HOW THE GATEWAY FUNCTIONS

The Gateway itself, exists in all universes and time periods suggesting that it was designed by an ancient and advanced race. It is basically a doorway to mirror dimensions whose exact nature is still unknown.
The Gateway is operated through the control console which requires an officer always to be present on monitor duty especially when crew are away on missions to track their location. A security detail is also on duty at all times to protect the Gateway from whatever emerges from it into our universe.
The original console was modified after the arrival of Starfleet for a number of reasons:
1) To allow safe passage and return of crew
2) To track the crew on away missions
3) To allow for enhanced control of Gateway functions
The Gateway is open at all times with no way to close it allowing free passage at any time.
Through the console, the size of the Gateway can be altered to allow the passage of crew, land rovers or shuttles and a ship. The passage of crew and land rovers or shuttles takes place within the Gateway complex and does not require a great deal of energy.
To expand the Gateway to allow passage of a ship, it is projected to landing bay where the ship is located. The projection, requires a great deal of energy and results in a sever power drain of the Gateway systems. The power drain results in the Gateway being inactive for a period of 48 hours before it can be opened again to allow return.