65 DAY IN THE LIFE: THE MAKING OF A MISSION CHAPTER 4 be attached to the space station at the nadir side of Node 3. But it was realized that interference could occur with the Russian Mini-Research Module projecting nadir from the Functional Cargo Block module. The nadir of the Mini-Research Module was also to be the location for the Soyuz and, possibly, Progress vehicles. Although visiting vehicles such as HTV, Orion, and Soyuz could likely dock and undock with no interference, the ISS Program officials decided to ensure a certain amount of clearance due to unexpected errors, uncertainties in sensors, or systems failures. A miscalculation could cause a collision (similar to when a Progress vehicle struck the Russian Mir station in 1997 with US astronaut Michael Foale on board), destroying a module, or worse, the entire station. To solve the clearance issue, ISS Program officials asked whether Node 3 module could be installed on the port (left) direction off of Node 1, as shown in Figure 1. Although the berthing mechanisms were designed to allow a module to be mounted in any orientation, the plumbing to that module was not as accommodating. All of the ventilation lines, computer circuits, water tubes, nitrogen lines, and communication cables had been installed years earlier in Node 1 under the assumption that Node 3 would be on the nadir. To place Node 3 on the port side meant all these had to be rerouted—in space. Furthermore, the electrical power cables and the external ammonia lines used for cooling the Node electronics would have to be rerouted. Figures 1 and 2 show the final proposed configuration. Figure 2. Drawing of the ISS now showing Node 3 berthed on the port side (red outline). As was typical of the flight control and engineering teams, the question was not whether they could do this, but how they could make it work. The first task was to figure out how to modify the Node 1 module that was already on orbit to accommodate the change and make sure the hardware and procedures could be done by the ISS crew. The task was analogous to modifying a bedroom by moving the bathroom to the other side of the room. The changes also would have to be somehow verified in advance to ensure that everything aligned just right when Node 3 was installed during the mission. Node 1 was already in orbit, so no direct fit checks could be performed. The teams had to use the Node 1 mock-up in the training facility. The mission would be a complete disaster if the shuttle was launched and then Node 3 could not be physically mated to Node 1. Even if the modifications to Node 1 could be made, they had to be done in the limited time available to the astronauts with the training that could be accommodated in the already- packed training schedules. If the modifications were not completed before NASA retired the Space Shuttle fleet, Node 3 module might never make it to orbit. The first of many issues arose as this was being worked out. Although the berthing mechanism could, in principle, accommodate a module in any one of four orientations 90 degrees apart, bumpers existed on both modules to provide additional protection when two modules were mated. The result was that Node 3 could only be installed in two of four orientations on Node 1. Either option had the module lights on the back