South Atlantic Anomaly (SAA) (keyword search)

[amicus]

As a follow up to an earlier post, “The Information Highway”, I offer the following as an indication of the information available on television and the internet.

While watching the NASA channel, with an acquaintance, the shuttle Endeavor was in the ‘docking stage’ with the International Space Station and NASA had an orbital map of the current and changing location of the space station around the earth. “Ah, they show the SAA,” said my nuclear engineer acquaintance, “the South American or South Atlantic Anomaly…”

“The ‘what?”, I queried.

So, he told me. Geez I hate to be ignorant of something, anything, but I had to admit that I was not aware of the SAA.

No longer…


http://www.ll.mit.edu/ST/sbv/saa.html

http://www.astronomycafe.net/qadir/q525.html

http://en.wikipedia.org/wiki/South_Atlantic_Anomaly

“…Earth is surrounded by a close-to-spherical magnetic field, the magnetosphere. According to what we know today, it is being generated by dynamo action in the Earth's interior where conducting liquid metals are kept in motion by the forces of convection (heat exchange), coriolis, and gravitation, and just as the charged windings in the coil of a dynamo generate a magnetic field when moved, these masses create the Earth's magnetic field. Without it, our compasses wouldn't work, there would be no northern lights (auroras), and it protects us from space radiation by deflecting high energy particles from deep space or by capturing them in the so-called Van Allen Belts. Of these, discovered by the first US satellite, Explorer 1, in 1958, there are two, one closer, the other farther away, and both surround the Earth like a doughnut.

Unfortunately, at a certain location over the South Atlantic Ocean, off the coast of Brazil, the shielding effect of the magnetosphere is not quite spherical but shows a "pothole", a dip, which scientists explain as a result of the eccentric displacement of the center of the magnetic field from the geographical center of the Earth (by 280 miles) as well as the displacement between the magnetic and geographic poles of Earth. For orbits tilted (inclined) between 35 and 60 degrees against Earth's equator and having altitudes of a few hundred miles, this oddity, called the South Atlantic Anomaly (SAA) becomes important, because spacecraft in those orbits periodically pass through that zone of reduced natural shielding and thus spend a few minutes during each passage exposed to higher particle flux than outside it. It requires higher shielding for the crew, particularly during spacewalks (EVAs), and is also of concern in the design of photovoltaic cells which are degraded faster by higher particle fluxes. The design of the International Space Station, which will fly at an inclination of 51.6 degrees, takes such effects of the SAA into account…’


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http://www.phy6.org/Education/Iradbelt.html (keywords: van allen belt explanations)

http://en.wikipedia.org/wiki/Van_Allen_radiation_belt

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Keyword search: (sprite lightning and van allen radiation)

http://tv.gsfc.nasa.gov/G05-009_space.htm

http://www.nasa.gov/vision/universe/solarsystem/space_lightning.html

http://www.spacedaily.com/reports/Gamma_Ray_Flare_From_Distant_Star_Disturbs_Daytime_Ionosphere.html

(That last link has interesting thoughts concerning ionospheric perturbations created by a neutron star gamma burst some 50,000 light years distant)

~~~~

If you notice, on the created orbital trajectory of the Space Station, the carefully avoid the SAA by purposeful planning.

As an aside, thinking of current plans to establish a ‘moon base’ in about 2018, and long range plans for a colony on Mars, I became curious as to some other aspects of those missions. Neither the Moon nor Mars has a molten iron core that might generate a protective magnetosphere to ward off solar radiation and gamma rays from deep space.

Which means that both the Moon and Mars are being bombarded with high intensity radiation, which seems to me, at least in a cumulative sense, would be dangerous and perhaps lethal to human life.

As there were in fact six lunar landings, then we know that man can survive the three day journey to the moon, the landing and the three day return trip. But, the time required for a journey to Mars, round trip, is approximately three years.

Does that indicate that perhaps man cannot, go into space, the nearest planet, with our current technology and understanding?

Does that sentence us to mechanical, robotic exploration only?

I realize that few have a serious interest in such things, but some do. And again, to reinforce my sense that this ‘Information Age’ we live in is truly unique in all of human history. I just don’t quite yet know what it means in the larger scheme of things.

By the way, the Science Channel program, “If we had no Moon” is showing again in about a half an hour.

Amicus…

 

[only_more_so]

I've heard that they originally believe that any astronaut would immediately be fried by the radiation in space. Of course, some physicists believed that the A-bomb would ignite the entire atmosphere of earth.

But for missions to the moon and to Mars, radiation shielding is very important. But there are numerous ways to do it that are well within our abilities. The most obvious solution for habitation of mars or the moon is an underground facility. The "dirt" would provide radiation shielding without having to lug tons of material. Also the extra material would provide thermal mass to keep the habitation's temperature more moderate.

 

[amicus]

[QUOTE=only_more_so]I've heard that they originally believe that any astronaut would immediately be fried by the radiation in space. Of course, some physicists believed that the A-bomb would ignite the entire atmosphere of earth.

But for missions to the moon and to Mars, radiation shielding is very important. But there are numerous ways to do it that are well within our abilities. The most obvious solution for habitation of mars or the moon is an underground facility. The "dirt" would provide radiation shielding without having to lug tons of material. Also the extra material would provide thermal mass to keep the habitation's temperature more moderate.[/QUOTE]

~~~

Yup, my nuclear engineer friend suggested underground also, digging a trench. I also note that some of the recent sci fi films about Mars, and some of NASA's projected ideas although use above ground habitats.

I think I omitted a question, that of the long range, hundreds of years project to 'terraform' Mars. Since I don't see the possibility of recreating a 'molten core' for Mars, thus no magnetosphere, perhaps the terraforming concept is not valid?

just curious...my education, such as it was, was in the Arts, science is just an interest.

thanks...


amicus...

 

[Liar]

First thing i thought when I read this was "so that's where the Lost island is".

Sorry, carry on.