Apr 29 1999
From The Space Library
NASA announced that the magnetometer on board Mars Global Surveyor had revealed "banded patterns of magnetic fields on the Martian surface," bearing a "striking similarity to patterns seen in the crust of the Earth's sea floors." Scientists interpreted the patterns as evidence that the Martian crust had shifted in the past. The discovery of banded patterns on the floor of Earth's oceans had provided a record of Earth's magnetic history, validating the theory of plate tectonics. Jack Connerney of NASA's GSFC, a member of Global Surveyor's magnetometer team, explained, "if the bands on Mars are an imprint of crustal spreading, they are a relic of an early era of plate tectonics on Mars." He added that such tectonic activity on Mars is likely extinct, unlike on Earth. The spacecraft's magnetometer had been able to capture the magnetic field observations because of the extended aerobraking phase, devised to protect against further damage to one of the spacecraft's solar panels. The period of aerobraking had permitted the magnetometer to "obtain better-than-planned regional measurements of Mars." Each time it reached the lowest point of its elliptically shaped orbit, below the planet's ionosphere, the probe encountered minimal magnetic interference and enabling it to obtain additional data.
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