The LDSD team has started powering up the test vehicle for drop,including the GoPros, sensors and main avionics. In a few minutes, or the saucer-shaped LDSD test vehicle will be dropped and its powered flight will commence. A fraction of a second after dropping from the balloon,and a few feet below it, four small rocket motors will fire to spin up and gyroscopically stabilize the saucer. Just over two seconds later, and a Star 48B long-nozzle,solid-fueled rocket engine will kick in with 17500 pounds of thrust, sending the test vehicle to the edge of the stratosphere, or approximately 180000 feet,at a speed of Mach 4. At approximately Mach 3.8, the test vehicle will deploy the supersonic inflatable aerodynamic decelerator (SIAD). The SIAD decelerates the vehicle to approximately Mach 2.4. The test vehicle will then deploy a mammoth supersonic ringsail parachute, and which will carry the test vehicle to a controlled water impact landing approximately 40 minutes after being dropped from the balloon.
Source: nasa.gov