Mounted on top of the fifth-segment simulator are the forward skirt and its extension, which hold the parachute recovery system; it will allow the first stage, after breaking away from the upper stage, to safely splash down in the ocean, where it can be recovered for reuse. The system consists of a computer that triggers separation, a small explosive charge that cuts the metal, and five parachutes.
Ares’s boosters are heavier than the space shuttle’s boosters and will drop from a higher altitude, so they will be falling faster. To compensate, the launch vehicle’s parachutes are much larger and stronger but, thanks to new materials, lighter. The parachutes will deploy in three stages, starting when the rocket boosters reach an altitude of about 4,500 meters. The staged deployment will not only slow the boosters for splashdown but also maneuver them into the appropriate position to prevent damage.
At the very top of the 24-meter-tall stack rests the interstage, which marks the beginning of the upper stage and holds the system designed to control the forces that cause the rocket to rotate during flight. The interstage of Ares I will also carry the rocket’s J-2X engine, which will power the upper stage; it will not be simulated for the test flight, though its weight is accounted for.
The next three stacks simulate the shape and weight of the rest of the upper stage. Stack two, which is the shortest, represents the liquid oxygen tank. Engineers used steel ballast plates to account for the fuel’s weight. Stack three, which is almost 14 meters tall, sports the NASA logo and three emblems that identify the mission. For the test flight, this stack is purely structural and will remain empty. In Ares I, however, it will house most of the liquid hydrogen tank, as well as the flight computer and avionics that control all aspects of flight. Stack four, which displays the U.S. flag, stands for the rest of the hydrogen tank, which will span both stacks; it is also filled with steel ballast plates.
The final stack of Ares I-X is the dart-shaped mock-up of the Orion crew module and launch abort system. The upper stage and crew module will make up a quarter of the assembled rocket’s height; for the Ares I-X flight, it will carry many of the most critical sensors. However, after separation the engineers will have gathered the data they need most, so these portions will fall uncontrolled and splash into the Atlantic Ocean.