— Ch. 1 · Origins And Congressional Mandate —
Space Launch System.
~5 min read · Ch. 1 of 6
The Space Launch System emerged from a specific legal requirement in 2010. Congress passed the NASA Authorization Act of 2010, Public Law 111, 267, which directed NASA to create a new system for launching payloads and crew into space. This mandate arrived as the Space Shuttle program drew to a close in 2009. The act set out clear goals such as lifting 70 to 100 tons into low earth orbit with an ability to evolve to 130 tons. A target date of the 31st of December 2016 appeared for the system to be fully operational. The legislation also included a directive to use existing components, hardware, and workforce from the Space Shuttle where practicable. This requirement shaped every subsequent design decision for the rocket. Senators representing states with significant aerospace industries opposed the cancellation of the shuttle-derived approach. Utah Senator Orrin Hatch ensured the new rocket used the Shuttle's solid boosters manufactured in his state. Alabama Senator Richard Shelby insisted that the Marshall Space Flight Center design and test the rocket. Florida Senator Bill Nelson brought billions of dollars to Kennedy Space Center to modernize its launch facilities.
Engineering Architecture And Components
The core stage measures 58 meters long by 8.4 meters in diameter and is visually similar to the Space Shuttle external tank. It contains liquid hydrogen and liquid oxygen tanks for the ascent phase along with avionics and the Main Propulsion System. Four RS-25 engines provide thrust alongside two outboard solid rocket boosters. The first four flights will each use and expend four of the remaining sixteen RS-25D engines previously flown on Space Shuttle missions. Aerojet Rocketdyne refits these engines with modernized engine controllers and higher throttle limits. Later flights switch to an RS-25E variant optimized for expended use which lowers per-engine costs by over 30 percent. The five-segment solid rocket boosters provide approximately 25 percent more total impulse than the Shuttle Solid Rocket Boosters. They possess an additional center segment, new avionics, and lighter insulation but lack a parachute recovery system. The propellants include aluminum powder and ammonium perchlorate held together by polybutadiene ac519acrylonitrile binder. The Interim Cryogenic Propulsion Stage uses a single RL10B-2 engine while later versions utilize the RL10C-2 variant.