Author Topic: Mars/Venus colonization calculations - Deuterium  (Read 6523 times)

Offline Rei

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Mars/Venus colonization calculations - Deuterium
« on: 04/09/2016 06:27 pm »
Hi all.  I've been working on Venus colonization calculations, and ran into an issue that applies (to a lesser extent) to Mars: the D/H ratio.

Both Mars and Venus have lost most of their water to space, and since H escapes easier than D, this shifts the D/H ratio.  Mars has about 5-7 times the D/H ratio as Earth and Venus has 150 (or according to newer measurements, 240) times the ratio.  Deuterium does not behave chemically the same as H - there are some subtle differences that have important effects (which is the basis for deuterated drugs - they tend to last longer in the body).  Some of these effects of high deuterium levels can be good - for example, fruit flies live longer at elevated (but not extremely elevated) deuterium levels:

http://www.ncbi.nlm.nih.gov/pubmed/23301756


However, deuterium has also been linked to depression:

http://www.ncbi.nlm.nih.gov/pubmed/23301756

Apparently a 10ppm increase in deuterium, according to the study, corresponds with a 1,8% increase in depression symptoms.  On Mars you have something like a 600ppm higher deuterium level.

Isn't this potentially... um... a problem?  I've not even heard of any mission proposal attempting to deal with this. 

Dealing with it (at least in a single stage enrichment) is relatively simple for Venus, since your water (and oxygen) comes from thermal decomposition of sulfuric acid mists... so you already have your water transitioning between high and low temperatures needed for the GS process, you just have to implement a proper H2S bubbling system.  For Mars, however, water production doesn't involve high temperatures - it involves melting ice, filtering it, chemically treating it, then running it through reverse osmosis or electrodialysis.  So you never get the high temperatures needed for GS (or distillation either). 

Is anyone here aware of anyone who's taken the D/H ratio into account in designing long-term Mars missions? 
« Last Edit: 04/19/2016 11:20 pm by Chris Bergin »

Offline The Amazing Catstronaut

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Re: Deuterium
« Reply #1 on: 04/09/2016 09:07 pm »
I'd heat it as much as possible anyway on the off chance of ingesting Martian microbial life, if there is any. If anything would kill off a Martian extremophile (and certainly a lot would), it's heat. Microorganisms adapted for the Martian environment would be unlikely to survive being run through a girdler sulfide process.

If you have sufficient electricity, this shouldn't be a problem as far as I can tell, although the risk is certainly... disturbing. Depression is really not something you want to tangle with on a mars mission, and that's only one symptom. Water is physiologically critical to human function and ideally we want to simulate Earth conditions as closely as possible in Martian water quality.

« Last Edit: 04/09/2016 09:16 pm by The Amazing Catstronaut »
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Offline Rei

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Re: Deuterium
« Reply #2 on: 04/12/2016 05:32 pm »
Aha!  Okay, some bad news, then some good news.

I was looking into how to make this work and was hitting a dead end.  Because while it's relatively easy to enrich, it's much harder to deplete.  A GS plant may discharge water that's only ~20% depleted in deuterium; think of how many stages that would take on Mars, let alone Venus, to get deuterium down to a reasonable level!

I was checking into all of the different methods and then something occurred to me.  The best separation factor by far comes from electrolysis (6-10 - protium really prefers a lot more to split than deuterium)... but it's not widely used except for end-stage enrichment because it wastes such a huge amount of energy, even if you recover all of the energy you can from the recombination.

But what if you *needed* to do electrolysis and recombination again and again and again?

I had initially just been planning, for my Venus work, to baseline batteries for nighttime power storage - it's common in Mars proposals as well.  But picture what happens if we switch to fuel cells.  A fuel cell / electrolysis stack can be made out of any number of smaller components.  And you can feed them however you want.  Aka, you can use your power storage system as a cascade.  Every day the electrolysis side of the cascade occurs, and every night the recombination side. At one end of the cascade, the produced water goes into your drinking water, plant watering, fertilizer, etc.   On the other end, it goes into fuel production, chemical feedstocks, etc. 

