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The Ulysses spacecraft has been orbiting the Sun on a highly inclined ellipse since it encountered Jupiter in February 1992. Since then it made almost three revolutions about the Sun. Here we report on the final three years of data taken by the on-board dust detector. During this time, the dust detector recorded 609 dust impacts of particles with masses 10^-16 g <= m <= 10^-7 g, bringing the mission total to 6719 dust data sets. The impact rate varied from a low value of 0.3 per day at high ecliptic latitudes to 1.5 per day in the inner solar system. The impact direction of the majority of impacts between 2005 and 2007 is compatible with particles of interstellar origin, the rest are most likely interplanetary particles. We compare the interstellar dust measurements from 2005/2006 with the data obtained during earlier periods (1993/1994) and (1999/2000) when Ulysses was traversing the same spatial region at southern ecliptic latitudes but the solar cycle was at a different phase. During these three intervals the impact rate of interstellar grains varied by more than a factor of two. Furthermore, in the two earlier periods the grain impact direction was in agreement with the flow direction of the interstellar helium while in 2005/2006 we observed a shift in the approach direction of the grains by approximately 30 deg away from the ecliptic plane. The reason for this shift remains unclear but may be connected with the configuration of the interplanetary magnetic field during solar maximum. We also find that the dust measurements are in agreement with the interplanetary flux model of Staubach et al. (1997) which was developed to fit a 5-year span of Ulysses data., Comment: 50 pages, 9 b/w Figures, 1 colour figure, 4 Tables; submitted to Planetary and Space Science

The Galileo spacecraft was orbiting Jupiter between Dec 1995 and Sep 2003. The Galileo dust detector monitored the jovian dust environment between about 2 and 370 R_J (jovian radius R_J = 71492 km). We present data from the Galileo dust instrument for the period January 2000 to September 2003. We report on the data of 5389 particles measured between 2000 and the end of the mission in 2003. The majority of the 21250 particles for which the full set of measured impact parameters (impact time, impact direction, charge rise times, charge amplitudes, etc.) was transmitted to Earth were tiny grains (about 10 nm in radius), most of them originating from Jupiter's innermost Galilean moon Io. Their impact rates frequently exceeded 10 min^-1. Surprisingly large impact rates up to 100 min^-1 occurred in Aug/Sep 2000 when Galileo was at about 280 R_J from Jupiter. This peak in dust emission appears to coincide with strong changes in the release of neutral gas from the Io torus. Strong variability in the Io dust flux was measured on timescales of days to weeks, indicating large variations in the dust release from Io or the Io torus or both on such short timescales. Galileo has detected a large number of bigger micron-sized particles mostly in the region between the Galilean moons. A surprisingly large number of such bigger grains was measured in March 2003 within a 4-day interval when Galileo was outside Jupiter's magnetosphere at approximately 350 R_J jovicentric distance. Two passages of Jupiter's gossamer rings in 2002 and 2003 provided the first actual comparison of in-situ dust data from a planetary ring with the results inferred from inverting optical images., Comment: 59 pages, 13 figures, 6 tables, submitted to Planetary and Space Science

The Ulysses spacecraft is orbiting the Sun on a highly inclined ellipse ($ i = 79^{\circ}$, perihelion distance 1.3 AU, aphelion distance 5.4 AU). Between January 1996 and December 1999 the spacecraft was beyond 3 AU from the Sun and crossed the ecliptic plane at aphelion in May 1998. In this four-year period 218 dust impacts were recorded with the dust detector on board. We publish and analyse the complete data set of both raw and reduced data for particles with masses $\rm 10^{-16} g$ to $\rm 10^{-8}$ g. Together with 1477 dust impacts recorded between launch of Ulysses and the end of 1995 published earlier \cite{gruen1995c,krueger1999b}, a data set of 1695 dust impacts detected with the Ulysses sensor between October 1990 and December 1999 is now available. The impact rate measured between 1996 and 1999 was relatively constant with about 0.2 impacts per day. The impact direction of the majority of the impacts is compatible with particles of interstellar origin, the rest are most likely interplanetary particles. The observed impact rate is compared with a model for the flux of interstellar dust particles. The flux of particles several micrometers in size is compared with the measurements of the dust instruments on board Pioneer 10 and Pioneer 11 beyond 3 AU (Humes 1980, JGR, 85, 5841--5852, 1980). Between 3 and 5 AU, Pioneer results predict that Ulysses should have seen five times more ($\rm \sim 10 \mu m$ sized) particles than actually detected., Comment: accepted by Planetary and Space Science, 22 pages, 8 figures (1 colour figure)

