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NASA NTRS2000

High Energy Continuum of High Redshift Quasars

Discussion with the RXTE team at GSFC showed that a sufficiently accurate background subtraction procedure had now, been derived for sources at the flux level of PKS 2126-158. However this solution does not apply to observations carried out before April 1997, including our observation. The prospect of an improved solution becoming available soon is slim. As a result the RXTE team agreed to re-observe PKS2126-158. The new observation was carried out in April 1999. Quasi-simultaneous optical observations were obtained, as Service observing., at the 4-meter Anglo-Australian Telescope, and ftp-ed from the AAT on 22April. The RXTE data was processed in late June, arriving at SAO in early July. Coincidentally, our collaborative Beppo-SAX observation of PKS2126-158 was made later in 1999, and a GTO Chandra observation (with which we are involved) was made on November 16. Since this gives us a unique monitoring data for a high redshift quasar over a broad pass-band we are now combining all three observations into a single comprehensive study Final publication of the RXTE data will thus take place under another grant.

Elvis, Martin↗

NASA NTRS1999

Epstein-Barr Virus Reactivation Associated with Diminished Cell-Mediated Immunity in Antarctic Expeditioners

Reactivation of Epstein-Barr virus (EBV) and cell-mediated immune (CMI) responses were followed in 16 Antarctic expeditioners during winter-over isolation at two Australian National Antarctic Research Expedition stations. Delayed-type hypersensitivity skin testing was used as an indicator of the CMI response, which was evaluated two times before winter isolation and three times during isolation. At all five evaluation times, 8 or more of the 16 subjects had a diminished. CMI response. Diminished CMI was observed on every test occasion in 4/16 subjects; only 2/16 subjects exhibited normal CMI responses for all five tests. A polymerase chain reaction (PCR) assay was used to detect EBV DNA in saliva specimens collected before, after, and during the winter isolation. EBV DNA was present in 17% (111/642) of the saliva specimens; all 16 subjects shed EBV in their saliva on at least one occasion. The probability of EBV shedding increased (p=0.013) from 6% before or after winter isolation to 13% during the winter period. EBV appeared in saliva during the winter isolation more frequently (p<0.0005) when CMI responsiveness was diminished than when CMI status was normal. The findings indicate that the psychosocial, physical, and other stresses associated with working and living in physical isolation during the Antarctic winter results in diminished CMI and an accompanying increased reactivation and shedding of latent viruses.

Pierson, Duane L.↗

NASA NTRS2000

Monsoon-Enso Relationships: A New Paradigm

This article is partly a review and partly a new research paper on monsoon-ENSO relationship. The paper begins with a discussion of the basic relationship between the Indian monsoon and ENSO dating back to the work of Sir Gilbert Walker up to research results in more recent years. Various factors that may affect the monsoon-ENSO, relationship, including regional coupled ocean-atmosphere processes, Eurasian snow cover, land-atmosphere hydrologic feedback, intraseasonal oscillation, biennial variability and inter-decadal variations, are discussed. The extreme complex and highly nonlinear nature of the monsoon-ENSO relationship is stressed. We find that for regional impacts on the monsoon, El Nino and La Nina are far from simply mirror images of each other. These two polarities of ENSO can have strong or no impacts on monsoon anomalies depending on the strength of the intraseasonal oscillations and the phases of the inter-decadal variations. For the Asian-Australian monsoon (AAM) as a whole, the ENSO impact is effected through a east-west shift in the Walker Circulation. For rainfall anomalies over specific monsoon areas, regional processes play important roles in addition to the shift in the Walker Circulation. One of the key regional processes identified for the boreal summer monsoon is the anomalous West Pacific Anticyclone (WPA). This regional feature has similar signatures in interannual and intraseasonal time scales and appears to determine whether the monsoon-ENSO relationship is strong or weak in a given year. Another important regional feature includes a rainfall and SST dipole across the Indian Ocean, which may have strong impact on the austral summer monsoon. Results are shown indicating that monsoon surface wind forcings may induce a strong biennial signal in ENSO and that strong monsoon-ENSO coupling may translate into pronounced biennial variability in ENSO. Finally, a new paradigm is proposed for the study of monsoon variability. This paradigm provides a unified framework in which monsoon predictability, the role of regional vs. basin-scale processes, its relationship with different climate subsystems, and causes of secular changes in monsoon-ENSO relationship can be investigated.

