United States’ liquid rocket propulsion technology has evolved over the past five decades to meet the changing needs of the commercial community, agree with Department of Defense (DoD) diminishing budgets, and ensure national access to space. The importance of the United States having assured access to space is best laid out by the National Presidential Directive Number 40 which states: Access to space through U.S. space transportation capabilities is essential to: (1) place critical United States Government assets and capabilities into space; (2) augment space-based capabilities in a timely manner in the event of increased operational needs or minimize disruptions due to on-orbit satellite failures, launch failures, or deliberate actions against U.S. space assets; and (3) support governme