 The first truss piece, the Z1 truss, launched aboard STS-92 in October 2000.It contains the control moment gyroscope (CMG) assemblies, electrical wiring, communications equipment, and two plasma contactors designed to neutralize the static electrical charge of the space station.Another objective of the Z1 truss was to serve as a temporary mounting position for the "P6 truss and solar array" until its relocation to the end of the P5 truss during STS-120.