共查询到20条相似文献,搜索用时 79 毫秒
1.
A. I. Eriksson R. Boström R. Gill L. Åhlén S.-E. Jansson J.-E. Wahlund M. André A. Mälkki J. A. Holtet B. Lybekk A. Pedersen L. G. Blomberg 《Space Science Reviews》2007,128(1-4):729-744
The Rosetta dual Langmuir probe instrument, LAP, utilizes the multiple powers of a pair of spherical Langmuir probes for measurements
of basic plasma parameters with the aim of providing detailed knowledge of the outgassing, ionization, and subsequent plasma
processes around the Rosetta target comet. The fundamental plasma properties to be studied are the plasma density, the electron
temperature, and the plasma flow velocity. However, study of electric fields up to 8 kHz, plasma density fluctuations, spacecraft
potential, integrated UV flux, and dust impacts is also possible. LAP is fully integrated in the Rosetta Plasma Consortium
(RPC), the instruments of which together provide a comprehensive characterization of the cometary plasma.
The LAP Team is listed in Table III. 相似文献
2.
C. Carr E. Cupido C. G. Y. Lee A. Balogh T. Beek J. L. Burch C. N. Dunford A. I. Eriksson R. Gill K. H. Glassmeier R. Goldstein D. Lagoutte R. Lundin K. Lundin B. Lybekk J. L. Michau G. Musmann H. Nilsson C. Pollock I. Richter J. G. Trotignon 《Space Science Reviews》2007,128(1-4):629-647
The Rosetta Plasma Consortium (RPC) will make in-situ measurements of the plasma environment of comet 67P/Churyumov-Gerasimenko.
The consortium will provide the complementary data sets necessary for an understanding of the plasma processes in the inner
coma, and the structure and evolution of the coma with the increasing cometary activity. Five sensors have been selected to
achieve this: the Ion and Electron Sensor (IES), the Ion Composition Analyser (ICA), the Langmuir Probe (LAP), the Mutual
Impedance Probe (MIP) and the Magnetometer (MAG). The sensors interface to the spacecraft through the Plasma Interface Unit
(PIU). The consortium approach allows for scientific, technical and operational coordination, and makes optimum use of the
available mass and power resources. 相似文献
3.
J. L. Burch R. Goldstein T. E. Cravens W. C. Gibson R. N. Lundin C. J. Pollock J. D. Winningham D. T. Young 《Space Science Reviews》2007,128(1-4):697-712
The ion and electron sensor (IES) is part of the Rosetta Plasma Consortium (RPC). The IES consists of two electrostatic plasma
analyzers, one each for ions and electrons, which share a common entrance aperture. Each analyzer covers an energy/charge
range from 1 eV/e to 22 keV/e with a resolution of 4%. Electrostatic deflection is used at the entrance aperture to achieve
a field of view of 90°× 360° (2.8π sr). Angular resolution is 5°× 22.5° for electrons and 5°× 45° for ions with the sector
containing the solar wind being further segmented to 5°× 5°. The three-dimensional plasma distributions obtained by IES will
be used to investigate the interaction of the solar wind with asteroids Steins and Lutetia and the coma and nucleus of comet
67P/Churyumov–Gerasimenko (CG). In addition, photoelectron spectra obtained at these bodies will help determine their composition. 相似文献
4.
H. Balsiger K. Altwegg P. Bochsler P. Eberhardt J. Fischer S. Graf A. Jäckel E. Kopp U. Langer M. Mildner J. Müller T. Riesen M. Rubin S. Scherer P. Wurz S. Wüthrich E. Arijs S. Delanoye J. De Keyser E. Neefs D. Nevejans H. Rème C. Aoustin C. Mazelle J.-L. Médale J. A. Sauvaud J.-J. Berthelier J.-L. Bertaux L. Duvet J.-M. Illiano S. A. Fuselier A. G. Ghielmetti T. Magoncelli E. G. Shelley A. Korth K. Heerlein H. Lauche S. Livi A. Loose U. Mall B. Wilken F. Gliem B. Fiethe T. I. Gombosi B. Block G. R. Carignan L. A. Fisk J. H. Waite D. T. Young H. Wollnik 《Space Science Reviews》2007,128(1-4):745-801
The Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) will answer important questions posed by the mission’s
main objectives. After Giotto, this will be the first time the volatile part of a comet will be analyzed in situ. This is
a very important investigation, as comets, in contrast to meteorites, have maintained most of the volatiles of the solar nebula.
