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Journal ArticleDOI

Global distribution of crustal magnetization discovered by the mars global surveyor MAG/ER experiment

TL;DR: Vector magnetic field observations of the martian crust were acquired by the Mars Global Surveyor (MGS) magnetic field experiment/electron reflectometer (MAG/ER) during the aerobraking and science phasing orbits, at altitudes between approximately 100 and 200 kilometers.
Abstract: Vector magnetic field observations of the martian crust were acquired by the Mars Global Surveyor (MGS) magnetic field experiment/electron reflectometer (MAG/ER) during the aerobraking and science phasing orbits, at altitudes between ∼100 and 200 kilometers. Magnetic field sources of multiple scales, strength, and geometry were observed. There is a correlation between the location of the sources and the ancient cratered terrain of the martian highlands. The absence of crustal magnetism near large impact basins such as Hellas and Argyre implies cessation of internal dynamo action during the early Naochian epoch (∼4 billion years ago). Sources with equivalent magnetic moments as large as 1.3 × 1017 ampere-meter2in the Terra Sirenum region contribute to the development of an asymmetrical, time-variable obstacle to solar wind flow around Mars.

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Citations
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Journal ArticleDOI
TL;DR: The Mars Orbiter Laser Altimeter (MOLA) has been used to measure the topography, surface roughness, and 1.064-μm reflectivity of Mars and the heights of volatile and dust clouds as mentioned in this paper.
Abstract: The Mars Orbiter Laser Altimeter (MOLA), an instrument on the Mars Global Surveyor spacecraft, has measured the topography, surface roughness, and 1.064-μm reflectivity of Mars and the heights of volatile and dust clouds. This paper discusses the function of the MOLA instrument and the acquisition, processing, and correction of observations to produce global data sets. The altimeter measurements have been converted to both gridded and spherical harmonic models for the topography and shape of Mars that have vertical and radial accuracies of ~1 m with respect to the planet's center of mass. The current global topographic grid has a resolution of 1/64° in latitude × 1/32° in longitude (1 × 2 km^2 at the equator). Reconstruction of the locations of incident laser pulses on the Martian surface appears to be at the 100-m spatial accuracy level and results in 2 orders of magnitude improvement in the global geodetic grid of Mars. Global maps of optical pulse width indicative of 100-m-scale surface roughness and 1.064-μm reflectivity with an accuracy of 5% have also been obtained.

1,542 citations

Journal ArticleDOI
01 Aug 2004-Icarus
TL;DR: In this paper, the authors used the most recent data for the rotational state of Mars, and a new numerical integration of the Solar System, to provide a precise solution for the evolution of Mars' spin over 10 to 20 Myr.

878 citations

Journal ArticleDOI
03 Nov 2011-Nature
TL;DR: Clay minerals, recently discovered to be widespread in Mars’s Noachian terrains, indicate long-duration interaction between water and rock over 3.7 billion years ago, and available data indicate substantial Martian clay formation by hydrothermal groundwater circulation and a Noachia rock record dominated by evidence of subsurface waters.
Abstract: Clay minerals, recently discovered to be widespread in Mars’s Noachian terrains, indicate long-duration interaction between water and rock over 3.7 billion years ago. Analysis of how they formed should indicate what environmental conditions prevailed on early Mars. If clays formed near the surface by weathering, as is common on Earth, their presence would indicate past surface conditions warmer and wetter than at present. However, available data instead indicate substantial Martian clay formation by hydrothermal groundwater circulation and a Noachian rock record dominated by evidence of subsurface waters. Cold, arid conditions with only transient surface water may have characterized Mars’s surface for over 4 billion years, since the early-Noachian period, and the longest-duration aqueous, potentially habitable environments may have been in the subsurface.

720 citations

Journal ArticleDOI
TL;DR: The MAVEN spacecraft has eight science instruments (with nine sensors) that measure the energy and particle input from the Sun into the Mars upper atmosphere, the response of the upper atmosphere to that input, and the resulting escape of gas to space as mentioned in this paper.
Abstract: The MAVEN spacecraft launched in November 2013, arrived at Mars in September 2014, and completed commissioning and began its one-Earth-year primary science mission in November 2014 The orbiter’s science objectives are to explore the interactions of the Sun and the solar wind with the Mars magnetosphere and upper atmosphere, to determine the structure of the upper atmosphere and ionosphere and the processes controlling it, to determine the escape rates from the upper atmosphere to space at the present epoch, and to measure properties that allow us to extrapolate these escape rates into the past to determine the total loss of atmospheric gas to space through time These results will allow us to determine the importance of loss to space in changing the Mars climate and atmosphere through time, thereby providing important boundary conditions on the history of the habitability of Mars The MAVEN spacecraft contains eight science instruments (with nine sensors) that measure the energy and particle input from the Sun into the Mars upper atmosphere, the response of the upper atmosphere to that input, and the resulting escape of gas to space In addition, it contains an Electra relay that will allow it to relay commands and data between spacecraft on the surface and Earth

628 citations


Cites methods from "Global distribution of crustal magn..."

  • ...With a Figure 3 MAVEN Type - II Ballistic Transfer decreasing C3 over the launch period, the MOl fl....

