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Electrical disturbances caused by charging of cables in spacecraft can impair electrical systems for long periods of time. The charging originates primarily from electrons trapped in the radiation belts of the earth. The model Space Electrons Electromagnetic Effects (SEEE) is applied in computing the transient charge and electric fields in cables on spacecraft at low to middle earth altitudes. The analysis indicated that fields exceeding dielectric breakdown strengths of common dielectric materials are possible in intense magnetic storms for systems with inadequate shielding. SEEE also computes the minimal shielding needed to keep the electric fields below that for dielectric breakdown.

Fracture split forged steel connecting rods are utilized in many new high performance automotive engines to increase durability. Higher strength levels are needed as the power density increases. Fracture splitting without plastic deformation is necessary for manufacturability. Metallurgical design is a key for achieving the required performance levels. Several medium carbon steels containing 0.07 wt pct P, 0.06 wt pct S and various amounts of Mn, Si, V, and N were produced by vacuum induction melting laboratory heats and hot working the cast ingots into plates. The plates were cooled at varying rates to simulate typical cooling methods after forging. Microstructures were generally ferrite and pearlite as evaluated by light optical and scanning electron microscopy. Mechanical properties were determined by standard tensile tests, high strain rate notched tensile tests, and Charpy V-notch impact tests to assess “splittability”.

Solar proton events (SPEs) represent the single-most significant source of acute radiation exposure during space missions. Historically, an exponential in rigidity (particle momentum) fit has been used to express the SPE energy spectrum using GOES data up to 100 MeV. More recently, researchers have found that a Weibull fit better represents the energy spectrum up to 1000 MeV (1 GeV). In addition, the availability of SPE data extending up to several GeV has been incorporated in analyses to obtain a more complete and accurate energy spectrum representation. In this paper we discuss the major SPEs that have occurred over the past five solar cycles (~50+ years) in detail - in particular, Aug 1972 and Sept & Oct 1989 SPEs. Using a high-energy particle transport/dose code, radiation exposure estimates are presented for various thicknesses of aluminum. The effects on humans and spacecraft systems are also discussed in detail.

This paper presents a new methodology for the safety assessment of complex software intensive systems such as is envisioned for the coming major upgrade of the air traffic management system known as NextGen. This methodology is based on a new, more inclusive model of accident causation called Systems Theoretic Accident Model and Process (STAMP) [1]. STAMP includes not just the standard component failure mechanisms but also the new ways that software and humans contribute to accidents in complex systems. A new hazard analysis method, called Systems Theoretic Process Analysis (STPA), is built on this theoretical foundation. The STPA is based on systems theory rather than reliability theory; it treats safety as a control problem rather than a failure problem with interactive and possibly nested control loops that may include humans. In this methodology, safety is assured by closed loop control of safety parameters.

This paper reviews the relevant literature on the effects of sulfated ash, phosphorus, and sulfur on DPF, LNT, and SCR catalysts. Exhaust backpressure increase due to DPF ash accumulation, as well as the rate at which ash is consumed from the sump, were the most studied lubricant-derived DPF effects. Based on several studies, a doubling of backpressure can be estimated to occur within 270,000 to 490,000 km when using a 1.0% sulfated ash oil. Postmortem DPF analysis and exhaust gas measurements revealed that approximately 35% to 65% less ash was lost from the sump than was expected based on bulk oil consumption estimates. Despite significant effects from lubricant sulfur and phosphorus, loss of LNT NOX reduction efficiency is dominated by fuel sulfur effects. Phosphorus has been determined to have a mild poisoning effect on SCR catalysts. The extent of the effect that lubricant phosphorus and sulfur have on DOCs remains unclear, however, it appears to be minor.

Both humans and onboard radiosensitive systems (electronics, materials, payloads and experiments) are exposed to the deleterious effects of the harsh space radiations found in the space environment. The purpose of this paper is to present the space radiation environment extended to deep space based on environment models for the moon, Mars, Jupiter, and Saturn and compare these radiation environments with the earth's radiation environment, which is used as a comparative baseline. The space radiation environment consists of high-energy protons and electrons that are magnetically “trapped” in planetary bodies that have an intrinsic magnetic field; this is the case for earth, Jupiter, and Saturn (the moon and Mars do not have a magnetic field). For the earth this region is called the “Van Allen belts,” and models of both the trapped protons (AP-8 model) and electrons (AE-8 model) have been developed.

