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NASA NTRS0992

Current status: Animal models of nausea

The advantages, and possible benefits of a valid, reliable animal model for nausea are discussed, and difficulties inherent to the development of a model are considered. A principle problem for developing models arises because nausea is a subjective sensation that can be identified only in humans. Several putative measures of nausea in animals are considered, with more detailed consideration directed to variation in cardiac rate, levels of vasopressin, and conditioned taste aversion. Demonstration that putative measures are associated with reported nausea in humans is proposed as a requirement for validating measures to be used in animal models. The necessity for a 'real-time' measure of nausea is proposed as an important factor for future research; and the need for improved understanding of the neuroanatomy underlying the emetic syndrome is discussed.

Robert A Fox↗
NASA NTRS1992

Current status and some future test directions for the U.S. National Transonic Facility

The construction of the National Transonic Facility was completed in September 1982 and the start-up and checkout of the tunnel systems were performed over the following two years. In August 1984, the facility was declared operational for final checkout of cryogenic instrumentation and control systems, and for the aerodynamics calibration and testing to commence. Since 1984 several operational problems have been identified and successfully solved which is demonstrated by the fact that the facility has operated the last year with no significant facility down times. Also during this time period, development of test techniques and instrumentation has continued. This paper will review some of the recent test techniques and instrumentation developments, and will briefly review the status of the facility.

Gloss, Blair B.↗
NASA NTRS1993

Current Status in Cavitation Modeling

Cavitation is a common problem for many engineering devices in which the main working fluid is in liquid state. In turbomachinery applications, cavitation generally occurs on the inlet side of pumps. The deleterious effects of cavitation include: lowered performance, load asymmetry, erosion and pitting of blade surfaces, vibration and noise, and reduction of the overall machine life. Cavitation models in use today range from rather crude approximations to sophisticated bubble dynamics models. Details about bubble inception, growth and collapse are relevant to the prediction of blade erosion, but are not necessary to predict the performance of pumps. An engineering model of cavitation is proposed to predict the extent of cavitation and performance. The vapor volume fraction is used as an indicator variable to quantify cavitation. A two-phase flow approach is employed with the assumption of the thermal equilibrium between liquid and vapor. At present velocity slip between the two phases is selected. Preliminary analyses of 2D flows shows qualitatively correct results.

Singhal, Ashok K.↗
NASA NTRS1996

Results and current status of the NPARC alliance validation effort

The NPARC Alliance is a partnership between the NASA Lewis Research Center (LeRC) and the USAF Arnold Engineering Development Center (AEDC) dedicated to the establishment of a national CFD capability, centered on the NPARC Navier-Stokes computer program. The three main tasks of the Alliance are user support, code development, and validation. The present paper is a status report on the validation effort. It describes the validation approach being taken by the Alliance. Representative results are presented for laminar and turbulent flat plate boundary layers, a supersonic axisymmetric jet, and a glancing shock/turbulent boundary layer interaction. Cases scheduled to be run in the future are also listed. The archive of validation cases is described, including information on how to access it via the Internet.

Towne, Charles E.↗
NASA NTRS1997

The Lunar Atmosphere: History, Status, Current Problems, and Context

After decades of speculation and fruitless searches, the lunar atmosphere was first observed by Apollo surface and orbital instruments between 1970 and 1972. With the demise of Apollo in 1972, and the termination of funding for Apollo lunar ground station studies in 1977, the field withered for many years, but has recently enjoyed a renaissance. This reflowering has been driven by the discovery and exploration of sodium and potassium in the lunar exosphere by groundbased observers, the detection of metal ions derived from the Moon in interplanetary space, the possible discoveries of H2O ice at the poles of the Moon and Mercury, and the detections of tenuous atmospheres around more remote sites in the solar system, including Mercury and the Galilean satellites. In this review we summarize the present state of knowledge about the lunar atmosphere, describe the important physical processes taking place within it, and then discuss related topics including a comparison of the lunar atmosphere to other surface boundary exospheres in the solar system.

Stern, S. Alan .↗
NASA NTRS1998

Spectroscopic Parameters for Ozone and its Isotopes: Current Status, Prospects for Improvement, and the Identification of 16O16O17O and O-16O-16O-17 and O-16O-17O-16 Lines in Infrared Ground-Based and Stratospheric Solar Absorption Spectra

We describe the updates to the spectroscopic parameters of ozone and its isotopes in the 1996 HITRAN compilation. Recent published studies not included in HITRAN are also summarized. Finally, we report the identification of infrared lines of the v(sub 3) bands of O-16O-16O-17 and O-16O-17O-16 in high-resolution solar spectra recorded by stratospheric balloon-borne and ground-based Fourier transform spectrometers.

Rinsland, C. P.↗
NASA NTRS1999

Modeling Studies of PVT Growth of ZnSe: Current Status and Future Course

Bulk growth of wide band gap II-VI semiconductors by physical vapor transport (PVT) has been developed and refined over the past several years at NASA Marshall Space Flight Center. Results from a modeling study of PVT crystal growth of ZnSe are reported in this paper. The PVT process is numerically investigated using a two-dimensional formulation of the governing equations and associated boundary conditions. Both the incompressible Boussinesq approximation and a compressible model are tested to determine the influence of gravity on the process and to discern the differences between the two approaches. The influence of a residual gas is included in the models. The results show that both the incompressible and compressible approximations provide comparable results and the presence of a residual gas tends to measurably reduce the mass flux in the system. Detailed flow, thermal and concentration profiles are provided. The simulations show that the Stefan flux dominates the system flow field and the subtle gravitational effects can be gauged by subtracting this flux from the calculated profiles. Shear flows, due to solutal buoyancy, of the order of 50 microns/s for the liorizont,-d growth orientation and 10 microns/s for the vertical orientation are predicted. Whether these flows can fully account for the observed gravity related growth morphological effects and inhomogeneous solute and dopant distributions is a matter of conjecture. A template for future modeling efforts in this area is suggested which incorporates a mathematical approach to the tracking of the growth front based on energy of formation concepts.

Ramachandran, N.↗
NASA NTRS1999

Current Status of Aerosol Retrievals from TOMS

Properties of atmospheric aerosols over all land and water surfaces are retrieved from TOMS measurements of backscattered radiances. The TOMS technique, uses observations at two wavelengths. In the near ultraviolet (330-380 nm) range, where the effects of gaseous absorption are negligible. The retrieved properties are optical depth and a measure of aerosol absorptivity, generally expressed as single scattering albedo. The main sources of error of the TOMS aerosol products are sub-pixel cloud contamination and uncertainty on the height above the surface of UV-absorbing aerosol layers. The first error source is related to the large footprint (50 x 50 km at nadir) of the sensor, and the lack of detection capability of sub-pixel size clouds. The uncertainty associated with the height of the absorbing aerosol layers, on the other hand, is related to the pressure dependence of the molecular scattering process, which is the basis of the near-UV method of absorbing aerosol detection. The detection of non-absorbing aerosols is not sensitive to aerosol layer height. We will report on the ongoing work to overcome both of these difficulties. Coincident measurements of high spatial resolution thermal infrared radiances are used to address the cloud contamination issue. Mostly clear scenes for aerosol retrieval are selected by examining the spatial homogeneity of the IR radiance measurements within a TOMS pixel. The approach to reduce the uncertainty associated with the height of the aerosol layer by making use of a chemical transport model will also be discussed.

Torres, O.↗
NASA NTRS2000

Current Status of Thin Film (Ba,Sr)TiO3 Tunable Microwave Components for RF Communications

The performance of proof-of-concept ferroelectric microwave devices has been moving steadily closer to the level needed for satellite and other rf communications applications. This paper will review recent progress at NASA Glenn in developing thin film Ba(x)Sr(1-x)TiO3 tunable micro-wave components for these applications. Phase shifters for phased array antennas, tunable filters and tunable oscillators employing microstrip and coupled microstrip configurations will be presented. Tunabilities, maximum dielectric constants, and phase shifter parameters will be discussed (e.g., coupled microstrip phase shifters with phase shift over 200 deg at 18 GHz and a figure of merit of 74.3 deg/dB). Issues of post-annealing, Mn-doping and Ba(x)Sr(1-x) TiO3 growth on sapphire and alumina substrates will be covered. The challenges of incorporating these devices into larger systems, such as yield, variability in phase shift and insertion loss, and protective coatings will also be addressed.

VanKeuls, F. W.↗
NASA NTRS2000

Light Scattering By Nonspherical Particles: Current Status and Challenging Issues

Quantitative analyses of remote sensing measurements of aerosols, clouds, precipitation, and particulate surfaces as well as computations of the Earth's radiation balance require detailed understanding of the interaction of small particles with light and other electromagnetic radiation. The convenient availability of the Lorenz-Mie theory has led to a widespread practice of treating all particles as if they were spheres. However, many natural and anthropogenic particles have nonspherical shapes, and the accumulated knowledge suggests that their scattering and radiative properties can be dramatically different from those of equivalent spheres. This presentation will summarize the recent significant progress achieved in the area of electromagnetic scattering by nonspherical particles and outline major problems that still await solution. The talk will cover the following specific topics: (1) comparison of most widely used exact and approximate theoretical techniques; (2) outline of laboratory and field measurement techniques; (3) compare theory and experiment; (4) need for a statistical approach in dealing with natural particles; (5) remote sensing and radiative transfer applications; and (6) major unsolved problems.

