In light of the small gouge to the underside of "Endeavour" that occurred on STS-118, in August 2007, NASA managers announced that they expected to add a fifth spacewalk to the STS-120 mission, designed to test a heat-shield repair tool. The repair technique was originally scheduled for a flight in 2008, but following STS-118, it was decided to move up the testing. The repair tool, called a TPS (thermal protection system) repair ablator dispenser (T-RAD), has never been tested in space, so the spacewalk would have allowed managers to evaluate its effectiveness in low gravity environments. During the course of the mission, issues with the S4 starboard Solar Alpha Rotary Joint (SARJ), and P6 Solar Array, deferred this test objective to a future mission.