In light of the recent solar flare, here's a breakdown of the radiation we're exposed to, how we're shielded, and how solar flares can actually protect our astronauts.
Image: Photograph taken by the Solar Dynamics Observatory of the solar flare mid-February, 2011
When solar activity flares up, a warning flag is raised. The danger of a massive solar flare crippling our electronics and endangering our astronauts is a real threat, but with a low enough magnitude and if our orbit is close enough to Earth, our space crew can benefit.
In the case of our Valentine's Day Solar Flare in Mid February, 2011, counter-intuitively, our astronauts in orbit actually experienced a few days worth of decreased radiation due to the Forbush Effect.
But first, a little bit about solar activity, cosmic radiation, and our natural shielding:
Cosmic rays are simply extraterrestrial particles that fly through space and happen to rudely elbow their way into our territory. Taken from
Macmillan Encyclopedia of Physics in 1996:
"
Cosmic rays include essentially all of the elements in the periodic table; about 89% of the nuclei are hydrogen (protons), 10% helium, and about 1% heavier elements. The common heavier elements (such as carbon, oxygen, magnesium, silicon, and iron) are present in about the same relative abundances as in the solar system."
However, the elements higher on the periodic table can spike, as shown via experiment results
published in June of 2009 (Cite 1 see bottom)
"We report abundances of elements from 26Fe to 34Se in the cosmic radiation measured during fifty days of exposure of the Trans-Iron Galactic Element Recorder (TIGER) balloon-borne instrument."
Shielding:
Image Credit: Wikimedia Commons
Solar, galactic, and extra-galactic radiation is one of the biggest hurdles we will eventually face with interstellar travel, but in the present, the magnetic field, as shown above, surrounds the earth, deflecting the solar wind, and shielding us from harm fairly effectively. If one were on the moon during this recent flare, the bombardment of protons from the sun could have had a potentially lethal effect. This is because nuclei from the
coronal mass ejection would slam into our bodies on the tiniest scale, and would seriously damage our cells and our DNA. What happened just recently isn't so much a threat to our astronauts because the magnetic field of the earth extends far enough into their orbit.
To quote
Space.com:
"
The orbiting lab sits just 220 miles (354 kilometers) above Earth — still cocooned within the planet's protective magnetic field. And the station protects well against most solar storms, Cucinotta said. So as long as astronauts stay inside, they should be fine."
The actual DECREASE in radiation they benefit from is due to the phenomenon known as the Forbush Effect our flare effectively a wash of particles clearing out the more dangerous particles already there. To quote concisely from wikipedia,
this is "
a rapid decrease in the observed galactic cosmic ray intensity following a coronal mass ejection (CME). It occurs due to the magnetic field of the plasma solar wind sweeping some of the galactic cosmic rays away from Earth."
Solar flares have a direct impact on our climate:
By measuring our clouds and cosmic rays, in correlation with solar activity and climate,
we can see the Forbush Effect.
In
Geophysical Research Letters(Cite 2 see bottom)
"
Close passages of coronal mass ejections from the sun are signaled at the Earth's surface by Forbush decreases in cosmic ray counts. We find that low clouds contain less liquid water following Forbush decreases, and for the most influential events the liquid water in the oceanic atmosphere can diminish by as much as 7%. Cloud water content as gauged by the Special Sensor Microwave/Imager (SSM/I)"
Galactic Cosmic Rays may have a direct impact on our climate:
CERN' CLOUD project is producing some exciting data.
Greater or fewer galactic cosmic rays (GCR) seem to be associated with a warmer or cooler climates.
This seems to be still under debate, to my understanding due to the lack of understanding the physical mechanism occuring, but evidence is increasing and experiments are being conducted.
Climate over time and Galactic Cosmic Rays, data from CLOUD
This doesn't debunk our impact on global warming. Don't misunderstand me, humans have had a verified effect on climate, a measurable impact, but on an extremely recent sliver of the Earth's history.
Continued close monitoring and study of extra-planetary particle bombardment will no doubt will lead to exciting new discoveries on how the rest of the universe impacts our tiny planet we call home.
CITE 1:
B. F. Rauch, J. T. Link, K. Lodders, M. H. Israel, L. M. Barbier, W. R. Binns, E. R. Christian, J. R. Cummings, G. A. de Nolfo, S. Geier, R. A. Mewaldt, J. W. Mitchell, S. M. Schindler, L. M. Scott, E. C. Stone, R. E. Streitmatter, C. J. Waddington, M. E. (2009). Cosmic-ray origin in OB associations and preferential acceleration of refractory elements: Evidence from abundances of elements 26Fe through 34Se Astrophys.J.697:2083-2088,2009 : arXiv:0906.2021v1
CITE2:
Svensmark, H., Bondo, T., & Svensmark, J. (2009). Cosmic ray decreases affect atmospheric aerosols and clouds Geophysical Research Letters, 36 (15) DOI: 10.1029/2009GL038429
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