Radiation

[Luke Pemberton]

I am confused.  Are you implying the solar flares are harmless and it is the CME's that pose the greatest danger to astronauts?

No, but there is a difference between flares and CMEs that is worth noting.

Only those CMEs that have speeds above a certain threshold are considered hazardous, as they produce shock driven plasma by separation of electrons and protons. This causes an SPE. Then it's mainly the halo-CMEs that are the impinge on the Earth with an SPE. These CMEs face directly towards the Earth, for the want of a better description.

Solar flares are like gunshots from the Sun. They are highly directional, so particle components very rarely enter the moon-Earth system owning to their position on the Sun and the magnetic field of the Sun.

Historically, flares and SPE events were referred to equally in the literature. More has been learned about the Sun. Solar flares and CMEs are different.

[timfinch]

What is this but a damn lie?

Why is it a lie?

The deception is obvious.  The Braeunig graph implies the path skirted the radiation area when in fact the path was <10^6 radiation for the entirety of the transit (or thereabouts)

Actually, the only deception comes from you.  The graph was presented as a general illustration to convey the mission's flight path as it circumvented the most intense portions of the VABs.  Because you found a graph that contains more detail than the one provided has nothing to do with the actual information used for computation.  You claim to have read the article thoroughly, yet seem to have missed, disregarded or completely whiffed at the understanding of this snippet prior to the table and graphs:

"There is no need to show all the data in this article. An abridged version is shown below, which includes electron fluxes for the first 30 minutes of flight following translunar injection (TLI). This is enough data to allow demonstration of the procedures used in this analysis. The actual analysis used matrices that contained a total of over 8,000 flux values."

P.S.  He also has a link earlier that allows you to gather all the data he used.

So you can provide the mission dose of a lunar transit through the VAB that can be used as the basis of a claim that a low radiation path was traveled?  I would love to see that calculation.

[Luke Pemberton]

So you can provide the mission dose of a lunar transit through the VAB that can be used as the basis of a claim that a low radiation path was traveled?  I would love to see that calculation.

So you could dismiss it out of hand and argue about log scales?

[MBDK]

What is this but a damn lie?

Why is it a lie?

The deception is obvious.  The Braeunig graph implies the path skirted the radiation area when in fact the path was <10^6 radiation for the entirety of the transit (or thereabouts)

Actually, the only deception comes from you.  The graph was presented as a general illustration to convey the mission's flight path as it circumvented the most intense portions of the VABs.  Because you found a graph that contains more detail than the one provided has nothing to do with the actual information used for computation.  You claim to have read the article thoroughly, yet seem to have missed, disregarded or completely whiffed at the understanding of this snippet prior to the table and graphs:

"There is no need to show all the data in this article. An abridged version is shown below, which includes electron fluxes for the first 30 minutes of flight following translunar injection (TLI). This is enough data to allow demonstration of the procedures used in this analysis. The actual analysis used matrices that contained a total of over 8,000 flux values."

P.S.  He also has a link earlier that allows you to gather all the data he used.

So you can provide the mission dose of a lunar transit through the VAB that can be used as the basis of a claim that a low radiation path was traveled?  I would love to see that calculation.

It was provided in the Braeunig article.  Total dose from the VABs were computed to be <1/10th of the total mission dose received.  It helps if you can understand part of his article considered unshielded astronauts (outside any spacecraft with no suit) and then the SHIELDED dose due to the known composition of the spacecraft (with acknowledgement that many other components would only increase the shielding dependent on a variety of factors).

[timfinch]

Several factors make accurate prediction of SPEs difficult. First, solar flares occur without much warning. The magnitude and intensity of a flare are difficult to determine until the event is in progress. The directional emission of particles from the sun further complicates predictions. Since SPEs are relatively directional, SPEs sensed by a terrestrial network may not threaten a Martian transit mission, and conversely, a flare injection of energetic solar particles that threatens a Martian transit mission may not produce particles at Earth.
SPEs pose the greatest threat to unprotected crews in polar, geostationary or interplanetary orbits. To date, the greatest threat to significant exposures to astronauts existed during the Apollo Program. Figure 10. illustrates the variation in timing and magnitude of SPEs that occurred during the course of the Apollo Program. The calculated dose for crewmembers within the command module, within the lunar module or in a space suit performing EVA is represented for each flare. As can be seen in the figure, it is only fortuitous that no significant SPEs occurred during the lunar missions.
Fortunately, most SPEs are relatively short-lived (less than 1-2 days), which allows for relatively small volume "storm shelters" to be feasible. To minimize exposure, the crew would be restricted to the storm shelter during the most intense portion of the SPE, which may last for several hours. Storm shelters with shielding of approximately with 20 g/cm2 or more of water equivalent material will provide sufficient shielding to protect the crew.

