SH21B-1592
The Heliosphere Interface in Different Models
In this paper results of modeling of the heliosphere interface obtained from the 3D MHD simulations are shown. We analyze heliosphere asymmetries for several sets of boundary conditions of the unperturbed solar wind and interstellar medium. Models are calculated for the spherical/non-spherical solar wind, and with/without the interplanetary magnetic field, in the presence of the interstellar magnetic field. The plasma - neutral hydrogen interaction via charge exchange is included. Comparison with other results is presented.
SH21B-1593
Unraveling the heliosphere using ENA data and computational models
Despite the success of the Voyager mission, whose twin spacecraft have crossed the heliospheric termination shock and are on their way to the heliopause, most of the heliospheric interface remains beyond reach. The method of remote sensing of the distant heliopshere using energetic neutral atoms (ENA's) has recently gained popularity. ENA's are created when an interstellar neutral atom (predominantly Hydrogen) charge-exchanges with a proton from the sub-sonic solar wind. The resulting H-atom has the velocity of the proton, but is no longer constrained by electric or magnetic fields and can travel large distances across the heliosphere before a secondary collisional encounter. Several missions have detected these heliospheric ENAs, and the recently launched IBEX mission is dedicated solely to ENA detection. To deconvolve the heliospheric proton distribution and to estimate heliospheric structure implied by ENA observations, it is useful to look at global computational models of the heliosphere for a variety of boundary conditions. I will present the latest results of our 3D model of the heliospheric interface which couples an MHD approach for the ionized component to a kinetic description of neutral Hydrogen. By self-consistent including a non-Maxwellian distribution function for heliospheric protons, we are able to approximate the effects of pick-up ions and the resulting suprathermal ENAs into our model.
SH21B-1594
Upper limits on Energetic Neutral Atom (ENA) emission from the heliosheath established by IMAGE/HENA
From the end of the year 2000 until nearly the end of 2005, high energy (10-200 keV/nuc) Energetic Neutral Atom (ENA) flux in the near Earth space environment was measured by the HENA instrument aboard the IMAGE spacecraft. Although the instrument was designed to sense ENA flux originating from magnetospheric sources, the instrument spent a significant amount of time pointed away from both the magnetosphere and the sun. During these periods, the instrument was pointed towards potential ENA emission sources in the outer heliosphere. The count rates in these areas of the sky were very much smaller than those when the instrument was pointed towards magnetospheric sources, thus long term integration is required to extract heliospheric signals. We present here images and spectra from these heliospheric viewing periods assembled from the entire time range of the mission. We've found that the heliospheric emission in areas sampled by HENA are at or very close to the background signal caused by ultraviolet light falling on the detectors. Because of the need to avoid the sun and the magnetosphere, our data set does not include directions close to the nose or interstellar inflow direction. Thus, the results presented here establish upper limits on heliospheric ENA emission in the 10-200 keV/nuc energy range, and can thus be used to constrain models of the processes thought to occur near the heliopause.
SH21B-1595
Combining the HSTOF ENA Observations With Voyager ion Data to Image the Forward Heliosheath
Since 1996 the HSTOF instrument on board SOHO has been measuring the flux of hydrogen and helium ENA. The most likely source of these atoms is neutralization of the energetic ions in the heliosheath by charge exchange with low energy neutral gas. After the crossing of the termination shock by Voyagers, the energy spectra of these ions were measured in situ. The energy range of the HSTOF ENA measurements overlaps with the Voyager LECP. By comparing the measured ENA fluxes with those of the parent ions we can thus calculate the column density of the neutral hydrogen gas in the forward heliosheath required to account for the observed ENA flux. This permits us to estimate the thickness of the forward heliosheath. We present our recent results which take into account both Voyager 1 and Voyager 2 ion spectra. We also discuss the relationship between the HSTOF and the STEREO ENA data and their implications for the structure of the forward heliosheath.
