The Launch Pad is a block added by Advanced Rocketry that is used to construct the multiblock structure of the same name. It is used to construct, fuel and launch rockets.
To construct the Launch Pad, place Launch Pad blocks in a square (3x3-16x16) on the ground, then build a tower of Structure Tower blocks next to it (the lowest Structure Tower needs to be on the same level as the Launch Pad). Then place a Rocket Assembling Machine next to and one level above the Launch Pad. Note that the Rocket Assembly Machine requires power.