https://srag.jsc.nasa.gov/Publications/TM104782/techmemo.htm

[Luke Pemberton]

It was provided in the Braeunig article.  Total dose from the VABs were computed to be <1/10th of the total mission dose received.  It helps if you can understand part of his article considered unshielded astronauts (outside any spacecraft with no suit) and then the SHIELDED dose due to the known composition of the spacecraft (with acknowledgement that many other components would only increase the shielding dependent on a variety of factors).

Someone posted a link to that from the wayback site recently. That link is no longer working me. I cannot find the link in the thread. Do you, or anybody else, have the link?

[jfb]

You guys are being disingenuous.  You have provided not a single fact or data to support your position that cislunar background radiation was low enough to justify Apollo 11's .22 mgy/day exposure level.  You insist they they found a low radiation path through the VAB but cannot provide any data to reflect such a path exist.  You refuse to accept the verifiable data that proves the surface of the moon is more radioactive than cislunar space and that lunar orbit is more radioactive than cislunar space.  You have all the evidence you need to arrive at a logical conclusion yet you distract yourself with the definition of log graphs and my technical competence.  I expected better from you and I am sorely disappointed.  I am embarrassed for you.

Ahem.

It has been pointed out that is data is not applicable to the apollo missions but I am willing to use it as the basis of my assertion if you are willing to accept the consequences.

And, just to make sure we are on the same page, your assertion is that the CRaTER data show that the cislunar radiation environment never gets below .22 mGy/day, correct? 

Yet, when I take the average dose across all 6 detectors, and plot those readings against a .22 mGy/day reference, we can find large spans of time where the readings fall below that .22 mGy/day threshold (pretty much all of 2013, for example).  I make that pretty explicit in the chart.

You don't like the non-linear y-axis, here's the same data plotted linearly (max capped at .5 mGy/day):

[MBDK]

https://web.archive.org/web/20170821064300/https://www.braeunig.us/apollo/VABraddose.htm

[Luke Pemberton]

https://web.archive.org/web/20170821064300/https://www.braeunig.us/apollo/VABraddose.htm

Thanks. That should keep Tim happy chewing through the calculations he would like to see.

Over to you Tim. Any comment on the calculations?

[MBDK]

https://web.archive.org/web/20170821064300/https://www.braeunig.us/apollo/VABraddose.htm

Thanks. That should keep Tim happy chewing through the calculations he would like to see.

The sad part is Timmy is the one who just brought that site into the fray.

[timfinch]

What is this but a damn lie?

Why is it a lie?

The deception is obvious.  The Braeunig graph implies the path skirted the radiation area when in fact the path was <10^6 radiation for the entirety of the transit (or thereabouts)

Actually, the only deception comes from you.  The graph was presented as a general illustration to convey the mission's flight path as it circumvented the most intense portions of the VABs.  Because you found a graph that contains more detail than the one provided has nothing to do with the actual information used for computation.  You claim to have read the article thoroughly, yet seem to have missed, disregarded or completely whiffed at the understanding of this snippet prior to the table and graphs:

"There is no need to show all the data in this article. An abridged version is shown below, which includes electron fluxes for the first 30 minutes of flight following translunar injection (TLI). This is enough data to allow demonstration of the procedures used in this analysis. The actual analysis used matrices that contained a total of over 8,000 flux values."

P.S.  He also has a link earlier that allows you to gather all the data he used.

So you can provide the mission dose of a lunar transit through the VAB that can be used as the basis of a claim that a low radiation path was traveled?  I would love to see that calculation.

It was provided in the Braeunig article.  Total dose from the VABs were computed to be <1/10th of the total mission dose received.  It helps if you can understand part of his article considered unshielded astronauts (outside any spacecraft with no suit) and then the SHIELDED dose due to the known composition of the spacecraft (with acknowledgement that many other components would only increase the shielding dependent on a variety of factors).

