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Thomas, L. Dale

Publications and source records attributed to Thomas, L. Dale.

13 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2017

Methodology for Assessing Reusability of Spaceflight Hardware

In 2011 the Space Shuttle, the only Reusable Launch Vehicle (RLV) in the world, returned to earth for the final time. Upon retirement of the Space Shuttle, the United States (U.S.) no longer possessed a reusable vehicle or the capability to send American astronauts to space. With the National Aeronautics and Space Administration (NASA) out of the RLV business and now only pursuing Expendable Launch Vehicles (ELV), not only did companies within the U.S. start to actively pursue the development of either RLVs or reusable components, but entities around the world began to venture into the reusable market. For example, SpaceX and Blue Origin are developing reusable vehicles and engines. The Indian Space Research Organization is developing a reusable space plane and Airbus is exploring the possibility of reusing its first stage engines and avionics housed in the flyback propulsion unit referred to as the Advanced Expendable Launcher with Innovative engine Economy (Adeline). Even United Launch Alliance (ULA) has announced plans for eventually replacing the Atlas and Delta expendable rockets with a family of RLVs called Vulcan. Reuse can be categorized as either fully reusable, the situation in which the entire vehicle is recovered, or partially reusable such as the National Space Transportation System (NSTS) where only the Space Shuttle, Space Shuttle Main Engines (SSME), and Solid Rocket Boosters (SRB) are reused. With this influx of renewed interest in reusability for space applications, it is imperative that a systematic approach be developed for assessing the reusability of spaceflight hardware. The partially reusable NSTS offered many opportunities to glean lessons learned; however, when it came to efficient operability for reuse the Space Shuttle and its associated hardware fell short primarily because of its two to four-month turnaround time. Although there have been several attempts at designing RLVs in the past with the X-33, Venture Star and Delta Clipper Experimental (DC-X), reusability within the spaceflight arena is still in its infancy. With unlimited resources (namely, time and money), almost any launch vehicle and its associated hardware can be made reusable. However, an endless supply of funds for space exploration is not the case in today's economy for neither government agencies nor their commercial counterparts. Therefore, any organization wanting to be a leader in space exploration and remain competitive in this unforgiving space faring industry must confront shrinking budgets with more cost conscious and efficient designs. Therefore, standards for developing reusable spaceflight hardware need to be established. By having standards available to existing and emerging companies, some of the potential roadblocks and limitations that plagued previous attempts at reuse may be minimized or completely avoided.

Childress-Thompson, Rhonda↗
NASA NTRS2017

Parameter Validation for Evaluation of Spaceflight Hardware Reusability

Within recent years, there has been an influx of companies around the world pursuing reusable systems for space flight. Much like NASA, many of these new entrants are learning that reusable systems are complex and difficult to acheive. For instance, in its first attempts to retrieve spaceflight hardware for future reuse, SpaceX unsuccessfully tried to land on a barge at sea, resulting in a crash-landing. As this new generation of launch developers continues to develop concepts for reusable systems, having a systematic approach for determining the most effective systems for reuse is paramount. Three factors that influence the effective implementation of reusability are cost, operability and reliability. Therefore, a method that integrates these factors into the decision-making process must be utilized to adequately determine whether hardware used in space flight should be reused or discarded. Previous research has identified seven features that contribute to the successful implementation of reusability for space flight applications, defined reusability for space flight applications, highlighted the importance of reusability, and presented areas that hinder successful implementation of reusability. The next step is to ensure that the list of reusability parameters previously identified is comprehensive, and any duplication is either removed or consolidated. The characteristics to judge the seven features as good indicators for successful reuse are identified and then assessed using multiattribute decision making. Next, discriminators in the form of metrics or descriptors are assigned to each parameter. This paper explains the approach used to evaluate these parameters, define the Measures of Effectiveness (MOE) for reusability, and quantify these parameters. Using the MOEs, each parameter is assessed for its contribution to the reusability of the hardware. Potential data sources needed to validate the approach will be identified.

