High above Pandora's surface, a new satellite takes orbit. It photographs and maps the surface and listens for radio chatter. Its hull is marked in a strange language. Eventually, it releases a large capsule that races for the surface.
As soon as it hits thicker air, its retrorockets fire. Its decent slowed dramatically, it inflates a hot-air balloon and floats, studying the atmosphere and mapping the surface in greater detail. Eventually, its balloon deflates greatly and it lands gently on the surface.
It's hard. It's hot. It's definitely concrete.
The probe lands in Hell's Gate, Pandora's artificial scar. Everything's quiet. The closest life forms are a few hidden scientists watching from afar.
The probe's not armed, as far as they can tell. Since there was no immediate danger, the scientists kept the anti-air defenses offline. No need to waste missiles that could shoot down RDA ships instead.
The probe finishes its assessment of the base and releases a rover unit. The rover wanders into the forest through a breach in the wall. Its dual thermo-cameras detect two large fauna nearby. It sneaks up close and examines them.
They were a pair of large, blue animals. The size of their arms and legs suggest that they are bipedal. The pair are too distracted to notice the rover sneaking closer. The rover fires a stream of sticky gel onto the pair and rushes in. Before they can break free from their gel prison, the rover turns them over and sprays them again. With the specimens cocooned, the rover drags them to Hell's Gate and signals the mother ship. It's time for colonization