Mishchenko, Michael↗
NASA NTRS2000

Current Status of Thin Film (Ba,Sr) TiO3 Tunable Microwave Components for RF Communications

The performance of proof-of-concept ferroelectric microwave devices has been moving steadily closer to the level needed for satellite and other rf communications applications. This paper will review recent progress at NASA Glenn in developing thin film Ba(x)Sr(1-x)TiO3 tunable microwave components for these applications. Phase shifters for phased array antennas, tunable filters and tunable oscillators employing microstrip and coupled microstrip configurations will be presented. Tunabilities, maximum dielectric constants, and phase shifter parameters will be discussed (e.g., coupled microstrip phase shifters with phase shift over 200 deg. at 18 GHz and a figure of merit of 74.3 deg./dB). Issues of postannealing, Mn-doping and Ba(x)Sr(1-x)TiO3 growth on sapphire and alumina substrates will be covered. The challenges of incorporating these devices into larger systems, such as yield, variability in phase shift and insertion loss, and protective coatings will also be addressed.

VanKeuls, F. W.↗
NASA NTRS2002

Double Beta Decay of Tellurium-130: Current Status

Geochemically measured values of Te-130 half-life form two distinct clusters. Two different experiments were performed to check two proposed explanations: Xe loss and Xe inheritance. Neither is observed. Additional information is contained in the original extended abstract.

Meshik, A. P.↗
NASA NTRS1994

Parallel Computational Fluid Dynamics: Current Status and Future Requirements

One or the key objectives of the Applied Research Branch in the Numerical Aerodynamic Simulation (NAS) Systems Division at NASA Allies Research Center is the accelerated introduction of highly parallel machines into a full operational environment. In this report we discuss the performance results obtained from the implementation of some computational fluid dynamics (CFD) applications on the Connection Machine CM-2 and the Intel iPSC/860. We summarize some of the experiences made so far with the parallel testbed machines at the NAS Applied Research Branch. Then we discuss the long term computational requirements for accomplishing some of the grand challenge problems in computational aerosciences. We argue that only massively parallel machines will be able to meet these grand challenge requirements, and we outline the computer science and algorithm research challenges ahead.

Simon, Horst D.↗
NASA NTRS2003

The Genesis Solar Wind Collection Mission: Current Status

The NASA Genesis spacecraft was launched August 8, 2001 on a mission to collect samples of solar wind for greater than or equal to 2 years and then return them to Earth in 2004. Detailed analyses of the solar wind ions implanted into high-purity collection substrates will subsequently be carried out in earth-based laboratories using various mass spectrometry techniques. These analyses are expected to determine key isotopic ratios and elemental abundances in the solar wind and, by extension, in the solar photosphere. Further, the photospheric composition is thought to be representative of the solar nebula with a few exceptions so that the Genesis mission will provide a baseline for the average solar nebula composition with which to compare present-day compositions of planets, meteorites, and asteroids. The implications of the solar oxygen isotopic composition have been discussed. A list of other isotopic and elemental measurement objectives, and some of the rationale behind them, is given.

Barraclough, B. L.↗
NASA NTRS2004

Review of X-43A Return to Flight Activities and Current Status

This paper provides an overview and status of the return to flight activities for the X-43A scramjet flight demonstrator after the first flight mishap. The first flight was attempted on June 2, 2001 and resulted in vehicle destruction by range safety when the booster went out of control early in the flight. In the time since the mishap much work has been done to examine the causes of the failure and make modifications to the booster to insure that the boost for the second flight will be successful. In addition, all other aspects of the flight have been examined to maximize the probability of a successful flight.

Reubush, David E.↗
NASA NTRS2004

MARIE: Current Status and Results from 20 Months of Observations at Mars

The MARIE instrument aboard the 2001 Mars Odyssey spacecraft detects energetic charged particles in the Galactic Cosmic Radiation (GCR) and during solar particle events (SPE) [1]. As of this writing (January 2004), MARIE has been turned off, after losing communication with the spacecraft during the large SPE of October 28, 2003. However, during the prior 20 months, MARIE collected data almost continuously, observing several solar events and the nearly-constant GCR. There is still a possibility the instrument can be recovered, and troubleshooting efforts are scheduled to begin in May 2004, following the completion of the primary missions of MER-A (Spirit) and MER-B (Opportunity). At present, Odyssey is acting as a telecommunications relay for the rovers and only routine science operations are permitted in this mode.

Zeitlin, C.↗
NASA NTRS2004

Characteristics and Current Status of Near Infrared Spectrometer for Hayabusa Mission

NIRS is a near infrared spectrometer on-boarded the spacecraft HAYABUSA (MUSESC), which aims to return samples from a near-earth asteroid, (25143) Itokawa (1998 SF36). HAYABUSA was successfully launched by Japanese M-V-5 rocket on May 19, 2003. After the earth swing-by in Jun 2004, the spacecraft will arrive at the asteroid in summer 2005. During the rendezvous phase with the asteroid, we will observe the asteroid surface using NIRS and obtain reflectance spectra of the surface materials across the wavelength range of 850nm to 2100nm. Based on ground-based observations [1],[2],[3], (25143) Itokawa appears to be an S(IV) type asteroid. NIRS can detect absorption bands due to olivine and pyroxene and investigate the mineralogical composition of the surface materials. Combining with the data from asteroid multiband imaging camera (AMICA) and X-ray spectrometer (XRS), we can reveal a relationship between asteroids and meteorites.

Abe, M.↗