To accomplish the very demanding objectives through all the different phases of the comet’s activity, ROSINA has unprecedented
capabilities including very wide mass range (1 to >300 amu), very high mass resolution (m/Δ m > 3000, i.e. the ability to resolve CO from N2 and 13C from 12CH), very wide dynamic range and high sensitivity, as well as the ability to determine cometary gas velocities, and temperature.
ROSINA consists of two mass spectrometers for neutrals and primary ions with complementary capabilities and a pressure sensor.
To ensure that absolute gas densities can be determined, each mass spectrometer carries a reservoir of a calibrated gas mixture
allowing in-flight calibration. Furthermore, identical flight-spares of all three sensors will serve for detailed analysis
of all relevant parameters, in particular the sensitivities for complex organic molecules and their fragmentation patterns
in our electron bombardment ion sources. 相似文献
5.
H. Nilsson R. Lundin K. Lundin S. Barabash H. Borg O. Norberg A. Fedorov J.-A Sauvaud H. Koskinen E. Kallio P. Riihelä J. L. Burch 《Space Science Reviews》2007,128(1-4):671-695
The Ion Composition Analyzer (ICA) is part of the Rosetta Plasma Consortium (RPC). ICA is designed to measure the three-dimensional
distribution function of positive ions in order to study the interaction between the solar wind and cometary particles. The
instrument has a mass resolution high enough to resolve the major species such as protons, helium, oxygen, molecular ions,
and heavy ions characteristic of dusty plasma regions. ICA consists of an electrostatic acceptance angle filter, an electrostatic
energy filter, and a magnetic momentum filter. Particles are detected using large diameter (100 mm) microchannel plates and
a two-dimensional anode system. ICA has its own processor for data reduction/compression and formatting. The energy range
of the instrument is from 25 eV to 40 keV and an angular field-of-view of 360° × 90° is achieved through electrostatic deflection
of incoming particles. 相似文献
6.
MIRO: Microwave Instrument for Rosetta Orbiter 总被引:1,自引:0,他引:1
S. Gulkis M. Frerking J. Crovisier G. Beaudin P. Hartogh P. Encrenaz T. Koch C. Kahn Y. Salinas R. Nowicki R. Irigoyen M. Janssen P. Stek M. Hofstadter M. Allen C. Backus L. Kamp C. Jarchow E. Steinmetz A. Deschamps J. Krieg M. Gheudin D. Bockelée-Morvan N. Biver T. Encrenaz D. Despois W. Ip E. Lellouch I. Mann D. Muhleman H. Rauer P. Schloerb T. Spilker 《Space Science Reviews》2007,128(1-4):561-597
The European Space Agency Rosetta Spacecraft, launched on March 2, 2004 toward Comet 67P/Churyumov-Gerasimenko, carries a
relatively small and lightweight millimeter-submillimeter spectrometer instrument, the first of its kind launched into deep
space. The instrument will be used to study the evolution of outgassing water and other molecules from the target comet as
a function of heliocentric distance. During flybys of the asteroids (2867) Steins and (21) Lutetia in 2008 and 2010 respectively,
the instrument will measure thermal emission and search for water vapor in the vicinity of these asteroids.
