When the Falcon 9 Block 5 rocket reaches Max-Q (maximum dynamic forces), the launch abort system of the Crew Dragon spacecraft will be triggered. This will fire up its SuperDraco engines and propel the spacecraft and its theoretical passengers away from the launch vehicle before landing back safely in the Atlantic Ocean. The goal of this test is to demonstrate the capacity of the spacecraft to ensure a safe return to the ground for the astronauts in the event of a launch vehicle failure. The booster for this launch will be B1046, a thrice-flown core which was the first of the Block 5 generation. It will not attempt to land and is expected to be destroyed by the SuperDracos and aerodynamic loads.
Space Exploration Technologies Corp., known as SpaceX, is an American aerospace manufacturer and space transport services company headquartered in Hawthorne, California. It was founded in 2002 by entrepreneur Elon Musk with the goal of reducing space transportation costs and enabling the colonization of Mars. SpaceX has many pads, on the East Coast of the US they own SLC-40 at Cape Canaveral and LC-39A at the Kennedy Space Center for their lower inclination launches. They also own SLC-4E at Vandenberg, California for their high inclination launches. Another site is also being developed at Boca Chica, Texas.