Giotto's Mission to planet Earth

Glaßmeier, K.‐H.; Neubauer, F. M.; Brach, Gilbert E.; Marschall, Horst R.; Acuña, M. H.; Burlaga, L. F.; Mariani, F.; Musmann, G.; Ness, N. F.; Wallis, M. K.; Ungstrup, E.; Schmidt, H. U.

doi:10.1029/91gl00550

Cited by 10 publications

(4 citation statements)

References 13 publications

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“…The Cassini Earth swing-by (ESB) manoeuvre on August 18, 1999 provided an excellent opportunity to undertake an investigation of the Earth's magnetosphere by a spacecraft having an unusual and rapid trajectory through the system. Such flybys are relatively rare, previous opportunities having been afforded by those of the Giotto and Galileo spacecraft [e.g., Glassmeier et al, 1991;Kivelson et al, 1993;Reeves et al, 1993]. Cassini entered the magnetosphere near the subsolar point, and after a close planetary approach in the dusk local time sector flew down the geomagnetic tail, exiting on the northern dawn side at a geocentric distance of-67 RE.…”

Section: Introductionmentioning

confidence: 99%

Observations of two complete substorm cycles during the Cassini Earth swing‐by: Cassini magnetometer data in a global context

Khan¹,

Cowley²,

Колесникова³

et al. 2001

J. Geophys. Res.

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Section: Introductionmentioning

confidence: 99%

Observations of two complete substorm cycles during the Cassini Earth swing‐by: Cassini magnetometer data in a global context

Khan¹,

Cowley²,

Колесникова³

et al. 2001

J. Geophys. Res.

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“…That Kelvin-Helmholtz instability (KHI) induced surface waves actually exist on the high-latitude magnetopause with sufficient amplitude is still an open question, primarily because this is a very infrequently sampled region of the magnetosphere. However, evidence which does support such a mechanism was provided by the July 2, 1990, Giotto-Earth encounter/ Glassmeier et al, 1991] during which the magnetic signatures of surface waves were detected in this region. It is therefore plausible that the required magnetoacoustic waves in the lobe could be generated by such surface waves, although it is also possible that they could be produced by bulk inward/outward motions of the magnetopause as well.…”

Section: Introductionmentioning

confidence: 99%

Comparison of Viking onset locations with the predictions of the Thermal Catastrophe Model

Henderson¹,

Murphree²

1995

J. Geophys. Res.

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In the thermal catastrophe model of substorms, onset is attributed to an explosive heating of the plasma sheet boundary layer (PSBL) due to the resonant absorption of Alfv•n waves. These waves are assumed to have their origins at the magnetopause where solar-wind-driven Kelvin-Helmholtz surface waves launch magnetoacoustic waves through the lobes toward the PSBL which are then mode-converted to kinetic Alfv•n waves in the PSBL. On the basis of this wave source mechanism, the thermal catastrophe model predicts the locations in the tail where catastrophe and hence onset is most likely to occur. In this paper, the model predictions are extended to include the effects of a realistic tail field (represented by the Tsyganenko 1987 long model) and are compared to observations of substorm onset as determined from Viking auroral images. The use of a realistic tail field causes a deflection of the catastrophe domain towards the dusk (dawn) flanks of the magnetosphere for gardenhose (orthogardenhose) interplanetary magnetic field (IMF) conditions, and it is also found that this region extends into the deep tail only for higher solar wind speeds, thereby confining catastrophe to the relatively near-Earth portions of the tail for typical conditions. Most of the other results obtained with the inclusion of a realistic tail field produce trends similar to the original model predictions including the results that onset should get closer to midnight for increasing solar wind speed and that onset should occur in the premidnight (postmidnight) sector for gardenhose (orthogardenhose) IMF conditions. Although a weak consistency with measured onset locations is observed, many more events than are contained in the Viking database are required in order to provide a firm conclusion. However, the reasonably well established result that onset occurs very close to the Earth on closed field lines is inconsistent with the predictions of the model which places onset on PSBL field lines. Thus the thermal catastrophe model is not a likely mechanism for typical substorm onsets. Nevertheless, evidence is shown that the mechanism may still operate in the magnetosphere to produce a different type of auroral intensification. Paper number 95JA00416. 0148-0227/95/95JA-00416505.00 and an explosive increase in temperature results. The magneto-acoustic waves in the lobe are assumed to be driven by surface fluctuations on the high-latitude magnetopause as a result of Kelvin-Helmholtz waves excited there by the interaction of the solar wind with the magnetosphere. An "equation of state" for the PSBL in the presence of resonant absorption results in which the temperature of the plasma sheet boundary layer (PSBL) depends on two control parameters and topologically takes the form of a classic cusp catastrophe manifold. Goertz and Smith [1989] suggested a variety of possible evolutionary tracks for substorms in terms of trajectories on this manifold. It is worth noting that Lewis [1993] has recently proposed a model in which substorm behavior is explained quali...