SH21B-1596
The Heliospheric Contribution to the Soft X-ray Background Emission
The soft x-ray background observed from Earth contains contributions not only from outside the solar system such as the local bubble but contributions from within the solar system including from the interplanetary medium and from the terrestrial geocorona and magnetosheath. Great effort was spent on removing non- cosmic contamination from data collected during the ROSAT all-sky survey. Some of the contamination, however, was due to X-ray emission from solar wind charge exchange with interstellar and geocoronal neutrals. The time varying component of this contamination was removed, but the steady state component of this X-ray emission was not. We will present all-sky maps of the soft X-ray emission with the heliospheric component removed, which will allow a re-interpretation of the nature of the local interstellar bubble. We have calculated this steady statement component for and will discuss its contribution to the ¼ and ¾ keV all- sky survey maps.
SH21B-1597
Mirror instability in the heliosheath
We investigate the nature of the heliosheath plasma behind the Termination Shock across which jump relations in anisotropic MHD are formulated. Along side analytical results for downstream parameters in the strictly parallel and perpendicular cases we numerically solve the Rankine-Hugoniot relations for arbitrary shock angle and strength. We then focus on conditions favorable to the triggering of a temperature anisotropy driven instability, the mirror instability. We confirm results showing that the heliosheath plasma observed by Voyager 1 immediately behind the Termination Shock is mirror unstable. Similar conditions are probable in the heliosheath recently encountered by Voyager 2. The variation with upstream parameters, which may be due to inward or outward motions of the shock, is also addressed. Finally, by comparing with studies in the Earth's magnetosheath context, we formulate predictions on the shapes of mirror associated magnetic fluctuations in the heliosheath. Both hole and peak magnetic structures were indeed observed by Voyager 1 and these shapes correspond to different stages of the mirror instability.
SH21B-1598
Effects Non-uniform Flux Transfer and Empirically Based Heliosheath Plasma Distributions on Global Maps of Heliospheric Energetic Neutral Atoms
The launch of the Interstellar Boundary Explorer (IBEX) begins a new generation of outer heliospheric science. From its high-altitude orbit, the IBEX mission will produce the first all-sky maps of energetic neutral atoms (ENAs) created directly from the heliosheath plasma, which carries the imprint of the global boundaries of the solar system. Here, we explore the importance of key interstellar and solar wind parameters to global maps of ENA flux at 1 AU, generated by a combination of physical models: a magnetohydrodynamic heliosheath plasma simulation, flux-transfer through the heliosphere including non-uniform loss, and a full IBEX instrument model. We also discuss the impact of the pick-up ion and thermal solar wind distributions as implied by recent STEREO and Voyager measurements.
SH21B-1599
Energy partition of the heliospheric termination shock
We have examined energy dissipation via ion reflection and transmission at the heliospheric termination shock in the presence of pickup ions. Our simulations using the Los Alamos hybrid code show that transmitted pickup ions and the reflected solar wind ions carry the dominant pressures downstream of the shock. These results agree well with Voyager 2's observations of the termination shock crossing, which showed that populations other than the core solar wind must carry the majority of the downstream pressure. An analytical model for energy partition at the termination shock is developed. Results of the hybrid simulation strongly support the results of the analytic model. We go on to use the analytic model to predict the distributions that may be observed by the Interstellar Boundary Explorer Mission. Thus, we provide a theoretical framework to bridge Voyager 2 observations of the termination shock with energetic neutral atom observations from IBEX.
SH21B-1600
Heliospheric current sheet in global SW-LISM structure
The distribution of interplanetary magnetic field (IMF) in the distant solar wind and in the heliosheath is of great interest for solar wind (SW) interaction with local interstellar medium (LISM). This is because it is measured by Voyager spacecraft and therefore can be used to tune up theoretical models on the basis of observational data. One of the main difficulties one encounters when modeling IMF is the necessity to resolve the heliospheric current sheet (HCS). The angle between the Sun's rotation and magnetic-dipole axes is never zero, varying from about 8-9 degrees during solar minima to 90 degrees at solar maxima. As a result of Sun's rotation, the distance between two consecutive crossings of the ecliptic plane by the HCS becomes as small as about 3 AU in the supersonic SW and about 1 AU in the inner heliosheath. In this study we investigate HCS evolution in the SW using our global multi-fluid simulations. To achieve desired resolution we use three-dimensional adaptive spherical meshes implemented in the framework of Multi-Scale Fluid-Kinetic Simulation Suite (MS-FLUKSS) – a software package developed with the support of the NASA and NSF grants.
