Five-Segment Booster (FSB) Abort to Orbit (ATO) Studies

The Five Segment Booster (FSB) concept has been evolving for a number of years as a means to enhance the overall safety and reliability of the Space Shuttle system by minimizing the need to fly the more challenging Return to Launch Site (RTLS) and Transoceanic Abort Landing (TAL) abort profiles. The initial evaluation of the FSB concept was conducted in 1996 to determine the feasibility of the FSB in achieving transatlantic abort leading TAL from the pad, thus eliminating the return to launch site (RTLS) abort mode. The initial study was conducted by ATK Thiokol and did show the potential for the FSB to eliminate the RTLS abort mode. Later Rockwell (now Boeing) conducted a similar study utilizing FSB performance characteristics and verified that the FSB could indeed achieve TAL from the pad, thereby eliminating the necessity for the RTLS abort. The purpose of this paper is to discuss the details of the enhancements achieved through the internally funded study conducted by Boeing and ATK Thiokol. To better understand the enhancements that were addressed as part of this follow-on study, some background on what was achieved in the Phase A study is appropriate.