On The magnetic field of Mars: Mars 2 and 3 evidence

Dolginov, Sh. Sh.

doi:10.1029/gl005i001p00089

Cited by 55 publications

(13 citation statements)

References 5 publications

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“…This study extends the initial Phobos 2 bow shock analyses [Riedler et al, 1989;Schwingenschuh et al, 1990] the passage of an interplanetary shock pair over the spacecraft. Unusually distant dayside bow shock crossings were also reported by Mars 2 and 3 and used to argue in favor of the existence of modest intrinsic magnetic field which can expand outward during intervals of weak solar wind dynamic pressure [Dolginov et al, 1973;Bogdanov and Vaisberg, 1975;Dolginov, 1978;Slavin et al, 1983]. The Phobos 2 observations appear to confirm that such events occur at a rate of about once per month.…”

Section: Introductionmentioning

confidence: 82%

The solar wind interaction with Mars: Mariner 4, Mars 2, Mars 3, Mars 5, and Phobos 2 observations of bow shock position and shape

Slavin

Schwingenschuh²,

Riedler³

et al. 1991

J. Geophys. Res.

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Observations taken by Mariner 4, Mars 2, Mars 3, Mars 5, and Phobos 2 are used to model the shape, position, and variability of the Martian bow shock for the purpose of better understanding the interaction of this planet with the solar wind. Emphasis is placed upon comparisons with the results of similar analyses at Venus, the only planet known to have no significant intrinsic magnetic field. Excellent agreement is found between Mars bow shock models derived from the earlier Mariner‐Mars data set (24 crossings in 1964–1974) and the far more extensive observations recently returned by Phobos 2 (94 crossings in 1989). The best fit model to the aggregate data set locates the subsolar bow shock at a planetocentric distance of 1.56±0.04 RM. Mapped into the terminator plane, the average distance to the Martian bow shock is 2.66±0.05 RM. Compared with Venus, the bow wave at Mars is significantly more distant in the terminator plane, 2.7 RM versus 2.4 RV, and over twice as variable in location with a standard deviation of 0.49 RM versus 0.21 RV at Venus. The Mars 2, 3, and 5 and Phobos 2 data also contain a small number of very distant dayside shock crossings with inferred subsolar obstacle radii derived from gasdynamic modeling of 2000 to 4000 km. Such distant bow shock occurrences do not appear to take place at Venus and may be associated with the expansion of a small Martian magnetosphere under the influence of unusually low solar wind pressure. Finally, the altitude of the Venus bow shock has a strong solar cycle dependence believed to be due to the effect of solar EUV on the neutral atmosphere and mass loading. Comparison of the Phobos 2 shock observations near solar maximum (Rz = 141) with the Mariner‐Mars measurements taken much farther from solar maximum (Rz = 59) indicates that the Martian bow shock location is independent of solar cycle phase and, hence, solar EUV flux. These results are interpreted in terms of a hybrid solar wind interaction model in which this planet possesses a weak, but significant, intrinsic magnetic field.

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Section: Introductionmentioning

confidence: 82%

The solar wind interaction with Mars: Mariner 4, Mars 2, Mars 3, Mars 5, and Phobos 2 observations of bow shock position and shape

Slavin

Schwingenschuh²,

Riedler³

et al. 1991

J. Geophys. Res.

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“…Second the Martian magnetosphere may contain more plasma at magnetopause altitudes than does the terrestrial analogue due to the large relative height of the ionosphere which is expected to be continuously losing particles to magnetospheric convection [see Bauer and Hartle, 1973]. Finally Bogdanov [ 1978Bogdanov [ , 1981 periapsis on a number of occasions such as 1/8/72, 2/22/72, 2/24/72, 4/6/72, 4/18/72, and 5/12/72 [Dolginov, 1978b ] when the magnetometer was turned on during the pericenter passage (note: the particles and fields experiments onboard Mars 2 and 3 were off during more than half of the low altitude passes; Gringauz [ 1976]). However, no direct determinations of magnetic moment have made from the measurements due to a lack of complete attitude information for Mars 2 with which to construct the vector field and also the resulting uncertainties regarding the magnetometer offsets [Dolginov et al, 1976a].…”

