Radiation

[jfb]

Played around with this a little.  Attached graph shows the daily combined D1&2 readings (blue dots), the average D1&2 reading over the entire set (grey horizontal line), and the .22 mGy/day threshold (gold line).  Scale is logarithmic.

Will play around with the other columns, but I think this one graph pretty definitively destroy's Tim's arguments (and shows why you shouldn't apply the average readings over the entire data set against a one-week mission).

Unless I am being a bit thick here, the grey line is the average dose from 1 and 2 detectors which is above the 0.22 mGy/day threshold. Does the grey line include the SPE events in the average?

The grey line is the average of all the combined D1&2 readings; I basically created a new column in the spreadsheet and filled all the entries with average(H$2:H$67919)¹.  IOW, I did a very naive computation a la Tim - I took a rather complicated time series and reduced it to a single number that has almost no explanatory value.  It's not useful as a predictive model, and it's not useful for any kind of analysis. 

Note that most of the daily readings straddle the .22 mGy/day line.  It's those spikes in 2014, 2015, and 2017 that skew the average way up. 


^{1.  Which is Not The Way To Do It - thought the macbook was going to have a heart attack.  Should have computed it once and replicated the value, but I was being lazy.  I would rather use R, but I don't have R on the mac side.} 

[Rob48]

I would have thought the median value would have been a lot more useful than the mean.

[Luke Pemberton]

Note that most of the daily readings straddle the .22 mGy/day line.  It's those spikes in 2014, 2015, and 2017 that skew the average way up.

That's what I thought, the peaks cause the average to rise. This really does highlight the point that you simply cannot use a reported average other than in order of magnitude calculations. Tim's second set of data showed an average that was cited at 0.24 and 0.60 mGr/day for the solar cycle extremes.

The CRaTER data has produced a debate between ourselves and the best way to represent the data, and we have access to the complete data set from CRaTER. Rob48's post about using a median is also a valid point.

Regardless, it really is anybody's guess how the 0.24-0.60 mGr/day was derived and the spread of that data set due to day-to-day fluctuations. Your grey line really drives home the point that averages can be quite useless (that's meant with respect for you). One really need to understand the distribution of the data in all its complexity before we can truly apply the data in a meaningful way to reality.

[jfb]

I would have thought the median value would have been a lot more useful than the mean.

Somewhat, yes.  But Tim didn't compute the median, he computed the mean, and used that to argue his point.  It was a naive, simplistic analysis that did not accurately reflect the reality of the CRaTER data as it would have applied to a lunar mission. 

IOW, the point of my graph is to show that Tim's analysis was deeply flawed. 

[gillianren]

I digress. Of course, the predictability plays out as the 'science types' wade in, and the water become shark infested. Your voice of reason and alternative angle gets lost. I don't think its personal, as I've waded into these threads half way through, and I'm ignored. Usually the person that brings the claim becomes engrossed with those that they have debated heavily over the course of the thread. The other issue is the Jay obsession, and then we all get ignored.

It's only very rarely that I think, "Oh.  This is because I don't have a Y chromosome, isn't it?"  Though that happens.  And I didn't get to this one as quickly as I might, because as established, I was off having a life instead.  By the time I got into it, he'd already decided who was worth his time, and newcomers didn't get much of it.  That's fine; my anniversary celebration was more important.  And really, is it fair of Jay to be so incredibly knowledgeable and such a good writer?  I ask you!

I did see you made a comment about you 4 year old and log scales. Where has that time gone? I hope you are still enjoying motherhood.

He starts kindergarten next year!  And, yeah, it's going pretty well for us.  The baby isn't a baby anymore; she turned fourteen months this week.  Still not talking, but she's expressing herself quite clearly and let me know this afternoon that it was time to put her down for a nap, and I love it when that happens.

[Luke Pemberton]

Somewhat, yes.  But Tim didn't compute the median, he computed the mean, and used that to argue his point.

