Author Topic: Radiation  (Read 616499 times)

Offline timfinch

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Re: Radiation
« Reply #255 on: March 25, 2018, 05:17:57 PM »
I do not expect the dosimeters of the apollo era were capable of reading directly GCR radiation.  I surmise what they picked up was the secondary emissions caused by the high energy particle bombardment.  Same difference.
A guess is not the "same difference".  That is why there are no old bold electricians.

Shouldn't that be "old" electricians?

Offline timfinch

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Re: Radiation
« Reply #256 on: March 25, 2018, 05:20:00 PM »
I think 99% of the footage is real.  Only the part that shows astronauts on the moon surface is fake.
Do you have any idea at all why it might be easier to actually perform a manned landing on the moon than to fake it on an Earth bound sound stage?

Truth be told, that is not my cup of tea.  I have one interest in all of this and it is the radiation dosages of the apollo missions.  The rest of it I am content to leave to others.

Offline raven

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Re: Radiation
« Reply #257 on: March 25, 2018, 05:27:34 PM »
To use a simple analogy.  If you were filling a bucket from 3 tanks of different concentrations then the lowest concentration you could get is to fill the bucket from the lowest concentrated tank.  In this example that wold be cislunar space.  The lowest exposure possible would be that obtained without contribution from lunar or VAB sources.  That is why all lunar missions have to be at least as high as cislunar space.
Someone correct me if I am wrong, I'm just a high school drop out, but the .6  millirads per hour of the lunar surface is measure separately from the 1 milirads per hour figure for cis-lunar, yes? So you have two separate buckets. Jay and I both already went over why the lunar and cis-lunar GCR doses are different, you got a whole moon between you and the GCR. Plus, we're measuring GCR here, not the bremsstrahlung from their interaction with the lunar surface. 

Offline Ranb

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Re: Radiation
« Reply #258 on: March 25, 2018, 05:29:09 PM »
Shouldn't that be "old" electricians?
Electricians like others in somewhat risky occupations can be old (careful and long living) or bold (risk takers who might die young) but not both.

Offline timfinch

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Re: Radiation
« Reply #259 on: March 25, 2018, 05:32:58 PM »
To use a simple analogy.  If you were filling a bucket from 3 tanks of different concentrations then the lowest concentration you could get is to fill the bucket from the lowest concentrated tank.  In this example that wold be cislunar space.  The lowest exposure possible would be that obtained without contribution from lunar or VAB sources.  That is why all lunar missions have to be at least as high as cislunar space.
Someone correct me if I am wrong, I'm just a high school drop out, but the .6  millirads per hour of the lunar surface is measure separately from the 1 milirads per hour figure for cis-lunar, yes? So you have two separate buckets. Jay and I both already went over why the lunar and cis-lunar GCR doses are different, you got a whole moon between you and the GCR. Plus, we're measuring GCR here, not the bremsstrahlung from their interaction with the lunar surface.

Raven,  I will keep posting this until it is fully understood: 

Measurements taken by NASA's Lunar Reconnaissance Orbiter show that the number of high energy particles streaming in from space did not tail off closer to the moon's surface, as would be expected with the body of the moon blocking half the sky.

Rather, the cosmic rays created a secondary — and potentially more dangerous -- shower by blasting particles in the lunar soil which then become radioactive.

"The moon is a source of radiation," said Boston University researcher Harlan Spence, the lead scientist for LRO's cosmic ray telescope. "This was a bit unexpected."

While the moon blocks galactic cosmic rays to some extent, the hazards posed by the secondary radiation showers counter the shielding effects, Spence said at a press conference at the American Geophysical Union meeting in San Francisco this week.

Overall, future lunar travelers face a radiation dose 30 percent to 40 percent higher than originally expected, Spence said.


Offline Ranb

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Re: Radiation
« Reply #260 on: March 25, 2018, 05:33:40 PM »
Truth be told, that is not my cup of tea.  I have one interest in all of this and it is the radiation dosages of the apollo missions.  The rest of it I am content to leave to others.
Neither is your ability to reconcile the differences in data collected near the moon with 1960's era dosimeters and space between the Earth and Mars with much improved technology.  Perhaps you should have used your electrical background to explain why the systems built into Apollo were sufficient (or not) to travel to and from the moon.