Lau, K. M.↗

NASA NTRS2001

Flow-Tagging Velocimetry for Hypersonic Flows Using Fluorescence of Nitric Oxide

We investigate a new type of flow-tagging velocimetry technique for hypersonic flows. The technique involves exciting a thin line of nitric oxide molecules with a laser beam and then, after some delay, acquiring an image of the displaced line. One component of velocity is determined from the time of flight. This method is applied to measure the velocity profile in a Mach 8.5 laminar, hypersonic boundary layer in the Australian National Universities T2 free-piston shock tunnel. The velocity is measured with an uncertainty of approximately 2%. Comparison with a CFD simulation of the flow shows reasonable agreement.

Danehy, P. M.↗

NASA NTRS2001

Multi-Technique Study of a Martian Aeolian Sand Analog

Potential scientific returns from technological advances in various forms of microscopy and benchmarking of currently available in-situ measurements using an aeolian red dune sand from the central Australian desert. Additional information is contained in the original extended abstract.

Kuhlman, K.↗

NASA NTRS2001

Importance of the Annual Cycles of SST and Solar Irradiance for Circulation and Rainfall: A Climate Model Simulation Study

Annual cycle of climate and precipitation is related to annual cycle of sunshine and sea-surface temperatures. Understanding its behavior is important for the welfare of humans worldwide. For example, failure of Asian monsoons can cause widespread famine and grave economic disaster in the subtropical regions. For centuries meteorologists have struggled to understand the importance of the summer sunshine and associated heating and the annual cycle of sea-surface temperatures (SSTs) on rainfall in the subtropics. Because the solar income is pretty steady from year to year, while SSTs depict large interannual variability as consequence of the variability of ocean dynamics, the influence of SSTs on the monsoons are better understood through observational and modeling studies whereas the relationship of annual rainfall to sunshine remains elusive. However, using NASA's state of the art climate model(s) that can generate realistic climate in a computer simulation, one can answer such questions. We asked the question: if there was no annual cycle of the sunshine (and its associated land-heating) or the SST and its associated influence on global circulation, what will happen to the annual cycle of monsoon rains? By comparing the simulation of a 4-year integration of a baseline Control case with two parallel anomaly experiments: 1) with annual mean solar and 2) with annual mean sea-surface temperatures, we were able to draw the following conclusions: (1) Tropical convergence zone and rainfall which moves with the Sun into the northern and southern hemispheres, specifically over the Indian, African, South American and Australian regions, is strongly modulated by the annual cycles of SSTs as well as solar forcings. The influence of the annual cycle of solar heating over land, however, is much stronger than the corresponding SST influence for almost all regions, particularly the subtropics; (2) The seasonal circulation patterns over the vast land-masses of the Northern Hemisphere at mid and high latitudes also get strongly influenced by the annual cycles of solar heating. The SST influence is largely limited to the oceanic regions of these latitudes; (3) The annual mode of precipitation over Amazonia has an equatorial regime revealing a maxima in the month of March associated with SST, and another maxima in the month of January associated with the solar annual cycles, respectively. The baseline simulation, which has both annual cycles, depicts both annual modes and its rainfall is virtually equal to the sum of those two modes; (4) Rainfall over Sahelian-Africa is significantly reduced (increased) in simulations lacking (invoking) solar irradiation with (without) the annual cycle. In fact, the dominant influence of solar irradiation emerges in almost all monsoonal-land regions: India, Southeast Asia, as well as Australia. The only exception is the Continental United States, where solar annual cycle shows only a relatively minor influence on the annual mode of rainfall.

Sud, Yogesh C.↗

NASA NTRS2002

STS-109 Flight Day 11 Highlights

On the 11th day of the STS-109 mission, Commander Scott Altman, Pilot Duane Carey, Payload Commander John Grunsfeld, and Mission Specialists Nancy Currie, James Newman, Richard Linnehan, and Michael Massimino are seen answering questions from students in an on-orbit interview. Various shots of the Earth are shown as Columbia orbits over the north of the Australian coast, the west coast of Mexico, Madagascar and the southern Indian Ocean, and the Atlantic coast of Africa.