Between Jan 1993 and Dec 1995 the Galileo spacecraft traversed interplanetary space between Earth and Jupiter and arrived at Jupiter on 7 Dec 1995. The dust instrument onboard was operating during most of the time. A relatively constant impact rate of interplanetary and interstellar (big) particles of 0.4 impacts per day was detected over the whole three-year time span. In the outer solar system (outside about 2.6 AU) they are mostly of interstellar origin, whereas in the inner solar system they are mostly interplanetary particles. Within about 1.7 AU from Jupiter intense streams of small dust particles were detected with impact rates of up to 20,000 per day whose impact directions are compatible with a Jovian origin. Two different populations of dust particles were detected in the Jovian magnetosphere: small stream particles during Galileo's approach to the planet and big particles concentrated closer to Jupiter between the Galilean satellites. There is strong evidence that the dust stream particles are orders of magnitude smaller in mass and faster than the instrument's calibration, whereas the calibration is valid for the big particles. Because the data transmission rate was very low, the complete data set for only a small fraction (2525) of all detected particles could be transmitted to Earth; the other particles were only counted. Together with the 358 particles published earlier, information about 2883 particles detected by the dust instrument during Galileo's six years' journey to Jupiter is now available., Comment: Accepted for Planetary and Space Science, 37 pages, 5 tables, 13 figures

The Ulysses spacecraft is orbiting the Sun on a highly inclined ellipse ($i = 79^{\circ}$). After its Jupiter flyby in 1992 at a heliocentric distance of 5.4 AU, the spacecraft reapproached the inner solar system, flew over the Sun's south polar region in September 1994, crossed the ecliptic plane at a distance of 1.3 AU in March 1995, and flew over the Sun's north polar region in July 1995. We report on dust impact data obtained with the dust detector onboard Ulysses between January 1993 and December 1995. We publish and analyse the complete data set of 509 recorded impacts of dust particles with masses between $10^{-16}$ g to $10^{-7}$ g. Together with 968 dust impacts from launch until the end of 1992 published earlier (Gr\"un et al., 1995, {\em Planet. Space Sci}, Vol. 43, p. 971-999), information about 1477 particles detected with the Ulysses sensor between October 1990 and December 1995 is now available. The impact rate measured between 1993 and 1995 stayed relatively constant at about 0.4 impacts per day and varied by less than a factor of ten. Most of the impacts recorded outside about 3.5 AU are compatible with particles of interstellar origin. Two populations of interplanetary particles have been recognised: big micrometer-sized particles close to the ecliptic plane and small sub-micrometer-sized particles at high ecliptic latitudes. The observed impact rate is compared with a model for the flux of interstellar dust particles which gives relatively good agreement with the observed impact rate. No change in the instrument's noise characteristics or degradation of the channeltron could be revealed during the three-year period., Comment: 35 pages, 8 figures, 3 Tables, rotating package and Latex 2e required

