed there.  However, the malfunctioning hyperdrive was not destroyed, and the zero point module used to power it continued functioning for another 10,000 years until very recently, when the power ran out and the hyperspace window was disconnected, dropping Rita, Goldar, and the putties back into normal space in a mostly destroyed ship on the dark side of the moon.

The ancient Lantean has had 10,000 years of being trapped in subspace to stew and plot her revenge on both Zordon and on the pitiful humans of Earth that she had once sought to rescue.