Are some cosmic rays iron nuclei?

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  • Thread starter swampwiz
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I had thought that cosmic rays were all protons, but this article says sometimes it's iron.

https://getpocket.com/explore/item/let-s-colonize-titan
GCRs include particles such as iron nuclei traveling at close to the speed of light that destroy brain tissue.
 

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  • #3
phyzguy
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It appears they are composed of heavier nuclei in addition to protons, especially the highest energy cosmic rays. This graph from this paper shows that in order to fit the data, the authors need to assume that cosmic rays include many heavier nuclei, up to and including iron. However, be aware that these very high energy events are extremely rare. As for the paper you linked, why would we choose to colonize Titan as opposed to just living underground on the moon?
Screen Shot 2021-04-30 at 6.41.58 AM.png
 
  • #4
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It appears they are composed of heavier nuclei in addition to protons, especially the highest energy cosmic rays. This graph from this paper shows that in order to fit the data, the authors need to assume that cosmic rays include many heavier nuclei, up to and including iron. However, be aware that these very high energy events are extremely rare. As for the paper you linked, why would we choose to colonize Titan as opposed to just living underground on the moon?
Titan could be a good place to go when the Sun gets to its red giant stage of life.
 
  • #5
phyzguy
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Titan could be a good place to go when the Sun gets to its red giant stage of life.
Since that is several billion years in the future, I for one am not going to worry about it.
 
  • #6
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Since that is several billion years in the future, I for one am not going to worry about it.
It says here that the Sun will become too hot for plants in about 600M years (a "Soylent Green" diet would be unsustainable :eek:). And even if the food problem could be solved, it's going to be too hot in about 1G years.

https://en.wikipedia.org/wiki/Future_of_Earth
The luminosity of the Sun will steadily increase, resulting in a rise in the solar radiation reaching the Earth. This will result in a higher rate of weathering of silicate minerals, affecting the carbonate-silicate cycle which will cause a decrease in the level of carbon dioxide in the atmosphere. In about 600 million years from now, the level of carbon dioxide will fall below the level needed to sustain C3 carbon fixation photosynthesis used by trees.
In about one billion years, the solar luminosity will be 10% higher than at present. This will cause the atmosphere to become a "moist greenhouse", resulting in a runaway evaporation of the oceans. As a likely consequence, plate tectonics will come to an end, and with them the entire carbon cycle.
 
  • #7
Vanadium 50
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So your position is that we don't have to worry about something that won't happen for 1B years, but 600M years is urgent?
 
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  • #8
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Just for scale, Homo Erectus, arguably the first pretty close human ancestor seems to have shown up (maybe) about two million years ago. Seem to me that there is a lot of evolutionary road to travel until we get close to the point that CO2 levels drop below the level needed to sustain photosynthesis.

--diogenesNY
 

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