Mars magnetism: a moot question?Mars magnetism: A moot question? Many space probes have landed on, orbited or flown past Mars, but none has clearly shown whether the planet produces its own magnetic field. A definitive answer may depend on an orbiting spacecraft called the Mars Observer, scheduled for launch in 1992. However, two NASA NASA: see National Aeronautics and Space Administration. NASA in full National Aeronautics and Space Administration Independent U.S. scientists now conclude that even if Mars does have an intrinsic magnetic field, it is "not of any consequence." In other words Adv. 1. in other words - otherwise stated; "in other words, we are broke" put differently , the magnetic field would be too weak to keep the solar wind from reaching Mars' upper atmosphere, or ionosphere ionosphere (īŏn`əsfēr), series of concentric ionized layers forming part of the upper atmosphere of the earth from around 30 to 50 mi (50 to 80 km) to 250 to 370 mi (400 to 600 km) where it merges with the magnetosphere, the region , assert Kushal K. Mahajan Mahajan is an Indian surname, found among the Vaishya castes (business communities). In India surname Mahajan is used by two communities: - one residing in North of India(mainly on the Amritsar to Jammu belt) and another belonging to North Maharashtra. and Hans G. Mayr of NASA's Goddard Space Flight Center The Goddard Space Flight Center (GSFC) is a major NASA space research laboratory established on May 1, 1959 as NASA's first space flight center. GSFC employs approximately 10,000 civil servants and contractors, and is located approximately 6.5 miles northeast of Washington, D.C. in Greenbelt, Md. The pressure of the solar wind varies. Thus the wind pushes with more or less force against a planet's ionosphere, altering the layer's height and denisty -- unless the planet has a magnetic field strong enough to deflect it. The Mariner 9 orbiter examined Mars' ionosphere in 1971 and 1972, as did the pair of Viking orbiters that circled the planet in 1976. Although none of these orbiters flew through the ionosphere, their radio beams pierced it at times when their radio signals grazed Mars on the way to Earth. In the ionosphere, extreme ultraviolet (EUV EUV Extreme Ultraviolet EUV Exclusive Use Vehicle EUV Extreme Ultra Violet ) light from the sun changes neutral atoms into electrically charged ions and free electrons. The more intense the EUV, the more ionization occurs. The Viking mission reached Mars when the sun was near the minimum in its 11-year activity cycle and showing relatively small EUV changes, whereas Mariner 9 orbited near a solar maximum, when the sunhs EUV brightness was more variable. Yet a new analysis of their Mars-grazing radio beams indicates the ionosphere was being disturbed on both occasions, Mahajan and Mayr report in the June 1 JOURNAL OF GEOPHYSICAL RESEARCH Journal of Geophysical Research is a publication of the American Geophysical Union. JGR was formerly titled Terrestrial Magnetism from its founding by the AGU's president Louis A. . This, they say, could result from variations in the pressure of the solar wind, and thus offers little if any sign that a magnetic field keeps the solar wind at bay. Even a modest magnetic field would probably hold off much of the wind, the authors say. The radio signals show that the Martian ionosphere can be disturbed by the solar wind's pressure changes at any time in the solar cycle, they maintain. |
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