Let's work with 1/10th mission dosage.  We know that the reported range for the apollo missions during solar cycle 20 was 2.4 mgy/day to 6 mgy/day.  Now 1/10 of .22 mgy/day is .022.  Now if we add 1.35 times .24 we get .324 mgy/day while in lunar orbit assuming they spent two days in lunar orbit or on the surface of the moon you can see the total mission dosage comes up short, don't you think?

[Luke Pemberton]

https://srag.jsc.nasa.gov/Publications/TM104782/techmemo.htm

Thanks. I've even saved that to may favourites as it has a lovely diagram of SPE events which neatly shows there were no SPE events during a single Apollo mission. So we can ignore SPEs in the discussion.

[timfinch]

You guys are being disingenuous.  You have provided not a single fact or data to support your position that cislunar background radiation was low enough to justify Apollo 11's .22 mgy/day exposure level.  You insist they they found a low radiation path through the VAB but cannot provide any data to reflect such a path exist.  You refuse to accept the verifiable data that proves the surface of the moon is more radioactive than cislunar space and that lunar orbit is more radioactive than cislunar space.  You have all the evidence you need to arrive at a logical conclusion yet you distract yourself with the definition of log graphs and my technical competence.  I expected better from you and I am sorely disappointed.  I am embarrassed for you.

Ahem.

It has been pointed out that is data is not applicable to the apollo missions but I am willing to use it as the basis of my assertion if you are willing to accept the consequences.

And, just to make sure we are on the same page, your assertion is that the CRaTER data show that the cislunar radiation environment never gets below .22 mGy/day, correct? 

Yet, when I take the average dose across all 6 detectors, and plot those readings against a .22 mGy/day reference, we can find large spans of time where the readings fall below that .22 mGy/day threshold (pretty much all of 2013, for example).  I make that pretty explicit in the chart.

You don't like the non-linear y-axis, here's the same data plotted linearly (max capped at .5 mGy/day):

I have got to ask the question.  Does it make sense that averaging in the SPE induced spikes would result in an average below .22 mgy/day?

[MBDK]

Let's work with 1/10th mission dosage.  We know that the reported range for the apollo missions during solar cycle 20 was 2.4 mgy/day to 6 mgy/day.  Now 1/10 of .22 mgy/day is .022.  Now if we add 1.35 times .24 we get .324 mgy/day while in lunar orbit assuming they spent two days in lunar orbit or on the surface of the moon you can see the total mission dosage comes up short, don't you think?

No, let's work with the actual data.  Your values for their exposures have been shown to be inconsistent with the data you did use, and irrelevant as they were from either average doses over a long time span, or taken from measurements of less intense solar cycle.  Try again. 

The actual data from Apollo is taken from their dosimeters.  Their dosimeters (as long as they functioned properly, and they would know this during their read-out) are their official, legal record for the exposure received.  An ex-nuc should already know this.

[Luke Pemberton]

Let's work with 1/10th mission dosage.  We know that the reported range for the apollo missions during solar cycle 20 was 2.4 mgy/day to 6 mgy/day.  Now 1/10 of .22 mgy/day is .022.  Now if we add 1.35 times .24 we get .324 mgy/day while in lunar orbit assuming they spent two days in lunar orbit or on the surface of the moon you can see the total mission dosage comes up short, don't you think?

2.4 mGr/day. Where are you getting this value from? Here is your initial post.

Cosmic ray fluxes, consisting of completely ionized atomic nuclei originating outside the solar system and accelerated to very high energies, provided average dose rates of 1.0 millirads per hour in cislunar space** and 0.6 millirads per hour on the lunar surface. These values are expected to double at the low point in the 11-year cycle of solar-flare activity (solar minimum) because of decreased solar magnetic shielding of the central planets. The effect of high-energy cosmic rays on humans is unknown but is considered by most authorities not to be of serious concern for exposures of less than a few years. Experimental evidence of the effects of these radiations is dependent on the development of highly advanced particle accelerators or the advent of long-term manned missions outside the Earth's geomagnetic influence.

https://history.nasa.gov/SP-368/s2ch3.htm

I am not sure but I think 1 millirad/hour is equal to .24 mgy/day.  Correct me if I am wrong.  This article was written back in the seventies.

But again, this was an average. By definition the values could be lower than 0.24 and higher than 0.24.