Asteroid may have switched Mars' magnetic field on and off
20 Jul 2008, 1302 Hrs

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London, July 20 (ANI): An asteroid may have flipped Mars' magnetic field on and off like a light switch around 4 billion years ago, says a group of scientists researching on the Red Planet.

The scientists have said that Mars once had a magnetic field that could have been set in action by a dynamo created from the convection of material in the core, much like the Earth's core.

However, according to crater records, it is believed that the Martian dynamo ceased in a short time of almost a few tens of thousands of years, a phenomenon that has not been explained by researchers as yet.

Now, a team led by Jafar Arkani-Hamed of the University of Toronto, Canada has said that the gravitational tug of an orbiting asteroid may have powered a dynamo by pulling on the fluid in Mars's core. The researchers made use of lab and model simulations to show that an asteroid orbiting 75,000 kilometres above Mars may have maintained a dynamo for 400 million years. This was followed by the rock crashing into the planet and switching it off.

The theory however, is not supported by some researchers, like David Stevenson of the California Institute of Technology in Pasadena who claimed that it is possible that an asteroid might have had enough energy to churn fluid in the planet's core, much more energy is needed to set up the dynamo to begin with.

"It would be like looking at a boulder on top of a hill without asking what it took to get it there," The New Scientist quoted him, as saying. (ANI)