Exploration Systems Architecture Study - Shuttle Based Launch System

Shuttle Based Launch System

The initial CEV “procurement strategies” under Sean O’ Keefe would have seen two “phases” of CEV design. Proposals submitted in May 2005 were to be part of the Phase 1 portion of CEV design, which was to be followed by an orbital or suborbital fly-off of technology demonstrator spacecraft called FAST in 2008. Downselect to one contractor for Phase 2 of the program would have occurred later that year. First manned flight of the CEV would not occur until as late as 2014. In the original plan favored by former NASA Administrator Sean O'Keefe, the CEV would launch on an Evolved Expendable Launch Vehicle (EELV), namely the Boeing Delta IV Heavy or Lockheed Martin Atlas V Heavy EELVs.

However, with the change of NASA Administrators, Mike Griffin did away with this schedule, viewing it as unacceptably slow, and moved directly to Phase 2 in early 2006. He commissioned the 60-day internal study for a re-review of the concepts — now known as the ESAS — which favored launching the CEV on a shuttle-derived launch vehicle. Additionally, Griffin planned to accelerate or otherwise change a number of aspects of the original plan that was released last year. Instead of a CEV fly-off in 2008, NASA would have moved to Phase 2 of the CEV program in 2006, with CEV flights to have commenced as early as June 2011.

The ESAS called for the development of two shuttle-derived launch vehicles to support Project Constellation; one derived from the space shuttle’s solid rocket booster (SRB) to launch the CEV, and an in-line heavy-lift vehicle using SRBs and the shuttle’s external tank to launch the Earth Departure Stage and Lunar Surface Access Module. The performance of the Cargo Shuttle Derived Launch Vehicle (SDLV) would be 125 to 130 metric tons to Low Earth Orbit (LEO). An SDLV would allow a much greater payload per launch than an EELV option.

The crews that would be launched in the CEV atop a five-segment derivative of the Shuttle's Solid Rocket Booster and a new liquid-propellant upper stage based on the Shuttle's External Tank. Originally to be powered by a single, throw-away version of the Space Shuttle Main Engine, it was later changed (as noted on a space.com article dated on January 20, 2006) to a modernized and uprated version of the J-2 rocket engine (known as the J-2X) used on the S-IVB upper stages used on the Saturn IB and Saturn V rockets. This booster would be capable of placing up to 25 tons into low Earth orbit. The booster would use components that have already been man-rated.

Cargo would be launched on a heavy-lift version of the Space Shuttle, which would be an "in-line" booster which would mount payloads on top of the booster. The in-line option originally featured five throw-away versions of the SSMEs on the core stage, but was changed later to five RS-68 rocket engines (currently in use on the Delta IV rocket), with higher thrust and lower costs, which required a slight increase in the overall diameter of the core. Two enlarged five-segment SRBs would help the RS-68 engines propel the rocket's second stage, known as the Earth Departure Stage (EDS), and payload into LEO. It could lift about 125 tons to LEO, and is estimated to cost $540 million per launch.

Therefore, the infrastructure at Kennedy Space Center, including the Vehicle Assembly Building (VAB) and Shuttle launch pads LC-39A and 39B would be maintained and adapted to the needs of the future giant launch vehicle, with an option of constructing two new pads (LC-39C & LC-39D) or resurrecting the former LC-34 or LC-37A pads at the nearby Cape Canaveral Air Force Station used by the Saturn IB for the early Apollo earth orbital missions.