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1.
A brief summary of the main results of magnetospheric ion composition measurements in general is first presented. PROGNOZ-7 measurements in the nightside plasma mantle are then described and analyzed. Some of the results are the following: In the nightside mantle not too far from midnight the properties of the mantle are sometimes consistent with the open magnetosphere model. However during most magnetic storm situations O+ ions appear in the mantle in large proportions and with high energies. The acceleration process affecting the ions has been found in several cases to give equal amounts of energy to all ions independent of mass. Along the flanks of the magnetosphere the flow of the plasma is often low or absent. The O+ content is high (up to 20%) and the energy spectrum of both ions and electrons may be very hot, even up to the level of the ring current plasma in the keV range.The O+ content in the plasma mantle is positively correlated with the magnetospheric activity level. The mantle, however, does not appear to be the dominating source for the storm time ring current. Direct acceleration of ionospheric ions onto the closed field lines of the plasma sheet and ring current is most likely the main source. The magnetopause on the nightside and along the flanks of the magnetosphere appears to be a fairly solid boundary for mantle ions of ionospheric origin. This is especially evident during periods with high geomagnetic activity, when the mantle is associated with fairly strong fluxes of O+ ions.An interesting observation in most of the mantle passages during geomagnetically disturbed periods is the occurrence of intense, magnetosheath like, regions deep inside the mantle. In some cases these regions with strong antisunward flow and with predominant magnetosheath ion composition was observed in the innermost part of the mantle, i.e. marking a boundary region between the lobe and the mantle. These magnetosheath penetration events are usually associated with strong fluxes of accelerated ionospheric ions in nearby parts of the mantle. Evanescent penetration regions with much reduced flow properties are frequently observed in the flank mantle. 相似文献
2.
Y. Futaana S. Barabash A. Grigoriev D. Winningham R. Frahm M. Yamauchi R. Lundin 《Space Science Reviews》2006,126(1-4):315-332
As a part of the global plasma environment study of Mars and its response to the solar wind, we have analyzed a peculiar case
of the subsolar energetic neutral atom (ENA) jet observed on June 7, 2004 by the Neutral Particle Detector (NPD) on board
the Mars Express satellite. The “subsolar ENA jet” is generated by the interaction between the solar wind and the Martian
exosphere, and is one of the most intense sources of ENA flux observed in the vicinity of Mars. On June 7, 2004 (orbit 485
of Mars Express), the NPD observed a very intense subsolar ENA jet, which then abruptly decreased within ∼10 sec followed
by quasi-periodic (∼1 min) flux variations. Simultaneously, the plasma sensors detected a solar wind structure, which was
most likely an interplanetary shock surface. The abrupt decrease of the ENA flux and the quasi-periodic flux variations can
be understood in the framework of the global response of the Martian plasma obstacle to the interplanetary shock. The generation
region of the subsolar ENA jet was pushed towards the planet by the interplanetary shock; and therefore, Mars Express went
out of the ENA jet region. Associated global vibrations of the Martian plasma obstacle may have been the cause of the quasi-periodic
flux variations of the ENA flux at the spacecraft location. 相似文献
3.
