Author Topic: SDLV/CEV - JULY AIAA Joint Propulsion Conference Document  (Read 38062 times)

Offline Chris Bergin

F. Payload Size vs. Mission Risk

The SDLV concepts are capable of delivering very large payloads to LEO in the 60–110 MT class. Although the
International Space Station (ISS) program is a marvel of systems engineering and has proven that a highly complex
spacecraft can be successfully assembled in LEO, there are significant integration costs for this approach.

Assembling these smaller elements together has required a considerable amount of resources and documentation to
plan, develop, process, and test each element to ensure that they meet the interface requirements of the mating
elements as well as the overall system. Once the elements are delivered to orbit, numerous, complex rendezvous,
docking, and extravehicular activities (EVAs) are required to assemble the individual elements. Although the skilled
astronauts and MCC staff make these interfaces look easy, they require months of planning and preparation to
successfully accomplish. EVAs significantly impact the crew timelines, both during training on the ground and
during the mission itself.

The capability to deliver very large payloads to LEO should reduce the complexity of the
payloads and improve the expected success rate for the exploration mission operations.

The number of launches required over a 10-year lunar exploration campaign has a very strong bearing on the
overall risk of mission failure. Assume SDLV launchers deliver 60–85 MT payloads to LEO with a per-launch
reliability of 0.995. A 10-year lunar campaign would require a total of 20 SDLV launches, resulting in a 9.1 percent
probability of losing one payload. For comparison, a launcher that could deliver 40 MT payloads to LEO with a
0.980 percent per-launch reliability would require 40 launches over a 10-year lunar campaign, with a 55.4 percent
probability of losing one payload. In addition to the cost of the lost payload, a major launch vehicle accident would most likely result in a program standdown for 2 years before returning to flight operations.

A 2-year standdown of
the exploration program could cost many billions of dollars. The reduced number of launches and the high reliability
offered by SDLV concepts would have a highly beneficial effect on the expected mission loss rate and the resulting
cost of unreliability over a 10-year lunar exploration campaign.

Offline Chris Bergin

G. Sustainability
The Vision for Space Exploration must be executed in a sustainable fashion to garner and retain the long-term
support of the nation and the world for such a massive endeavor. The SDLV concept supports the sustainability
issue from many aspects. SDLV supports transition of resources from the SSP to the exploration program by
retaining critical skills that would otherwise leave the “sunset” Shuttle at a time when Shuttle’s completion of ISS
assembly is the first step in the exploration program. The SDLV concept would retain a portion of this skilled
workforce and softens the impact of the SSP ending in key congressional districts in California, Utah, Texas,
Louisiana, Mississippi, Alabama, and Florida (Fig. 14). An orderly transition to SDLV provides a safe and gradual
draw down of the government’s largest operational space system, the Space Shuttle. Management of the transition
process focuses on the following objectives:
?? Meet mission and safety objectives in the SSP through its final flight
?? Maintain critical skills and workforce motivation
?? Retain critical supply chains
?? Ensure efficient and cost-effective transfer of needed assets
Without an SDLV, the phaseout of current Shuttle capabilities will begin, some gradually and others more
abruptly. The Michoud facility will begin a closeout process as assembly of the last Shuttle ET is started. A similar
fate is facing the large solid rocket motor manufacturing facilities in Utah. The beginning of the closure process for
these unique facilities and their suppliers is within the next several years unless redirection is received. Critical
suppliers will eliminate capabilities due to a lack of business to keep those capabilities in place. There are numerous
assets and capabilities that will start to disG. Sustainability
The Vision for Space Exploration must be executed in a sustainable fashion to garner and retain the long-term
support of the nation and the world for such a massive endeavor. The SDLV concept supports the sustainability
issue from many aspects. SDLV supports transition of resources from the SSP to the exploration program by
retaining critical skills that would otherwise leave the “sunset” Shuttle at a time when Shuttle’s completion of ISS
assembly is the first step in the exploration program. The SDLV concept would retain a portion of this skilled
workforce and softens the impact of the SSP ending in key congressional districts in California, Utah, Texas,
Louisiana, Mississippi, Alabama, and Florida (Fig. 14). An orderly transition to SDLV provides a safe and gradual
draw down of the government’s largest operational space system, the Space Shuttle. Management of the transition
process focuses on the following objectives:
?? Meet mission and safety objectives in the SSP through its final flight
?? Maintain critical skills and workforce motivation
?? Retain critical supply chains
?? Ensure efficient and cost-effective transfer of needed assets
Without an SDLV, the phaseout of current Shuttle capabilities will begin, some gradually and others more
abruptly. The Michoud facility will begin a closeout process as assembly of the last Shuttle ET is started. A similar
fate is facing the large solid rocket motor manufacturing facilities in Utah. The beginning of the closure process for
these unique facilities and their suppliers is within the next several years unless redirection is received. Critical
suppliers will eliminate capabilities due to a lack of business to keep those capabilities in place. There are numerous
assets and capabilities that will start to disappear without active NASA intervention. Without timely decisions to
retain critical facilities and suppliers, the cost and risks involved in restarting these capabilities after a significant
hiatus could be prohibitive. Thus, failure to make timely decisions about SDLV could be a de facto decision. A
robust transition planning process would clearly identify the SSP capability decrements and the SDLV capability
requirements to permit informed decision making by the agency, congress, and the administration.appear without active NASA intervention. Without timely decisions to
retain critical facilities and suppliers, the cost and risks involved in restarting these capabilities after a significant
hiatus could be prohibitive. Thus, failure to make timely decisions about SDLV could be a de facto decision. A
robust transition planning process would clearly identify the SSP capability decrements and the SDLV capability
requirements to permit informed decision making by the agency, congress, and the administration.

