Stargate power node
Device approximately the width of a Stargate, apparently designed to power a gate placed in outer space in the absence of a dial-home device. Space gates are equipped with three nodes placed at 120 degree intervals around the gate's outer edge. They may also be equipped with thrusters, which maintain the position of a Stargate in space.
Each power node is likely equipped with an Ancient power cell, possibly even a long-lasting Zero Point Module -- as the millennia-old space gate network requires power to be able to function without attached D.H.D.s. Lights illuminate the devices as they gently spin the floating gate in a clockwise motion.
It is also likely that the power nodes themselves illuminate all nine chevrons on a Stargate in a greater effort to show that they are active and in-use. Whether this technology is Ancient is not known for certain, but it is likely that the Ancients placed the gates in outer space, and thus equipped them with long-lasting power sources.
Rising, Part 1 - Sheppard and his team witness, for the first time, a Stargate deliberately placed in space, and held in-position by a trio of power nodes.