Section: Bothmentioning

confidence: 99%

The solar wind interaction with Mars revisited

Slavin¹,

Holzer²

1982

J. Geophys. Res.

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Owing to a paucity of observational data, no clear consensus has been reached concerning the general nature of the solar wind interaction with Mars. In particular, the previous analyses are still at odds regarding the existence of a small intrinsic field magnetosphere at Mars as opposed to a Venus‐type ionospheric interaction (e.g., Russell, 1978a,b; Dolginov, 1978b,c). This study contributes to the resolution of this question in three ways. First, an improved determination of effective obstacle altitude and shape is obtained from the Mars 2,3, and 5 bow shock encounters through the use of a recently published catalog of gasdynamic flow solutions (Spreiter and Stahara, 1980a,b). Second, building upon the Pioneer Venus findings at a field‐free planet (Brace et al., 1980; Elphic et al., 1980), it is shown that the Martian ionosphere cannot support a Venus‐type ionopause at the obstacle altitudes inferred through our modeling of the bow wave observations even when maximal induced ionospheric magnetic fields and solar maximum EUV levels are assumed. These results allow an effective Mars magnetic dipole moment of 1.4 (±0.6) × 1022 G‐cm3 to be determined that stands off the solar wind over the dayside hemisphere at altitudes ranging from∼500 km at the subsolar point to ∼1000 km near the terminator with no direct aid from the ionosphere under average solar wind/magnetospheric conditions. Third, a search of published Mars and Mariner radio occultation measurements produced no evidence for the existence of an ionopause at Mars in agreement with the Viking study of Lindal et al. (1979). Rather, the electron density altitude profiles appear qualitatively consistent with the Martian ionosphere terminating in a chemopause associated with the effects of magnetospheric convection as first proposed by Bauer and Hartle (1973). After a review of the various arguments in the literature, as supplemented by the results of this study, we conclude that Mars most probably possesses a small intrinsic field magnetosphere.

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“…This scenario suggests that Mars has an intrinsic magnetosphere produced by a dipole magnetic field and the Martian ionosphere is protected from the SW flow [Dolginov, 1978;Gringauz et Hanson and Mantas [1988] analyzed the altitude profile of thermal pressure using the electron density profiles within the altitude range 120-300 km and the SZA: 380-44 ø (Viking 1) and 46ø-51 ø (Viking 2), corresponding to the solar minimum. They concluded that the thermal pressure of the ionospheric plasma alone is lower than the mean value of the SW dynamic pressure near Mars.…”

Section: Magnetic Field In the Martian Ionospherementioning

confidence: 99%

Effects of magnetic anomalies discovered at Mars on the structure of the Martian ionosphere and solar wind interaction as follows from radio occultation experiments

Ness¹,

Acuña²,

Connerney³

et al. 2000

J. Geophys. Res.

100

103

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On The magnetic field of Mars: Mars 2 and 3 evidence

Abstract: Recently the existence of an intrinsic field of Mars has been questioned. In this note we review the evidence from Mars 2 and 3 from which our original conclusion of a Martian magnetic field was deduced and reaffirm our original conclusions.

Cited by 55 publications

References 5 publications

The solar wind interaction with Mars: Mariner 4, Mars 2, Mars 3, Mars 5, and Phobos 2 observations of bow shock position and shape

The solar wind interaction with Mars: Mariner 4, Mars 2, Mars 3, Mars 5, and Phobos 2 observations of bow shock position and shape

The solar wind interaction with Mars revisited

Effects of magnetic anomalies discovered at Mars on the structure of the Martian ionosphere and solar wind interaction as follows from radio occultation experiments

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