I wasn't aware Tim computed anything. He visually inspected the graph and misread the log scale. The issue being that Tim didn't accept the data once it was handed on a plate to him.

[Luke Pemberton]

The baby isn't a baby anymore; she turned fourteen months this week.  Still not talking, but she's expressing herself quite clearly and let me know this afternoon that it was time to put her down for a nap, and I love it when that happens.

I haven't been around here properly for 18 months, with a hiatus of 10 months. I do vaguely remember there being a second child on the way, but didn't want to impose questions on that front. I'm glad it is going so well for you all. 

[jfb]

Somewhat, yes.  But Tim didn't compute the median, he computed the mean, and used that to argue his point.

I wasn't aware Tim computed anything. He visually inspected the graph and misread the log scale. The issue being that Tim didn't accept the data once it was handed on a plate to him.

Actually, I got it wrong - he averaged across all the detectors, not across the date range.  In which case, we get the attached graph, which pretty much shows the same thing as previous graphs - the bulk of the daily readings were below the .22 mGy/day threshold. 

To be honest, he did enough gish galloping that I'm not even sure what his arguments wrt CRaTER were anymore, other than that they proved people didn't walk on the moon. 

[inconceivable]

The thing that gets me about moon mission are the unknowns that have come to light over the years about craters on the moon using computer models and analyzing newer data.  Many unknowns that they weren't aware of back then.  Amazed that they were just so lucky for instance with no threatening solar flares during the missions?  Driving buggies around not concerned with the density or the properties of the regolith?  Hitting golf balls, not concerned with static discharge?  Not knowing that the leading edges of craters could potentially have 100s of volts of electricity created by the solar wind, waiting to be discharged.  Potentially damaging suits, buggies, shorting out equipment.  It's probable that a lot of the data from these instruments was inaccurate to begin with.   It's amazing they picked all the right areas to avoid the dangerous affects of solar radiation.

[Luke Pemberton]

Amazed that they were just so lucky for instance with no threatening solar flares during the missions?

They indeed were, but now we refer to them as solar storms or SPEs produced by shock driven CMEs.

Driving buggies around not concerned with the density or the properties of the regolith?

Surveyor probes were sent before the landings, these provided insight into the regolith depth. The regolith was a concern, but as I say, they sent the Surveyors.

Hitting golf balls, not concerned with static discharge?

You need to explain that one a bit more. I'm not sure why they would get the discharge. A heath Robinson golf club falling apart and hitting the LM was probably a bigger problem

Not knowing that the leading edges of craters could potentially have 100s of volts of electricity created by the solar wind, waiting to be discharged.  Potentially damaging suits, buggies, shorting out equipment.

Volts don't discharge, current does. Objects can be at 100s of volts and the current discharged will be micro-ammeters and less. Hardly noticeable. A table top van de Graaf used in school demos and science fairs can have potentials in the 1000s of volts. School children play with them all the time.

https://extkits.co.uk/product/mini-van-de-graaff-generator/

It's probable that a lot of the data from these instruments was inaccurate to begin with.   It's amazing they picked all the right areas to avoid the dangerous affects of solar radiation.

What areas, and what dangerous effects?

[LunarOrbit]

The thing that gets me about moon mission are the unknowns that have come to light over the years about craters on the moon using computer models and analyzing newer data.  Many unknowns that they weren't aware of back then.  Amazed that they were just so lucky for instance with no threatening solar flares during the missions?  Driving buggies around not concerned with the density or the properties of the regolith?  Hitting golf balls, not concerned with static discharge?  Not knowing that the leading edges of craters could potentially have 100s of volts of electricity created by the solar wind, waiting to be discharged.  Potentially damaging suits, buggies, shorting out equipment.  It's probable that a lot of the data from these instruments was inaccurate to begin with.   It's amazing they picked all the right areas to avoid the dangerous affects of solar radiation.

Imagine where we'd be as a civilization if we had not explored the Earth out of fear of the unknown.