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Journal ArticleDOI
01 Nov 2001-Icarus
TL;DR: In this article, the authors consider the hydraulic and thermal conditions that gave rise to the elevated source regions of the Late Hesperian outflow channels and explore their implications for the evolution of the Martian hydrosphere.

590 citations


Cites background from "Global distribution of crustal magn..."

  • ...This conclusion is reinforced by the recent discovery of residual magnetic lineations within the southern highland crust (Acuña et al. 1999, Connerny et al. 1999), the potential signature of an early period of incipient plate tectonics (e.g., Sleep 1994)....

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References
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Journal ArticleDOI
30 Apr 1999-Science
TL;DR: The Mars Global Surveyor spacecraft obtained vector magnetic field measurements above the surface of Mars and groups of quasi-parallel linear features of alternating magnetic polarity were found, reminiscent of similar magnetic features associated with sea floor spreading and crustal genesis on Earth but with a much larger spatial scale.
Abstract: The Mars Global Surveyor spacecraft, in a highly elliptical polar orbit, obtained vector magnetic field measurements above the surface of Mars (altitudes >100 kilometers). Crustal magnetization, mainly confined to the most ancient, heavily cratered martian highlands, is frequently organized in east-west-trending linear features, the longest extending over 2000 kilometers. Crustal remanent magnetization exceeds that of terrestrial crust by more than an order of magnitude. Groups of quasi-parallel linear features of alternating magnetic polarity were found. They are reminiscent of similar magnetic features associated with sea floor spreading and crustal genesis on Earth but with a much larger spatial scale. They may be a relic of an era of plate tectonics on Mars.

481 citations

Journal ArticleDOI
10 May 1984-Nature
TL;DR: In this article, the authors proposed that the large expanse of lowlands of Mars is substantially due to the formation of a large impact basin early in the planet's history, which has markedly influenced the character of the Martian surface.
Abstract: Of the two approximately hemispherical, fundamentally different geological provinces into which Mars is divided, the more southerly province is heavily cratered, while the northern is lightly cratered and contains younger geological units. Lowlands occupy about one-third of Mars, and these are separated from the highlands by a distinct scarp or by a sloping transitional zone which is characterized by a variety of landforms that are unknown on other planets. It is presently proposed that the largest expanse of lowlands is substantially due to the formation of a large impact basin early in the planet's history, which has markedly influenced the character of the Martian surface.

260 citations

Journal ArticleDOI
TL;DR: In this article, the authors test the hypothesis that the crustal dichotomy on Mars is due to a single giant (mega) impact early in Martian history by determining the number of missing basins, the difference between the observed number of large impact basins on Mars and the number expected from a 1/D-squared distribution.
Abstract: The hypothesis that the crustal dichotomy on Mars is due to a single giant (mega) impact early in Martian history is tested by determining the number of 'missing' basins, the difference between the observed number of large impact basins on Mars and the number expected from a 1/D-squared distribution. If the Borealis Basin was the largest member of a 1/D-squared impact population, a large number of 'missing' basins is expected which is too large to be hidden by the younger surface units. If Chryse is the largest member of a 1/D-squared impact population, the more modest number of 'missing' basins could be confined to areas of Mars that have been resurfaced or reworked by subsequent geologic processes.

151 citations

Journal ArticleDOI
TL;DR: The magnetic field experiment designed for the Mars Observer mission will provide definitive measurements of the Martian magnetic field from the transition and mapping orbits planned for the MARS Observer as mentioned in this paper, which will investigate the nature of the magnetic field and the Mars-solar wind interaction, the mapping of crustal magnetic fields, and studies of the Mars ionosphere.
Abstract: The magnetic fields experiment designed for the Mars Observer mission will provide definitive measurements of the Martian magnetic field from the transition and mapping orbits planned for the Mars Observer. The paper describes the instruments (which include a classical magnetometer and an electron reflection magnetometer) and techniques designed to investigate the nature of the Martian magnetic field and the Mars-solar wind interaction, the mapping of crustal magnetic fields, and studies of the Martian ionosphere, which are activities included in the Mars Observer mission objectives. Attention is also given to the flight software incorporated in the on-board data processor, and the procedures of data processing and analysis.

125 citations

Journal ArticleDOI
TL;DR: The marked dichotomy in topography, surface age, and crustal thickness between the northern lowland and southern upland of Mars has been explained as due to an initially inhomogeneous crust, a single megaimpact event, several overlapping large basin impacts, and first-order convective overtum of the Martian mantle as mentioned in this paper.
Abstract: The marked dichotomy in topography, surface age, and crustal thickness between the northern lowland (NL) and southern upland of Mars has been explained as due to an initially inhomogeneous crust, a single megaimpact event, several overlapping large basin impacts, and first-order convective overtum of the Martian mantle. All of these hypotheses propose that the dichotomy was formed before the end of the primordial heavy bombardment. Geological data indicate episodes of fracturing and faulting in the late Noachian and the early Hesperian, within the NL and along the lowland/highland boundary. Igneous activity also peaked in the late Noachian and early Hesperian. These data suggest a tectonic event near the Noachian/Hesperian boundary characterized by enhanced heat loss and extensive fracturing, including formation of the faults that define much of the highland/lowland boundary. It is argued that the major result of this tectonic event was formation of the dichotomy by thinning of the crust above a large convection cell or plume.

105 citations

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