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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.

Reynolds number effects noted from selected test programs conducted in the Langiey 0.3-Meter Transonic Cryogenic Tunnel (0.3-m TCT) are discussed. The tests, which cover a unit Reynolds number range from about 2.0 to 80.0 million per foot, summarize effects of Reynolds number on: 1) aerodynamic data from a supercritical airfoil, 2) results from several wall interference correction techniques, and 3) results obtained from advanced, cryogenic test techniques. The test techniques include 1) use of a cryogenic sidewall boundary layer removal system, 2) detailed pressure and hot wire measurements to determine test section flow quality, and 3) use of a new hot film system suitable for transition detection in a cryogenic wind tunnel. The results indicate that Reynolds number effects appear most significant when boundary layer transition effects are present and at high lift conditions when boundary layer separation exists on both the model and the tunnel sidewall.

Aerodynamic effects induced from vectoring an exhaust jet are investigated using a well established thin-layer Reynolds averaged Navier-Stokes code. This multiple block code has been modified to allow for the specification of jet properties at a block face. The applicability of the resulting code for thrust vectoring applications is verified by comparing numerically and experimentally determined pressure coefficient distributions for a jet-wing afterbody configuration with a thrust-vectoring 2-D nozzle. Induced effects on the body and nearby wing from thrust vectoring are graphically illustrated.

The Mars Reconnaissance Orbiter (MRO) launched on August 12, 2005 and began aerobraking at Mars in March 2006. In order to save propellant, MRO used aerobraking to modify the initial orbit at Mars. The spacecraft passed through the atmosphere briefly on each orbit; during each pass the spacecraft was slowed by atmospheric drag, thus lowering the orbit apoapsis. The largest area on the spacecraft, most affected by aeroheating, was the solar arrays. A thermal analysis of the solar arrays was conducted at NASA Langley Research Center to simulate their performance throughout the entire roughly 6-month period of aerobraking. A companion paper describes the development of this thermal model. This model has been correlated against many sets of flight data. Several maneuvers were performed during the cruise to Mars, such as thruster calibrations, which involve large abrupt changes in the spacecraft orientation relative to the sun.

The Mars Reconnaissance Orbiter (MRO) launched on August 12, 2005 and started aerobraking at Mars in March 2006. During the spacecraft's design phase, thermal models of the solar panels and instruments were developed to determine which components would be the most limiting thermally during aerobraking. Having determined the most limiting components, (from a temperature limit standpoint), thermal limits in terms of heat rate were established. Advanced thermal modeling techniques were developed utilizing Thermal Desktop and Patran Thermal. Heat transfer coefficients were calculated using a Direct Simulation Monte Carlo technique. Analysis established that the solar panels were the most limiting components during the aerobraking phase of the mission.

To meet the challenge of future deep space programs an accurate and efficient engineering code for analyzing the shielding requirements against high-energy galactic heavy radiations is needed. Such engineering design codes require establishing validation processes using laboratory ion beams and space flight measurements in realistic geometries. In consequence, a new version of the HZETRN code capable of simulating HZE ions with either laboratory or space boundary conditions is currently under development. The new code, GRNTRN, is based on a Green's function approach to the solution of Boltzmann's transport equation and like its predecessor is deterministic in nature. Code validation in the laboratory environment is addressed by showing that GRNTRN accurately predicts energy loss spectra as measured by solid-state detectors in ion beam experiments.

This paper presents a simplified orbit analysis program developed to calculate orbital parameters for the thermal analysis of spacecraft and space-flight instruments. The program calculates orbit data for inclined and sunsynchronous earth orbits. Traditional orbit analyses require extensive knowledge of orbital mechanics to produce a simplified set of data for thermal engineers. This program was created to perform orbital analyses with minimal input and provides the necessary output for thermal analysis codes. Engineers will find the program to be a valuable analysis tool for fast and simple orbit calculations. A description of the program inputs and outputs is included. An overview of orbital mechanics for inclined and Sun-synchronous orbits is also presented. Finally, several sample cases are presented to illustrate the thermal analysis applications of the program.

