The Lambda-class Side Boosters were designed to give the Zeta-class Launch System an extra boost to assist in getting it as close to an orbit as possible before they Jettison off of the main launch vehicle, attaching to each other behind the vehicle, and then doing a Return to Launch Site burn. The side boosters have undergone one change to the deisgn, where the computer was fully integrated into the fuselage. This slight change was done to ensure that the vehicle would be reusible for a prolonged period of time.