Viola, deuterium separation at no extra cost!  Well, okay, there's the extra cost of using multiple smaller storage tanks instead of a couple big ones, extra piping, extra pumping or valves, etc... but no separate enrichment system or associated (huge) power consumption!

Now, the question remains of how fuel cells compare to batteries.  They are significantly less efficient, for example, and their lifespans as bad or worse.  On Mars you have to use compressed H2 tanks (heavy) and your solar panels need to be at least semirigid (your best bet would be something like ATK Ultraflex).  Even still, though, I would wager (haven't run the numbers) that the net system mass works out to lighter than batteries, or at least close.  But the more I think about the Venus case the more ideal fuel cells there seem.  Because solar there is extremely light (built into the envelope) and the H2 can be a secondary (uncompressed) envelope inside the ballonets (aka, no fire risk). 

The main downside I'm seeing is I'm going to need to redo all of my lift calculations, including a larger ammonia phase-change envelope to compensate for the daily lift fluctuations....

Offline Hotblack Desiato

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Re: Deuterium
« Reply #3 on: 04/14/2016 08:55 am »
That's a very interesting point. It's virtually useless, if we go to Mars, harvest water-ice just to find out, that it's unconsumable.

The additional thing is with depressions, that it may lead to suicides. And some people become creative when it comes to suicides, taking a lot of others with them.

I wonder if ultracentrifuges can be used for splitting protium and deuterium. The use of fuel cells for depletition is nice. Maybe both systems can be connected?

Offline The Amazing Catstronaut

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Re: Deuterium
« Reply #4 on: 04/14/2016 04:55 pm »
How much actual awareness by mission planners is there of this problem? Even if self-harm, suicide, apathy or any other extremes of depressive symptoms that may cause an otherwise completely successful mission/colony go off the rails never occurs, the last thing we want is astronauts (who have devoted their entire life to getting there) moaning about their life on Mars if we want people to feel enthused about going there. The problem is technically solvable without bringing tonnes of mass, but the more terrifying prospect is it being overlooked, although unlikely.
« Last Edit: 04/14/2016 04:56 pm by The Amazing Catstronaut »
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Offline Rei

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Re: Deuterium
« Reply #5 on: 04/14/2016 05:35 pm »
That's my concern - I can't find any evidence of *any* awareness by mission planners as to this issue.

It's not just about depression, either:

https://en.wikipedia.org/wiki/Deuterium-depleted_water
"Experiments have shown that consumption of light water may be beneficial as an adjunct to chemotherapy. A 1999 Romanian study found that water with only 30 ppm deuterium produced marked improvement in survival rates of mice bombarded with ionizing radiation.[3] A study of four patients with brain metastases from lung cancer found a three-month regimen of light water "noticeably prolonged" their survival time.[4] A 2010 Hungarian study found significant improvement in the survival times of prostate cancer patients treated with light water.[5] Despite Gilbert Lewis' call in 1934 for such experiments,[6] research on the effects of deuterium-depletion on living cells has been very limited with less than a dozen peer-reviewed research papers available via PubMed in mid-2011[7]"

The lack of study on the issue that they mention matches my experience in digging up information.  The existing research points to a significant potential problem here - depression, radiation vulnerability, susceptibility to cancer, etc all seem positively correlated with deuterium levels.  Yet it seems to just be flying under the radar.

There are solutions.  But is anyone paying enough attention to incorporate them?
« Last Edit: 04/15/2016 03:22 am by Rei »

Offline Robotbeat

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Re: Deuterium
« Reply #6 on: 04/14/2016 06:32 pm »
Good thing is that it'll make D-D fusion fuel easier to get on Mars! :)
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

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Offline Rei

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Re: Deuterium
« Reply #7 on: 04/15/2016 03:21 am »
It's a potential export item, too, if you can get your transport costs down enough.  Of course, Venus is even richer in deuterium - the ratio there is just crazy, like 1,2% in the habitable zone.  ;)  But Mars presents a significantly weaker gravity well to lift it out of.  There's no question that access to orbit on  Mars could be achieved by a SSTO; Venus is a big "maybe" in this regard.

