Assessment of Mars Science and Mission Priorities (2003) / Chapter Skim
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10. Upper Atmosphere, Ionosphere, and Solar Wind Interactions
10. Upper Atmosphere, Ionosphere, and Solar Wind Interactions
Pages 77-82
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From page 77... ...
Lyman-oc airglow observations have provided information on the daytime thermal hydrogen densities, indicating a value on the order of 105 cm-3 at an altitude of 150 km.3 The first observations of a hot atom corona anywhere in the solar system were provided by the Lyman-oc measurements of hydrogen at Venus.4 An extended hot oxygen and carbon corona has also been observed at Venus.5 6 Although no corresponding observations are yet available for Mars, theoretical models predict the presence of a similarly hot atom corona.7 ~ The z-axis accelerometer carried by the Mars Global Surveyor (MGS) provided a great deal of important information about total densities and temperatures during its extended aerobraking period.9 It made measurements over about 900 orbits between altitudes of approximately 110 to 160 km during solar minimum to moderate conditions.
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From page 78... ...
, and they are quite successful in accounting for the overall MGS temperature observations.~° However, the dynamical and radiative processes that drive the Mars lower and upper atmospheres on the short time scales corresponding to short-lived dust storms are yet to be explained, and of course no direct information on the winds is available. Ionosphere and Solar Wind Interaction The only in situ measurements of the thermal plasma composition, density, and temperature in the ionosphere of Mars were obtained by the retarding potential analyzers earned aboard the two Viking landersii and by the mass spectrometers mentioned above.
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From page 79... ...
and Soviet spacecraft that either flew by or orbited Mars earned magnetometers and some limited plasma instrumentation; they discovered a well-defined bow shock around the planet and provided limited information on the fields and particles inside the bow shock. The Soviet Phobos mission was the first (and so far the only)
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From page 80... ...
Mars Global Surveyor carried a magnetometer and electron reflectometer package, and during the extended aerobraking phase of the mission it made many low-altitude measurements. One of the most exciting and unexpected results of the MGS mission was the finding that although Mars has no intrinsic magnetic field, relatively strong and widespread remnant crustal magnetization is present (see Chapter 2 in this report)
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From page 81... ...
These small magnetospheric regions may undergo reconnection with the compressed interplanetary magnetic field in the magnetosheath. These reconnection events must depend on the specific location of the crustal field with respect to the subsolar location and solar wind parameters, such as magnetic field angle.
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From page 82... ...
Ness, "Solar Wind Interaction with Mars: Locations and Shapes of the Bow Shock and Magnetic-Pile-Up Boundary from the Observations of the MAG/ER Experiment Onboard Mars Global Surveyor," Geophysical Research Letters 27: 49-52, 2000.
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