Phillip A. Williams

Catalyst design using nanoporous iron for the chemical vapor deposition synthesis of single-walled carbon nanotubes

Single-walled carbon nanotubes (SWNTs) have been synthesized via a novel chemical vapor deposition (CVD) approach utilizing nanoporous, iron-supported catalysts. Stable aqueous dispersions of the CVD-grown nanotubes using an anionic surfactant were also obtained. The properties of the as-produced SWNTs were characterized through atomic force microscopy and Raman spectroscopy and compared with purified SWNTs produced via the high-pressure CO (HiPCO) method as a reference, and the nanotubes were observed with greater lengths than those of similarly processed HiPCO SWNTs.

ANALYSIS OF EDDY CURRENT CAPABILITIES FOR THE DETECTION OF OUTER DIAMETER CRACKING IN SMALL BORE METALLIC STRUCTURES

The use of eddy current techniques for the detection of outer diameter damage in tubing and many complex aerospace structures often requires the use of an inner diameter probe due to a lack of access to the outside of the part. In small bore structures the probe size and orientation are constrained by the inner diameter of the part, complicating the optimization of the inspection technique. Detection of flaws through a significant remaining wall thickness becomes limited not only by the standard depth of penetration, but also geometrical aspects of the probe. Recently, an orthogonal eddy current probe was developed for detection of such flaws in space shuttle primary reaction control system (PRCS) thrusters. In this case, the detection of deeply buried intergranular cracking by an inner diameter eddy current probe was sought. Probe optimization was performed based upon the limiting spatial dimensions, flaw orientation, and required detection sensitivity. Analysis of the probe/flaw interaction was performe...

Visualization and natural control systems for microscopy

This chapter presents these microscope systems, along with brief descriptions of the science experiments driving the development of each system. Beginning with a discussion of the philosophy that has driven the Nanoscale Science Research Group (NSRG) and the methods used, the chapter describes the lessons learned during system development, including both useful directions and blind alleys. The first lesson is to begin software development at least as soon as hardware development. The second lesson is to partner with experts in required technologies. The NSRG attempts to use the best available computer technology to develop effective systems for use by the physical science team, which then become cost-effective and can be deployed on widely available hardware as technology marches on. The chapter also describes techniques to enable telemicroscopy in the context of remote experiments and outreach.

Multigenerational Independent Colony for Extraterrestrial Habitation, Autonomy, and Behavior Health (MICEHAB): An Investigation of a Long Duration, Partial Gravity, Autonomous Rodent Colony

The path from Earth to Mars requires exploration missions to be increasingly Earth-independent as the foundation is laid for a sustained human presence in the following decades. NASA pioneering of Mars will expand the boundaries of human exploration, as a sustainable presence on the surface requires humans to successfully reproduce in a partial gravity environment independent from Earth intervention. Before significant investment is made in capabilities leading to such pioneering efforts, the challenges of multigenerational mammalian reproduction in a partial gravity environment need be investigated. The Multi-generational Independent Colony for Extraterrestrial Habitation, Autonomy, and Behavior health is designed to study these challenges. The proposed concept is a conceptual, long duration, autonomous habitat designed to house rodents in a partial gravity environment with the goal of understanding the effects of partial gravity on mammalian reproduction over multiple generations and how to effectively design such a facility to operate autonomously while keeping the rodents healthy in order to achieve multiple generations. All systems are designed to feed forward directly to full-scale human missions to Mars. This paper presents the baseline design concept formulated after considering challenges in the mission and vehicle architectures such as: vehicle automation, automated crew health management/medical care, unique automated waste disposal and hygiene, handling of deceased crew members, reliable long-duration crew support systems, and radiation protection. This concept was selected from an architectural trade space considering the balance between mission science return and robotic and autonomy capabilities. The baseline design is described in detail including: transportation and facility operation constraints, artificial gravity system design, habitat design, and a full-scale mock-up demonstration of autonomous rodent care facilities. The proposed concept has the potential to integrate into existing mission architectures in order to achieve exploration objectives, and to demonstrate and mature common capabilities that enable a range of destinations and missions.

Space Science and Technology Partnership Forum: Value Proposition, Strategic Framework, and Capability Needs for In-Space Assembly

The Space Science and Technology (S&T) Partnership Forum was established in 2015 to identify synergistic efforts and technologies across the government, with a focus on key pervasive and game-changing technologies across government space agencies in order to more efficiently and effectively manage S&T resources. As principal partners of the interagency S&T Partnership Forum, the U.S. Air Force (USAF), the National Aeronautics and Space Administration (NASA), and the National Reconnaissance Office (NRO) identified and prioritized several S&T collaboration topic areas. Autonomous and semi-autonomous inspace assembly (iSA) is the focus of the topic area that NASA, under the direction of the Office of Chief Technologist, is currently coordinating among the S&T principal partners and affiliate partners, such as the Defense Advanced Research Projects Agency (DARPA) and the U.S. Naval Research Laboratory (NRL). The S&T iSA facilitation and analysis team, led by NASA, collected data from the participating agencies on their current developments, activities, and needs in the area of in-space assembly. This paper provides an overview of the S&T iSA facilitation and analysis team’s efforts in establishing the value proposition and strategic framework for interagency collaboration in iSA within the partnership as a foundation to deliver value and achieve iSA topic objectives across government space agencies. Further, this paper describes the early products of these efforts in the definition of the iSA capabilities, design drivers, and stakeholder goals to facilitate dialogue within the partnership and the larger community.

Graphical Visualization of Human Exploration Capabilities

NASAs pioneering space strategy will require advanced capabilities to expand the boundaries of human exploration on the Journey to Mars (J2M). The Evolvable Mars Campaign (EMC) architecture serves as a framework to identify critical capabilities that need to be developed and tested in order to enable a range of human exploration destinations and missions. Agency-wide System Maturation Teams (SMT) are responsible for the maturation of these critical exploration capabilities and help formulate, guide and resolve performance gaps associated with the EMC-identified capabilities. Systems Capability Organization Reporting Engine boards (SCOREboards) were developed to integrate the SMT data sets into cohesive human exploration capability stories that can be used to promote dialog and communicate NASAs exploration investments. Each SCOREboard provides a graphical visualization of SMT capability development needs that enable exploration missions, and presents a comprehensive overview of data that outlines a roadmap of system maturation needs critical for the J2M. SCOREboards are generated by a computer program that extracts data from a main repository, sorts the data based on a tiered data reduction structure, and then plots the data according to specified user inputs. The ability to sort and plot varying data categories provides the flexibility to present specific SCOREboard capability roadmaps based on customer requests. This paper presents the development of the SCOREboard computer program and shows multiple complementary, yet different datasets through a unified format designed to facilitate comparison between datasets. Example SCOREboard capability roadmaps are presented followed by a discussion of how the roadmaps are used to: 1) communicate capability developments and readiness of systems for future missions, and 2) influence the definition of NASAs human exploration investment portfolio through capability-driven processes. The paper concludes with a description of planned future work to modify the computer program to include additional data and of alternate capability roadmap formats currently under consideration.

MODELS IN THE DESIGN AND VALIDATION OF EDDY CURRENT INSPECTION FOR CRACKING IN THE SHUTTLE REACTION CONTROL SYSTEM THRUSTER

A case study is presented for using models in eddy current NDE design for crack detection in Shuttle Reaction Control System thruster components. Numerical methods were used to address the complex geometry of the part and perform parametric studies of potential transducer designs. Simulations were found to show agreement with experimental results. Accurate representation of the coherent noise associated with the measurement and part geometry was found to be critical to properly evaluate the best probe designs.