The instrument, named MIRO (Microwave Instrument for the Rosetta Orbiter), consists of a 30-cm diameter, offset parabolic
reflector telescope followed by two heterodyne receivers. Center-band operating frequencies of the receivers are near 190
GHz (1.6 mm) and 562 GHz (0.5 mm). Broadband continuum channels are implemented in both frequency bands for the measurement
of near surface temperatures and temperature gradients in Comet 67P/Churyumov-Gerasimenko and the asteroids (2867) Steins
and (21) Lutetia. A 4096 channel CTS (Chirp Transform Spectrometer) spectrometer having 180 MHz total bandwidth and 44 kHz
resolution is, in addition to the continuum channel, connected to the submillimeter receiver. The submillimeter radiometer/spectrometer
is fixed tuned to measure four volatile species – CO, CH3OH, NH3 and three, oxygen-related isotopologues of water, H2
16O, H2
17O and H2
18O. The basic quantities measured with the MIRO instrument are surface temperature, gas production rates and relative abundances,
and velocity and excitation temperature of each species, along with their spatial and temporal variability. This paper provides
a short discussion of the scientific objectives of the investigation, and a detailed discussion of the MIRO instrument system. 相似文献
7.
Philippe L. Lamy Imre Toth Björn J. R. Davidsson Olivier Groussin Pedro Gutiérrez Laurent Jorda Mikko Kaasalainen Stephen C. Lowry 《Space Science Reviews》2007,128(1-4):23-66
In 2003, comet 67P/Churyumov–Gerasimenko was selected as the new target of the Rosetta mission as the most suitable alternative
to the original target, comet 46P/Wirtanen, on the basis of orbital considerations even though very little was known about
the physical properties of its nucleus. In a matter of a few years and based on highly focused observational campaigns as
well as thorough theoretical investigations, a detailed portrait of this nucleus has been established that will serve as a
baseline for planning the Rosetta operations and observations. In this review article, we present a novel method to determine
the size and shape of a cometary nucleus: several visible light curves were inverted to produce a size–scale free three–dimensional
shape, the size scaling being imposed by a thermal light curve. The procedure converges to two solutions which are only marginally
different. The nucleus of comet 67P/Churyumov–Gerasimenko emerges as an irregular body with an effective radius (that of the
sphere having the same volume) = 1.72 km and moderate axial ratios a/b = 1.26 and a/c = 1.5 to 1.6. The overall dimensions
measured along the principal axis for the two solutions are 4.49–4.75 km, 3.54–3.77 km and 2.94–2.92 km. The nucleus is found
to be in principal axis rotation with a period = 12.4–12.7 h. Merging all observational constraints allow us to specify two
regions for the direction of the rotational axis of the nucleus: RA = 220°+50°
−30° and Dec = −70° ± 10° (retrograde rotation) or RA = 40°+50°
-30° and Dec = +70°± 10° (prograde), the better convergence of the various determinations presently favoring the first solution. The phase function,
although constrained by only two data points, exhibits a strong opposition effect rather similar to that of comet 9P/Tempel
1. The definition of the disk–integrated albedo of an irregular body having a strong opposition effect raises problems, and
the various alternatives led to a R-band geometric albedo in the range 0.045–0.060, consistent with our present knowledge of cometary nuclei. The active fraction
is low, not exceeding ~ 7% at perihelion, and is probably limited to one or two active regions subjected to a strong seasonal
effect, a picture coherent with the asymmetric behaviour of the coma. Our slightly downward revision of the size of the nucleus
of comet 67P/Churyumov-Gerasimenko resulting from the present analysis (with the correlative increase of the albedo compared
to the originally assumed value of 0.04), and our best estimate of the bulk density of 370 kg m−3, lead to a mass of ~ 8 × 1012 kg which should ease the landing of Philae and insure the overall success of the Rosetta mission. 相似文献
8.
