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Recognizing that grains in the cometary dust tail are electrically charged, we study the effect of an interplanetary sector boundary crossing on their distribution. We specifically consider Halley's comet around the time of encounter by the GIOTTO and VEGA 1 and 2 spacecrafts in March 1986. The smallest dust particles (r
g0.3 m) are strongly effected, and the projection of their distributions in a plane containing the Sun-Comet axis and normal to the orbital plane show a wavy appearance. Also, since reversals in the interplanetary magnetic field occur with a periodicity of 5 to 10 days, the spacecrafts, which follow 3 to 4 days apart are likely to encounter entirely different dust distributions at the lower end of the mass spectrum. 相似文献
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E. Grün Z. Sternovsky M. Horanyi V. Hoxie S. Robertson J. Xi S. Auer M. Landgraf F. Postberg M.C. Price R. Srama N.A. Starkey J.K. Hillier I.A. Franchi P. Tsou A. Westphal Z. Gainsforth 《Planetary and Space Science》2012,60(1):261-273
The Stardust mission returned two types of unprecedented extraterrestrial samples: the first samples of material from a known solar system body beyond the moon, the comet 81P/Wild2, and the first samples of contemporary interstellar dust. Both sets of samples were captured in aerogel and aluminum foil collectors and returned to Earth in January 2006. While the analysis of particles from comet Wild 2 yielded exciting new results, the search for and analysis of collected interstellar particles is more demanding and is ongoing.Novel dust instrumentation will tremendously improve future dust collection in interplanetary space: an Active Cosmic Dust Collector is a combination of an in-situ dust trajectory sensor (DTS) together with a dust collector consisting of aerogel and/or other collector materials, e.g. such as those used by the Stardust mission. Dust particles’ trajectories are determined by the measurement of induced electrical signals when charged particles fly through a position sensitive electrode system. The recorded waveforms enable the reconstruction of the velocity vector with high precision.The DTS described here was subject to performance tests at the Heidelberg dust accelerator at the same time as the recording of impact signals from potential collector materials. The tests with dust particles in the speed range from 3 to 40 km/s demonstrate that trajectories can be measured with accuracies of ～1° in direction and ～1% in speed. The sensitivity of the DTS electronics is of the order of 10?16 C and thus the trajectory of cosmic dust particles as small as 0.4 μm size can be measured. The impact position on the collector can be determined with better than 1 mm precision, which will ease immensely the task of locating sub-micron-sized particles on the collector. Statistically significant numbers of trajectories of interplanetary and interstellar dust particles can thus be collected in interplanetary space and their compositions correlated with their trajectories. 相似文献
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Ralf Srama Thomas Stephan Eberhard Grün Norbert Pailer Anton Kearsley Amara Graps Rene Laufer Pascale Ehrenfreund Nicolas Altobelli Kathrin Altwegg Siegfried Auer Jack Baggaley Mark J. Burchell James Carpenter Luigi Colangeli Francesca Esposito Simon F. Green Hartmut Henkel Mihaly Horanyi Annette Jäckel Sascha Kempf Neil McBride Georg Moragas-Klostermeyer Harald Krüger Pasquale Palumbo Andre Srowig Mario Trieloff Peter Tsou Zoltan Sternovsky Oliver Zeile Hans-Peter Röser 《Experimental Astronomy》2009,23(1):303-328
The scientific community has expressed strong interest to re-fly Stardust-like missions with improved instrumentation. We
propose a new mission concept, SARIM, that collects interstellar and interplanetary dust particles and returns them to Earth.
SARIM is optimised for the collection and discrimination of interstellar dust grains. Improved active dust collectors on-board
allow us to perform in-situ determination of individual dust impacts and their impact location. This will provide important
constraints for subsequent laboratory analysis.
The SARIM spacecraft will be placed at the L2 libration point of the Sun–Earth system, outside the Earth’s debris belts and
inside the solar-wind charging environment. SARIM is three-axes stabilised and collects interstellar grains between July and
October when the relative encounter speeds with interstellar dust grains are lowest (4 to 20 km/s). During a 3-year dust collection
period several hundred interstellar and several thousand interplanetary grains will be collected by a total sensitive area
of 1 m2. At the end of the collection phase seven collector modules are stored and sealed in a MIRKA-type sample return capsule.