D2O is worth about $300-400/kg.  Given that D2O is only 20% deuterium by mass, pure D2 gas would probably be around $1,2k/kg; creating D2O from D2 is as simple as burning it.  Of course with D2 gas there's the tankage mass issue.  Other options that are deuterium-richer than D2O but easier to store than D2 include CD4 (40%), C2D6 (33%), C3D8(31%), ND3 (30%), C4D10(29%), BeD2(29%), etc.

 A kind of neat "trick" would be to package any liquids or gases inside deuterated plastics, so that the packaging itself is a valuable export item that can also be burned to produce D2O back on Earth.  Even plastics sent from Earth can be deuterated in-situ on Mars or Venus - deuterium and hydrogen tend to exchange places until they reach an equilibrium.  So for example, build vessels for liquids or gases out of dyneema (UHMWPE) composites - deuterated UHMWPE is 25% deuterium by weight.

The global market for deuterium on Earth is only going to grow.  It's increasingly popular in fission reactors, essential in forseeable-future fusion reactors (D-T), needed for all sorts of medical and analytical technologies, etc.

You just don't want to be consuming it in significantly elevated quantities in your drinking water and food.  :Þ
« Last Edit: 04/15/2016 03:42 am by Rei »

Online Welsh Dragon

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Re: Deuterium
« Reply #8 on: 04/15/2016 09:01 am »
That's my concern - I can't find any evidence of *any* awareness by mission planners as to this issue.

It's not just about depression, either:

https://en.wikipedia.org/wiki/Deuterium-depleted_water
"Experiments have shown that consumption of light water may be beneficial as an adjunct to chemotherapy. A 1999 Romanian study found that water with only 30 ppm deuterium produced marked improvement in survival rates of mice bombarded with ionizing radiation.[3] A study of four patients with brain metastases from lung cancer found a three-month regimen of light water "noticeably prolonged" their survival time.[4] A 2010 Hungarian study found significant improvement in the survival times of prostate cancer patients treated with light water.[5] Despite Gilbert Lewis' call in 1934 for such experiments,[6] research on the effects of deuterium-depletion on living cells has been very limited with less than a dozen peer-reviewed research papers available via PubMed in mid-2011[7]"

The lack of study on the issue that they mention matches my experience in digging up information.  The existing research points to a significant potential problem here - depression, radiation vulnerability, susceptibility to cancer, etc all seem positively correlated with deuterium levels.  Yet it seems to just be flying under the radar.

There are solutions.  But is anyone paying enough attention to incorporate them?

I'm a neurobiologist in my day job. I can assure you that all of the papers you linked to/cited are in journals nobody takes seriously or bothers reading. Basically nobody has properly looked at this, but from basic biology, there is no reason to assume there would be any effect of deuterium depletion, and very limited effects of increases, which are only significant in vastly higher fractions.

Offline The Amazing Catstronaut

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Re: Deuterium
« Reply #9 on: 04/15/2016 10:12 am »

I'm a neurobiologist in my day job. I can assure you that all of the papers you linked to/cited are in journals nobody takes seriously or bothers reading. Basically nobody has properly looked at this, but from basic biology, there is no reason to assume there would be any effect of deuterium depletion, and very limited effects of increases, which are only significant in vastly higher fractions.

Thank you for your response - it's always excellent to have an expert moderate our discussions before they veer off into the impractical.

What do you consider to be a vastly higher fraction? Nothing that could be achieved through the average consumption of a human performing considerable exercise, or anything that could be cumulatively attained over a human lifespan?
« Last Edit: 04/15/2016 10:13 am by The Amazing Catstronaut »
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Offline The Amazing Catstronaut

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Re: Deuterium
« Reply #10 on: 04/15/2016 10:15 am »
It's a potential export item, too, if you can get your transport costs down enough.  Of course, Venus is even richer in deuterium - the ratio there is just crazy, like 1,2% in the habitable zone.  ;)  But Mars presents a significantly weaker gravity well to lift it out of.  There's no question that access to orbit on  Mars could be achieved by a SSTO; Venus is a big "maybe" in this regard.

