1.   Endeavour carries another piece of hardware, the Unity connecting node, that is to be docked with Zarya in the first step of assembling the International Space Station.

2.   If a connecting node between A and B fails, it is easy to find an alternative route.

3.   One is a connecting node called Unity made by Boeing at its space station manufacturing building here in Huntsville.

4.   The third main section, the American-made Unity connecting node, remains largely dormant while awaiting more power.

5.   Unity is a connecting node for future modules.