Childress-Thompson, Rhonda↗
NASA NTRS2014

Tailoring Enterprise Systems Engineering Policy for Project Scale and Complexity

Space systems are characterized by varying degrees of scale and complexity. Accordingly, cost-effective implementation of systems engineering also varies depending on scale and complexity. Recognizing that systems engineering and integration happen everywhere and at all levels of a given system and that the life cycle is an integrated process necessary to mature a design, the National Aeronautic and Space Administration's (NASA's) Marshall Space Flight Center (MSFC) has developed a suite of customized implementation approaches based on project scale and complexity. While it may be argued that a top-level system engineering process is common to and indeed desirable across an enterprise for all space systems, implementation of that top-level process and the associated products developed as a result differ from system to system. The implementation approaches used for developing a scientific instrument necessarily differ from those used for a space station. .

Cox, Renee I.↗
NASA NTRS2013

National Institute for Rocket Propulsion Systems 2012 Annual Report: A Year of Progress and Challenge

The National Institute for Rocket Propulsion Systems (NIRPS) maintains and advances U.S. leadership in all aspects of rocket propulsion for defense, civil, and commercial uses. The Institute's creation is in response to widely acknowledged concerns about the U.S. rocket propulsion base dating back more than a decade. U.S. leadership in rocket and missile propulsion is threatened by long-term industry downsizing, a shortage of new solid and liquid propulsion programs, limited ability to attract and retain fresh talent, and discretionary federal budget pressures. Numerous trade and independent studies cite erosion of this capability as a threat to national security and the U.S. economy resulting in a loss of global competitiveness for the U.S. propulsion industry. This report covers the period between May 2011 and December 2012, which includes the creation and transition to operations of NIRPS. All subsequent reports will be annual. The year 2012 has been an eventful one for NIRPS. In its first full year, the new team overcame many obstacles and explored opportunities to ensure the institute has a firm foundation for the future. NIRPS is now an active organization making contributions to the development, sustainment, and strategy of the rocket propulsion industry in the United States. This report describes the actions taken by the NIRPS team to determine the strategy, organizational structure, and goals of the Institute. It also highlights key accomplishments, collaborations with other organizations, and the strategic framework for the Institute.

Thomas, L. Dale↗
NASA NTRS2011

Constellation Lessons Learned Executive Summary

This slide presentation reviews the lessons learned from the Constellation Program (CxP) and identified several factors that contributed to the inability of the CxP to meet the cost and schedule commitments. The review includes a significant section on the context in which the CxP operated since new programs are likely to experience the same constraints.

Thomas, L. Dale↗
NASA NTRS2007

The MSFC Systems Engineering Guide: An Overview and Plan

This paper describes the guiding vision, progress to date and the plan forward for development of the Marshall Space Flight Center (MSFC) Systems Engineering Guide (SEG), a virtual systems engineering handbook and archive that describes the system engineering processes used by MSFC in the development of ongoing complex space systems such as the Ares launch vehicle and forthcoming ones as well. It is the intent of this website to be a "One Stop Shop' for MSFC systems engineers that will provide tutorial information, an overview of processes and procedures and links to assist system engineering with guidance and references, and provide an archive of relevant systems engineering artifacts produced by the many NASA projects developed and managed by MSFC over the years.

Shelby, Jerry↗
NASA NTRS2007

The MSFC Systems Engineering Guide: An Overview and Plan

As systems and subsystems requirements become more complex in the pursuit of the exploration of space, advanced technology will demand and require an integrated approach to the design and development of safe and successful space vehicles and there products. System engineers play a vital and key role in transforming mission needs into vehicle requirements that can be verified and validated. This will result in a safe and cost effective design that will satisfy the mission schedule. A key to successful vehicle design within systems engineering is communication. Communication, through a systems engineering infrastructure, will not only ensure that customers and stakeholders are satisfied but will also assist in identifying vehicle requirements; i.e. identification, integration and management. This vehicle design will produce a system that is verifiable, traceable, and effectively satisfies cost, schedule, performance, and risk throughout the life-cycle of the product. A communication infrastructure will bring about the integration of different engineering disciplines within vehicle design. A system utilizing these aspects will enhance system engineering performance and improve upon required activities such as Development of Requirements, Requirements Management, Functional Analysis, Test, Synthesis, Trade Studies, Documentation, and Lessons Learned to produce a successful final product. This paper will describe the guiding vision, progress to date and the plan forward for development of the Marshall Space Flight Center (MSFC) Systems Engineering Guide (SEG), a virtual systems engineering handbook and archive that will describe the system engineering processes that are used by MSFC in the development of complex systems such as the Ares launch vehicle. It is the intent of this website to be a "One Stop Shop" for our systems engineers that will provide tutorial information, an overview of processes and procedures and links to assist system engineering with guidance and references, and provide an archive of systems engineering artifacts produced by the many NASA projects developed and managed by MSFC over the years.

