The Committee anticipates that in order to meet the specified vehicle capabilities and requirements, the most cost-effective and `evolvable’ design concept is likely to follow what is known as an `in-line’ vehicle design,
with a large center tank structure with attached multiple liquid propulsion engines and, at a minimum,
two solid rocket motors composed of at least four segments being attached to the tank structure to form the core, initial stage of the propulsion vehicle. The Committee will closely monitor NASA’s early planning and design efforts to ensure compliance with the intent of this section.