SH21B-1601
Numerical simulations and stability of magnetic structures in the heliosheath
We extend the three fluid model of Avinash and Zank [2007] for magnetic structures in the heliosheath to a four fluid model consisting of electrons, pick-up ions (PUIs), solar wind ions (SWI), and neutral hydrogen. The PUIs are generated by neutrals via charge exchange with SWI. Since the kinetic pressure of PUIs is nearly three to four times the pressure of SWI, these are more suited to mediate small scale structures in the heliosheath such as magnetic holes/humps etc. The constant energy exchange between these two fluids drives them non-adiabatic. The PUIs are isothermal while SWI are non adiabatic with an index ~1.25. The four fluid model captures these effects via a modified equation of state for PUI and SWI. The phase space of time independent solutions in terms of the Mach numbers of PUI and SWI is constructed to delineate the parameter space which allows structure formation in the heliosheath. We examine the stability of the time independent solutions by evolving them via a full system of Hall –MHD equations. The simulation results show that these solutions are not quite stable. As the structure propagates it develops growing oscillations in the wings. Concomitantly, there are changes in the amplitude and width of the structure. This instability could be due to local changes in the velocity of the structure and reflects an exchange between the kinetic and magnetic parts of the total energy. Our results showing the presence of growing oscillations in the wings of solitary wave solutions are consistent with the recent analysis of magnetic holes in the heliosheth by Burlaga et al [2007].
SH21B-1602
The Charging of Dust Grains in the Inner Heliosheath
Equilibrium electric charge and surface potential on a dust grain in the heliosheath are calculated. The grain is charged due to heliosheath plasma flux, photo electrons flux, secondary electron emission flux and transmission flux. Realistically, the heliosheath plasma consists of solar electrons, solar wind ions [SWI] and pick up ions [PUI]. These species interact differently with TS and thus have different characteristics down stream in the heliosheath. The PUI suffer multiple reflections at TS and are accelerated to high energies in the range of ~ 106 K. The solar electrons, on the other hand, are heated adiabatically through the TS and have temperature in the range ~ 5x105 K. The SWI may have a smaller temperature typically in the range 1-5x104 K The density of electrons could be in the range ~5 x 10-4 cm-3, while the ratio of PUI to SWI density could range from 0.1 to 0.5. Taking into account these parameters, grain charging due to different plasma species and other fluxes mentioned earlier, is calculated. Our results show that (a) surface potential is very sensitive to electron temp. It goes through a maxima and for realistic values close to or less than 5x105 K it can be as big as 26V which is twice the value calculated by Kimura and Mann1. This may have implications for electrostatic disruption and the size distribution of dust particles in the heliosheath. With PUI density the surface potential increases about 10 to 20 %. Though temperature of PUI is significantly larger than that of electrons, it is not large enough to make up for the mass ratio of electrons to protons. On account small temperature and electron/proton mass ratio, the effect of SWI on dust charge is very weak. (1) H. Kimura and I. Mann, Ap.J. 499, 454 (1998).