D2O is worth about $300-400/kg.  Given that D2O is only 20% deuterium by mass, pure D2 gas would probably be around $1,2k/kg; creating D2O from D2 is as simple as burning it.  Of course with D2 gas there's the tankage mass issue.  Other options that are deuterium-richer than D2O but easier to store than D2 include CD4 (40%), C2D6 (33%), C3D8(31%), ND3 (30%), C4D10(29%), BeD2(29%), etc.



I wonder if MTC MCT counts as "cheap enough", since that's the largest cargo return vehicle Mars is likely to see in the next 30 years. Of course, the actual mass of the deuterium it could bring back would be inhibited, but since it needs to return to Earth anyway it's effectively free shipping.
« Last Edit: 04/15/2016 11:51 am by The Amazing Catstronaut »
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Offline Rei

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Re: Deuterium
« Reply #11 on: 04/15/2016 11:15 am »
Quote
Basically nobody has properly looked at this, but from basic biology, there is no reason to assume there would be any effect of deuterium depletion, and very limited effects of increases, which are only significant in vastly higher fractions.

If that were true than why would anyone make deuterated drugs

Quote
Many, like Concert’s deuterated version of GHB, will work best only when partially deuterated in a specific way. But Graham Timmins, a medicinal chemist at the University of New Mexico who has been studying the field, reckons that when all is done and dusted, perhaps 5-10% of drugs on the market will be deuterated. The question is by whom?

This paper estimates the market for deuterated drugs at $1B:
http://www.ncbi.nlm.nih.gov/pubmed/25069517

The reason that chemical enrichment works well with deuterium is that deuterium has a significantly higher affinity for certain bonds relative to 1H than to others, which interferes with a number of enzymatic pathways:
http://dmd.aspetjournals.org/content/40/3/625.full

A quick summary of effects here:
http://www.isb.vt.edu/brarg/brasym96/kushner96.htm

Deuterated drugs can last many times as long in the body as their non-deuterated equivalents, sometimes orders of magnitude longer.  So you can't just assume that deuterium's effects are going to be linearly proportional to its ratio with 1H.  You also can't assume uniform distribution.  You also can't assume a lack of biological enrichment.  Indeed, biological enrichment has been demonstrated, at least with single-celled organisms:

https://books.google.is/books?id=CN88gBPtiucC&pg=PA49&lpg=PA49&d
q=biological+enrichment+%22deuterium%22&source=bl&ots=
OI-546wfKQ&sig=WJecbfpon16gSS14ml-0r4X6L9I&hl=is&sa=X&ved=0ahUKEwjXzP74uZDMAhUHiw8KHaaWBLQQ6AEIWTAH
#v=onepage&q=biological%20enrichment%20%22deuterium%22&f=false

Quote
Chemical isotope effects are particularly large for lighter elements in biological systems. The chlorella algae prefers deuterium over hydrogen, and tritium over deuterium. The enrichment factor depends on the conditions of growth; for deuterium to hydrogen an enrichment factor of 1.6 - 3 has been found, while for tritium to hydrogen the enrichment factor is about 2.5. Bacteria behave similarly, e.g. coli bacteria showing an enrichment factor for deuterium of 3.9.

In as much as some of the hydrogen atoms are not exchanged readily due to the inertness of their chemical bonds, the isotopic fractionation which involves the easily exchangeable hydrogen atoms in these biological processes must have even larger enrichment factors for deuterium and tritium than their measured values would indicate

That's just for the whole organism; let alone individual chemicals.  If whole cell concentrations are achieving those levels of enrichment, then surely cyclic reactions which cause the enrichment experience dramatically higher levels of enrichment than the bulk cell, which is comprised mainly of water (water does not enrich itself).

You have enrichment and you have some compounds lasting longer than their non-deuterated equivalents, sometimes with a difference in terms of orders of magnitude.  You see no no grounds for how deuterium levels could cause significant biological effects?

