SDLV/CEV - JULY AIAA Joint Propulsion Conference Document

[Chris Bergin]

Ok, here is the full text and images from the PDF file we've aquired. (Thanks to user Colby for uploading most of the images).

It's written by:

William J. Rothschild* and Debra A. Bailey†
The Boeing Company, NASA Systems, Houston, TX 77059
Edward M. Henderson‡
NASA/Johnson Space Center 2, Houston, TX 77058
and
Chris Crumbly§
NASA/Marshall Space Flight Center, Huntsville, AL 35812


* Director, Space Transportation, Boeing NASA Systems, 13100 Space Ctr. Blvd. (MC HS4-20), Houston, TX (AIAA Member)
† Project Engineer, Space Shuttle R&D, Boeing NASA Systems, 13100 Space Ctr. Blvd. (MC HS1-30), Houston, TX (AIAA Member)
‡ Deputy Manager, Strategic Planning Office, Space Shuttle Program, NASA/Johnson Space Center (AIAA Member)
§ Manager, Cargo Launch Vehicle Study, Space Transportation Programs and Projects Office, NASA/MSFC-NP01 (AIAA Member)

The AIAA Joint Propulsion Conference in Tucson, Arizona was July 10 - 13, 2005.

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I. Introduction

Space Transportation System (STS) assets have been in operation since 1981. They are well understood from
technical performance, reliability, operations, and cost aspects. Adapting these proven STS assets to yield new
launch systems would take full advantage of demonstrated mature, reliable, human-rated systems to develop
impressive performance capabilities with minimum technical, schedule, cost, and programmatic uncertainties.
Independent studies done by several industry and NASA teams have shown that such STS-Derived Launch Vehicle
(SDLV) concepts offer payload performance over a wide range from 16 to 110 metric tons (MT) to low Earth orbit
(LEO). Because of the high technical readiness level (TRL) associated with these STS assets, rapid demonstrations
and flight test opportunities could provide early program successes with low schedule and cost risks. Importantly,
SDLV development and test activities would enhance the safe “flyout” of the current STS program through
continuity of critical skills and manufacturing infrastructure during the transition period. Viable technical and
management approaches have been identified that could dramatically reduce the annual recurring costs compared to
the current STS system. These operational cost savings are achievable by eliminating the labor- and facilityintensive
Shuttle orbiter processes plus the low marginal cost associated with using ongoing STS assets.

II. Objective

The objective of this collaborative industry/NASA study has been to define a broad range of SDLV alternatives
that could support NASA’s space exploration launch infrastructure needs. We have attempted to assess NASA’s
current STS assets and evaluate their applicability to future exploration systems’ Earth-to-Orbit (ETO) launch needs.
Our goal has been to provide timely, useful information on a full range of options, supported by objective facts and
data. It was not the intent of these collaborative SDLV studies to recommend an ETO architecture approach or any
specific launcher configurations.

III. Options for ETO Transportation Using STS-Derived Launch Vehicles

SDLV offers a variety of configuration approaches to satisfy the crew and the heavy-lift cargo requirements of
future human space exploration. The current STS can reliably propel 118 MT to LEO, including the mass of the
Space Shuttle orbiter. By conceptually mixing and matching the basic human-rated propulsion system elements of
the STS—Space Shuttle Main Engine (SSME), solid rocket boosters (SRBs), and external tank (ET)—one can
create a wide range of new launch vehicle concepts, providing payload lift capabilities in the 16 to 110 MT range
(Fig. 1). The SDLV work reported in this paper has focused on three main configuration alternatives: a side-mount
heavy lifter (~77 MT payload), an in-line medium lifter (~22 MT Crew Exploration Vehicle [CEV] payload), and an
in-line heavy lifter (~110 MT payload).

A. Side-Mount Heavy Lifter (43 to 91 MT payloads to LEO)
This configuration is a straight-forward derivative of the current STS configuration, replacing the reusable
Shuttle orbiter with an expendable payload carrier. The side-mount heavy lifter SDLV concepts would benefit from
the long heritage and extensive learning provided by more than 110 STS launches. The side-mount heavy lifter
configuration also enjoys an impressive library of previous design and planning work completed as part of the
Shuttle-C project during the 1986–1992 timeframe, making this the most well-understood heavy-lift launch system
concept available today. The side-mount heavy lifter concepts require the design and development of a new
cylindrical payload carrier that would mount three SSMEs along with the avionics and other subsystems. The
standard four-segment SRB configuration would use the current ET propellant volume to yield 77 MT payloads to
LEO (Fig. 2). The five-segment SRB configuration could be used with a stretched ET to yield 91 MT payloads to
LEO. Both side-mount heavy lifter SDLV configurations could carry either cargo only or a combination of cargo
and a CEV (Fig. 3). Preliminary reliability estimates indicate the loss-of-vehicle (LOV) rate would be approximately
1/160 to 1/240, depending on configuration and operational details. In addition to heavy payload mass, these SDLV
options offer large payload sizes up to 7.5 meters in diameter and 35 meters long. Taking advantage of the existing
or modified STS hardware for the side-mount launcher also allows the use of the current STS infrastructure.
Expensive and time-consuming development of rocket engines and boosters would be avoided, enabling the sidemount
heavy lifter Design, Development, Test, and Evaluation (DDT&E) program to achieve a first flight test in as
little as 48 months from the start of Full-Scale Development (FSD) (Fig. 4). This would enable parallel operations of
a side-mount heavy lifter SDLV for a wide range of exploration cargo missions along with a CEV launcher for lunar
missions using the same basic launcher and infrastructure. When operated with a CEV the side-mount heavy lifter SDLV concept could offer an Abort-to-Orbit (ATO) capability, with an engine-out payload penalty of roughly
30 percent. Of the many ETO launcher options available to NASA, the side-mount heavy lifter SDLV configuration
is probably the lowest cost and least risk approach for payloads in excess of 45 MT to LEO. In addition to
supporting exploration missions beyond LEO, both crew or cargo, the Side-Mount Heavy lifter can be used to
support ISS requirements for logistics support.

