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551.
X.-Q. Wang J. Cui X.-D. Wang J.-J. Liu H.-B. Zhang W. Zuo Y. Su W.-B. Wen H. Rème I. Dandouras C. Aoustin M. Wang X. Tan J. Shen F. Wang Q. Fu C.-L. Li Z.-Y. Ouyang 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
In this paper, we present the first and preliminary results on the near-Moon plasma environment, based on the spectrogram data obtained with the Solar Wind Ion Detector (SWID) onboard Chang’E-2 from four lunar orbits on 10–11 Oct 2010. These orbits, at a constant altitude of ∼100 km, approach gradually the Lunar Magnetic Anomaly (LMA) at the Serenitatis antipode. The data reveal tentatively a region with decrement in proton density and enhancement in temperature. The near coincidence of this region with the Serenitatis antipode probably suggests the presence of a minimagnetosphere associated with the LMA, which effectively shields and heats the incident Solar Wind (SW) protons. 相似文献
552.
G. N. Zastenker J. Safrankova Z. Nemecek L. Prech I. Cermak I. Vaverka A. Komarek J. Voita L. S. Chesalin B. T. Karimov Yu. N. Agafonov N. L. Borodkova E. A. Gavrilova T. I. Gagua I. T. Gagua P. A. Dalin A. V. D’yachkov I. V. Koloskova A. V. Leibov N. P. Semena V. V. Chernov Ya. I. Markov E. E. Ryazanova M. O. Ryazanrtseva N. N. Shevyrev V. V. Chrapchenkov O. M. Chugunova A. S. Yurasov 《Cosmic Research》2013,51(2):78-89
Design of the plasma spectrometer BMSW (Fast Monitor of the Solar Wind, possessing high temporal resolution) is described in the paper, as well as its characteristics and modes of operation. Some examples of measurements of various properties of the solar wind, made with this instrument installed onboard the high-apogee satellite Spektr-R, are presented. 相似文献
553.
Daniel B. Reisenfeld Roger C. Wiens Bruce L. Barraclough John T. Steinberg Marcia Neugebauer Jim Raines Thomas H. Zurbuchen 《Space Science Reviews》2013,175(1-4):125-164
We describe the Genesis mission solar-wind sample collection period and the solar wind conditions at the L1 point during this 2.3-year period. In order to relate the solar wind samples to solar composition, the conditions under which the samples were collected must be understood in the context of the long-term solar wind. We find that the state of the solar wind was typical of conditions over the past four solar cycles. However, Genesis spent a relatively large fraction of the time in coronal-hole flow as compared to what might have been expected for the declining phase of the solar cycle. Data from the Solar Wind Ion Composition Spectrometer (SWICS) on the Advanced Composition Explorer (ACE) are used to determine the effectiveness of the Genesis solar-wind regime selection algorithm. The data collected by SWICS confirm that the Genesis algorithm successfully separated and collected solar wind regimes having distinct solar origins, particularly in the case of the coronal hole sample. The SWICS data also demonstrate that the different regimes are elementally fractionated. When compared with Ulysses composition data from the previous solar cycle, we find a similar degree of fractionation between regimes as well as fractionation relative to the average photospheric composition. The Genesis solar wind samples are under long-term curation at NASA Johnson Space Center so that as sample analysis techniques evolve, pristine solar wind samples will be available to the scientific community in the decades to come. This article and a companion paper (Wiens et al. 2013, this issue) provide post-flight information necessary for the analysis of the Genesis array and foil solar wind samples and the Genesis solar wind ion concentrator samples, and thus serve to complement the Space Science Review volume, The Genesis Mission (v. 105, 2003). 相似文献
554.