SH21B-1603
Pick-up Ion Distribution Functions and Revisions to the 2-3 kHz Radiation Theory
The 2-3 kHz radio emissions observed by the Voyager spacecraft are thought to result from the acceleration of nonthermal electrons by shocks associated with global merged interaction regions (GMIRs) traveling through the outer heliosheath. It has been proposed that the nonthermal electrons are accelerated by lower-hybrid waves, generated by pick-up ions which form ring beam distribution functions in velocity space perpendicular to B. Here, we calculate the distribution function of pick-up ions formed in the outer heliosheath by charge exchange with neutrals born in the outer heliosheath (region 1), inner heliosheath (region 2), and solar wind (region 3). It is found that pick-up ions formed by charge exchange with the slow region 2 neutrals do not have ring-beam distributions as previously thought. These pick-up ions only form a shoulder without large gradients ∂ f/∂ v⊥ able to drive waves, since the neutrals are rather warm. Instead, ring-beams are formed by charge exchange with region 3 neutrals. This causes the ring speed to be a factor of ~~4 higher and the number density to decreased by a factor of ~~1/10 compared with the earlier estimates. The maximum energy available for waves and so particle acceleration increases by a factor of ~ 1.6. With this change in the source population of neutrals/pick-up ions the earlier theory for the radio emissions [Cairns and Zank, 2002, Mitchell et al., 2004] proceeds without qualitative changes. Combining this higher ring beam speed vr with constraints on the ratio vr/vA for lower-hybrid waves to accelerate electrons effectively increases the maximum magnetic field in the VLISM to ~~0.2~nT (here vA is the Alfvén speed). Calculations are ongoing for the spatial variation in the pick-up ion number density as a function of interstellar magnetic field orientation. It is found that pick-up ion kinematics is vital and that v∥ ≫ vE × B, contrary to earlier expectations. Cairns, I.~H., and G.~P. Zank (2002), Geophys. Res. Lett., 29(7), 47. Mitchell, J.~J., I.~H. Cairns, and P.~A. Robinson (2004), J. Geophys. Res., 109, 6108.
SH21B-1604
Solar Magnetic Polarity Dependence of the Seasonal Occurrence of Geomagnetic Storms
To investigate the seasonal variation and its solar magnetic polarity dependence of geomagnetic activity, we performed the statistical analysis on the geomagnetic storms defined by Dst index. We used storm data for 5 years each at solar minimums during the 4 solar cycles 19 to 22 (1962-1998) for even two of each solar magnetic polarities. We selected total 156 geomagnetic storms of Dst(min) < -50 nT, |Dst| > 100 nT and compared the monthly occurrence of those storms. The geomagnetic storms occurred more frequently in spring and fall seasons for all solar cycle minimums regardless of the solar magnetic polarity. It is in the summer and winter seasons that the geomagnetic storm occurrence rate increased more for the solar cycles 20 and 22 when the solar magnetic polarity is anti-parallel to the Earth's than the solar cycles 19 and 21.
SH21B-1605
Temporal and Spatial Variations of Pickup Ions seen on STEREO/PLASTIC
Pickup ions seem to be a perfect tracer of interplanetary discontinuities in the heliosphere and they provide important information on acceleration processes at these structures and in the turbulent solar wind (i.e. suprathermal tails). Studies of pickup ions using AMPTE, Ulysses, SOHO, Wind and ACE demonstrated that pickup ion fluxes and the shape of their distributions can vary substantially on time scales from less than one hour to many days. These variations have been attributed to changes in the interplanetary magnetic field (IMF) direction and strength in the sense of incomplete pickup and/or density compressions and decompressions. For instance, at CIRs one observes the most intense and most prolonged enhancements of energetic helium pickup ions. At present, the vast majority of the observed temporal variations remain unexplained. Furthermore, spatial variations of pickup ion distributions could not be studied with single spacecraft observation. Simultaneous observations of pickup ion distributions with the PLASTIC instrument on STEREO A and B now provide the opportunity to follow pickup ion variations on spatial scales from a few 106 km to 108 km. In the early mission phase STEREO A and B were often along the same magnetic field flux tubes. This allows us to study temporal effects. With increasing spacecraft separation spatial effects can be studied. In this presentation we will show STEREO observations of helium pickup ion spectra and fluxes for 2007/8 in their dependence on solar wind density, speed and flux as well IMF direction and strength on both spacecraft. We then determined whether the observed variations are mainly correlated features that are associated with spatial structures passing the STEREO spacecraft at different times (such as CIRs or the focusing cone), or whether they have a substantial uncorrelated component indicative of temporal variations.