Stefano Mottola Gabriele Arnold Hans-Georg Grothues Ralf Jaumann Harald Michaelis Gerhard Neukum Jean-Pierre Bibring 《Space Science Reviews》2007,128(1-4):241-255
ROLIS (Rosetta Lander Imaging System) is one of the two imaging systems carried by Rosetta’s Lander Philae, successfully launched
to comet 67P/ Churyumov-Gerasimenko in March 2004. Consisting of a highly-miniaturized CCD camera, ROLIS will operate as a descent imager, acquiring imagery
of the landing site with increasing spatial resolution. After touchdown ROLIS will focus at an object distance of 30 cm, taking
pictures of the comet’s surface below the Lander. Multispectral imaging is achieved through an illumination device consisting
of four arrays of monochromatic light emitting diodes working in the 470, 530, 640 and 870 nm spectral bands. The drill sample
sites, as well as the Alpha X-Ray Spectrometer (APXS) target locations will be imaged to provide context for the measurements
performed by the in situ analyzers. After the drilling operation, the borehole will be inspected to study its morphology and to search for stratification.
Taking advantage of the Lander’s rotation capability, stereo image pairs will be acquired, which will facilitate the mapping
and identification of surface structures. 相似文献
9.
M. Baguhl E. Grün D. P. Hamilton G. Linkert R. Riemann P. Staubach H. A. Zook 《Space Science Reviews》1995,72(1-2):471-476
Interstellar dust detected by the dust sensor onboard Ulysses was first identified after the Jupiter flyby when the spacecraft's trajectory changed dramatically (Grün et al., 1994). Here we report on two years of Ulysses post-Jupiter data covering the range of ecliptic latitudes from 0° to –54° and distances from 5.4 to 3.2 AU. We find that, over this time period, the flux of interstellar dust particles with a mean mass of 3·10–13 g stays nearly constant at about 1·10–4, m–2 s–1 ( sr)–1, with both ecliptic latitude and heliocentric distance.Also presented are 20 months of measurements from the identical dust sensor onboard the Galileo spacecraft which moved along an in-ecliptic orbit from 1.0 to 4.2 AU. From the impact direction and speeds of the measured dust particles we conclude that Galileo almost certainly sensed interstellar dust outside 2.8 AU; interstellar particles may also account for part of the flux seen between 1 and 2.8 AU. 相似文献
10.
高温耐辐照声发射传感器 总被引:1,自引:0,他引:1
研制了一种新的耐高温抗辐照声发射传感器,并讨论了传感器制作工艺上的特点和优点。在经受400℃和2.4×10~6GYγ辐照的考验后,传感器仍保持性能稳定。 相似文献
11.
光纤传感器作为一种新的测量信息传输方式,在航空发动机部件材料高温测量领域具有重要的应用价值。基于多光束干涉原理,制作一种新型结构的非本征光纤 Fabry-Perot(F-P)传感器,探索其在航空发动机部件材料室温/高温环境静力拉伸试验过程中的变形测量性能。采用平板和圆棒两种形状的试样,在不同表面粗糙度和两种加载速率下,分别对比高级视频引伸计(AVE)进行室温、高温环境下静力拉伸试验。结果表明:新型结构的非本征光纤 F-P 传感器具有测量范围大,测量精度高,测量结果不受外界因素影响等优势,可实现航空发动机部件材料的超量程全应变测量;此外,在测量精度和设备体积方面明显优于 AVE。 相似文献
12.
W. Riedler K. Torkar H. Jeszenszky J. Romstedt H. St. C. Alleyne H. Arends W. Barth J. V. D. Biezen B. Butler P. Ehrenfreund M. Fehringer G. Fremuth J. Gavira O. Havnes E. K. Jessberger R. Kassing W. Klöck C. Koeberl A. C. Levasseur-Regourd M. Maurette F. Rüdenauer R. Schmidt G. Stangl M. Steller I. Weber 《Space Science Reviews》2007,128(1-4):869-904
The International Rosetta Mission is set for a rendezvous with Comet 67 P/Churyumov-Gerasimenko in 2014. On its 10 year journey
to the comet, the spacecraft will also perform a fly-by of the two asteroids Stein and Lutetia in 2008 and 2010, respectively.
The mission goal is to study the origin of comets, the relationship between cometary and interstellar material and its implications
with regard to the origin of the Solar System. Measurements will be performed that shed light into the development of cometary
activity and the processes in the surface layer of the nucleus and the inner coma.
