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Klaus, David M.

Overview
Works: 11 works in 11 publications in 1 language and 478 library holdings
Roles: Other
Publication Timeline
Key
Publications about David M Klaus
Publications by David M Klaus
Most widely held works by David M Klaus
Dynamic thermal modeling for moving objects on the Moon by Philipp Benjamin Hager( file )
1 edition published in 2013 in English and held by 43 libraries worldwide
A systematic process for assessing human spacecraft conceptual designs in terms of relative safety and operational characteristics by Kevin Paul Higdon( file )
1 edition published in 2012 in English and held by 2 libraries worldwide
The research efforts in this dissertation are focused on reducing uncertainty in the conceptual design phase through a process of establishing a minimum functionality baseline before trading Safety and Operability in proposed spacecraft configurations. The challenge in human spacecraft development is how to combine the parts into a working design that complies with many requirements for top level mission objectives, safety, and mission success. The design methodologies presented here provides designers and decision makers with additional methods that provide an overall view of candidate design concepts
Characterization and measurement standardization of lunar dust abrasion for spacecraft design and operations by Ryan Lauren Kobrick( file )
1 edition published in 2010 in English and held by 2 libraries worldwide
Three-body abrasion tests, designed to be more representative of actual lunar system operational interactions, were conducted using a new tribotester with lunar simulants and industrial abrasives. Due to the ease and flexibility of changing abrasive variables and other test parameters, this device provided a versatile means of conducting abrasion testing to evaluate candidate materials for use in planetary exploration systems
Phenotypic and gene expression responses of E. coli to antibiotics during spaceflight by Luis Zea( file )
1 edition published in 2015 in English and held by 2 libraries worldwide
Bacterial susceptibility to antibiotics has been shown in vitro to be reduced during spaceflight; however, the underlying mechanisms responsible for this outcome are not fully understood. In particular, it is not yet clear whether this observed response is due to increased drug resistance (a microbial defense response) or decreased drug efficacy (a microgravity biophysical mass transport effect). To gain insight into the differentiation between these two potential causes, an investigation was undertaken onboard the International Space Station (ISS) in 2014 termed Antibiotic Effectiveness in Space-1 (AES-1). For this purpose, E. coli was challenged with two antibiotics, Gentamicin Sulfate and Colistin Sulfate, at concentrations higher than those needed to inhibit growth on Earth. Phenotypic parameters (cell size, cell envelope thickness, population density and lag phase duration) and gene expression were compared between the spaceflight samples and ground controls cultured in varying levels of drug concentration. It was observed that flight samples proliferated in antibiotic concentrations that were inhibitory on Earth, growing on average to a 13-fold greater concentration than matched 1g controls. Furthermore, at the highest drug concentrations in space, E. coli cells were observed to aggregate into visible clusters. In spaceflight, cell size was significantly reduced, translating to a decrease in cell surface area to about one half of the ground controls. Smaller cell surface area can in turn proportionally reduce the rate of antibiotic molecules reaching the cell. Additionally, it was observed that genes -- in some cases more than 2000 -- were overexpressed in space with respect to ground controls. Up-regulated genes include poxB, which helps catabolize glucose into organic acids that alter acidity around and inside the cell, and the gadABC family genes, which confer resistance to extreme acid conditions. The next step is to characterize the mechanisms behind the observed gene expression, its implications, and most importantly, how this knowledge can help prevent the acquisition and spread of antibiotic resistance in pathogens on Earth
Development and application of spaceflight performance shaping factors for human reliability analysis by Jennifer Mindock( file )
1 edition published in 2012 in English and held by 2 libraries worldwide
The ability of crewmembers to perform various critical functions during spacecraft operations is widely recognized as being essential to mission success. This necessity motivates the desire to better characterize factors that can influence crewmember performance so that those with positive effects can be enhanced, while those with negative impacts can be minimized. Established Human Reliability Analysis methods exist for analyzing performance within the context of myriad terrestrial scenarios. Many of the existing methods have their roots in nuclear power plant operations. While perhaps similar, the factors influencing performance traditionally used in these methods do not take into account the unique conditions encountered during spaceflight. Therefore, this research has identified a tailored set of factors that influence human task performance during space missions. This thesis describes an organizational scheme developed to aid in classifying and communicating the factors across disciplines and organizations. Definitions of identified factors are given for the spaceflight-specific context. A visual display of the factors, called the Contributing Factor Map, is presented and its use as a risk communication tool is discussed
A Quantitative Human Spacecraft Design Evaluation Model for Assessing Crew Accommodation and Utilization by Christine Fanchiang( file )
1 edition published in 2017 in English and held by 2 libraries worldwide
While the model is the primary tangible product from this research, the more interesting outcome of this work is the structure of the framework and what it tells future researchers in terms of where the gaps and limitations exist for developing a better framework. It also identifies metrics that can now be collected as part of future validation efforts for the model