Offline Chris Bergin


Offline Chris Bergin

The ability to meet SSP safety objectives would be improved with an orderly transition to an SDLV to ensure the
assets required to develop and operate an SDLV would continue to be well maintained through the life of the current
SSP. A NASA Headquarters transition team is expected to manage the cross-program dependencies to make
decisions in the best interest of the nation. Each affected program, SSP and SDLV, would have representation on
this transition team to coordinate the effort for each program and maintain frequent communication about each
other’s plans and requirements. The SSP transition team would identify all SSP assets and their “last need-date,”
along with overseeing the orderly decommissioning of those assets. The SDLV transition team would ensure timely
identification of SSP asset requirements and schedules to support the SDLV development, production, and
operations needs, along with overseeing a smooth transfer of responsibilities for those assets. Overlaying the SSP
retirement and the SDLV development schedules provides the basis for the many maintain, scrap, or buy decisions.
In addition, the overlay of workforce requirements shows how critical skills and assets would be impacted such that
informed retention decisions could be made. Upgrade and maintenance investments could be made knowing that the
life of those assets extends beyond the current STS program end date. The NASA Headquarters transition team will
make decisions on which program bears the cost responsibility if it is unclear.

Offline Chris Bergin

IV. Summary
There have been a number of parallel activities pursued by several government and industry teams over the past
year evaluating a wide range of SDLV approaches. The results of these independent studies have shown remarkably
good correlation. Collaborative efforts between the government and industry study teams have identified several
areas worthy of more detailed study. These government and industry studies have concluded that there are a number
of viable SDLV concepts offering attractive options for ETO launch services. These SDLV concepts support
NASA’s Space Exploration Vision in the following important ways:
?? The large payload size and mass offered by SDLV concepts could substantially reduce exploration mission
complexity and operational risks.
?? Using high-reliability STS propulsion elements and subsystems that are already human rated offers the
opportunity to develop derivative launch vehicles that could carry crew as well as cargo.
?? Using proven, and well-understood, STS systems should reduce SDLV development risks and costs compared to
developing new launch systems.

Offline Flightstar

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RE: SDLV Images and Information relating to article on site
« Reply #25 on: 08/14/2005 12:15 AM »
Where do I start! I don't know!!!  :o

Offline newsartist

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RE: SDLV/CEV - JULY AIAA Joint Propulsion Conference Document
« Reply #26 on: 08/14/2005 12:32 AM »
Chris; can you lock this thread as a reference-only feature before we clutter it up?


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