Multimodal characteristics of a piezoelectric lead zirconate titanate element impacted with iron particles having velocities above 20 km/s

The responses of a piezoelectric lead zirconate titanate (PZT) element to hypervelocity collisions were experimentally studied. In this study, the particles of masses ranging from 0.3 to 10 fg were made to collide with PZT at velocities between 20 and 96 km/s. The amplitude and the corresponding rise time of the single-pulse output signals that were produced in the piezoelectric PZT element were measured to determine the possible collision states. The results revealed an apparently multimodal output; three classes were assumed to be involved in the pulse formation mechanism. The amplitude and rise time were sensitive to the collision velocity. The multimodal behavior implied that the PZT-based cosmic dust detectors should be calibrated according to the class they belong to.     

Surface Composition of Vesta: Issues and Integrated Approach

The instruments on the Dawn spacecraft are exceptionally well suited to characterize and map the surface composition of Vesta in an integrated manner. These include a framing camera with multispectral capabilities, a high spectral resolution near-infrared imaging spectrometer, and a gamma-ray and neutron spectrometer. Three examples of issues addressed at Vesta are: (1) What is the composition of Vesta??s interior and differentiation state as exposed by the Great South Crater? (2) How has space weathering affected Vesta, both globally and at a local scale? and (3) Are volatiles or hydrated material present on Vesta??s surface? We predict that Dawn finds many surprises, such as an olivine-bearing mantle exposed near the south-pole, a weakly or un-weathered surface that has been relatively recently resurfaced, and a very thin layer of surficial volatiles derived from interaction with the solar wind.     

Characteristics of Icy Surfaces

The surfaces of the Solar System’s icy satellites show an extraordinary variety of morphological features, which bear witness to exchange processes between the surface and subsurface. In this paper we review the characteristics of surface features on the moons of Jupiter, Saturn, Uranus and Neptune. Using data from spacecraft missions, we discuss the detailed morphology, size, and topography of cryovolcanic, tectonic, aeolian, fluvial, and impact features of both large moons and smaller satellites.     

The Cassini Visual And Infrared Mapping Spectrometer (Vims) Investigation

The Cassini visual and infrared mapping spectrometer (VIMS) investigation is a multidisciplinary study of the Saturnian system. Visual and near-infrared imaging spectroscopy and high-speed spectrophotometry are the observational techniques. The scope of the investigation includes the rings, the surfaces of the icy satellites and Titan, and the atmospheres of Saturn and Titan. In this paper, we will elucidate the major scientific and measurement goals of the investigation, the major characteristics of the Cassini VIMS instrument, the instrument calibration, and operation, and the results of the recent Cassini flybys of Venus and the Earth–Moon system.This revised version was published online in July 2005 with a corrected cover date.     

Correction to: Determining the Relative Cratering Ages of Regions of Psyche’s Surface

Space Science Reviews - Analysis of Homestake, Gallex and GNO measurements reveals evidence of variability of presumed solar-neutrino-flux measurements. Analysis of Super-Kamiokande neutrino...     

A laboratory study on the thermally induced transformation of hydrogen cyanide (HCN) to the cyanogen anion (CN) in Solar System analog ices

Mixtures of molecular nitrogen and methane have been identified in numerous outer Solar Systemices including the icy surfaces of Pluto and Triton. We have simulated the interaction of ionizing radiation in the Solar System by carrying out a radiolysis experiment on a methane – molecular nitrogen ice mixture with energetic electrons. We have identified the hydrogen cyanide molecule as the most prominent carbon–nitrogen-bearing reaction product formed. Upon warming the irradiated sample, we followed for the first time the kinetics and temporal evolution of the underlying acid–base chemistry which resulted in the formation of the cyanide ion from hydrogen cyanide. On the surfaces of Triton and Pluto and on comets in Oort’s cloud this sort of complex chemistry is likely to occur. In particular, hydrogen cyanide can be produced in low temperature environments (Oort cloud comets) and may be converted into cyanide ions once the comets reach the warmer regions of the Solar System.     

Flexbus — an attractive technical solution for small missions

Responding to the demand for a ‘faster, cheaper, better’ implementation of space related services, Domier Satellitensysteme GmbH has established and exercised an approach for the development and production of satellites and the corresponding ground equipment for small missions, referred to as Flexbus. It allows to support space service customers starting from mission engineering via design, development and manufacturing of the necessary hardware, the launch service and ending with the hand-over of the operational system. Flexbus harmonises a modular component concept with a sound design and development approach, as a whole providing the means to offer high quality products in a fairly short time and for competitive pricing. This paper will outline the major features of the Flexbus approach and describe application examples.     

Geophysical Constraints on the Evolution of Mars

The evolution of Mars is discussed using results from the recent Mars Global Surveyor (MGS) and Mars Pathfinder missions together with results from mantle convection and thermal history models and the chemistry of Martian meteorites. The new MGS topography and gravity data and the data on the rotation of Mars from Mars Pathfinder constrain models of the present interior structure and allow estimates of present crust thickness and thickness variations. The data also allow estimates of lithosphere thickness variation and heat flow assuming that the base of the lithosphere is an isotherm. Although the interpretation is not unambiguous, it can be concluded that Mars has a substantial crust. It may be about 50 km thick on average with thickness variations of another ±50 km. Alternatively, the crust may be substantially thicker with smaller thickness variations. The former estimate of crust thickness can be shown to be in agreement with estimates of volcanic production rates from geologic mapping using data from the camera on MGS and previous missions. According to these estimates most of the crust was produced in the Noachian, roughly the first Gyr of evolution. A substantial part of the lava generated during this time apparently poured onto the surface to produce the Tharsis bulge, the largest tectonic unit in the solar system and the major volcanic center of Mars. Models of crust growth that couple crust growth to mantle convection and thermal evolution are consistent with an early 1 Gyr long phase of vigorous volcanic activity. The simplest explanation for the remnant magnetization of crustal units of mostly the southern hemisphere calls for an active dynamo in the Noachian, again consistent with thermal history calculations that predict the core to become stably stratified after some hundred Myr of convective cooling and dynamo action. The isotope record of the Martian meteorites suggest that the core formed early and rapidly within a few tens of Myr. These data also suggest that the silicate rock component of the planet was partially molten during that time. The isotope data suggest that heterogeneity resulted from core formation and early differentiation and persisted to the recent past. This is often taken as evidence against vigorous mantle convection and early plate tectonics on Mars although the latter assumption can most easily explain the early magnetic field. The physics of mantle convection suggests that there may be a few hundred km thick stagnant, near surface layer in the mantle that would have formed rapidly and may have provided the reservoirs required to explain the isotope data. The relation between the planform of mantle convection and the tectonic features on the surface is difficult to entangle. Models call for long wavelength forms of flow and possibly a few strong plumes in the very early evolution. These plumes may have dissolved with time as the core cooled and may have died off by the end of the Noachian.     

Mercury Dust Monitor (MDM) Onboard the Mio Orbiter of the BepiColombo Mission

Space Science Reviews - In this chapter, we review the contribution of space missions to the determination of the elemental and isotopic composition of Earth, Moon and the terrestrial planets, with...