Yuri N. Kulikov Helmut Lammer Herbert I. M. Lichtenegger Thomas Penz Doris Breuer Tilman Spohn Rickard Lundin Helfried K. Biernat 《Space Science Reviews》2007,129(1-3):207-243
Because the solar radiation and particle environment plays a major role in all atmospheric processes such as ionization, dissociation,
heating of the upper atmospheres, and thermal and non-thermal atmospheric loss processes, the long-time evolution of planetary
atmospheres and their water inventories can only be understood within the context of the evolving Sun. We compare the effect
of solar induced X-ray and EUV (XUV) heating on the upper atmospheres of Earth, Venus and Mars since the time when the Sun
arrived at the Zero-Age-Main-Sequence (ZAMS) about 4.6 Gyr ago. We apply a diffusive-gravitational equilibrium and thermal
balance model for studying heating of the early thermospheres by photodissociation and ionization processes, due to exothermic
chemical reactions and cooling by IR-radiating molecules like CO2, NO, OH, etc. Our model simulations result in extended thermospheres for early Earth, Venus and Mars. The exospheric temperatures
obtained for all the three planets during this time period lead to diffusion-limited hydrodynamic escape of atomic hydrogen
and high Jeans’ escape rates for heavier species like H2, He, C, N, O, etc. The duration of this blow-off phase for atomic hydrogen depends essentially on the mixing ratios of CO2, N2 and H2O in the atmospheres and could last from ∼100 to several hundred million years. Furthermore, we study the efficiency of various
non-thermal atmospheric loss processes on Venus and Mars and investigate the possible protecting effect of the early martian
magnetosphere against solar wind induced ion pick up erosion. We find that the early martian magnetic field could decrease
the ion-related non-thermal escape rates by a great amount. It is possible that non-magnetized early Mars could have lost
its whole atmosphere due to the combined effect of its extended upper atmosphere and a dense solar wind plasma flow of the
young Sun during about 200 Myr after the Sun arrived at the ZAMS. Depending on the solar wind parameters, our model simulations
for early Venus show that ion pick up by strong solar wind from a non-magnetized planet could erode up to an equivalent amount
of ∼250 bar of O+ ions during the first several hundred million years. This accumulated loss corresponds to an equivalent mass of ∼1 terrestrial
ocean (TO (1 TO ∼1.39×1024 g or expressed as partial pressure, about 265 bar, which corresponds to ∼2900 m average depth)). Finally, we discuss and
compare our findings with the results of preceding studies. 相似文献
4.
A. Galli P. Wurz H. Lammer H. I. M. Lichtenegger R. Lundin S. Barabash A. Grigoriev M. Holmström H. Gunell 《Space Science Reviews》2006,126(1-4):447-467
We have evaluated the Lyman-α limb emission from the exospheric hydrogen of Mars measured by the neutral particle detector of the ASPERA-3 instrument on Mars Express in 2004 at low solar activity (solar activity index = 42, F10.7=100). We derive estimates for the hydrogen exobase density, n H = 1010 m?3, and for the apparent temperature, T > 600 K. We conclude that the limb emission measurement is dominated by a hydrogen component that is considerably hotter than the bulk temperature at the exobase. The derived values for the exosphere density and temperature are compared with similar measurements done by the Mariner space probes in the 1969. The values found with Mars Express and Mariner data are brought in a broader context of exosphere models including the possibility of having two hydrogen components in the Martian exosphere. The present observation of the Martian hydrogen exosphere is the first one at high altitudes during low solar activity, and shows that for low solar activity exospheric densities are not higher than for high solar activity. 相似文献
5.
A. Galli P. Wurz S. Barabash A. Grigoriev H. Gunell R. Lundin M. Holmström A. Fedorov 《Space Science Reviews》2006,126(1-4):267-297
We present measurements of energetic hydrogen and oxygen atoms (ENAs) on the nightside of Mars detected by the neutral particle
detector (NPD) of ASPERA-3 on Mars Express. We focus on the observations for which the field-of-view of NPD was directed at
the nightside of Mars or at the region around the limb, thus monitoring the flow of ENAs towards the nightside of the planet.
We derive energy spectra and total fluxes, and have compiled maps of hydrogen ENA outflow. The hydrogen ENA intensities reach
105 cm−2 sr−1 s−1, but no oxygen ENA signals above the detection threshold of 104 cm−2 sr−1 s−1 are observed. These intensities are considerably lower than most theoretical predictions. We explain the discrepancy as due
to an overestimation of the charge-exchange processes in the models for which too high an exospheric density was assumed.
Recent UV limb emission measurements (Galli et al., this issue) point to a hydrogen exobase density of 1010 m−3 and a very hot hydrogen component, whereas the models were based on a hydrogen exobase density of 1012 m−3 and a temperature of 200 K predicted by Krasnopolsky and Gladstone (1996). Finally, we estimate the global atmospheric loss
rate of hydrogen and oxygen due to the production of ENAs. 相似文献
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8.
THE CLUSTER ION SPECTROMETRY (CIS) EXPERIMENT 总被引:5,自引:0,他引:5
H. RÈME J. M. Bosqued J. A. Sauvaud A. Cros J. Dandouras C. Aoustin J. Bouyssou Th. Camus J. Cuvilo C. Martz J. L. MÉDALE H. Perrier D. Romefort J. Rouzaud C. D'Uston E. MÖBIUS K. Crocker M. Granoff L. M. Kistler M. Popecki D. Hovestadt B. Klecker G. Paschmann M. Scholer C. W. Carlson D. W. Curtis R. P. Lin J. P. Mcfadden V. Formisano E. Amata M. B. Bavassano-CATTANEO P. Baldetti G. Belluci R. Bruno G. Chionchio A. Di Lellis E. G. Shelley A. G. Ghielmetti W. Lennartsson A. Korth H. Rosenbauer R. Lundin S. Olsen G. K. Parks M. Mccarthy H. Balsiger 《Space Science Reviews》1997,79(1-2):303-350
The Cluster Ion Spectrometry (CIS) experiment is a comprehensive ionic plasma spectrometry package on-board the four Cluster spacecraft capable of obtaining full three-dimensional ion distributions with good time resolution (one spacecraft spin) with mass per charge composition determination. The requirements to cover the scientific objectives cannot be met with a single instrument. The CIS package therefore consists of two different instruments, a Hot Ion Analyser (HIA) and a time-of-flight ion COmposition and DIstribution Function analyser (CODIF), plus a sophisticated dual-processor-based instrument-control and Data-Processing System (DPS), which permits extensive on-board data-processing. Both analysers use symmetric optics resulting in continuous, uniform, and well-characterised phase space coverage. CODIF measures the distributions of the major ions (H+, He+, He++, and O+) with energies from ~0 to 40 keV/e with medium (22.5°) angular resolution and two different sensitivities. HIA does not offer mass resolution but, also having two different sensitivities, increases the dynamic range, and has an angular resolution capability (5.6° × 5.6°) adequate for ion-beam and solar-wind measurements. 相似文献
9.
L. Eliasson O. Norberg R. Lundin K. Lundin S. Olsen H. Borg M. André H. Koskinen P. Riihelä M. Boehm B. Whalen 《Space Science Reviews》1994,70(3-4):563-576
The Hot Plasma Experiment, F3H, on boardFreja is designed to measure auroral particle distribution functions with very high temporal and spatial resolution. The experiment consists of three different units; an electron spectrometer that measures angular and energy distributions simultaneously, a positive ion spectrometer that is using the spacecraft spin for three-dimensional measurements, and a data processing unit. The main scientific objective is to study positive ion heating perpendicular to the magnetic field lines in the auroral region. The high resolution measurements of different positive ion species and electrons have already provided important information on this process as well as on other processes at high latitudes. This includes for example high resolution observations of auroral particle precipitation features and source regions of positive ions during magnetic disturbances. TheFreja orbit with an inclination of 63° allows us to make detailed measurements in the nightside auroral oval during all disturbance levels. In the dayside, the cusp region is covered during magnetic disturbances. We will here present the instrument in some detail and some outstanding features in the particle data obtained during the first months of operation at altitudes around 1700 km in the northern hemisphere auroral region. 相似文献
10.
H. Nilsson E. Carlsson H. Gunell Y. Futaana S. Barabash R. Lundin A. Fedorov Y. Soobiah A. Coates M. Fränz E. Roussos 《Space Science Reviews》2006,126(1-4):355-372
Using data from the Mars Express Ion Mass Analyzer (IMA) we investigate the distribution of ion beams of planetary origin
and search for an influence from Mars crustal magnetic anomalies. We have concentrated on ion beams observed inside the induced
magnetosphere boundary (magnetic pile-up boundary). Some north-south asymmetry is seen in the data, but no longitudinal structure
resembling that of the crustal anomalies. Comparing the occurrence rate of ion beams with magnetic field strength at 400 km
altitude below the spacecraft (using statistical Mars Global Surveyor results) shows a decrease of the occurrence rate for
modest (< 40 nT) magnetic fields. Higher magnetic field regions (above 40 nT at 400 km) are sampled so seldom that the statistics
are poor but the data is consistent with some ion outflow events being closely associated with the stronger anomalies. This
ion flow does not significantly affect the overall distribution of ion beams around Mars. 相似文献