13

The item designated with the number '13' in relation to a NASA Space Shuttle Solid Rocket Booster (SRB) aft skirt represents a structural component of the Space Shuttle launch stack rather than an independent conventional aircraft. Manufactured as a flared, cone-shaped aerospace structure, each aft skirt was designed to bolt directly to the mobile launcher platform, housing crucial thrust vector control actuators, avionics, and the hold-down posts that bore the weight of the entire vehicle stack before liftoff.

Throughout the operational lifespan of the Space Shuttle program, SRB components including aft skirts were reusable structural hardware flown on multiple missions. Following liftoff and separation at approximately two minutes into flight, the booster assemblies descended into the Atlantic Ocean via parachutes, where dedicated NASA recovery ships retrieved them for transport to the booster refurbishment facility at Kennedy Space Center. Because components were dismantled, inspected, and swapped between flights, individual serial-numbered hardware assemblies repeatedly rotated across diverse STS missions.

Following the conclusion of the Space Shuttle program in 2011, surplus booster casings and structural elements were retired, preserved for the Space Launch System (SLS) program, or transferred to government surplus channels. Some decommissioned structural artifacts, including selected SRB aft skirt sections, were released to aerospace memorabilia collectors and preservationists (such as PlaneTags) to be converted into historical keepsakes, while others remain preserved or scrapped as excess government aerospace hardware.