The Micro-Imaging Dust Analysis System (MIDAS) instrument is an essential element of Rosetta’s scientific payload. It will
provide 3D images and statistical parameters of pristine cometary particles in the nm-μm range from Comet 67P/Churyumov-Gerasimenko.
According to cometary dust models and experience gained from the Giotto and Vega missions to 1P/Halley, there appears to be
an abundance of particles in this size range, which also covers the building blocks of pristine interplanetary dust particles.
The dust collector of MIDAS will point at the comet and collect particles drifting outwards from the nucleus surface. MIDAS
is based on an Atomic Force Microscope (AFM), a type of scanning microprobe able to image small structures in 3D. AFM images
provide morphological and statistical information on the dust population, including texture, shape, size and flux. Although
the AFM uses proven laboratory technology, MIDAS is its first such application in space. This paper describes the scientific
objectives and background, the technical implementation and the capabilities of MIDAS as they stand after the commissioning
of the flight instrument, and the implications for cometary measurements. 相似文献
13.
An equatorial coronal hole has been observed on 18 and 19 October 1996 with SOHO-CDS and with the Nancąy Radioheliograph (RH).
The CDS EUV line intensities are used to determine the coronal hole Differential Emission Measure (DEM); in turn this is used
to compute the radio brightness temperature Tb at the observed frequencies, leaving the coronal electron temperature and density as free parameters. EUV line intensities,
calculated from the derived models, show a good agreement with EUV observations.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
14.
电子式差定温探测器的研究 总被引:1,自引:0,他引:1
阐述了电子式差定温火灾探测器的工作原理,并对该探测器进行了深入的理论研究,提出了按探测器的不同灵敏度要求进行探测器设计的方法。使用所提出的设计方法,进行了原理样机的设计、实现和调试。原理洋机的研制成功,证明了用该设计方法进行电子式差定温探测器设计与调试的简便性、实用性和可靠性。 相似文献
15.
基于钇稳定二氧化锆(Yttria-stabilized Zirconia,YSZ)的阻温特性,设计了以YSZ热敏电阻为感受元件的火焰传感器,以传感器热敏电流信号表征火焰状态。采用伏安法,测量了YSZ热敏电阻在673K~1523K温度下的阻值,验证了YSZ阻值与温度的倒数呈指数关系。在Tirril喷灯点火、熄火试验中,研究了激励电压(3V~15V)、火焰温度(720K~1480K)和燃气流量(60L/h~150L/h)对传感器阶跃响应特性的影响。结果表明:热敏电流与激励电压呈正比,随火焰温度的升高而增大;点火响应时间随火焰温度、燃气流量的升高而减小;熄火响应时间基本不受火焰温度与燃气流量的影响。YSZ传感器能够对火焰产生正确响应,并且信号稳定、幅值强烈。 相似文献
16.
17.
针对有机工质高温高压下密度的测量较为困难的问题,特别是超临界状态下,设计出高温高压下密度的测量方法,并提出了基于最小二乘支持向量机(LSSVM)的密度预测方法.该方法首先利用实验手段对有机工质在不同温度、压力点下的密度进行测量,并通过对该离散的实验段数据的学习,利用最小二乘支持向量机方法预测得到T-p面上密度的连续值,尤其是实验手段难以测量的超临界下的密度.基于该方法,以有机工质六甲基二硅氧烷为例,得到了其在T(600~850K)与p(1.3~2.25MPa)范围内的密度值及密度关于温度压力的函数公式,并将其结果与公布的密度数据对比,结果表明:两者的相对误差仅为2.4%,证明了方法的有效性. 相似文献
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20.
The remote sensing of comets in the ultraviolet bandpass has been a valuable tool for studying the structure, composition,
variability, and physical processes at work in cometary comae. By extension, these studies of comae have revealed key insights
into the composition of cometary nuclei. Here we briefly review the ultraviolet studies of comets, and then take a look toward
the future of such work as anticipated by the advent of several key new instruments.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献