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B. In-Line Medium Lifter (16 to 26 MT payloads to LEO)
The NASA Exploration Vision requires ETO launch vehicles that have lift capabilities in the 20 MT range to
support robotic precursor missions and CEV missions to LEO. In-line medium-lift SDLV concepts could meet both
these exploration cargo and crew launch needs (Fig. 5 and 6).

These in-line medium-lift SDLV concepts are based
on a simple two-stage configuration that uses an existing SRB for the first stage plus a new cryogenic liquid
propellant upper stage. The upper stage would use a single J-2S (based on the human-rated Saturn upper stage
engine), or a single SSME, or multiple new, high-performance upper stage rocket engines (Fig. 7).

The relatively
high length/diameter ratio of this in-line medium-lift SLDV configuration initially raised concerns about potential
control problems. Preliminary stability and control analyses done independently by NASA and industry teams have
shown that this configuration should maintain reasonable control margins under worst-case ascent conditions. Using
the same basic launch infrastructure, the SDLV medium-lift launch vehicle concept could operate as a CEV launcher
in parallel with various SDLV heavy-lift cargo launch vehicles to satisfy the full spectrum of NASA exploration
mission ETO requirements in a cost-effective manner. All of the propulsion components such as the CEV launcher
have flight-proven, human-rated heritage. Preliminary reliability estimates indicate the LOV rate would be
approximately 1/438 with a J-2S upper stage, making the in-line medium-lift SDLV an attractive option as a CEV
launcher.

The immediate availability of the key CEV launcher components could facilitate early flight
demonstrations to support CEV development and test, as well as lunar precursor missions. Having such in-line
medium-lift SDLV flights manifested during the “flyout” portion of the current STS significantly increases the
effectiveness and commitment of the Shuttle team for the later flights. In addition to supporting exploration missions
beyond LEO, the in-line medium lifter could also be used to support ISS requirements for crew and cargo resupply.

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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
FSD.

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There is a great deal of flexibility inherent in the in-line heavy-lift SDLV concept. The large payload diameters
offered by in-line heavy-lift SDLV concepts are of particular interest for Mars missions. Although the need date for
this class of launch capability may be several years away, this family of SDLV concepts can easily evolve from the
medium payload class to the super-heavy class using the same basic engines, SRB, and subsystems currently
existing in the STS inventory. Variations of the in-line heavy-lift SDLV concept involve flying with no SRB,
replacing the SSME engines on the core stage with RS-68 rocket engines, flying with no upper stage, or replacing
the J-2S upper stage engine with multiple new high-performance rocket engines. Each combination offers unique
performance, reliability, cost, and risk benefits (Fig. 10).

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D. Affordability

Affordability is recognized as one of the primary constraints to the success of the exploration vision. Developing
reasonable DDT&E, production, and operations cost estimates along with program funding profiles could become a serious impediment unless there is a disciplined and focused push to reduce costs in all areas. Current NASA Space
Shuttle Program (SSP) costs are driven by reuse, crewed systems, flexibility, and size of the workforce. Each of
these factors must be attacked aggressively to develop a viable exploration transportation system.

Eliminating major cost elements previously associated with the SSP would significantly reduce operations costs
in both facilities and workforce (Fig. 11).

These valuable assets and trained workforce will undoubtedly be needed
and applied to other aspects of the exploration architecture. Replacing the Shuttle orbiter with an expendable
payload carrier allows a great many of the current STS facilities and personnel to be shifted to uses other than SDLV. Ground operations systems not applied to SDLV would include landing operations and navigation aids,
wheel and tire shop, flight crew and lithium hydroxide (LIOH) labs, thermal protection system (TPS) shops,
hypergolic maintenance facilities (HMF), and any other facilities previously used to support the orbiter vehicle.
Other facilities not applied to SDLV include the orbiter landing facilities including the Shuttle Landing Facility in
Florida, Dryden Flight Research Center in California, and several trans-Atlantic landing sites.

The uncrewed aspect
of the SDLV greatly reduces facilities and workforce associated with a crewed vehicle, primarily in the area of crew
training and training facilities such as the Shuttle Engineering Simulator (SES), Single System Trainer (SST),
Dynamic Skills Trainer (DST), Shuttle Mission Simulator (SMS), and Neutral Buoyancy Lab (NBL). Additional
assets related to fight crew equipment (FCE) and flight crew operations training, such as the T-38 aircraft and
hangers at Ellington Field, would not be employed by the SDLV program.

Consolidation of similar work activities
provides significant cost savings in facilities and workforce efficiencies. Flight controllers performing tasks similar
to those of current Mission Control Center (MCC) positions would still be required. However, since interaction with
the SDLV would be minimal after launch, their tasks are greatly simplified; and many positions may be combined.
In addition, flight control positions that monitor the crew activities and health status, or communicate with
crewmembers, would no longer be needed for the uncrewed SDLV.