In addition to three general-purpose pods, a laboratory-equipped pod (Pod 5) is available for use on rescue missions, and transported to the danger zone by Thunderbird 2.
The small, well-equipped facility allows Brains to conduct on-the-spot research, and carry out essential experiments - as he does in Pit of Peril, when he, Scott and Virgil study close-up images of an enormous smoldering pit, into which the Army's unwieldy Sidewinder vehicle (and its crew) has toppled...
Pit of Peril
After Thunderbird 2, with Virgil and Brains, arrives at the danger zone, Scott joins them in the laboratory pod. The three IR members watch the video footage of the depths of the pit, taken by Thunderbird 1's remote camera. Brains realizes the pit is, in fact, an open-cast mine - one which had been used as a military equipment dump after the Second World War.
He shows Scott and Virgil a plan he has drawn. Its first phase involves Virgil being lowered into the pit to lay explosive charges, after which Scott will retrieve him using the Mole. Once the charges detonate, they'll remove the walls of the pit - so that the Sidewinder can then be dragged up to the surface, and out of danger, by the Recovery Vehicles...
30 Minutes After Noon
Vault of Death
Move - And You're Dead
Thunderbirds Are Go
In the Haynes Agents' Technical Manual, it is stated that Pod 5 has a storage platform (description follows):
"To maximize the available space inside the pod, some vehicles can be vertically stacked on the pod vehicle storage platform. When the vehicle below has been driven out, the platform is lowered at the door-facing end so that the vehicle above can be deployed. On arrival at the danger zone this vehicle is driven out of the pod first, followed by the vehicle on the top deck. After the mission, the vehicle on the top deck is reversed first and clamped into position".
- The use of this platform was not seen in any episode or film. Nor is it noticeable in the composite picture above
The only cutaway drawing of the Laboratory pod, was published in the Haynes Agents' Technical Manual