Protecting astronauts from space radiation exposure is an important challenge for mission design and operations for future exploration-class and long-duration missions. Crew members are exposed to sporadic solar particle events (SPEs) as well as to the continuous galactic cosmic radiation (GCR). If sufficient protection is not provided the radiation risk to crew members from SPEs could be significant. To improve exposure risk estimates and radiation protection from SPEs, detailed evaluations of radiation shielding properties are required. A model using a modern CAD tool ProE™, which is the leading engineering design platform at NASA, has been developed for this purpose. For the calculation of radiation exposure at a specific site, the cosine distribution was implemented to replicate the omnidirectional characteristic of the 4π particle flux on a surface.

A procedure for calculating the engine inlet diffuser section liquid water content and mass fractions of liquid water content associated with the water droplet size distribution for wind milling engine ice accretion analysis is presented. Critical fuel reserve calculation for extended twin-engine operation requires the determination of drag increase due to ice accretion on inoperative wind milling engine fan blade and guide vane.

This study was designed to answer what percent of “required” traffic pilots acquire visually using the current “visual acquisition system” of windows, eyes and the Traffic Collision Avoidance System (TCAS). “Required Traffic” was defined as Air Traffic Control (ATC) calls to the research aircraft, TCAS Traffic Alerts and/or TCAS Resolution Advisories. The results of the approximately 40 hours of flight were that the majority of (“required”) traffic was NOT visually acquired (39% visually acquired; 61% not visually acquired). When traffic was identified to the pilots by more than one source, the visual acquisition rate was 58%. For validation purposes, an additional 10 hours of flight observations were made during revenue flights with a major airline. Flight test and airline observations were found to be comparable.

Fine water mist has become a commercial technology for fire suppression in multiple applications. With funding from NASA, ADA Technologies, Inc. (ADA) is developing a handheld fine water mist fire extinguisher for use on manned spacecraft and in future planetary habitats. This design employs only water and nitrogen as suppression agents to allow local refill and reuse. The prototype design incorporates features to generate a uniform fine water mist regardless of the direction of the gravitational vector or lack of gravity altogether. The system has been proven to extinguish open fires and hidden fire scenarios in tests conducted at the Colorado School of Mines (CSM). This design can be deployed as a portable extinguisher or as an automated system for local fire protection in instrument racks or storage spaces. Continued development will result in prototype hardware suitable for use on future manned spacecraft.

The aim of this study was to explore if fingernail delamination injury following EMU glove use may be caused by compression-induced blood flow occlusion in the finger. During compression tests, finger blood flow decreased more than 60%, however this occurred more rapidly for finger pad compression (4 N) than for fingertips (10 N). A pressure bulb compression test resulted in 50% and 45% decreased blood flow at 100 mmHg and 200 mmHg, respectively. These results indicate that the finger pad pressure required to articulate stiff gloves is more likely to contribute to injury than the fingertip pressure associated with tight fitting gloves.

ADA Technologies, Inc. has designed and built a microgravity-tolerant portable fire extinguisher prototype for use in manned spacecraft and planetary habitats. This device employs Fine Water Mist (FWM) as the fire extinguishing agent, and is refillable from standard stores on long-duration missions. The design uses a single storage tank for minimal mass and volume. The prototype employs a dual-fluid atomizer concept where the pressurant gas (nitrogen) also enhances the water atomization process to generate a droplet size distribution in the optimum diameter range of 10 to 50 micrometers. The expanding discharge gas plume carries the mist to the immediate vicinity of the fire where its extensive surface area promotes high heat transfer rates. A series of 80 fire suppression tests was recently completed to evaluate design options for the hardware and validate performance on three representative fire scenarios.

Thin sandwich sheets hold a promise for widespread use in automotive industry due to their good crash and formability properties. In this paper, thin stainless steel sandwich sheets with low-density core materials are investigated with regard to their performance in crashworthiness applications. The total thickness of the sandwich materials is about 1.2mm: 0.2mm thick facings and a 0.8mm thick sandwich core. Throughout the crushing of prismatic sandwich profiles, the sandwich facings are bent and stretched while the sandwich core is crushed under shear loading. Thus, a high shear crushing strength of the sandwich core material is beneficial for the overall energy absorption of the sandwich profile. It is shown theoretically that the weight specific shear crushing strength of hexagonal metallic honeycombs is higher than the one of fiber cores - irrespective of their relative density or microstructural geometry.