Upon its approach to orbit the dwarf planet Ceres in early 2015, optical navigation and dedicated satellite search images were acquired with the Dawn mission's framing camera 2. A team of searchers individually processed and examined the images for evidence of objects moving with Ceres. Completeness of search with respect to the space searched was calculated as a function of distance to Ceres and found to be complete down to 15 Ceres radii (Ceres' mean radius is 470 kilometers). Upper limits of detectable magnitude were determined for each observed set of images and an upper limit in size was calculated assuming for the putative objects, Ceres' geometric albedo of 0.11. Nothing was found associated with Ceres down to a radius of 12 meters for the most sensitive search, and down to a radius of 323m for the least sensitive search circumstances. Examination of the physical properties of the 41 largest and most massive main belt asteroids suggests that large asteroids without satellites are intact and their interiors have internal strength. This is consistent with results from the Dawn mission at both Vesta and Ceres. Ceres' volatile-rich composition also is a likely contributor to both the absence of satellites at Ceres and of Ceres meteorites at Earth. These results suggest that collisional disruption creating rubble pile structure is a necessary condition for formation of satellites around main belt asteroids.

On 12-Dec-2011, the Dawn spacecraft commenced low altitude mapping of the giant asteroid, 4 Vesta (264-km mean radius). Dawn's roughly circular, polar, low altitude mapping orbit (LAMO) has a mean radius of 470 km, placing the spacecraft within about 210 km of Vesta's surface. At these altitudes, Dawn s Gamma Ray and Neutron Detector (GRaND) is sensitive to Vesta's elemental com-position (Fig. 1). GRaND will acquire data in LAMO for up to 16 weeks, which is sufficient to map the elemental composition of the entire surface of Vesta. The timing of LAMO enables us to report the first results of our geochemistry investigation at this conference. In this abstract, we present an overview of our initial observations, based on data acquired at high altitude and during the first weeks of LAMO. GRaND overview. A detailed description of the GRaND instrument, science objectives and prospective results is given in [1]. At low altitudes, GRaND is sensitive to gamma rays and neutrons produced by cosmogenic nuclear reactions and radioactive decay occurring within the top few decimeters of the surface and on a spatial scale of a few hundred kilometers. From these nuclear emissions, the abundance of several major- and minor-elements, such as Fe, Mg, Si, K, and Th can be determined. Assuming the howardite, eucrite, and diogenite (HED) meteorites are representative of Vesta s crustal composition [2], then GRaND will be able to map the mixing ratios of whole-rock HED end-members, enabling the determination of the relative proportions of basaltic eucrite, cumulate eucrite, and diogenite as well as the proportions of mafic and plagioclase minerals [1,3]. GRaND will also search for compositions not well-represented in the meteorite collection, such as evolved, K-rich lithologies [4], and outcrops of olivine from Vesta s mantle or igneous intrusions in major impact basins [5]. The search for a possible mesosiderite source region is described in [6]. GRaND will globally map the abundance of H, providing constraints on the delivery of H by solar wind and the infall of carbonaceous chondrite materials.

Dawn?s Gamma Ray and Neutron Detector (GRaND) successfully completed Low Altitude Mapping Orbit (LAMO) at Vesta. Over four months were spent acquiring data in a 460-km radius orbit around Vesta (265-km mean radius). In LAMO, strong signatures from Vesta were observed for gamma rays and neutrons. We present preliminary abundances, detection limits, and global maps of the elemental composition of Vesta.

Upon approach to asteroid 4 Vesta, the Dawn mission included a dedicated satellite search observation of the operational sphere of the spacecraft around Vesta. Discovery of moons of Vesta would constrain theories of satellite f()rmation. The sequence using the framing camera and clear filter includes three mosaics of six stations acquired on July 9-10. 2011. Each station consists of four sets with three different exposures, 1.5,20 and 270 s. We also processed and scanned the optical navigation sequences until Vesta filled the field of view. Analysis of images involves looking for moving objects in the mosaics and identifying catalogued stars, subtracting them from the image and examining residual objects for evidence of bodies in orbit around Vesta. Celestial coordinates were determined using Astrometry.net, an astrometry calibration service (http://astrometry.net/use.html). We processed the images by subtracting dark and bias fields and dividing by a Hatfield. Images were further filtered subtracting a box car filter (9x9 average) to remove effects of scattered light from Vesta itself. Images were scanned by eye for evidence of motion in directions different from the background stars. All objects were compared with Hubble Space Telescope's Guide Star Catalogue and US Naval Observatory's UCAC3 catalog. We report findings from these observations and analysis, including limits of magnitude, size and motion of objects in orbit around Vesta. We gratefully acknowledge modifications made to Astrometrica http://www.astrometrica.at/ for purposes of this effort.