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NASA NTRS2002

Studying X-Ray Binaries with High Energy Frequency Quasi-Periodic Oscillations

The goal of this investigation is to further our understanding of the dynamics of secreting neutron stars and black holes in the hope of using these systems as probes of the physics of strong gravitational fetus. The main focus of this work has been a multi-year program of simultaneous millisecond X-ray timing and spectral observations carried out with the Rossi X-Ray Timing Explorer (RXTE) to perform the X-ray timing and one of the satellites Asca, BeppoSAX, or Chandra to perform X-ray spectral measurements. With the advent of Chandra, we have extended our work to incLude extragalactic X-ray binaries. We conducted a comprehensive study of the X-ray and radio behavior of the Black Hole Candidate (BHC) X-ray transient XTE J1550-564 using RXTE, Chandra, and the Australian Telescope Compact Array (ATCA). We showed that strong radio emission is associated with major X-ray outbursts involving an X-ray state transition, while a compact radio jet is seen in the low/hard X-ray state found in the outburst decay. Interesting, the total energy required to produce the compact jet may be a substantial fraction of the total accretion energy of the system in that state. We also performed a detailed study of the spectral and timing properties of the decay. In joint RXTE/BeppoSAX observations of the neutron-star X-ray binary Cyg X-2, we discovered a correlation between the timing properties (the frequency of the horizontal branch oscillations) and the properties of a soft, thermal component of the X-ray spectrum. d e showed that more det<iiled measurements of this source may lead to constraints on models of the accretion flow and the emission of X- ray from accreting neutron stars. We have completed analysis of RXTE observations of the X-ray transient SAX J1750.8-2900 made after detection of X-ray bursts from the source with the BeppoSAX Wide-Field Camera. We discovered millisecond oscillations in both the persistent emission and in the X-ray bursts.

Kaaret, P.↗

NASA NTRS1996

Infrared Observations of G0.18-0.04

The Galactic Center H(II) region, G0.18-0.04, the 'Sickle', is located where the nonthermal 'Arc' crosses the Galactic plane. The Sickle appears to be the ionized edge of a dense molecular cloud. The source of ionization has been ascribed to both the interaction of the cloud with the magnetic field of the Arc and to the hot stars in the adjacent cluster, AFGL 2004, also known as the 'Quintuplet Cluster'. This paper addresses the relative locations of the stars, the ionized and molecular gas, and the sources of gas excitation and dust heating. Using NASA's Kuiper Airborne Observatory, we have observed the far infrared forbidden lines of [S(III)] 18.7 and 33.5 micrometers, [Si(II)] 34.8 micrometers, [Ne(III)] 36.0 micrometers, [O(III)] 51.8 and 88.4 micrometers, [N(III)] 57.3 micrometers, [O(II)] 63.2 and 146 micrometers, [C(II)] 158 micrometers, and [N(II)] 205 micrometers and the adjacent continua at 11 positions around G0.18-0.04, including G0.15-0.05, the 'Pistol', in a beamsize of 40 - 60 arcsec. The electron density, the ionic abundances, and the ionization structure of the H(II) region are estimated from the doubly ionized line fluxes. The density and radiation field found in the photodissociation region (PDR) between the H(II) region and the molecular cloud are estimated from the [C(II)] and [O(I)] line fluxes and the far-infrared continuum. We compare the ionization structure and the PDR properties to shell models of H(II) regions with varying distances from their exciting stars. The agreement of observations and models indicates that the hot stars of AFGL 2004 are the likely source of ionization of the Sickle. Additional hot stars are necessary to ionize the more outlying positions. However, because of its low ionization and high PDR radiation field, the Pistol cannot be as close to AFGL 2004 as indicated by its close proximity on the sky. Instead, the Pistol is probably ionized by the luminous blue variable candidate, Pistol Source A. We estimated the extinction to the region from the distribution of the J, H, and K' magnitudes of the stars in the field that we measured from the Anglo-Australian telescope and from the IRAS LRS spectrum of AFGL 2004. The extinction is fairly uniform, with no enhancement from the molecular cloud. The strength of Brackett gamma, the 19-micrometer lines and continuum, and the IRAS 25-micrometer continuum are all consistent with the absence of a dense, foreground molecular cloud. We conclude that the H(II) region is on the near side of the dense cloud.