A set of physically based retrieval algorithms has been developed to derive from multispectral satellite imagery a variety of cloud properties that can be used to diagnose icing conditions when upper-level clouds are absent. The algorithms are being applied in near-real time to the Geostationary Operational Environmental Satellite (GOES) data over Florida, the Southern Great Plains, and the midwestern USA. The products are available in image and digital formats on the world-wide web. The analysis system is being upgraded to analyze GOES data over the CONUS. Validation, 24-hour processing, and operational issues are discussed.

A theoretically based algorithm to derive super-cooled liquid water (SLW) cloud macrophysical and microphysical properties is applied to operational satellite data and compared to pilot reports (PIREPS – from commercial and private aircraft) of icing and to in-situ measurements collected from a NASA icing research aircraft. The method has been shown to correctly identify the existence of SLW provided there are no higher-level ice crystal clouds (i.e. cirrus) above the SLW deck. The satellite-derived SLW cloud properties, particularly the cloud temperature, optical thickness or water path and water droplet size, show good qualitative correspondence with aircraft observations and icing intensity reports. Preliminary efforts to quantify the relationship between the satellite retrievals, PIREPS and aircraft measurements are reported here. The goal is to determine the extent to which the satellite-derived cloud parameters can be used to improve icing diagnoses and forecasts.

As shielding materials are developed for protection against the hazards of galactic cosmic rays, it is desirable to develop a protocol for rapid assessment of shielding properties. Solid state energy loss detectors are often used to estimate the charge and energy of particles in ion beam experiments. The direct measurement is energy deposited in the detector. As a means of separating the charge components in typical shield transmission studies with observation, a stack of many such detectors is used. With high-energy beams and thin targets, surviving primaries and fragments emerging from the target have nearly-equal velocities and deposited energy scales with the square of the charge, simplifying the data analysis. The development of a transport model for the shield and detector arrangement and evaluation of prediction of the energy loss spectrum for direct comparison with the experimentally derived data allows a rapid assessment of the shield transmission characteristics.

The long term exposure of astronauts on the developing International Space Station (ISS) requires an accurate knowledge of the internal exposure environment for human risk assessment and other onboard processes. The natural environment is moderated by the solar wind, which varies over the solar cycle. The HZETRN high charge and energy transport code developed at NASA Langley Research Center can be used to evaluate the neutron environment on ISS. A time dependent model for the ambient environment in low earth orbit is used. This model includes GCR radiation moderated by the Earth’s magnetic field, trapped protons, and a recently completed model of the albedo neutron environment formed through the interaction of galactic cosmic rays with the Earth’s atmosphere. Using this code, the neutron environments for space shuttle missions were calculated and comparisons were made to measurements by the Johnson Space Center with onboard detectors.

The effect on general aviation (GA) pilots' abilities to fly a small airplane while using a prototype data-linked weather information system (WIS) display, located in various cockpit positions, was investigated in comparison to the effect on their flying of acquiring weather information through conventional means. Ten GA pilots performed en route flying tasks of varying difficulty while concurrently performing weather information acquisition tasks. Pilots' subjective workload ratings, weather information acquisition times and accuracy levels, and preliminary flight path parameter deviation data indicate that using a WIS display results in smaller flight path parameter deviations, lower workload, and faster and slightly more accurate information retrieval than when weather information is obtained via the radio.

All but a small fraction of human space radiation exposure has been in Low Earth Orbit (LEO) where significant protection from extraterrestrial ionizing radiation is provided as a result of its deflection in the Earth's magnetic field. The placement of a manned outpost at the L1 Lagrange Point could mark the first long-term venture into a “deep space” radiation environment, giving rise to the associated problems of long-term space exposure. One of the first issues to address is providing protection within an L1 station from a large solar particle event. A safe haven area could be used over the duration of the event or one may consider the sleep stations where it is already necessary to have added shielding. The surrounding bodies of other closely packed crewmembers in such a shelter are expected to provide a significant fraction of a crewmember's total shielding.

