This hollow structural section shields the engine nozzle of the upper stage during the lower stage's ascent and transmits thrust loads through the vehicle stack. It contains separation mechanisms like explosive bolts or pneumatic pushers that sever the connection when the lower stage is depleted. Once the lower stage falls away, the interstage is often jettisoned to shed dead weight before the upper stage ignites.
The telemetry shows successful booster cutoff, and we have confirmed interstage separation.
On some rockets, the interstage remains attached to the lower booster for recovery, while on others it is dropped as a separate piece of space debris.
Related terms
Multistage
A multistage vehicle uses two or more distinct rocket sections that fire and discard sequentially.
Launch vehicle
A rocket or other system used to carry a payload from the Earth's surface into space.
Umbilical
A physical line providing power, fluids, or data to a vehicle or astronaut before separation.