C. In-Line Heavy Lifter (more than 100 metric ton payloads to LEO)
In-line heavy-lift SDLV concepts can achieve payload capabilities in excess of 110 MT by adapting flightproven
and reliable hardware and modifying existing infrastructure. These in-line heavy-lift SDLV configurations
offer a wide range of payload options based on existing or modified SSME, SRB, and ET elements combined with a
new cryogenic liquid propellant upper stage (Fig.
Such ultra-heavy configurations would require the
development of a new in-line core stage as an evolution of the current ET, based on existing tooling and
manufacturing processes coupled to mature boosters, rocket engines, and tanks. The basic in-line heavy-lift SDLV
concept would use a pair of five-segment SRBs combined with a core stage using a standard ET volume mounting
four SSMEs, plus an upper stage using a single J-2S engine (Fig. 9).
This configuration is estimated to yield 110 MT
to LEO, with a payload volume that is 9 meters in diameter by 35 meters in length. Preliminary reliability estimates
indicate the LOV rate would be approximately 1/130 to 1/240, depending on configuration and operational details.
Considerable development schedule, cost, and risk would be avoided by taking advantage of existing long-lead
elements such as rocket engines and boosters, enabling a first flight test capability in 60 months from the start of