As for your comments dismissing peer-reviewed research... I don't have time to check every journal, but I pulled up the journal for one of them at random:
http://www.ncbi.nlm.nih.gov/pubmed/23441611

... and looked up its impact factor:
http://www.tandfonline.com/toc/hnuc20/current

2.322.  Now, that's not spectacular, but it's not exactly fly-by-night either.  Looking further:

http://www.scimagojr.com/journalsearch.php?q=13308&tip=sid&clean=0

.... we see that it's 2-3 quartile ranking for cancer research, first quartile for medicine, 1-2 quartile for nutrition, and 1-2 quartile for oncology.  Do you really think that justifies just dismissing it offhand, just because it's not in Nature or something?

Concerning the original depression study I posted:

http://www.sciencedirect.com/science/article/pii/S0166432814004884

... it's in Behavioral Brain Research.  It has an impact factor of 3.028 (5-year=3.298)  Again, hardly fly-by-night.

One dismisses peer reviewed research at their own peril.  Or, in this case, at the peril of their crew.
« Last Edit: 04/19/2016 11:18 pm by Chris Bergin »

Offline Rei

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Re: Deuterium
« Reply #12 on: 04/15/2016 11:31 am »
To be more to the point about mechanisms: the depression study team was not just studying symptoms, but literally dissecting mice and measuring SERT expression in the hippocampus.  They really did a battery of tests, and the deuterium-depleted subjects rated as well or better than those on citalopram in every one.  And it was a multi-institutional study, with members from:

* Department of Pharmacology, Oxford University, Oxford, UK
* Institute for Hygiene and Tropical Medicine, New University of Lisbon, Portugal
* School for Mental Health and Neuroscience, Department of Neuroscience, Maastricht University, Maastricht, Netherlands
* Laboratory of Cognitive Dysfunctions, Institute of General Pathology and Pathophysiology, Moscow, Russia
* Timantti AB, Stockholm, Sweden
* Claude Bernard University, Faculty of Medicine, EA 4170 Lyon, France
* IsoForensics Inc., Salt Lake City, UT, USA
* GIGA Neuroscience, University of Liege, Liege, Belgium
* Division of Molecular Psychiatry, Laboratory of Translational Neuroscience, Department of Psychiatry, Psychosomatics and Psychotherapy, University of Wuerzburg, Wuerzburg, Germany

How are you considering this to be something not worth "taking seriously"?
« Last Edit: 04/15/2016 11:32 am by Rei »

Online Welsh Dragon

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Re: Deuterium
« Reply #13 on: 04/15/2016 12:10 pm »
Quote
Basically nobody has properly looked at this, but from basic biology, there is no reason to assume there would be any effect of deuterium depletion, and very limited effects of increases, which are only significant in vastly higher fractions.

If that were true than why would anyone make deuterated drugs

Patentbusting

Quote

As for your comments dismissing peer-reviewed research... I don't have time to check every journal, but I pulled up the journal for one of them at random:
http://www.ncbi.nlm.nih.gov/pubmed/23441611

... and looked up its impact factor:
http://www.tandfonline.com/toc/hnuc20/current

2.322.  Now, that's not spectacular, but it's not exactly fly-by-night either.  Looking further:

Something that low means it's essentially irrelevant.

Quote
Concerning the original depression study I posted:

http://www.sciencedirect.com/science/article/pii/S0166432814004884

... it's in Behavioral Brain Research.  It has an impact factor of 3.028 (5-year=3.298)  Again, hardly fly-by-night.

One dismisses peer reviewed research at their own peril.  Or, in this case, at the peril of their crew.
Still not impressive, and this is evident in the poorly controlled experiments they did, again, rendering them essentially meaningless.

Offline Rei

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Re: Deuterium
« Reply #14 on: 04/15/2016 01:47 pm »
Quote
Basically nobody has properly looked at this, but from basic biology, there is no reason to assume there would be any effect of deuterium depletion, and very limited effects of increases, which are only significant in vastly higher fractions.