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“…On December 8, 1990, the Galileo spacecraft flew by Earth as part of a series of gravity-assist maneuvers designed to send the spacecraft on its way to Jupiter. Many spacecraft equipped to measure particles and fields have flown in orbit about Earth, but Galileo was only the second spacecraft to make a rapid flyby of the sort familiar from many planetary missions (the first was Giotto, as reported by Glassmeier et al [1991]). It is evident from Figure l a that the encounter trajectory, traversed at a higher speed than typical for an orbiting spacecraft, was directed up the center of the magnetotail.…”

Section: Introductionmentioning

confidence: 99%

The Galileo Earth encounter: Magnetometer and allied measurements

Kivelson

Kennel²,

McPherron³

et al. 1993

J. Geophys. Res.

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The Galileo spacecraft flew by Earth on December 8, 1990, at high speed along a trajectory that traversed the magnetotail and the near Earth magnetosphere. Galileo's orbit through a region of the magnetotail from which limited data are available provided a unique opportunity to study a number of substorm-related phenomena. Several groups cooperated in collecting correlative data in order to take advantage of this special opportunity. Fortunately, geomagnetic conditions were rather disturbed during the entire day, and an interplanetary shock passed Earth when the spacecraft was in the magnetotail at about 30 Re geocentric distance. In this first report we provide an overview of the Galileo magnetometer observations from the crossing of the tail magnetopause at an antisolar distance of close to 100 Re through exit into the solar wind on the dayside. We link these measurements with correlative data from ground stations and from IMP 8 which was ideally located to serve as a monitor of the solar wind upstream of the bow shock. Based on our analysis, we present a time line of the important geomagnetic events of the day that we believe provides a framework for the full multi-instrument analysis of the flyby data. In this paper we use the observations to investigate aspects of the relationship between magnetotail dynamics and the separate intensifications of a multiple onset substorm inferred from ground-based data. The spacecraft spent 6 h downstream of lunar orbit, of which more than 4 h were spent outside of the plasma sheet in regions where traveling compressional regions (TCRs) should have been apparent. Although six substorm intensifications were recorded on the ground during this interval, we did not observe a detectable TCR or plasmoid for every intensification. Our interpretation has important implications for the description of substorm dynamics in the tail. We propose that the signatures associated with individual substorm intensifications are localized in dawn-to-dusk extent even at remote locations in the magnetotail, just as they are in the ionosphere, and that the tail disturbances associated with successive substorm intensifications step across the tail towards the dusk flank. This latter interpretation is appealing as it can explain the failure of Galileo to observe a signature associated with each intensification without invalidating the conclusion of ISEE 3 investigators that in the same region of the magnetotail at least one signature can be associated with each substorm viewed as a collection of individual intensifications. Plasmoidlike signatures with strong axial fields along the GSM y axis and parallel to the By of the interplanetary magnetic field (IMF) were present when the spacecraft was embedded close to the center of the plasma sheet. We interpret these signatures as flux ropes, that is, twisted magnetic structures with one end possibly tied to the ionosphere. The modeled structure yields j x B/jB << 1 which suggests that the flux ropes are magnetically force free to within the limitations of...

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Giotto's Mission to planet Earth

Cited by 10 publications

References 13 publications

Observations of two complete substorm cycles during the Cassini Earth swing‐by: Cassini magnetometer data in a global context

Observations of two complete substorm cycles during the Cassini Earth swing‐by: Cassini magnetometer data in a global context

Comparison of Viking onset locations with the predictions of the Thermal Catastrophe Model

The Galileo Earth encounter: Magnetometer and allied measurements

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