SARIM will return the capsule containing the stardust to Earth to allow for an extraction and investigation of interstellar
samples by latest laboratory technologies. 相似文献
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Eberhard Grün Ralf Srama Nicolas Altobelli Kathrin Altwegg James Carpenter Luigi Colangeli Karl-Heinz Glassmeier Stefan Helfert Hartmut Henkel Mihaly Horanyi Annette Jäckel Sascha Kempf Markus Landgraf Neil McBride Georg Moragas-Klostermeyer Pasquale Palumbo Han Scholten Andre Srowig Zoltan Sternovsky Xavier Vo 《Experimental Astronomy》2009,23(3):981-999
The DuneXpress observatory will characterize interstellar and interplanetary dust in-situ, in order to provide crucial information
not achievable with remote sensing astronomical methods. Galactic interstellar dust constitutes the solid phase of matter
from which stars and planetary systems form. Interplanetary dust, from comets and asteroids, represents remnant material from
bodies at different stages of early solar system evolution. Thus, studies of interstellar and interplanetary dust with DuneXpress
in Earth orbit will provide a comparison between the composition of the interstellar medium and primitive planetary objects.
Hence DuneXpress will provide insights into the physical conditions during planetary system formation. This comparison of
interstellar and interplanetary dust addresses directly themes of highest priority in astrophysics and solar system science,
which are described in ESA’s Cosmic Vision. The discoveries of interstellar dust in the outer and inner solar system during
the last decade suggest an innovative approach to the characterization of cosmic dust. DuneXpress establishes the next logical
step beyond NASA’s Stardust mission, with four major advancements in cosmic dust research: (1) analysis of the elemental and
isotopic composition of individual interstellar grains passing through the solar system, (2) determination of the size distribution
of interstellar dust at 1 AU from 10 − 14 to 10 − 9 g, (3) characterization of the interstellar dust flow through the planetary system, (4) establish the interrelation of interplanetary
dust with comets and asteroids. Additionally, in supporting the dust science objectives, DuneXpress will characterize dust
charging in the solar wind and in the Earth’s magnetotail. The science payload consists of two dust telescopes of a total
of 0.1 m2 sensitive area, three dust cameras totaling 0.4 m2 sensitive area, and a nano-dust detector. The dust telescopes measure high-resolution mass spectra of both positive and negative
ions released upon impact of dust particles. The dust cameras employ different detection methods and are optimized for (1)
large area impact detection and trajectory analysis of submicron sized and larger dust grains, (2) the determination of physical
properties, such as flux, mass, speed, and electrical charge. A nano-dust detector searches for nanometer-sized dust particles
in interplanetary space. A plasma monitor supports the dust charge measurements, thereby, providing additional information
on the dust particles. About 1,000 grains are expected to be recorded by this payload every year, with 20% of these grains
providing elemental composition. During the mission submicron to micron-sized interstellar grains are expected to be recorded
in statistically significant numbers. DuneXpress will open a new window to dusty universe that will provide unprecedented
information on cosmic dust and on the objects from which it is derived. 相似文献
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We have considered the electrodynamic effects on small Al2O3 spherules dumped into the Earth's magnetosphere in large quantities during solid rocket propellant burns. The charges acquired by these grains in all regions of the terrestrial environment (plasmasphere, magnetosphere, and solar wind) are modest. Consequently electrodynamic effects are significant only at the lower end of the dust size spectrum (R
g0.1 m). In that case, the electrodynamic forces conspire with solar radiation pressure to eliminate the grains from the magnetosphere in a comparatively short time. Although not studied here in detail, we anticipate a similar fate for fine micrometeoroids entering the Earth's magnetosphere, with the electro-dynamic effects playing an even more important role.Paper dedicated to Professor Hannes Alfvén on the occasion of his 80th birthday, 30 May 1988. 相似文献
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The Electrostatic Lunar Dust Analyzer (ELDA) for the detection and trajectory measurement of slow-moving dust particles from the lunar surface 总被引：1，自引：0，他引：1
N. Duncan Z. Sternovsky E. Grün S. Auer M. Horanyi K. Drake J. Xie G. Lawrence D. Hansen H. Le 《Planetary and Space Science》2011,59(13):1446-1454
Micron and submicron-sized dust particles can be lifted from the lunar surface due to continual micrometeoroid bombardment and electrostatic charging. The characteristics of these dust populations are of scientific interest and engineering importance for the design of future equipment to operate on the lunar surface. The mobilized grains are expected to have a low velocity, which makes their detection difficult by traditional methods that are based on momentum transfer or impact energy. We describe a newly developed instrument concept, the Electrostatic Lunar Dust Analyzer (ELDA), which utilizes the charge on the dust for detection and analysis. ELDA consists of an array of wire electrodes combined with an electrostatic deflection field region, and measures the mass, charge, and velocity vector of individual dust grains. The first basic prototype of the ELDA instrument has been constructed, tested and characterized in the laboratory. The instrument is set up to measure over a velocity range 1–100 m/s and is sensitive to particles from an approximate mass range from 2×10−16 to 10−11 kg, depending on the charge state and velocity. 相似文献
