Magnetic stripes on the surface of Mars are similar to fields in the sea floors of Earth and may indicate ancient crustal movements on the Red Planet.

Apr. 29, 1999: NASA's Mars Global Surveyor has discovered surprising new evidence of past movement of the Martian crust, suggesting that ancient Mars was a more dynamic, Earth-like planet than it is today. Scientists using the spacecraft's magnetometer have found banded patterns of magnetic fields on the Martian surface. The adjacent magnetic bands point in opposite directions, giving these invisible stripes a striking similarity to patterns seen in the crust of Earth's sea floors. Right: An artist's concept comparing the present day magnetic fields on Earth and Mars. Earth's magnetic field is generated by an active dynamo - a hot core of molten metal. The magnetic field surrounds Earth and is considered global (image B, below). The various Martian magnetic fields (image A, above) do not encompass the entire planet and are local. The Martian dynamo is extinct, and its magnetic fields are "fossil" remnants of its ancient, global magnetic field. IMAGE CREDIT: NASA Mario Acuna, Jack Connerney, Chris Meaney On the Earth, the sea floor spreads apart slowly at mid-oceanic ridges as new crust flows up from Earth's hot interior. Meanwhile, the direction of Earth's magnetic field reverses occasionally, resulting in alternating stripes in the new crust that carry a fossil record of the past hundreds of million years of Earth's magnetic history, a finding that validated the once-controversial theory of plate tectonics. "The discovery of this pattern on Mars could revolutionize current thinking of the red planet's evolution," said Dr. Jack Connerney of NASA's Goddard Space Flight Center, Greenbelt, MD, an investigator on the Global Surveyor's magnetometer team. "If the bands on Mars are an imprint of crustal spreading, they are a relic of an early era of plate tectonics on Mars. However, unlike on Earth, the implied plate tectonic activity on Mars is most likely extinct." Alternate explanations for the banded structure may involve the fracturing and breakup of an ancient, uniformly magnetized crust due to volcanic activity or tectonic stresses from the rise and fall of neighboring terrain.
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