Robert Knepper and Julie McNiven have joined Syfy's Stargate Universe as guest stars for the second season.

Knepper will appear in a six-episode arc and will portray Simeon, a member of the Lucian Alliance. McNiven joins the cast for a five-episode arc, portraying Ginn, a member of the Lucian Alliance. Season two of Stargate Universe will premiere on Syfy fall 2010.

Production is underway in Vancouver, Canada. The second-half of Stargate Universe first season premieres Friday, April 2, at 9PM (ET/PT).

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Stargate Universe stars Robert Carlyle, Louis Ferreira, Brian J. Smith, Elyse Levesque, David Blue, Alaina Huffman, Jamil Walker Smith, Ming-Na and Lou Diamond Phillips.

The series follows a band of soldiers, scientists and civilians, who must fend for themselves as they are forced through a Stargate when their hidden base comes under attack. The desperate survivors emerge aboard an ancient ship, which is locked on an unknown course and unable to return to Earth. Faced with meeting the most basic needs of food, water and air, the group must unlock the secrets of the ship's Stargate to survive. The danger, adventure and hope they find on board the Destiny will reveal the heroes and villains among them