dsc06862.jpg

This exhibit demonstrates the "star" shape of the Space Shuttle Solid Rocket Booster (SRB) fuel grain. This pattern is formed into the fuel to optimize the surface area which is burned at any one time.

It is my understanding that the grain pattern varies along the length of the SRB, based on the position of the SRB segment, and that the pattern is also varied to modify the thrust during different portions of the the flight.