If that were true than why would anyone make deuterated drugs

Patentbusting

Seriously, you're dismissing the entire concept, which there are tons of companies involved in and lots of papers being written about?  So people are throwing their money at nothing and wasting their time researching nothing?  Even just the filing costs on the patents alone - have you ever filed a patent?  Just getting protection in a single country usually costs over $10k.  Global rights can run into the hundreds of thousands. For a single patent. 

People don't pour large amounts of money into products on a whim.  And you're seriously going to dismiss all of the research on deuterated drugs.... because why again?  Are we just going to pretend that deuterium and hydrogen behave chemically the same, and ignore the fact that they demonstrably don't, and that's the very basis for how deuterium is commercially separated?  Are we going to pretend that small quantities of "similar but different" chemicals can't have profound substitution effects in the body, such as arsenic substituting for phosphorus?

Quote
Something that low means it's essentially irrelevant.
...
Still not impressive, and this is evident in the poorly controlled experiments they did

Okay, what sort of journals are you publishing in?  There's nothing at all wrong with a 3+ impact factor in neuroscience.  And asserting that the peer review process must simply be wrong because you don't like the results is weak tea.
« Last Edit: 04/15/2016 01:58 pm by Rei »

Online Welsh Dragon

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Re: Deuterium
« Reply #15 on: 04/15/2016 01:53 pm »
Quote
Basically nobody has properly looked at this, but from basic biology, there is no reason to assume there would be any effect of deuterium depletion, and very limited effects of increases, which are only significant in vastly higher fractions.

If that were true than why would anyone make deuterated drugs

Patentbusting

Seriously, you're dismissing the entire concept, which there are tons of companies involved in and lots of papers being written about?  So people are throwing their money at nothing and wasting their time researching nothing?  Even just the filing costs on the patents alone - have you ever filed a patent?  Just getting protection in a single country usually costs over $10k.  Global rights can run into the hundreds of thousands. For a single patent. 
Which is small change compare to the billions you can make on drugs, so yes, patentbusting. Don't confuse scientific merit with commercial merit. Pharmaceutical companies priorities the latter.

Quote
Quote
Something that low means it's essentially irrelevant.
...
Still not impressive, and this is evident in the poorly controlled experiments they did

Okay, what sort of journals are you publishing in?  There's nothing at all wrong with a 3+ impact factor in neuroscience.  And asserting that the peer review process must simply be wrong because you don't like the results is weak tea.
J Neurosci and above. I said nothing about peer review. I said their experimental setup was not good, not using the right controls.

I don't see how this discussion (or indeed topic) is relevant.

Offline Rei

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Re: Deuterium
« Reply #16 on: 04/15/2016 02:02 pm »
Which is small change compare to the billions you can make on drugs, so yes, patentbusting. Don't confuse scientific merit with commercial merit. Pharmaceutical companies priorities the latter.

And how do you make "billions" if the concept is bunk, as you seem to think it is?  And if you'd actually check pubmed, you'd find that there's an awful lot of research papers, in a wide range of journals, about deuterated drugs.  All bunk, I assume?

Quote
I said nothing about peer review. I said their experimental setup was not good, not using the right controls.

And it passed peer-review.  So if you think it's bunk, you're saying that their peer review was lousy.

Quote
I don't see how this discussion (or indeed topic) is relevant.

You don't see how health effects of 5-7 times higher of a chemical that research shows has effects at even small variations is a  relevant topic?
« Last Edit: 04/15/2016 02:06 pm by Rei »

Offline Rei

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Re: Deuterium
« Reply #17 on: 04/15/2016 02:13 pm »
Or to put it simpler: the appropriate response to "I don't agree with this peer reviewed paper" is "Here is some different peer-reviewed work, which is more reputable for reasons X, Y, and Z, which says otherwise."  Not simply "It's wrong because I say it's wrong."

If you have peer-reviewed counterevidence, present it.

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Re: Deuterium
« Reply #18 on: 04/15/2016 02:25 pm »
Are you seriously claiming peer review prevents crap from being published? If you believe that there is nothing left to discuss.

For other readers, this is a non-item. I don't know why the OP insists it's a problem, but it can be safely disregarded in the context discussed here. No properly done study has ever shown a problem with deuterium at Martian levels. I'm not here to prove a negative.