Assessing feasibility of electrochromic space suit radiators for reducing extravehicular activity water consumption by Jonathan Glen Metts( file )
1 edition published in 2010 in English and held by 2 libraries worldwide
Water consumption for space suit thermal control is a limiting factor on long-term space exploration missions. A concept is proposed for an integrated, flexible suit radiator using infrared electrochromic materials for modulated heat rejection from the suit. Properties of electrochromic materials, the structure of electrochromic devices, and relevant heat transfer processes are presented as background information. Analytical methods are employed to bound theoretical performance and determine required emissivity ranges for lunar surface operations. Case studies are presented incorporating Apollo program and Advanced Walkback Test metabolic and environmental data to estimate sublimator water consumption and hypothetical water savings with the electrochromic radiator. Concepts are presented and analyzed for integrating an electrochromic radiator with existing and future space suit designs. A preliminary systems-level trade analysis is performed with the Equivalent System Mass metric used to compare this technology with the legacy sublimator and other extravehicular activity cooling technologies in development. Experimental objectives, procedures, and results are presented for both bench-top and thermal vacuum testing of electrochromic radiator materials
Characterization of dynamic thermal control schemes and heat transfer pathways for incorporating variable emissivity electrochromic materials into a space suit heat rejection system by Christopher James Massina( file )
1 edition published in 2016 in English and held by 1 library worldwide
The feasibility of conducting long duration human spaceflight missions is largely dependent on the provision of consumables such as oxygen, water, and food. In addition to meeting crew metabolic needs, water sublimation has long served as the primary heat rejection mechanism in space suits during extravehicular activity (EVA). During a single eight hour EVA, approximately 3.6 kg (8 lbm) of water is lost from the current suit. Reducing the amount of expended water during EVA is a long standing goal of space suit life support systems designers; but to date, no alternate thermal control mechanism has demonstrated the ability to completely eliminate the loss. One proposed concept is to convert the majority of a space suit's surface area into a radiator such that the local environment can be used as a radiative thermal sink for rejecting heat without mass loss. Due to natural variations in both internal (metabolic) loads and external (environmental) sink temperatures, radiative transport must be actively modulated in order to maintain an acceptable thermal balance. Here, variable emissivity electrochromic devices are examined as the primary mechanism for enabling variable heat rejection. This dissertation focuses on theoretical and empirical evaluations performed to determine the feasibility of using a full suit, variable emissivity radiator architecture for space suit thermal control. Operational envelopes are described that show where a given environment and/or metabolic load combination may or may not be supported by the evaluated thermal architecture. Key integration considerations and guidelines include determining allowable thermal environments, defining skin-to-radiator heat transfer properties, and evaluating required electrochromic performance properties. Analysis also considered the impacts of dynamic environmental changes and the architecture's extensibility to EVA on the Martian surface. At the conclusion of this work, the full suit, variable emissivity radiator architecture is considered to be at a technology readiness level of 3/4, indicating that analytical proof-of-concept and component level validation in a laboratory environment have been completed. While this is not a numeric increase from previous investigations, these contributions are a significant iteration within those levels. These results improve the understanding of the capabilities provided by the full suit, variable emissivity architecture
Buoyancy-Driven Fluid Flow Generated by Bacterial Metabolism and its Proposed Relationship to Increased Bacterial Growth in Space ( file )
1 edition published in 2005 in English and held by 0 libraries worldwide
Previous investigations have reported that bacterial growth increases in space flight; however, the underlying physical mechanisms responsible for these changes have not been fully determined. As bacteria consume nutrients, they excrete by-products whose presence can influence the onset of exponential growth and affect final cell population density. It is assumed that these metabolic processes create a reduced-density fluid zone and/or a solute gradient around each cell. On Earth, this density difference may result in local buoyancy-driven convection of the excreted by-products. The absence of convection and sedimentation in the low-gravity space flight environment, however, can be expected to alter the fluid dynamics surrounding the cells by limiting transport to diffusion only. Based on this biophysical model, it was hypothesized that acceleration affects the lag phase duration and final cell concentration of suspended bacterial cultures in a predictable, non-linear manner, due to the resultant changes incurred in the extracellular fluid composition. Eight experiments at various levels of acceleration consistently supported this hypothesis, resulting in predictable growth kinetics. In additional experiments, macroscopic plumes of fluid were observed and analyzed rising from metabolizing bacterial cultures. If similar fluid dynamics were found to occur on a microscopic level, it would help explain how acceleration affects bacterial growth kinetics
Validation of proposed metrics for two-body abrasion scratch test analysis standards by Ryan L Kobrick( file )
1 edition published in 2011 in English and held by 0 libraries worldwide
Defining an abrasion index for lunar surface systems as a function of dust interaction modes and variable concentration zones by Ryan L Kobrick( file )
1 edition published in 2010 in English and held by 0 libraries worldwide
 
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