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Technical Paper

Guidance for Trade Studies of Flight-Equivalent Hardware

Spacecraft hardware trade studies compare options primarily on mass while considering impacts to cost, risk, and schedule. Historically, other factors have been considered in these studies, such as reliability, technology readiness level (TRL), volume and crew time. In most cases, past trades compared two or more technologies across functional and TRL boundaries, which is an uneven comparison of the technologies. For example, low TRL technologies with low mass were traded directly against flight-proven hardware without consideration for requirements and the derived architecture. To provide for even comparisons of spacecraft hardware, trades need to consider functionality, mission constraints, integer vs. real number of flight hardware units, and mass growth allowances by TRL.
Technical Paper

Advances in Testing and Analytical Simulation Methodologies to Support Design and Structural Integrity Assessment of Large Monolithic Parts

Significant system efficiency gains can be achieved in high-performance aircraft via a unitized structure that reduces parts count. For instance, reduced parts count leads to substantial engineering logistic cost savings through higher levels of subsystem and mounting hardware integration. It also creates performance benefits by eliminating structural connections. Residual stress management, however, remains a major obstacle to capturing full benefits and broadening the application of unitized structure solutions. This paper describes how Alcoa and others are developing tools to overcome limitations in current testing, evaluation, and design practices attributed to residual stress effects. The authors present recent advancements in fracture toughness and fatigue crack growth characterization, along with a new, integrated approach for improved accounting of residual stress effects during fracture critical component design, manufacturing planning, and life management.
Technical Paper

Toward Human-Robot Interface Standards: Use of Standardization and Intelligent Subsystems for Advancing Human-Robotic Competency in Space Exploration

NASA's plans to implement the Vision for Space Exploration include extensive human-robot cooperation across an enterprise spanning multiple missions, systems, and decades. To make this practical, strong enterprise-level interface standards (data, power, communication, interaction, autonomy, and physical) will be required early in the systems and technology development cycle. Such standards should affect both the engineer and operator roles that humans adopt in their interactions with robots. For the engineer role, standards will result in reduced development lead-times, lower cost, and greater efficiency in deploying such systems. For the operator role, standards will result in common autonomy and interaction modes that reduce operator training, minimize workload, and apply to many different robotic platforms. Reduced quantities of spare hardware could also be a benefit of standardization.
Technical Paper

Evaluation of a Full-Body Scanning Technique for the Purpose of Extracting Anthropometrical Measurements

A method for capturing full-body scans for the purpose of extracting Extravehicular Activity (EVA) suit measurements is being evaluated. Subjects were marked using reflective spheres enabling researchers to acquire all 118 measurements of the suit sizing protocol. Several researchers measured the subjects using a full-body laser scanner, a motion analysis system, and standard anthropometrical equipment. The linear scanner measurements were compared to the motion analysis data, while the circumferential scanner measurements were compared to the manual data. The mean percent difference between the scanner measurements and motion analysis linear/manual circumferential measurements was 4.21%. It was concluded that the scanner measurements were accurate enough for preliminary sizing of EVA suits.
Technical Paper

Adsorption Modeling with ACM: ISS CDRA Simulation

A dynamic simulation of the ISS CDRA hardware was created using the Aspen Custom Modeler software platform. The dynamic model calculates the material and energy balances that describe the system properties. The model was calibrated by comparison to test data results from a flight-like CDRA at NASA Marshall Space Flight Center. While other FORTRAN models of the CDRA already exist, developing an ACM simulation is the first step towards creating a generic tool to simulate larger collections of life support hardware. The ACM tool should make it possible to be very flexible when rearranging these models to simulate possible configurations of the life support subsystems that could be used in the future, especially for advanced life support applications.
Technical Paper

Testing of the Prototype Plant Research Unit Subsystems

The Plant Research Unit (PRU) is currently under development by the Space Station Biological Research Project (SSBRP) team at NASA Ames Research Center (ARC) with a scheduled launch in 2001. The goal of the project is to provide a controlled environment that can support seed-to-seed and other plant experiments for up to 90 days. This paper describes testing conducted on the major PRU prototype subsystems. Preliminary test results indicate that the prototype subsystem hardware can meet most of the SSBRP science requirements within the Space Station mass, volume, power and heat rejection constraints.