Simpson, Janet P.↗

NASA NTRS1992

A Boom in Boomerangs

Ted Bailey, a highly-ranked international boomerang designer and thrower, used information from a variety of NASA technical reports on aerodynamics and low-speed airfoils to design more competitive boomerangs. Because the boomerang is essentially an airfoil like an airplane wing, the technology transferred effectively and even contributed to the 1981 American victory over Australian throwers. In 1985, using four NASA reports, Bailey designed a new MTA (maximum time aloft) boomerang that broke the one-minute barrier, enabled throwers to throw and catch in less than three minutes and allowed competitors to complete the difficult "Super Catch" - five throw/catch sequences after launching the original boom while it is still aloft. Bailey is now considering other boomerang applications.

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NASA NTRS1988

Racing with the Sun

In 1,950 mile Australian race, the General Motors Sunraycer, was powered by space-derived solar cell technology incorporating a number of other aerospace technologies. The 547 lb one seater averaged better than 41 miles per hour and finished 600 miles ahead of the nearest competitor.

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NASA NTRS2002

Structural Life and Reliability Metrics: Benchmarking and Verification of Probabilistic Life Prediction Codes

Over the past two decades there has been considerable effort by NASA Glenn and others to develop probabilistic codes to predict with reasonable engineering certainty the life and reliability of critical components in rotating machinery and, more specifically, in the rotating sections of airbreathing and rocket engines. These codes have, to a very limited extent, been verified with relatively small bench rig type specimens under uniaxial loading. Because of the small and very narrow database the acceptance of these codes within the aerospace community has been limited. An alternate approach to generating statistically significant data under complex loading and environments simulating aircraft and rocket engine conditions is to obtain, catalog and statistically analyze actual field data. End users of the engines, such as commercial airlines and the military, record and store operational and maintenance information. This presentation describes a cooperative program between the NASA GRC, United Airlines, USAF Wright Laboratory, U.S. Army Research Laboratory and Australian Aeronautical & Maritime Research Laboratory to obtain and analyze these airline data for selected components such as blades, disks and combustors. These airline data will be used to benchmark and compare existing life prediction codes.

Litt, Jonathan S.↗

NASA NTRS1981

Hang Gliders

Francis M. Rogallo and his wife Gertrude researched flexible controllable fabric airfoils with a delta, V-shaped, configuration for use on inexpensive private aircraft. They were issued a flex-wing patent and refined their designs. Development of Rogallo wings, used by U.S. Moyes, Inc. substantially broadened the flexible airfoil technology base which originated from NASA's reentry parachute. The Rogallo technology, particularly the airfoil frame was incorporated in the design of a kite by John Dickenson. The Dickenson kite served as prototype for the Australian Moyes line of hang gliders. Company no longer exists.

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NASA NTRS2002

Prospects for Improved Forecasts of Weather and Short-Term Climate Variability on Subseasonal (2-Week to 2-Month) Times Scales

This workshop, held in April 2002, brought together various Earth Sciences experts to focus on the subseasonal prediction problem. While substantial advances have occurred over the last few decades in both weather and seasonal prediction, progress in improving predictions on these intermediate time scales (time scales ranging from about two weeks to two months) has been slow. The goals of the workshop were to get an assessment of the "state of the art" in predictive skill on these time scales, to determine the potential sources of "untapped" predictive skill, and to make recommendations for a course of action that will accelerate progress in this area. One of the key conclusions of the workshop was that there is compelling evidence for predictability at forecast lead times substantially longer than two weeks. Tropical diabatic heating and soil wetness were singled out as particularly important processes affecting predictability on these time scales. Predictability was also linked to various low-frequency atmospheric "phenomena" such as the annular modes in high latitudes (including their connections to the stratosphere), the Pacific/North American (PNA) pattern, and the Madden Julian Oscillation (MJO). The latter, in particular, was highlighted as a key source of untapped predictability in the tropics and subtropics, including the Asian and Australian monsoon regions.

