Study of Geometric Porosity on Static Stability and Drag Using Computational Fluid Dynamics for Rigid Parachute Shapes

This paper explores use of computational fluid dynamics to study the eect of geometric porosity on static stability and drag for NASA's Multi-Purpose Crew Vehicle main parachute. Both of these aerodynamic characteristics are of interest to in parachute design, and computational methods promise designers the ability to perform detailed parametric studies and other design iterations with a level of control previously unobtainable using ground or flight testing. The approach presented here uses a canopy structural analysis code to define the inflated parachute shapes on which structured computational grids are generated. These grids are used by the computational fluid dynamics code OVERFLOW and are modeled as rigid, impermeable bodies for this analysis. Comparisons to Apollo drop test data is shown as preliminary validation of the technique. Results include several parametric sweeps through design variables in order to better understand the trade between static stability and drag. Finally, designs that maximize static stability with a minimal loss in drag are suggested for further study in subscale ground and flight testing

Rocket Plume Scaling for Orion Wind Tunnel Testing

A wind tunnel test program was undertaken to assess the jet interaction effects caused by the various solid rocket motors used on the Orion Launch Abort Vehicle (LAV). These interactions of the external flowfield and the various rocket plumes can cause localized aerodynamic disturbances yielding significant and highly non-linear control amplifications and attenuations. This paper discusses the scaling methodologies used to model the flight plumes in the wind tunnel using cold air as the simulant gas. Comparisons of predicted flight, predicted wind tunnel, and measured wind tunnel forces-and-moments and plume flowfields are made to assess the effectiveness of the selected scaling methodologies

The Origin of Nitrogen on Jupiter and Saturn from the 15^{15}N/14^{14}N Ratio

The Texas Echelon cross Echelle Spectrograph (TEXES), mounted on NASA's Infrared Telescope Facility (IRTF), was used to map mid-infrared ammonia absorption features on both Jupiter and Saturn in February 2013. Ammonia is the principle reservoir of nitrogen on the giant planets, and the ratio of isotopologues ($^{15}$N/$^{14}$N) can reveal insights into the molecular carrier (e.g., as N$_2$ or NH$_3$) of nitrogen to the forming protoplanets, and hence the source reservoirs from which these worlds accreted. We targeted two spectral intervals (900 and 960 cm$^{-1}$) that were relatively clear of terrestrial atmospheric contamination and contained close features of $^{14}$NH$_3$ and $^{15}$NH$_3$, allowing us to derive the ratio from a single spectrum without ambiguity due to radiometric calibration (the primary source of uncertainty in this study). We present the first ground-based determination of Jupiter's $^{15}$N/$^{14}$N ratio (in the range from $1.4\times10^{-3}$ to $2.5\times10^{-3}$), which is consistent with both previous space-based studies and with the primordial value of the protosolar nebula. On Saturn, we present the first upper limit on the $^{15}$N/$^{14}$N ratio of no larger than $2.0\times10^{-3}$ for the 900-cm$^{-1}$ channel and a less stringent requirement that the ratio be no larger than $2.8\times10^{-3}$ for the 960-cm$^{-1}$ channel ($1\sigma$ confidence). Specifically, the data rule out strong $^{15}$N-enrichments such as those observed in Titan's atmosphere and in cometary nitrogen compounds. To the extent possible with ground-based radiometric uncertainties, the saturnian and jovian $^{15}$N/$^{14}$N ratios appear indistinguishable, implying that $^{15}$N-enriched ammonia ices could not have been a substantial contributor to the bulk nitrogen inventory of either planet, favouring the accretion of primordial N$_2$ from the gas phase or as low-temperature ices.Comment: 33 pages, 19 figures, manuscript accepted for publication in Icaru

Effects of the Orion Launch Abort Vehicle Plumes on Aerodynamics and Controllability

Characterization of the launch abort system of the Multi-purpose Crew Vehicle (MPCV) for control design and accurate simulation has provided a significant challenge to aerodynamicists and design engineers. The design space of the launch abort vehicle (LAV) includes operational altitudes from ground level to approximately 300,000 feet, Mach numbers from 0-9, and peak dynamic pressure near 1300psf during transonic flight. Further complicating the characterization of the aerodynamics and the resultant vehicle controllability is the interaction of the vehicle flowfield with the plumes of the two solid propellant motors that provide attitude control and the main propulsive impulse for the LAV. These interactions are a function of flight parameters such as Mach number, altitude, dynamic pressure, vehicle attitude, as well as parameters relating to the operation of the motors themselves - either as a function of time for the AM, or as a result of the flight control system requests for control torque from the ACM. This paper discusses the computational aerodynamic modeling of the aerodynamic interaction caused by main abort motor and the attitude control motor of the MPCV LAV, showing the effects of these interactions on vehicle controllability

Conformation of the Transmembrane Domain of the Anthrax Toxin Receptor

Restauració dels vitrallsFoto final, plafó a6, cara interna, amb llum a través. Geomètric