Shelby, Jerry A.↗
NASA NTRS2005

ESMD Risk Management Workshop: Systems Engineering and Integration Risks

This report has been developed by the National Aeronautics and Space Administration (NASA) Exploration Systems Mission Directorate (ESMD) Risk Management team in close coordination with the Systems Engineering Team. This document provides a point-in-time, cumulative, summary of key lessons learned derived from the SE RFP Development process. Lessons learned invariably address challenges and risks and the way in which these areas have been addressed. Accordingly the risk management thread is woven throughout the document.

Systems Engineering↗
NASA NTRS2001

Requirements, Verification, and Compliance (RVC) Database Tool

This paper describes the development, design, and implementation of the Requirements, Verification, and Compliance (RVC) database used on the International Space Welding Experiment (ISWE) project managed at Marshall Space Flight Center. The RVC is a systems engineer's tool for automating and managing the following information: requirements; requirements traceability; verification requirements; verification planning; verification success criteria; and compliance status. This information normally contained within documents (e.g. specifications, plans) is contained in an electronic database that allows the project team members to access, query, and status the requirements, verification, and compliance information from their individual desktop computers. Using commercial-off-the-shelf (COTS) database software that contains networking capabilities, the RVC was developed not only with cost savings in mind but primarily for the purpose of providing a more efficient and effective automated method of maintaining and distributing the systems engineering information. In addition, the RVC approach provides the systems engineer the capability to develop and tailor various reports containing the requirements, verification, and compliance information that meets the needs of the project team members. The automated approach of the RVC for capturing and distributing the information improves the productivity of the systems engineer by allowing that person to concentrate more on the job of developing good requirements and verification programs and not on the effort of being a "document developer".

Rainwater, Neil E., II↗
NASA NTRS2000

Advanced Engineering Environments for Space Transportation System Development

There are significant challenges facing today's launch vehicle industry. Global competition, more complex products, geographically-distributed design teams, demands for lower cost, higher reliability and safer vehicles, and the need to incorporate the latest technologies quicker, all face the developer of a space transportation system. Within NASA, multiple technology development and demonstration projects are underway toward the objectives of safe, reliable, and affordable access to space. New information technologies offer promising opportunities to develop advanced engineering environments to meet these challenges. Significant advances in the state-of-the-art of aerospace engineering practice are envisioned in the areas of engineering design and analytical tools, cost and risk tools, collaborative engineering, and high-fidelity simulations early in the development cycle. At the Marshall Space Flight Center, work has begun on development of an advanced engineering environment specifically to support the design, modeling, and analysis of space transportation systems. This paper will give an overview of the challenges of developing space transportation systems in today's environment and subsequently discuss the advanced engineering environment and its anticipated benefits.

Thomas, L. Dale↗
NASA NTRS1990

Human subjects concerns in ground based ECLSS testing - Managing uncertainty in closely recycled systems

U.S. space missions have to this point used water either made on board or carried from earth and discarded after use. For Space Station Freedom, long duration life support will include air and water recycling using a series of physical-chemical subsystems. The Environmental Control and Life Support System (ECLSS) designed for this application must be tested extensively at all stages of hardware maturity. Human test subjects are required to conduct some of these tests, and the risks associated with the use of development hardware must be addressed. Federal guidelines for protection of human subjects require careful consideration of risks and potential benefits by an Institutional Review Board (IRB) before and during testing. This paper reviews the ethical principles guiding this consideration, details the problems and uncertainties inherent in current hardware testing, and presents an incremental approach to risk assessment for ECLSS testing.

Crump, William J.↗
NASA NTRS1989

The principle of commonality and its application to the Space Station Freedom Program

The principle of commonality has achieved wide application in the communication, automotive, and aircraft industries. By the use of commonality, component development costs are minimized, logistics are simplified, and the investment costs of spares inventory are reduced. With space systems, which must be maintained and repaired in orbit, the advantages of commonality are compounded. Transportation of spares is expensive, on-board storage volume for spares is limited, and crew training and special tools needed for maintenance and repair are significant considerations. This paper addresses the techniques being formulated to realize the benefits of commonality in the design of the systems and elements of the Space Station Freedom Program, and include the criteria for determining the extent of commonality to be implemented.

Hopson, George D.↗