The professor exits the explorer with a hand-held recorder, the light blinking to indicate that he is already recording. He cocks his head to one side as he looks at the gate, then he turns about in a slow circle, surveying the area. "Odd. It looks defensive in nature, but the structure fits the pattern of a tomb. Why would a tomb require defenses?" As he flops out of the explorer dragging a case of equipment, Drogo mumbles, "to keep something in, or out?"
Alexis doesn't see any mechanism on top, but there is a space to allow the gate to rise through the upper part, essentially coming out the top as it opens.