NASA has long recognized the advantages of providing improved information interfaces to EVA astronauts and has pursued this goal through a number of development programs over the past decade. None of these activities or parallel efforts in industry and academia has so far resulted in the development of an operational system to replace or augment the current extravehicular mobility unit (EMU) Display and Controls Module (DCM) display and cuff checklist. Recent advances in display, communications, and information processing technologies offer exciting new opportunities for EVA information interfaces that can better serve the needs of a variety of NASA missions. Hamilton Sundstrand Space Systems International (HSSSI) has been collaborating with Simon Fraser University and others on the NASA Haughton Mars Project and with researchers at the Massachusetts Institute of Technology (MIT), Boeing, and Symbol Technologies in investigating these possibilities.

A series of low-speed static and dynamic wind tunnel tests of a commercial transport configuration over an extended angle of attack/sideslip envelope was conducted at NASA Langley Research Center. The test results are intended for use in the development of an aerodynamic simulation database for determining aircraft flight characteristics at extreme and loss-of-control conditions. This database will be used for the development of loss-of-control prevention or mitigation systems, pilot training for recovery from such conditions, and accident investigations. An overview of the wind-tunnel tests is presented and the results of the tests are evaluated with respect to traditional simulation database development techniques for modeling extreme conditions to identify regions where simulation fidelity should be addressed.

This paper presents a PC based mathematical and rapid prototyping technique for anthropometric accommodation in a maintenance environment using the principle of simulation based design. The developed technique is capable of analyzing anthropometric data using multivariate (Principal component Analysis) approach to describe the body size variability of any given population. A number of body size representative cases are established which, when used properly within the constraints of the maintenance environments, will ensure the accommodation of a desired percentage of a population. This technique evaluates the percentage accommodation of a given population for the environment using the specific manikin cases as boundary conditions. In the case where any member of a maintenance crew cannot be accommodated, the technique has the capability of informing the designer of the environment why the member(s) is/are not accommodated.

Jet fighter missions have been known to last extended period of time. The need for a comfortable and safe seat has become paramount considering that fact that uncomfortable seats can lead to numerous health issues. Several health effects like numbness, pressure sore, low back pain, and vein thrombosis have been associated with protracted sitting. The cushion, and of late the installation rail angle are the only components of the ejection seat system that can be modified to reduce these adverse effects. A comprehensive static comfort evaluation study for ejection seats was conducted. It provides comparison between a variety of operational and prototype cushions (baseline cushion, honeycomb and air-cushion) and three different installation rail angles (14°, 18°, and 22°). Three operational cockpit environment mockups with adjustable installation rail angle were built. Ten volunteer subjects, six females and four males, ages 19 to 35, participated in the seat comfort evaluation.

The desire to operate rotorcraft in icing conditions has renewed the interest in developing high-fidelity analysis methods to predict ice accumulation and the ensuing rotor performance degradation. A subset of providing solutions for rotorcraft icing problems is predicting two-dimensional ice accumulation on rotor airfoils. While much has been done to predict ice for fixed-wing airfoil sections, the rotorcraft problem has two additional challenges: first, rotor airfoils tend to experience flows in higher Mach number regimes, often creating glaze ice which is harder to predict; second, rotor airfoils oscillate in pitch to produce balance across the rotor disk. A methodology and validation test cases are presented to solve the rotor airfoil problem as an important step to solving the larger rotorcraft icing problem. The process couples Navier-Stokes CFD analysis with the ice accretion analysis code, LEWICE3D.

Since flight requirements often necessitate last-minute re-analysis, it became crucial to develop flexible and comprehensive transport phenomena analysis software that would quickly ensure all vehicle and payload requirements would be satisfied. The software would replace various mainframe-based software, such as the Thermal Radiation Analyzer System (TRASYS) and the Systems Improved Numerical Differencing Analyzer (SINDA). The software would need to have the flexibility to employ models that could be developed and modified as vehicle systems change. By use of event files which contain simple, intuitive commands, the characteristics of individual missions could be built as inputs to the model. By moving the Environmental Control & Life Support (ECLS) system model to the PC environment, each analyst would have execution, storage, and processing management control. And of course, software portability would be greatly increased.

Currently, states that are out of compliance with the National Ambient Air Quality Standards must, according to the Clean Air Act Amendments of 1990 (CAAA), develop and implement control strategies that demonstrate specific degrees of reduction in emissions-with the degree of reduction depending upon the severity of the problem. One tool that has been developed to aid regulators in both deciding an appropriate course of action and to demonstrate the desired reductions in mobile emissions is EPA's Mobile 5a emission estimation model. In our study, Mobile 5a has been used to examine the effects of regulatory strategies, as applied to the Northeast United States, on vehicle emissions under worst-case ozone-forming conditions.