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Frank Postberg Eberhard Grün Mihaly Horanyi Sascha Kempf Harald Krüger Jürgen Schmidt Frank Spahn Ralf Srama Zoltan Sternovsky Mario Trieloff 《Planetary and Space Science》2011,59(14):1815-1825
Classical methods to analyze the surface composition of atmosphereless planetary objects from an orbiter are IR and gamma ray spectroscopy and neutron backscatter measurements. The idea to analyze surface properties with an in-situ instrument has been proposed by Johnson et al. (1998). There, it was suggested to analyze Europa's thin atmosphere with an ion and neutral gas spectrometer. Since the atmospheric components are released by sputtering of the moon's surface, they provide a link to surface composition. Here we present an improved, complementary method to analyze rocky or icy dust particles as samples of planetary objects from which they were ejected. Such particles, generated by the ambient meteoroid bombardment that erodes the surface, are naturally present on all atmosphereless moons and planets. The planetary bodies are enshrouded in clouds of ballistic dust particles, which are characteristic samples of their surfaces. In situ mass spectroscopic analysis of these dust particles impacting onto a detector of an orbiting spacecraft reveals their composition. Recent instrumental developments and tests allow the chemical characterization of ice and dust particles encountered at speeds as low as 1 km/s and an accurate reconstruction of their trajectories. Depending on the sampling altitude, a dust trajectory sensor can trace back the origin of each analyzed grain with about 10 km accuracy at the surface. Since the detection rates are of the order of thousand per orbit, a spatially resolved mapping of the surface composition can be achieved. Certain bodies (e.g., Europa) with particularly dense dust clouds, could provide impact statistics that allow for compositional mapping even on single flybys. Dust impact velocities are in general sufficiently high at orbiters about planetary objects with a radius >1000 km and with only a thin or no atmosphere. In this work we focus on the scientific benefit of a dust spectrometer on a spacecraft orbiting Earth's Moon as well as Jupiter's Galilean satellites. This ‘dust spectrometer' approach provides key chemical and isotopic constraints for varying provinces or geological formations on the surfaces, leading to better understanding of the body's geological evolution. 相似文献
8.
Each year the Moon is bombarded by about 106 kg of interplanetary micrometeoroids of cometary and asteroidal origin. Most of these projectiles range from 10 nm to about 1 mm in size and impact the Moon at 10–72 km/s speed. They excavate lunar soil about 1000 times their own mass. These impacts leave a crater record on the surface from which the micrometeoroid size distribution has been deciphered. Much of the excavated mass returns to the lunar surface and blankets the lunar crust with a highly pulverized and “impact gardened” regolith of about 10 m thickness. Micron and sub-micron sized secondary particles that are ejected at speeds up to the escape speed of 2300 m/s form a perpetual dust cloud around the Moon and, upon re-impact, leave a record in the microcrater distribution. Such tenuous clouds have been observed by the Galileo spacecraft around all lunar-sized Galilean satellites at Jupiter. The highly sensitive Lunar Dust Experiment (LDEX) onboard the LADEE mission will shed new light on the lunar dust environment. LADEE is expected to be launched in early 2013.Another dust related phenomenon is the possible electrostatic mobilization of lunar dust. Images taken by the television cameras on Surveyors 5, 6, and 7 showed a distinct glow just above the lunar horizon referred to as horizon glow (HG). This light was interpreted to be forward-scattered sunlight from a cloud of dust particles above the surface near the terminator. A photometer onboard the Lunokhod-2 rover also reported excess brightness, most likely due to HG. From the lunar orbit during sunrise the Apollo astronauts reported bright streamers high above the lunar surface, which were interpreted as dust phenomena. The Lunar Ejecta and Meteorites (LEAM) Experiment was deployed on the lunar surface by the Apollo 17 astronauts in order to characterize the lunar dust environment. Instead of the expected low impact rate from interplanetary and interstellar dust, LEAM registered hundreds of signals associated with the passage of the terminator, which swamped any signature of primary impactors of interplanetary origin. It was suggested that the LEAM events are consistent with the sunrise/sunset-triggered levitation and transport of charged lunar dust particles. Currently no theoretical model explains the formation of a dust cloud above the lunar surface but recent laboratory experiments indicate that the interaction of dust on the lunar surface with solar UV and plasma is more complex than previously thought. 相似文献
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