The General Aviation Element of the Aviation Safety Program's Synthetic Vision Systems (SVS) Project is developing technology to eliminate low visibility induced General Aviation (GA) accidents. SVS displays present computer generated 3-dimensional imagery of the surrounding terrain on the Primary Flight Display (PFD) to greatly enhance pilot's situation awareness (SA), reducing or eliminating Controlled Flight into Terrain, as well as Low-Visibility Loss of Control accidents. SVS-conducted research is facilitating development of display concepts that provide the pilot with an unobstructed view of the outside terrain, regardless of weather conditions and time of day. A critical component of SVS displays is the appropriate presentation of terrain to the pilot. An experimental study is being conducted at NASA Langley Research Center (LaRC) to explore and quantify the relationship between the realism of the terrain presentation and resulting enhancements of pilot SA and performance.

Recently, there has been a strong emphasis on aerodynamic and aeroacoustic wind tunnel testing of automobiles. While significant level resources have been spent on investigating aerodynamics, the methodology has not changed appreciably since the beginning of aerodynamics as a science. Over the past decade, a number of global flow diagnostic techniques have been developed that drastically increase the quality and quantity of data from wind tunnel testing. One of these technologies is the use of pressure sensitive luminescent coatings, known as pressure-sensitive paint, a method which has matured considerably since its inception and is now used extensively in aerospace applications with good results. The goal of this research is to implement this technology in the full scale testing of high performance automotive vehicles. This paper discusses the details of a preliminary test, such as technique, paint formulation, camera and lighting hardware, and data reduction and analysis.

Not only is the common dream of frequent personal flight travel going unfulfilled, the current generation of General Aviation (GA) is facing tremendous challenges that threaten to relegate the Single Engine Piston (SEP) aircraft market to a footnote in the history of U.S. aviation. A case is made that this crisis stems from a generally low utility coupled to a high cost that makes the SEP aircraft of relatively low transportation value and beyond the means of many. The roots of this low value are examined in a broad sense, and a Next Generation NASA Advanced GA Concept is presented that attacks those elements addressable by synergistic aircraft design.

On January 14, 2004 President George W Bush outlined a new vision for NASA that has humans venturing back to the moon by 2020. With this ambitious goal, new tools and models have been developed to help define and predict the amount of space radiation astronauts will be exposed to during transit and habitation on the moon. A representative scenario is used that includes a trajectory from LEO to a Lunar Base, and simplified CAD models for the transit and habitat structures. For this study galactic cosmic rays, solar proton events, and trapped electron and proton environments are simulated using new dynamic environment models to generate energetic electron, and light and heavy ion fluences. Detailed calculations are presented to assess the human exposure for transit segments and surface stays.

Meeting radiation protection requirements during EVA is predominantly an operational issue with some potential considerations for temporary shelter. The issue of spacesuit shielding is mainly guided by the potential of accidental exposure when operational and temporary shelter considerations fail to maintain exposures within operational limits. In this case, very high exposure levels are possible which could result in observable health effects and even be life threatening. Under these assumptions, potential spacesuit radiation exposures have been studied using known historical solar particle events to gain insight on the usefulness of modification of spacesuit design in which the control of skin exposure is a critical design issue and reduction of blood forming organ exposure is desirable.

Research committed by the Langley Research Center through 1995 resulting in the HZETRN code provides the current basis for shield design methods according to NASA STD-3000 (2005). With this new prominence, the database, basic numerical procedures, and algorithms are being re-examined with new methods of verification and validation being implemented to capture a well defined algorithm for engineering design processes to be used in this early development phase of the Bush initiative. This process provides the methodology to transform the 1995 HZETRN research code into the 2005 HZETRN engineering code to be available for these early design processes. In this paper, we will review the basic derivations including new corrections to the codes to insure improved numerical stability and provide benchmarks for code verification.

A new Green’s function code (GRNTRN) capable of simulating HZE ions with either laboratory or space boundary conditions is currently under development. The computational model consists of combinations of physical perturbation expansions based on the scales of atomic interaction, multiple scattering, and nuclear reactive processes with use of the Neumann-asymptotic expansions with non-perturbative corrections. The code contains energy loss due to straggling, nuclear attenuation, nuclear fragmentation with energy dispersion and downshifts. Recent publications have focused on code validation in the laboratory environment and have shown that the code predicts energy loss spectra accurately as measured by solid-state detectors in ion beam experiments. In this paper emphasis is placed on code validation with space boundary conditions.