Schubert, Siegfried↗

NASA NTRS2002

Unsafe acts and unsafe outcomes in aircraft maintenance

Road safety studies using the Driver Behaviour Questionnaire (DBQ) have provided support for a three-way distinction between violations, skill-based errors and mistakes, and have indicated that a tendency to commit driving violations is associated with an increased risk of accident involvement. The aims of this study were to examine whether the three-way distinction of unsafe acts is applicable in the context of aircraft maintenance, and whether involvement in maintenance safety occurrences can be predicted on the basis of self-reported unsafe acts. A Maintenance Behaviour Questionnaire (MBQ) was developed to explore patterns of unsafe acts committed by aircraft maintenance mechanics. The MBQ was completed anonymously by over 1300 Australian aviation mechanics, who also provided information on their involvement in workplace accidents and incidents. Four factors were identified: routine violations, skill-based errors, mistakes and exceptional violations. Violations and mistakes were related significantly to the occurrence of incidents that jeopardized the quality of aircraft maintenance, but were not related to workplace injuries. Skill-based errors, while not related to work quality incidents, were related to workplace injuries. The results are consistent with the three-way typology of unsafe acts described by Reason et al. (1990) and with the DBQ research indicating an association between self-reported violations and accidents. The current findings suggest that interventions addressed at maintenance quality incidents should take into account the role of violations and mistakes, and the factors that promote them. In contrast, interventions directed at reducing workplace injury are likely to require a focus on skill-based errors.

Maintenance/manpower/methods↗

NASA NTRS2000

Is it really so bad? A comparison of positive and negative experiences in Antarctic winter stations

This study examined the range of positive and negative themes reported by 104 Australian Antarctic winter personnel at four stations during two austral winters. Reports from the expeditioners were subjected to a content analysis using the TextSmart software from SPSS, Inc. Results indicated that, although the list of negative experiences is lengthy, most events are relatively rare. On the other hand, although the list of positive experiences is short, the frequencies with which they are reported are much greater than for most of the problems. Possible explanations for these themes and for future directions are discussed.

NASA Discipline Space Human Factors↗

NASA NTRS1999

Space analogue studies in Antarctica

Medical research has been carried out on the Australian National Antarctic Research Expeditions (ANARE) for 50 years. As an extension of this program collaborative Australian/United States research on immunology, microbiology, psychology and remote medicine has produced important data and insight on how humans adapt to the stress of extreme isolation, confinement and the harsh environment of Antarctica. An outstanding analogue for the isolation and confinement of space missions (especially planetary outposts), ANARE has been used as an international research platform by Australia and the United States since 1993. Collaborative research has demonstrated a lowered responsiveness of the immune system under the isolation and confinement of Antarctic winter-over; a reduction of almost 50% in T cell proliferation to mitogen phytohaemogglutinin, as well as changes in latent herpesvirus states and the expansion of the polyclonal latent Epstein-Barr virus infected B cell populations. Although no clinically significant disease has been found to result from these immune changes, research is currently assessing the effects of psychological factors on the immune system. This and associated research performed to date and its relevance to both organisations is discussed, and comment made on possible extensions to the program in both medical and other fields.

NASA Center HQS↗

NASA NTRS1999

Psychological changes in hundred-day remote Antarctic field groups

Psychological adaptation to extreme environments has been examined from several perspectives. In this study, two Australian teams, each consisting of six male crew members, completed computer-administered questionnaires twice weekly during 100-day traverses around the Lambert Glacier Basin, Antarctica. Only small trends were noted when data were aggregated at the group level, which is consistent with the findings of others. Data were then analyzed using pooled time-series regression. These analyses incorporated personality characteristics, environmental factors, and interpersonal factors as predictors of Group Tensions, Personal Morale, Emotional State, Cognitive Readiness, and the Team's Work Life. Most of the psychological discomfort and problems that occurred appeared to be within the individual or between individuals. They did not affect all members of the group equally.

NASA Discipline Space Human Factors↗