Quote
Overall, future lunar travelers face a radiation dose 30 percent to 40 percent higher than originally expected
I wouldn't be surprised to hear we were off by a factor of 200 percent in our measurements of exposure during Apollo.
« Last Edit: March 25, 2018, 05:36:58 PM by Ranb »

Offline raven

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Re: Radiation
« Reply #261 on: March 25, 2018, 05:38:15 PM »
And I'll keep posting this: bremsstrahlung from Galactic Cosmic Rays is not the same as Galactic Cosmic Rays. If nothing else, conservation of energy means it's lower energy, and, moreover, some of it is going to be released as EM radiation and not charged particle radiation, which alters the shielding strategies immensely.

Offline timfinch

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Re: Radiation
« Reply #262 on: March 25, 2018, 06:02:34 PM »
And I'll keep posting this: bremsstrahlung from Galactic Cosmic Rays is not the same as Galactic Cosmic Rays. If nothing else, conservation of energy means it's lower energy, and, moreover, some of it is going to be released as EM radiation and not charged particle radiation, which alters the shielding strategies immensely.

I am not sure it would be technically correct to label the secondary radiation "bremsstrahlung" as bremsstrahlung is electromagnetic radiation, normally in the form of a photon as were the GCR lunar reaction is primarily a neutron radiation from radioactive particle decay.  I could be wrong on this as I have very little time looking at it.

Offline raven

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Re: Radiation
« Reply #263 on: March 25, 2018, 06:03:52 PM »
And I'll keep posting this: bremsstrahlung from Galactic Cosmic Rays is not the same as Galactic Cosmic Rays. If nothing else, conservation of energy means it's lower energy, and, moreover, some of it is going to be released as EM radiation and not charged particle radiation, which alters the shielding strategies immensely.

I am not sure it would be technically correct to label the secondary radiation "bremsstrahlung" as bremsstrahlung is electromagnetic radiation, normally in the form of a photon as were the GCR lunar reaction is primarily a neutron radiation from radioactive particle decay.  I could be wrong on this as I have very little time looking at it.
OK, perhaps my bad, but the term 'secondary radiation' certainly applies.

Offline timfinch

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Re: Radiation
« Reply #264 on: March 25, 2018, 06:05:44 PM »
Truth be told, that is not my cup of tea.  I have one interest in all of this and it is the radiation dosages of the apollo missions.  The rest of it I am content to leave to others.
Neither is your ability to reconcile the differences in data collected near the moon with 1960's era dosimeters and space between the Earth and Mars with much improved technology.  Perhaps you should have used your electrical background to explain why the systems built into Apollo were sufficient (or not) to travel to and from the moon.

Quote
Overall, future lunar travelers face a radiation dose 30 percent to 40 percent higher than originally expected
I wouldn't be surprised to hear we were off by a factor of 200 percent in our measurements of exposure during Apollo.

It is interesting to note that the article says "originally expected" and not measured.  I could read volumes into that.

Offline timfinch

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Re: Radiation
« Reply #265 on: March 25, 2018, 06:08:01 PM »
The relevant point is the lunar orbit and surface are both at a higher radiation level than cislunar space.

Offline timfinch

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Re: Radiation
« Reply #266 on: March 25, 2018, 06:13:44 PM »
This could mean sixties radiation monitoring was as shitty as Submarine's ELT's in radiation monitoring or it could mean they never left ELO.  I imagine if one was so inclined he could check the spacesuits for identifying isotopes that remained on the suits as generally radioactive decay has a long half life.  It really doesn't matter one way or the other because what is done cannot be undone.

Offline timfinch

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Re: Radiation
« Reply #267 on: March 25, 2018, 06:19:55 PM »
It has occurred to me that we are like the devoutly religious.  God himself could appear and inform people they got it all wrong and they wouldn't believe him and in the same fashion NASA could own up to the deception and we wouldn't believe them.  I admire your passion and convictions.  Thanks for this momentary diversion from the curse of boredom.

Offline Ranb

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Re: Radiation
« Reply #268 on: March 25, 2018, 06:23:34 PM »
It is interesting to note that the article says "originally expected" and not measured.  I could read volumes into that.
Sure you could.  Knowing that what we've learned about radiation in space has been built upon since the 1950's, there is volumes to be told at least.

It's been my experience that the more we learn about radiation, the lower we tend to keep the dose allowed for workers.  From what I've read NASA and other space organizations may need to raise their limits.

Offline Ranb

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Re: Radiation
« Reply #269 on: March 25, 2018, 06:25:31 PM »
This could mean sixties radiation monitoring was as shitty as Submarine's ELT's in radiation monitoring...
That is unfair.  The DT-526 was miles ahead of film badges as far as I know.  You know as well as I do that we (Sailors, soldiers) get the tools we're given, not always the tools we want.