SH21B-1606
Expected Performance of the IBEX Star Sensor for Accurate Pointing of IBEX-lo Sensor
One of the key objectives of the IBEX mission is to compare the interstellar O with the He flow through the solar system in order to assess deceleration and deflection of O in the heliospheric interface. This comparison requires an accurate determination of the direction of incoming energetic neutral atoms (ENAs) of the interstellar gas flow with the IBEX-Lo sensor. To achieve the needed accuracy without placing stringent pointing requirements on the satellite, a simple star sensor that works with an aperture mask has been integrated into the sensor itself. It makes stars, planets and the moon available as pointing reference for the ENA observations. In comprehensive calibrations of the flight and flight spare models, it has been demonstrated that the pointing accuracy is better than 0.1o as required. For a star sensor that is based on an aperture mask rather than a high-resolution image, diffuse sky background poses a challenge. Therefore, we have also shown that the dynamic range is large enough to incorporate the moon and planets as target objects. In addition, we have modeled the diffuse sky background so that effective subtraction of this light component is possible and thus improves the contrast for stars of moderate magnitude. Further modeling of the spectral dependence of the diffuse components is ongoing. We will discuss the expected flight performance of the star sensor based on these calibration measurements and simulations.
SH21B-1607
Diagnosing Pickup Ion Distributions beyond the Termination Shock through Ener-getic Neutral Atoms
The solar wind accumulates interstellar pickup ions throughout the heliosphere, which can be described with an isotropic velocity distribution in the plasma frame with a cut-off at the solar wind speed. This distribution is then transported across the termination shock where it is slowed down and heated, thus producing a distribution with a significant portion of ions that show velocity components towards the Sun. In the interaction with the interstellar gas flow through the heliosphere a fraction of these pickup ions is turned into energetic neutral atoms (ENAs), the sunward pointing portion of which can then be observed by ENA sensors in the inner heliosphere, such as instruments on Mars Express, STEREO, and IBEX. In this contribution we generate a simplified analytical model of the pickup ions and their ENA counterparts for a hydrodynamic flow pattern in the heliosheath. The energy distribution of the ENAs is sensitive to the radial component of the heliosheath flow. The attempt is made to predict spatial patterns of the ENA spectra based on the heliosheath flow pattern for comparison with future IBEX maps. These patterns will also be compared with angular variations and temporal changes in the recently published ENA observations with STEREO STE (Wang, L., R.P. Lin, D.E. Larson, J. Luhman, Nature, 454, 81-83, 2008).
SH21B-1608
Modeling the neutral hydrogen distribution function at the termination shock
Recent results from the Voyager termination shock crossings, and the interpretation of the forthcoming IBEX measurements, underscore the necessity to understand and accurately model neutral hydrogen throughout the heliosphere, and the consequent production of pickup ions in the inner heliosphere and energetic neutral atoms in the heliosheath. The neutral distribution functions at the termination shock are necessary as boundary input for detailed models of the inner heliosphere. In this contribution, the termination shock is characterized with the help of a global heliospheric multi-fluid model; its distance, shock strength, and downstream effective temperature change as a function of angle from the stagnation axis. The neutrals crossing the termination shock (both outbound and inbound) are characterized and decomposed into components of different heliospheric origin. With this information taken as an outer boundary, the modeling of the neutral particle distributions in the region of the supersonic solar wind (inner heliosphere) is taken over by a trajectory and ionization-losses simulation that interfaces at the termination shock with the multi-fluid model. The latter is responsible for modeling the heliosphere from the termination shock outwards. The neutral distribution functions in the inner heliosphere are found to be complex, and deviate from the often- used "hot model" of heliospheric neutrals.
