[ RadSafe ] Solar Flares

Susan Gawarecki loc at icx.net
Mon Oct 10 14:37:00 CDT 2005

I've not received a digest since Oct. 6 - are things quiet or broken?

Below is a teaser and link to an interesting article. I expect this has 
implications for radiation exposure during airline travel as well.

--Susan Gawarecki

Who's Afraid of a Solar Flare? Solar activity can be surprisingly good 
for astronauts.

October 7, 2005: Last month, the sun went haywire. Almost every day for 
two weeks in early September, solar flares issued from a giant sunspot 
named "active region 798/808." X-rays ionized Earth’s upper atmosphere. 
Solar protons peppered the Moon. It was not a good time to be in space.

Or was it?

During the storms, something strange happened onboard the International 
Space Station (ISS): radiation levels dropped.

"The crew of the ISS absorbed about 30% fewer cosmic rays than usual," 
says Frank Cucinotta, NASA's chief radiation health officer at the 
Johnson Space Center. "The storms actually improved the radiation 
environment inside the station."

Scientists have long known about this phenomenon. It's called a "Forbush 
decrease," after American physicist Scott E. Forbush, who studied cosmic 
rays in the 1930s and 40s. When cosmic rays hit Earth's upper 
atmosphere, they produce a shower of secondary particles that can reach 
the ground. By monitoring these showers he noticed, contrary to 
intuition, that cosmic ray doses dropped when solar activity was high.


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