Mariner 6 and 7 Ultraviolet Spectrometer Experiment: Analysis of hydrogen Lyman-alpha data

Anderson, Donald E.

doi:10.1029/ja076i028p06666

Cited by 215 publications

(144 citation statements)

References 9 publications

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“…The error bars of the Mariner values are notably smaller because the Mariner measurements were obtained with a UV spectrometer that was designed for this task. Since our interpretation of the Mariner measurements is consistent with the one published 35 years ago by Anderson and Hord (1971) we conclude that the values derived from UV airglow measurements do not critically depend on the specific exosphere model. (20) to (25)), whereas for the three lower rows we have assumed the co-existence of a cool and a hot hydrogen component.…”

Section: One Single Hydrogen Componentsupporting

confidence: 76%

The Hydrogen Exospheric Density Profile Measured with ASPERA-3/NPD

Galli¹,

Würz²,

Lämmer

et al. 2007

The Mars Plasma Environment

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Abstract.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, F 10.7 = 100). We derive estimates for the hydrogen exobase density, n H = 10 10 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.

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Section: One Single Hydrogen Componentsupporting

confidence: 76%

The Hydrogen Exospheric Density Profile Measured with ASPERA-3/NPD

Galli¹,

Würz²,

Lämmer

et al. 2007

The Mars Plasma Environment

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“…Mariner 10 measurements of the He corona gave a T o of about 375 + 105 K . Anderson (1976) reanalyzed the Mariner 5 Lc~ data and reported for the inner component a dayside temperature of 275 K and a nightside temperature of 150 K. These low values were later confirmed by the Pioneer Venus in situ measurements. A value of T o of 275 + 15 K was derived from the He densities measured by the Bus Neutral Mass Spectrometer at 08" 30 local time, 37.9 ~ S latitude (von Zahn et al, 1980).…”

Section: Exospheric Temperaturementioning

confidence: 96%

Structure, luminosity, and dynamics of the Venus thermosphere

Fox

Bougher

1991

Space Sci Rev

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We review here observations and models related to the chemical and thermal structures, airglow and auroral emissions and dynamics of the Venus thermosphere, and compare empirical models of the neutral densities based in large part on in situ measurements obtained by the Pioneer Venus spacecraft.Observations of the intensities of emissions are important as a diagnostic tool for understanding the chemical and physical processes taking place in the Venus thermosphere. Measurements, ground-based and from rockets, satellites, and spacecraft, and model predictions of atomic, molecular and ionic emissions, are presented and the most important sources are elucidated. Coronas of hot hydrogen and hot oxygen have been observed to surround the terrestrial planets. We discuss the observations of and production mechanisms for the extended exospheres and models for the escape of lighter species from the atmosphere. Over the last decade and a half, models have attempted to explain the unexpectedly cold temperatures in the Venus thermosphere; recently considerable progress has been made, although some controversies remain. We review the history of these models and discuss the heating and cooling mechanisms that are presently considered to be the most important in determining the thermal structure. Finally, we discuss major aspects of the circulation and dynamics of the thermosphere: the sub-solar to anti-solar circulation, superrotation, and turbulent processes.

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“…For hydrogen, the density profile used is a combination of results from Anderson & Hord (1971) and Krasnopolsky (2002): …”

Section: Solar Parametersmentioning

confidence: 99%

Solar wind charge exchange X-ray emission from Mars

Koutroumpa¹,

Modolo²,

Chanteur³

et al. 2012

A&A

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Aims. We study the soft X-ray emission induced by charge exchange (CX) collisions between solar-wind, highly charged ions and neutral atoms of the Martian exosphere. Methods. A 3D multispecies hybrid simulation model with improved spatial resolution (130 km) is used to describe the interaction between the solar wind and the Martian neutrals. We calculated velocity and density distributions of the solar wind plasma in the Martian environment with realistic planetary ions description, using spherically symmetric exospheric H and O profiles. Following that, a 3D test-particle model was developed to compute the X-ray emission produced by CX collisions between neutrals and solar wind minor ions. The model results are compared to XMM-Newton observations of Mars. Results. We calculate projected X-ray emission maps for the XMM-Newton observing conditions and demonstrate how the X-ray emission reflects the Martian electromagnetic structure in accordance with the observed X-ray images. Our maps confirm that X-ray images are a powerful tool for the study of solar wind-planetary interfaces. However, the simulation results reveal several quantitative discrepancies compared to the observations. Typical solar wind and neutral coronae conditions corresponding to the 2003 observation period of Mars cannot reproduce the high luminosity or the corresponding very extended halo observed with XMM-Newton. Potential explanations of these discrepancies are discussed.

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Mariner 6 and 7 Ultraviolet Spectrometer Experiment: Analysis of hydrogen Lyman-alpha data

Cited by 215 publications

References 9 publications

The Hydrogen Exospheric Density Profile Measured with ASPERA-3/NPD

The Hydrogen Exospheric Density Profile Measured with ASPERA-3/NPD

Structure, luminosity, and dynamics of the Venus thermosphere

Solar wind charge exchange X-ray emission from Mars

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