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Solar Winds to Protect Earth During Magnetic Pole Reversal
me98411 writes "A study published in April, hinted at possible anamolies/reversal in Earth's magnetic field. This study found that there is an anamoly in a large patch near South Africa where the Earth's magnetic field points in the opposite direction. Now, according to New Scientist, this planet might be safe during reversal of poles due to formation of replacement field created by interaction with solar winds. Phew! I was worried I will not be able to use my compass." Even better than compasses not being obsoleted, we won't be bombarded with dangerous levels of radiation, or so the scientists say.
are from the Aeronautics and Astronautics
group at the University of Washington.
They also have nice slides on airplane/spacecraft design,
also in PDF here
Mars does indeed have a significant magnetic field, it is just that it has several dozen north and south poles, which is the current theory about what will happen during the transition phase when the poles switch:
At first the poles weaken in strength.
New "North" & "South" poles start to appear in strage places, like in equatorial regions.
For a geologically brief period of time there are dozens to hundreds of magnetic "poles" scattered throughout the planet.
Eventually the number of poles start to drop, and the new magnetic "North" & "South" poles become more established and start to gain more strength. At this point the reversal is complete.
Mars appears to have gone geologically dead during the middle of one of these pole reversals, so Mars is also being used to provide a "snapshot" as to what the Earth might be like in the next 500 years.
It just doesn't make any sense in this case. If a stream of particles is coming towards the Earth, Earth's gravity will not cause those particles to veer off and miss the planet. Unless there is such a thing as negative mass, gravity is always attractive.
OK, IAAP (I am a physicist) and I'll tell you flat out that second order effects only become really significant when the radiation is VERY powerful, and can cause nasty showers. Most of the cosmic radiation showers don't come anywhere close to hitting the earth's surface, so this won't be an issue. Now if you were flying at 60,000 feet, who knows, it might almost be relevant, but even then I wouldn't count on it.
You tend to get secondary showers when you have things like proton beams at huge energies hitting targets (or high energy beta radiation, etc....). The secondary showers are worse than the original beam, but only if the shielding is "thin". There is very little reason to believe that our atmosphere (dozens of miles thick) would count as "thin"
The direct/secondary effects logic you propose is almost entirely opposite from what I would tend to say. I'd say that usuall direct effects are the operative force, and only within certain corner cases to secondary effects become prominent, in general.
In any case, the vast majority of cosmic radiation would be stopped by the atmosphere, magnetic field or no.
The idea that the atmosphere/ionosphere can be used to set up counter-currents to exclude the solar wind from the planet (or at least shield it a lot) isn't really revolutionary. It's possible that the Earth-magnetospheres people aren't talking to the planetary folks enough, but the latter have been thinking about this for years. When you wonder how the solar wind behaves when it encounters, say, Venus, you're in this regime. It's also the basic category that includes those ever-sexy critters, comets.
I don't know that anyone has done a similar calculation for the Earth and if so if this new model is significantly different. But the basic idea has been out there. We covered it in my magnetospheres class 4 years ago and it was in the textbook well before that.
It wasn't so much the strength, but with the very localized north & south poles (like I said, dozens of "poles", sometimes only 10 km apart.), it makes for a very different magnetic field than what you find right now on the Earth.
Originally planetary astronomers were looking for a classical Magnetosphere like is found on the Earth and Jupiter, but Mars simply doesn't have that because it isn't organized on a planetary scale.
An interesting side-effect to the paper suggested by the parent article is that planets may mean something more significant than simply a rock to anchor your building to. If a planetary body (like Mars or Veuns) can capture a portion of the solar wind and form a magnetic barrier to Cosmic Radiation, it might be more valuable than trying to make cities and settlements on smaller bodies that this effect wouldn't be nearly so strong, such as building in the Asteroids or even building Human constructed bodies such as the classical L-5 space habitats, at least until space born populations start becoming significant.
Several people have suggested that Mars is a dead-end for human settlement due to the fact that it too is at the bottom of a signficant gravity well. It is nice to see that potentially some theories that might support a manned Martian presence are being brought forth.
http://www.pbs.org/wgbh/nova/magnetic/
Radition is dangerous because it severes DNA strands or other protien strands. Normal protien strands that are damaged don't ussually become a problem, they can be fixed. DNA on the other hand is different, many combinations of damage can result in mutations which eventually (in high enough doeses) are lethal (ie you lose the ability to make certain protiens and then you die). 1 gamma ray going through you might cut a thousand strands but 50 lower energy gamma rays will cut mullions of strands. I think thats what he's agetting at. although it doesn't seem liek he had much of a clue on the how lower energy rays can be more damaging.
"There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy."