Abstract: The throttleable solid propellant system includes a substantially solid propellant, a shape-altering structure, and an actuation source. The shape-altering structure is at least partially disposed within the substantially solid propellant. The actuation source is to be coupled to the shape-altering structure. The actuation source is to be configured to actuate the shape-altering structure between a first position and a second position. Transitioning the shape-altering structure between the first position and the second position may crack and/or deform the substantially solid propellant. Cracking and/or deforming the substantially solid propellant may increase the burning surface area of the propellant, thereby altering the thrust produced from the throttleable solid propellant system.