 The Z1 truss is now solely used to house the CMGs, communications equipment and the plasma contactors; furthermore Z1 connects now solely to "Unity" (Node 1) and no longer houses other space station elements.In December 2008, the Ad Astra Rocket Company announced an agreement with NASA to place a flight test version of its VASIMR ion thruster on the station to take over reboost duties.In 2013, the thruster module was intended to be placed on top of the Z1 truss in 2015.