The unrealized promise of forensic science – a study of its production and use

In theory, forensic science provides objective, dispassionate evidence in criminal justice proceedings often charged with emotion, cognitive biases, and the failings of human recollection. By being theoretically objective and independent from other actors and processes in the criminal justice process, forensic science has the potential to make the criminal process more reliable by reducing both wrongful convictions and unsolved crimes. But how does it work in practice? Its leading role in many wrongful convictions suggests caution. To better understand the actual role of forensic science, we collected data on the prevalence and use of forensic evidence in five jurisdictions in multiple stages of the criminal process. We also analyzed existing data on crime labs and conducted an experimental survey of prosecutors and criminal defense attorneys to measure the effect of forensic evidence on the plea-bargaining process. Our findings are sobering. While forensic evidence is regularly in homicide cases, it is(still) being analyzed in only a small fraction of cases in which it is available. In those few cases, its use is highly limited by resource constraints, resulting in long turnaround times for less serious offenses, which encourage police and prosecutors to rely on other types of evidence. When it is used, it is often tested late in the criminal process, sometimes to meet juror expectations. While an understandable reaction to limited forensic resources, this late timing may lead to both unsolved crimes and pressure to conform to pre existing theories of guilt. Despite the theoretical potential of forensic science to improve the reliability of the criminal process, the way it is actually used squanders many of its advantages. As a result, the potential of forensic evidence to improve the criminal process remains largely unrealized

Book Reviews

The Hebrew God: Portrait of an Ancient Deity Lang, Bernhard New Haven and London: Yale University Press, 2002 Reviewed By Bill T. Arnold A Marginal Jew, vol. 3, Companions and Competitors Meier, John P New York, N.Y.: Doubleday, 2001 Reviewed By Mattie Greathouse The Gospel of Mark: A Soda-Rhetorical Commentary Witherington, Ill, Ben Grand Rapids: William B. Eerdmans, 2001 Reviewed By Greg Carey After Our Likeness: The Church as the Image of the Trinity. Trans. Doug Scott Voli, Miroslav Grand Rapids, MI: William B. Eerdmans, 1998 Reviewed By Howard A. Snyder The Literary Structure of the Old Testament: A Commentary on Genesis-Malachi Dorsey, David A. Grand Rapids: Baker, 1999 Reviewed By Joel H. Hunt Make the Old Testament Live: From Curriculum to Classroom Hess, Richard S., and Cordon J. Wenham, editors Eerdmans, 1998 Reviewed By Joel H. Hunt Christology Schwarz, Hans Grand Rapids : William B. Eerdmans, 1998 Reviewed By Greg Carey New Testament History: A Narrative Account Witherington, Ben Grand Rapids: Baker, 2001 Reviewed By Ruth Anne Reese The Omphalos and the Cross: Pagans and Christians in Search of a Divine Center Ciholas, Paul Macon : Mercer University Press, 2003 Reviewed By Michael Harstad Participating in God: Creation and Trinity Powell, Samuel M. Minneapolis: Fortress Press, 2003 Reviewed By James Holsinger Judges. Interpretation Commentary Series McCann, J. Clinton Louisville: Westminster/John Knox, 2002 Reviewed By Victor H. Matthews Clark H. Pinnock: Journey Toward Renewal: An Intellectual Biography Callen, Barry L Published in Cooperation with The Wesleyan Theological Society. Nappanee, IN: Evangel Publishing House, 2000 Reviewed By Howard A. Snyder Radical Christianity: The Believers Church Tradition in Christianity\u27s History and Future Callen, Barry L Nappanee, IN: Evangel Publishing House, 1999 Reviewed By Howard A. Snyder The Unity Movement Vahle, Neal Philadelphia: Templeton Foundation Press, 2002 Reviewed By Steven Tsoukala

Astro2020 Science White Paper: Triggered High-Priority Observations of Dynamic Solar System Phenomena

Unexpected dynamic phenomena have surprised solar system observers in the past and have led to important discoveries about solar system workings. Observations at the initial stages of these events provide crucial information on the physical processes at work. We advocate for long-term/permanent programs on ground-based and space-based telescopes of all sizes - including Extremely Large Telescopes (ELTs) - to conduct observations of high-priority dynamic phenomena, based on a predefined set of triggering conditions. These programs will ensure that the best initial dataset of the triggering event are taken; separate additional observing programs will be required to study the temporal evolution of these phenomena. While not a comprehensive list, the following are notional examples of phenomena that are rare, that cannot be anticipated, and that provide high-impact advances to our understandings of planetary processes. Examples include: new cryovolcanic eruptions or plumes on ocean worlds; impacts on Jupiter, Saturn, Uranus, or Neptune; extreme eruptions on Io; convective superstorms on Saturn, Uranus, or Neptune; collisions within the asteroid belt or other small-body populations; discovery of an interstellar object passing through our solar system (e.g. 'Oumuamua); and responses of planetary atmospheres to major solar flares or coronal mass ejections.Comment: Astro2020 white pape

Enhanced C2_2H2_2 absorption within Jupiter's southern auroral oval from Juno UVS observations

Reflected sunlight observations from the Ultraviolet Spectrograph (UVS) on the Juno spacecraft were used to study the distribution of acetylene (C$_2$H$_2$) at Jupiter's south pole. We find that the shape of the C$_2$H$_2$ absorption feature varies significantly across the polar region, and this can be used to infer spatial variability in the C$_2$H$_2$ abundance. There is a localized region of enhanced C$_2$H$_2$ absorption which coincides with the location of Jupiter's southern polar aurora; the C$_2$H$_2$ abundance poleward of the auroral oval is a factor of 3 higher than adjacent quiescent, non-auroral longitudes. This builds on previous infrared studies which found enhanced C$_2$H$_2$ abundances within the northern auroral oval. This suggests that Jupiter's upper-atmosphere chemistry is being strongly influenced by the influx of charged auroral particles and demonstrates the necessity of developing ion-neutral photochemical models of Jupiter's polar regions.Comment: Accepted in JGR: Planet

NASA Standing Review Board Handbook

No abstract availabl