موشک ترمزی

right|thumb|Descent of a Martian lander halted by retrorockets (computer-generated impression) thumb|Soyuz (spacecraft)|Soyuz space capsule retro-rockets cushion the landing impact A retrorocket (short for retrograde rocket) is a rocket engine providing thrust opposing the motion of a vehicle, thereby causing it to decelerate. They have mostly been used in spacecraft, with more limited use in short-runway aircraft landing. New uses are emerging since 2010 for retro-thrust rockets in reusable launch systems.