[gillianren]

Hell, I just watched Planet Earth II with the kids this week, and all of life everywhere is all about danger.  The known is dangerous, too; we've just all agreed to treat that danger as normal.

[Jason Thompson]

The thing that gets me about moon mission

The thing that gets me about your posts, inconceivable, is why you make them. You drop in, post stuff like this, then utterly fail to return to it before dropping in randomly later and posting another comment like this. What are your reasons for being here?

are the unknowns that have come to light over the years about craters on the moon using computer models and analyzing newer data.

Yes, amazing how science keeps finding new things, isn't it? 

Amazed that they were just so lucky for instance with no threatening solar flares during the missions?

That was not just dumb luck, that was a calculated risk. What exactly is the frequency of major, life-threatening solar flares that are directed right at us? How does that compare to minor flares, or those that don't blast us directly? And how does that fit with a two-week mission duration?

Not that I expect an answer. You have a pretty consistent record of failure to respond.

Driving buggies around not concerned with the density or the properties of the regolith?

How exactly do you conclude they were 'not concerned'? They had several lunar landings, manned or otherwise, under their belt by the time the first rover was used. Properties of the regolith were well known.

Hitting golf balls, not concerned with static discharge?

Why would static discharge be a problem for anyone encased in a spacesuit? They're not exactly conductive. What would provide the route to earth the static charge?

Not knowing that the leading edges of craters could potentially have 100s of volts of electricity created by the solar wind, waiting to be discharged.

Again, what would it discharge through? And is hundreds of volts actually a problem? A simple static shock of the kind you get touching a doorknob is on the order of thousands of volts.  And that's the voltage required to allow the charge to travel across the air between the thing with the accumulated charge and your finger. What would the voltage need to be to allow discharge across a vacuum? In any case, it's not the voltage that is an issue, it's the current.

It's amazing they picked all the right areas to avoid the dangerous affects of solar radiation.

This is why I don't actually believe you are anything but a rather mild example of a troll. This entire thread is literally devoted to this subject. They didn't 'pick the right areas', the radiation a) wasn't at a damaging background level anyway for someone in a spacecraft or spacesuit, and b) the chance of a damaging flare was calculated and considered an acceptable risk for the mission goal. Everything you just said about static discharge is meaningless because, like the radiation, it is a) not high enough to be of concern and b) unlikely to discharge anyway.

[AtomicDog]

The Apollo 14 astronauts used a wheeled cart to carry their equipment. I'm sure that they reported back to NASA how it performed in the regolith.

https://en.wikipedia.org/wiki/Modular_Equipment_Transporter

[JayUtah]

The thing that gets me about moon mission are the unknowns that have come to light over the years about craters on the moon using computer models and analyzing newer data.

Yeah, that's what exploration is for.  You find out what you didn't previously know.  Duh.

Amazed that they were just so lucky for instance with no threatening solar flares during the missions?

The statistical basis for predicting solar weather goes back to the early 1800s.  What makes you think that they relied entirely on luck?  They relied on statistics, but that's something different.

Driving buggies around not concerned with the density or the properties of the regolith?

What makes you think they were not concerned?  What makes you think that by the fourth manned mission studying the surface on foot they did not have sufficient understanding of the physics of lunar regolith to consider a wheeled vehicle an acceptable risk.

Hitting golf balls, not concerned with static discharge?

Now you're just reaching.

Not knowing that the leading edges of craters could potentially have 100s of volts of electricity created by the solar wind, waiting to be discharged.

100 volts of static electricity is negligible.  Regular discharges from shuffling your feet across the floor and touching a doorknob can reach thousands of volts.  You're still reaching.

It's amazing they picked all the right areas to avoid the dangerous affects of solar radiation.

Science is amazing that way.

To put this in perspective, Utah highways have a mortality rate of about 350 per year.  Meaning that my morning commute exposes me to that risk twice a day.  Yet it's amazing I get to work every day.  The question is not whether Apollo was risky.  It was, and that's why it deserves so much attention.  But there's no reason to question its validity because it was risky.