SH21B-1609
Examination of the Voyager 2 Plasma Observations in the Vicinity of the Termination Shock
We examine the plasma distributions obtained by the MIT plasma probe on Voyager 2 in 2007. These are the first plasma data obtained in the vicinity of the termination shock. The Voyager 2 plasma observations (Richardson et al., Nature, 454, July 2008,doi:10.10338, p.63) were somewhat surprising. Richardson et al. reported that following the termination shock crossing the solar wind flow did not become subsonic as expected. Rather Richardson et al. reported the solar wind flow slowed, but still remained supersonic. We examine some of the details of the MIT plasma data. We compare the plasma data with other in-situ spacecraft measurements. The results also are evaluated in terms of theoretical expectations. Our detailed analyses show that the time periods around the reported termination shock crossings are more complex and revealing than earlier believed. This work is sponsored by NASA Grant NNX08AE40G and by Carmel Research Center. We are grateful to John Richardson for providing the Voyager 2 MIT plasma data.
SH21B-1610
The Effects of Pickup Ions on Magnetic Reconnection at the Heliopause
Recent observations by the Voyager 2 spacecraft after crossing the termination shock suggest that interstellar pickup ions account for most of the plasma energy downstream from the heliopause. This implies that the plasma beta (the ratio of the thermal to magnetic pressure) is significantly larger than unity and that strong gradients in the temperature exist at the heliopause. Previous work has shown that for similar conditions at the Earth's magnetopause the diamagnetic drift of X-lines stabilizes magnetic reconnection unless the reconnecting fields are nearly anti-parallel. We explore the heliospheric case with a combination of MHD simulations of the heliosphere and PIC simulations of the region near the X-line and make predictions for the Voyager crossings of the heliopause.
SH21B-1611
Initial Results From the 3D Hybrid Heliospheric Modeling System With Pickup Protons
Interstellar neutral hydrogen flows into the heliosphere and becomes ionized by photoionization and by charge exchange with solar wind protons. These "pickup" protons cause a slowing and heating of the solar wind flow in the outer heliosphere. We are adding the physics of these processes to our time-dependent 3D Hybrid Heliospheric Modeling System. We plan to present initial results for the "Halloween" 2003 events, and to show comparisons with both ACE and Ulysses observations and with our previous results (without pickup protons). This work is sponsored by NASA Grant NNX08AE40G and by Carmel Research Center. Detman et al., 2006, A hybrid heliospheric modeling system: Background solar wind, J. Geophys. Res., V 111, doi:10.1029/2005JA011340
SH21B-1612
The Local Interstellar Magnetic Field: A View From Voyagers
Voyager 2 (V2) crossed the termination shock (TS) on August 30, 2007 at a distance 84 AU and about 10 AU closer to the Sun than Voyager 1 (V1) on December 16, 2004. This asymmetry can result from the solar wind dynamic pressure asymmetry, from the shock motion or from the local interstellar magnetic field (LIMF) asymmetric pressure. We show that if the interstellar magnetic field were the only factor responsible for the measured asymmetries, it is possible to find such a shape of the TS, which would reflect the real positions of V1 and V2 when they crossed the shock. It places an additional constraint on the orientation and magnitude of the interstellar magnetic field. Our predictions on the LIMF are well correlated with observations and measurements reported by Lallement et al., Science 307, p. 1447, 2005, Gurnett et al., AIP 858, p.129, 2006, and Wang et al., Nature 454, p.81, 2008.
SH21B-1613
The Direction of the Interstellar Magnetic Field at the Sun
The direction of the interstellar magnetic field (ISMF) at the heliosphere has been obtained from the weak polarizations of optical light from nearby stars in the direction of the heliosphere nose. Polarization position angles (PA) trace the magnetic field direction, and the optical polarization PA agrees with the ISMF direction traced by the offset between the upwind directions of interstellar HeI and HI inside of the heliosphere. (The upwind directions of HI and HeI must first be adjusted to a consistent coordinate system, which here is taken to be the J2000 system.) These findings suggest that high signal-to-noise ground-based polarization data of nearby stars may possibly provide a low-cost method to monitor the magnetic field in the outer heliosheath.