John F. Cavanaugh James C. Smith Xiaoli Sun Arlin E. Bartels Luis Ramos-Izquierdo Danny J. Krebs Jan F. McGarry Raymond Trunzo Anne Marie Novo-Gradac Jamie L. Britt Jerry Karsh Richard B. Katz Alan T. Lukemire Richard Szymkiewicz Daniel L. Berry Joseph P. Swinski Gregory A. Neumann Maria T. Zuber David E. Smith 《Space Science Reviews》2007,131(1-4):451-479
The Mercury Laser Altimeter (MLA) is one of the payload science instruments on the MErcury Surface, Space ENvironment, GEochemistry,
and Ranging (MESSENGER) mission, which launched on August 3, 2004. The altimeter will measure the round-trip time of flight
of transmitted laser pulses reflected from the surface of the planet that, in combination with the spacecraft orbit position
and pointing data, gives a high-precision measurement of surface topography referenced to Mercury’s center of mass. MLA will
sample the planet’s surface to within a 1-m range error when the line-of-sight range to Mercury is less than 1,200 km under
spacecraft nadir pointing or the slant range is less than 800 km. The altimeter measurements will be used to determine the
planet’s forced physical librations by tracking the motion of large-scale topographic features as a function of time. MLA’s
laser pulse energy monitor and the echo pulse energy estimate will provide an active measurement of the surface reflectivity
at 1,064 nm. This paper describes the instrument design, prelaunch testing, calibration, and results of postlaunch testing. 相似文献
555.
Tilman Spohn Karsten Seiferlin Axel Hagermann Jörg Knollenberg Andrew J. Ball Marek Banaszkiewicz Johannes Benkhoff Stanislaw Gadomski Wojciech Gregorczyk Jerzy Grygorczuk Marek Hlond Günter Kargl Ekkehard Kührt Norbert Kömle Jacek Krasowski Wojciech Marczewski John C. Zarnecki 《Space Science Reviews》2007,128(1-4):339-362
MUPUS, the multi purpose sensor package onboard the Rosetta lander Philae, will measure the energy balance and the physical parameters in the near-surface layers – up to about 30 cm depth- of the
nucleus of Rosetta’s target comet Churyumov-Gerasimenko. Moreover it will monitor changes in these parameters over time as
the comet approaches the sun. Among the parameters studied are the density, the porosity, cohesion, the thermal diffusivity
and conductivity, and temperature. The data should increase our knowledge of how comets work, and how the coma gases form.
The data may also be used to constrain the microstructure of the nucleus material. Changes with time of physical properties
will reveal timescales and possibly the nature of processes that modify the material close to the surface. Thereby, the data
will indicate how pristine cometary matter sampled and analysed by other experiments on Philae really is. 相似文献
556.
John O. Goldsten Edgar A. Rhodes William V. Boynton William C. Feldman David J. Lawrence Jacob I. Trombka David M. Smith Larry G. Evans Jack White Norman W. Madden Peter C. Berg Graham A. Murphy Reid S. Gurnee Kim Strohbehn Bruce D. Williams Edward D. Schaefer Christopher A. Monaco Christopher P. Cork J. Del Eckels Wayne O. Miller Morgan T. Burks Lisle B. Hagler Steve J. DeTeresa Monika C. Witte 《Space Science Reviews》2007,131(1-4):339-391
A Gamma-Ray and Neutron Spectrometer (GRNS) instrument has been developed as part of the science payload for NASA’s Discovery
Program mission to the planet Mercury. Mercury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) launched
successfully in 2004 and will journey more than six years before entering Mercury orbit to begin a one-year investigation.
The GRNS instrument forms part of the geochemistry investigation and will yield maps of the elemental composition of the planet
surface. Major elements include H, O, Na, Mg, Si, Ca, Ti, Fe, K, and Th. The Gamma-Ray Spectrometer (GRS) portion detects
gamma-ray emissions in the 0.1- to 10-MeV energy range and achieves an energy resolution of 3.5 keV full-width at half-maximum
for 60Co (1332 keV). It is the first interplanetary use of a mechanically cooled Ge detector. Special construction techniques provide
the necessary thermal isolation to maintain the sensor’s encapsulated detector at cryogenic temperatures (90 K) despite the
intense thermal environment. Given the mission constraints, the GRS sensor is necessarily body-mounted to the spacecraft,
but the outer housing is equipped with an anticoincidence shield to reduce the background from charged particles. The Neutron
Spectrometer (NS) sensor consists of a sandwich of three scintillation detectors working in concert to measure the flux of
ejected neutrons in three energy ranges from thermal to ∼7 MeV. The NS is particularly sensitive to H content and will help
resolve the composition of Mercury’s polar deposits. This paper provides an overview of the Gamma-Ray and Neutron Spectrometer
and describes its science and measurement objectives, the design and operation of the instrument, the ground calibration effort,
and a look at some early in-flight data. 相似文献
557.
