Earth Losing Magnetic Shields As Prelude to Pole Reversal 7

Mars lost its magnetic field 4 billion years ago.  Exposure to the solar wind and other space weather gradually stripped away the water, atmosphere and ability to support life.

Contrary to Popular Misconception, the Loss of Magnetic Field During Pole Reversal Transition is Not Catastrophic

Lost in migration: Earth’s magnetic field overdue a flip
By Chris Wickham
LONDON | Wed Oct 3, 2012 3:18pm EDT  (Reuters) – The discovery by NASA rover Curiosity of evidence that water once flowed on Mars – the most Earth-like planet in the solar system – should intensify interest in what the future could hold for mankind.

There is no planet wide Mars magnetic field. What the planet does have are magnetic bands that are probable remnants of an ancient planetary magnetic field. Without a magnetic field the planet is constantly bombarded by the Sun’s radiation and the solar wind, making it the barren world we see today.

Most planets produce a magnetic field through a dynamo effect. The metals in a planet’s core are molten and constantly moving. The moving metals create an electrical charge that eventually manifests itself as a magnetic field. This is how the Earth, Mercury, and Jupiter create their magnetic fields.

The magnetic bands that Mars does have are thought to be the remnants of an ancient magnetic field. They are similar to features found at the bottom of oceans here on Earth. Scientists believe that their presence is a possible sign that Mars had plate tectonics, but other evidence suggests that those plate movements shut down about 4 billion years ago. The bands themselves are quite strong; nearly as strong as Earth’s magnetic field, and can extend hundreds of kilometers into the atmosphere. They interact with the solar wind to create auroras much like those seen as the Northern Lights here. Scientists have observed over 13,000 of these aurora events.

The lack of a planet wide magnetic field exposes the surface to 2.5 times as much radiation as we endure here on Earth. Those levels are right at the edge of human tolerance and would cause health problems over time. If humans are going to explore the planet, a way to shield that radiation needs to be found. It should be fairly easy, since only a few cm of soil can filter enough radiation to prevent problems. Thicker suits for surface activity and using bases inside of Martian caves might be possible short term solutions.

The lack of a planet wide Mars magnetic field can be overcome, but one of the consequences of this lack is harder to ignore. The radiation and solar wind combine to make it impossible for liquid water to exist on the surface for more than a few days. Rovers have found plenty of water ice under the surface and scientists think that there may be liquid water if a rover could dig deep enough. The lack of water just adds to the obstacles that NASA engineers must overcome in order to explore the Red Planet.

Here’s an article from Universe Today about mini-magnetic fields on Mars. And an article about how Mars used to have plate tectonics.

Want more? NASA kids has great info about Martian magnetic fields, and what happens when the solar wind hits Mars.

Finally, if you’d like to learn more about Mars in general, we have done several podcast episodes about the Red Planet at Astronomy Cast. Episode 52: Mars, and Episode 91: The Search for Water on Mars.

Read more: http://www.universetoday.com/14949/mars-magnetic-field/#ixzz2DHl1CE8o

Read more: http://www.universetoday.com/14949/mars-magnetic-field/#ixzz2DHkOTWyj
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Lost in migration: Earth’s magnetic field overdue a flip By Chris Wickham
LONDON | Wed Oct 3, 2012 3:18pm EDT (Reuters) – The discovery by NASA rover Curiosity of evidence that water once flowed on Mars – the most Earth-like planet in the solar system – should intensify interest in what the future could hold for mankind.
http://www.reuters.com/article/2012/10/03/us-science-earth-magneticfield-idUSBRE8920X620121003

Scientist say Earth may soon lose its magnetic field Sarah Wolfe
| GlobalPost.com |
Oct 06, 2012 The magnetic field surrounding Earth is weakening, and scientists say it could be gone in as little as 500 years. The result? Earth’s magnetic poles could, literally, flip upside down
http://www.alaskadispatch.com/article/scientist-say-earth-may-soon-lose-its-magnetic-field

Ice Age Polarity Reversal Was Global Event: Extremely Brief Reversal of Geomagnetic Field, Climate Variability, and Super Volcano
ScienceDaily (Oct. 16, 2012) — Some 41,000 years ago, a complete and rapid reversal of the geomagnetic field occured. Magnetic studies of the GFZ German Research Centre for Geosciences on sediment cores from the Black Sea show that during this period, during the last ice age, a compass at the Black Sea would have pointed to the south instead of north.
http://www.sciencedaily.com/releases/2012/10/121016084936.htm
Earth’s Magnetic Field Reversals Illuminated By Lava Flows Study
ScienceDaily (Sep. 26, 2008) — Earth’s north magnetic pole is shifting and weakening. Ancient lava flows are guiding a better understanding of what generates and controls the Earth’s magnetic field – and what may drive it to occasionally reverse direction.
http://www.sciencedaily.com/releases/2008/09/080926105021.htm