SH21B-1614
Evolution of the Anomalous Cosmic Ray Energy Spectra at Voyager 1 and 2 in the Heliosheath
In December 2008 the Voyager 1 (V1) spacecraft will be at ~108 AU and 34 deg N. It is in the heliosheath, ~17 AU beyond the solar wind termination shock (TS) at that latitude. The Voyager 2 (V2) spacecraft will be at ~88 AU and 28 deg S. It also is in the heliosheath, having crossed the TS several times from 30 August to 1 September 2007 at 83.7 AU. The energy spectra of H, He, and O in the heliosheath show evidence of three separate components: a low-energy termination shock particle (TSP) component that likely originates locally at the TS and is convected to the spacecraft, a high-energy galactic cosmic ray (GCR) component, and a mid-energy anomalous cosmic ray (ACR) component whose source region and acceleration mechanism are the subject of differing models. Since ~mid-2005 the TSP component at Voyager 1 has been remarkably steady. Subtracting this component and the GCR component reveals evolving ACR spectra that appear to be unfolding towards source spectra as V1 moves deeper into the heliosheath. At V2 there has been significant evolution in the TSP energy spectra during its ~one year in the heliosheath. Recently, however, the TSP energy spectra resemble those at V1 and the ACR energy spectra have a heavily modulated shape resulting in an energy-dependent positive gradient between the two spacecraft. We will examine the ACR energy spectra at both V1 and V2 and compare with predictions of competing theoretical models for the origin and acceleration of ACRs. This work was supported by NASA under contract NAS7-03001.
SH21B-1615
New Access and Analysis Tools for Voyager LECP Data
The Low Energy Charged Particle (LECP) instruments on the Voyager 1 and 2 spacecraft have been returning unique scientific measurements since launching in 1977, most notably observations from the historic tour of the giant planets. As these spacecraft continue on their exit trajectories from the Solar system they have become an interstellar mission and have begun to probe the boundary between the heliosphere and the interstellar cloud and continue to make exciting discoveries. As the mission changed from one focused on discrete encounters to an open ended search for heliospheric boundaries and transitory disturbances, the positions and timing of which are not known, the data processing needs have changed. Open data policies and the push to draw data under the umbrella of emerging Virtual Observatories have added a data sharing component that was not a part of the original mission plans. We present our work in utilizing new, reusable software analysis tools to access legacy data in a way that leverages pre-existing data analysis techniques. We took an existing Applied Physics Laboratory application, Mission Independent Data Layer (MIDL) -- developed originally under a NASA Applied Information Research Program (AISRP) and subsequently used with data from Geotail, Cassini, IMP-8, ACE, Messenger, and New Horizons -- and applied it to Voyager data. We use the MIDL codebase to automatically generate standard data products such as daily summary plots and associated tabulated data that increase our ability to monitor the heliospheric environment on a regular basis. These data products will be publicly available and updated automatically and can be analyzed by the community using the ultra portable MIDL software launched from the data distribution website. The currently available LECP data will also be described with SPASE metadata and incorporated into the emerging Virtual Energetic Particle Observatory (VEPO).
SH21B-1616
Pickup Ion Acceleration at Quasiperpendicular Shock Waves
The detailed dynamics of pickup ion reflection from the electrostatic potential of a perpendicular collisionless shock is treated at the test particle level. Both shell and filled-shell distributions are considered, the first being a simplification model for the distribution of pickup ions that have been pitch-angle-scattered onto a bispherical shell in velocity space associated with backward and forward traveling Alfvén waves; the second is an extension of the shell but with the interior of the sphere filled in according to the isotropic solar wind, cold neutral gas model of the PUI velocity distribution. Both shell and fill-shell PUI distributions are energized by multiply ion reflection from the cross-shock potential. Efficiently energized hard power law spectra with maximum energy gain depending on the narrowness of the ramp width of the cross shock potential are found. Energized filled-shell spectra are found to be more smooth and, in some narrow ramp cases, more physically plausible then shell.