Z. Kolísková L. Sihver I. Ambro?ová T. Sato F. Spurný V.A. Shurshakov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
The health risks associated with exposure to various components of space radiation are of great concern when planning manned long-term interplanetary missions, such as future missions to Mars. Since it is not possible to measure the radiation environment inside of human organs in deep space, simulations based on radiation transport/interaction codes coupled to phantoms of tissue equivalent materials are used. However, the calculated results depend on the models used in the codes, and it is therefore necessary to verify their validity by comparison with measured data. The goal of this paper is to compare absorbed doses obtained in the MATROSHKA-R experiment performed at the International Space Station (ISS) with simulations performed with the three-dimensional Monte Carlo Particle and Heavy-Ion Transport code System (PHITS). The absorbed dose was measured using passive detectors (packages of thermoluminescent and plastic nuclear track detectors) placed on the surface of the spherical tissue equivalent phantom MATROSHKA-R, which was exposed aboard the ISS in the Service Zvezda Module from December 2005 to September 2006. The data calculated by PHITS assuming an ISS shielding of 3 g/cm2 and 5 g/cm2 aluminum mass thickness were in good agreement with the measurements. Using a simplified geometrical model of the ISS, the influence of variations in altitude and wall mass thickness of the ISS on the calculated absorbed dose was estimated. The uncertainties of the calculated data are also discussed; the relative expanded uncertainty of absorbed dose in phantom was estimated to be 44% at a 95% confidence level. 相似文献
558.
Comparisons of several transport models in their predictions in typical space radiation environments 总被引:1,自引:0,他引:1
Z.W. Lin J.H. Adams Jr. A.F. Barghouty S.D. Randeniya R.K. Tripathi J.W. Watts P.P. Yepes 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
We have used several transport codes to calculate dose and dose equivalent values as well as the particle spectra behind a slab or inside a spherical shell shielding in typical space radiation environments. Two deterministic codes, HZETRN and UPROP, and two Monte Carlo codes, FLUKA and Geant4, are included. A soft solar particle event, a hard solar particle event, and a solar minimum galactic cosmic rays environment are considered; and the shielding material is either aluminum or polyethylene. We find that the dose values and particle spectra from HZETRN are in general rather consistent with Geant4 except for neutrons. The dose equivalent values from HZETRN and Geant4 are not far from each other, but the HZETRN values behind shielding are often lower than the Geant4 values. Results from FLUKA and Geant4 are mostly consistent for considered cases. However, results from the legacy code UPROP are often quite different from the other transport codes, partly due to its non-consideration of neutrons. Comparisons for the spherical shell geometry exhibit the same qualitative features as for the slab geometry. In addition, results from both deterministic and Monte Carlo transport codes show that the dose equivalent inside the spherical shell decreases from the center to the inner surface and this decrease is large for solar particle events; consistent with an earlier study based on deterministic radiation transport results. This study demonstrates both the consistency and inconsistency among these transport models in their typical space radiation predictions; further studies will be required to pinpoint the exact physics modules in these models that cause the differences and thus may be improved. 相似文献
559.
Interplanetary spacecraft navigation using pulsars 总被引:1,自引:0,他引:1
X.P. Deng G. Hobbs X.P. You M.T. Li M.J. Keith R.M. Shannon W. Coles R.N. Manchester J.H. Zheng X.Z. Yu D. Gao X. Wu D. Chen 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
We demonstrate how observations of pulsars can be used to help navigate a spacecraft travelling in the solar system. We make use of archival observations of millisecond pulsars from the Parkes radio telescope in order to demonstrate the effectiveness of the method and highlight issues, such as pulsar spin irregularities, which need to be accounted for. We show that observations of four millisecond pulsars every seven days using a realistic X-ray telescope on the spacecraft throughout a journey from Earth to Mars can lead to position determinations better than ∼20 km and velocity measurements with a precision of ∼0.1 ms−1. 相似文献
560.