The Dawn mission has completed its Survey and High-Altitude Mapping Orbit (HAMO) phases at Vesta, resulting in 60-70 meter per pixel imaging, high-resolution image-derived topography, and visual and infrared spectral data covering up to approx.50 degrees north latitude (the north pole was in shadow during these mission phases). These data have provided unprecedented views of the south polar impact structure first detected in HST imaging [1], now named Rheasilvia, and in addition hint at the existence of a population of ancient basins. Smaller craters are seen at all stages from fresh to highly-eroded, with some exposing atypically bright or dark material. The morphology of some craters has been strongly influenced by regional slope. Detailed studies of crater morphology are underway. We have begun making crater counts to constrain the relative ages of different regions of the surface, and are working towards developing an absolute cratering chronology for Vesta's surface.

In the past Science Planning for space missions has been comprised of using ad-hoc software toolscollected or reconstructed from previous missions, tools used by other groups who often speak a different 'technical' language or even 'the backs of envelopes'. In addition to the tools being rough, the work done with these tools often has had to be redone or at least re-entered when it came time to determine actual observations. Science Opportunity Analyzer (SOA), a Java-based application, has been built for scientists to enable them to identify/analyze observation opportunities and then, to create corresponding observation designs.

For many years the diverse scientific community that supports JPL's wide variety ofinterplanetary space missions has needed a tool in order to plan and develop their experiments. The tool needs to be easily adapted to various mission types and portable to the user community. The Science Opportunity Analyzer, SOA, now in its third year of development, is intended to meet this need. SOA is a java-based application that is designed to enable scientists to identify and analyze opportunities for science observations from spacecraft. It differs from other planning tools in that it does not require an in-depth knowledge of the spacecraft command system or operation modes to begin high level planning. Users can, however, develop increasingly detailed levels of design. SOA consists of six major functions: Opportunity Search, Visualization, Observation Design, Constraint Checking, Data Output and Communications. Opportunity Search is a GUI driven interface to existing search engines that can be used to identify times when a spacecraft is in a specific geometrical relationship with other bodies in the solar system. This function can be used for advanced mission planning as well as for making last minute adjustments to mission sequences in response to trajectory modifications. Visualization is a key aspect of SOA. The user can view observation opportunities in either a 3D representation or as a 2D map projection. The user is given extensive flexibility to customize what is displayed in the view. Observation Design allows the user to orient the spacecraft and visualize the projection of the instrument field of view for that orientation using the same views as Opportunity Search. Constraint Checking is provided to validate various geometrical and physical aspects of an observation design. The user has the ability to easily create custom rules or to use official project-generated flight rules. This capability may also allow scientists to easily impact the cost to science if flight rule changes occur. Data Output generates information based on the spacecraft's trajectory, opportunity search results or based on a created observation. The data can be viewed either in tabular format or as a graph. Finally, SOA is unique in that it is designed to be able to communicate with a variety of existing planning and sequencing tools. From the very beginning SOA was designed with the user in mind. Extensive surveys of the potential user community were conducted in order to develop the software requirements. Throughout the development period, close ties have been maintained with the science community to insure that the tool maintains its user focus. Although development is still in its early stages, SOA is already developing a user community on the Cassini project, which is depending on this tool for their science planning. There are other tools at JPL that do various pieces of what SOA can do; however, there is no other tool which combines all these functions and presents them to the user in such a convenient, cohesive, and easy to use fashion.

The Science Opportunity Analyzer, SOA, now in its third year of development, is intended to meet the need of adaptability to the various mission types at JPL and portability for the user community.

Ganymede presents an unique example of an internally magnetized moon whose intrinsic magnetic field excludes the plasma present at its orbit, thereby forming a magnetospheric cavity.

Identical in situ dust detectors are flown on board the Galileo and Ulysses spacecraft. They record impacts of micrometeoroids in the ecliptic plane at heliocentric distances from 0.7 to 5.4 AU and in a plane almost perpendicular to the ecliptic from -79 deg to +79 deg ecliptic latitude. The combination of both Ulysses and Galileo measurements yield information about the radial and latitudinal distributions of micron and sub-micron sized dust in the solar system. Two types of dust particles were found to dominate the dust flux in interplanetary space: (1) Interplanetary micrometeoroids covering a wide mass range from 10(exp -16) to 10(exp -6) gr are mostly recorded inside 3 AU, and at latitudes below 30 deg; and (2) Interstellar grains with masses between 10(exp -14) and 10(exp -12) gr have been positively identified outside 3 AU near the ecliptic plane and outside 1.8 AU at high ecliptic latitudes (> 50 deg). Interstellar grains move on hyperbolic trajectories through the planetary system and constitute the dominant dust flux (1.5 x 10(exp -4)/ sq m sec) in the outer solar system and at high ecliptic latitudes. In order to compare and analyze the Galileo and Ulysses data sets, a new model is developed based on Divine's (1993) "Five populations of interplanetary meteoroids" model. By using this model, which takes into account the measured velocities and the effect of radiation pressure on small particles, we define four populations of meteoroids on elliptical orbits plus one population on hyperbolic orbits that all can fit the micrometeoroid flux observed by Galileo and Ulysses.

Data from Galileo's two asteroid flybys reveal magnetic fluctuations that we interpret as perturbations of the solar wind magnetic field caused by an interaction with the nearby asteroid. The scale sizes of the bodies (approximately 14 km for Gaspra and approximately 30 km for Ida) are intermediate between the ion and electron gyroradii, which implies that the asteroid-imposed perturbations propagate in the whistler mode. Special properties of the whistler mode include phase phase velocities that can exceed the solar wind speed and confinement of the disturbance to directions nearly aligned with the magnetic field. These features of the interaction impose a structure on the solar wind disturbance that differs greatly from the forms familiar for either magnetized or unmagnetized bodies of magnetohydrodynamic spatial scales. We examine both data and computer simulations of the interaction with special attention to what can be inferred about the interaction itself from analysis of the data.

As the Galileo spacecraft passed the asteroids Gaspra in 1990 and Ida in 1993, the magnetometer recorded changes in the solar wind magnetic field that we associate with the presence of the nearby body. This paper focuses on the types of interactions that can produce perturbations in the solar wind. We have suggested that the interaction at Gaspra is consistent with expectations of flow diversion by a magnetic dipole moment and an associated 'magnetosphere' whose scale size is much larger than the diameter of the solid body. The conditions for the Ida flyby leave more room for ambiguity. The observations could plausibly be related to either interaction with a magnetized body or with a conducting body. We will report on details of the observations that may enable us to distinguish between the different types of interaction and to provide quantitative estimates of the physical properties of the asteroids themselves.

In 1991 and 1992, the dust detector onboard the Ulysses spacecraft detected several dust streams apparently originating from the jovian system. The timing and measured speeds of the final two dust streams are compatible with dust from comet Shoemaker-Levy 9's (SL9) disruption in 1992. Our further investigations of stream characteristics and dust acceleration mechanisms, however, shed some doubt that two of the eleven dust streams are of SL9 origin. In July 1994 when SL9 impacts Jupiter, the Galileo spacecraft will be about 3500 jovian radii away from the planet. Submicronsized dust released into, and accelerated by, the jovian magnetosphere during this event may reach Galileo and impact its dust detector between September and November 1994. We also discuss the possibility of directly sampling dust from SL9 during Galileo's orbital tour.