Offline Rei

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Re: Deuterium
« Reply #19 on: 04/15/2016 03:44 pm »
Are you seriously claiming peer review prevents crap from being published?

I'm claiming that peer-review is the cornerstone of the modern scientific process, and while certainly not perfect, it's the best thing we've got - certainly far better than "proof by vigorous assertion".

Quote
For other readers, this is a non-item. I don't know why the OP insists it's a problem, but it can be safely disregarded in the context discussed here. No properly done study has ever shown a problem with deuterium at Martian levels. I'm not here to prove a negative.

Quite to the contrary, there are a number of peer-reviewed studies that show problems with deuterium at far lower than Martian levels, some of which have been linked in this very thread.  You just choose not to believe them.

Nobody it talking about "proving a negative".  You are stating that peer-reviewed research pointing out specific effects is wrong.  That is a positive assertion on your part.  Science is based around evidence confirmed by the peer-review process.  Your peer-reviewed evidence that these specific claims are wrong is....?
« Last Edit: 04/15/2016 03:51 pm by Rei »

Offline Robotbeat

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Re: Deuterium
« Reply #20 on: 04/15/2016 04:38 pm »
I decided to research this a bit:
Astronauts on Mars (or especially colonists) would likely be tapping ancient water on Mars, whether deep reservoirs or hydrated sulfates (like gypsum). This is likely FAR less deuterium-rich than atmospheric water.

And making light water (deuterium-depleted water) is not particularly hard, and cost on the order of $1/liter. You can buy light water for around $8/liter from eastern European places, or much, much higher in the West. ...which brings me to my main point: Those most vocal about the effects of heavy or light water are those selling this WAY over-priced deuterium-depleted water. Are your snake-oil flags going up? Because mine are. Poorly controlled experiments in secondary research journals touted by people selling over-priced miracle cures (literally one of the products is called "Miracle Light Water") is a major clue to be skeptical of these claims.

So I'd go with what the neuroscientist here says. This is almost certainly horse-hockey, and if it's not, it's not even that hard to mitigate (compared to all the other hazards out there).
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

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Offline Rei

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Re: Deuterium
« Reply #21 on: 04/15/2016 08:28 pm »
The lowest D/H ratio found on Mars was from Cumberland, which was formed before the Hesperian - but it's still over double Earth levels.

Depleted water absolutely can be produced reasonably.  I haven't run the numbers on a Mars cascade, but on a Venus cascade with an enrichment factor of 6 and 11 stages about 15% of the water in the system on every cycle-through would come out at 80ppm (with the other end enriched to 99,6%) - and that's with a 1,2%D starting rate, much higher than on Mars.  But the key issue is that light water doesn't produce itself - it has to be planned to be produced.  It has to be on a mission planner's radar.  Otherwise, what people drink will be heavy.

You're free to ignore peer-reviewed literature based on someone's unreferenced say-so if you choose.  :)

Quote
Poorly controlled experiments in secondary research journals touted by people selling over-priced miracle cures (literally one of the products is called "Miracle Light Water") is a major clue to be skeptical of these claims.

What exactly are you looking at?  The initial paper on depression was from researchers from:

* Department of Pharmacology, Oxford University, Oxford, UK
* Institute for Hygiene and Tropical Medicine, New University of Lisbon, Portugal
* School for Mental Health and Neuroscience, Department of Neuroscience, Maastricht University, Maastricht, Netherlands
* Laboratory of Cognitive Dysfunctions, Institute of General Pathology and Pathophysiology, Moscow, Russia
* Timantti AB, Stockholm, Sweden
* Claude Bernard University, Faculty of Medicine, EA 4170 Lyon, France
* IsoForensics Inc., Salt Lake City, UT, USA
* GIGA Neuroscience, University of Liege, Liege, Belgium
* Division of Molecular Psychiatry, Laboratory of Translational Neuroscience, Department of Psychiatry, Psychosomatics and Psychotherapy, University of Wuerzburg, Wuerzburg, Germany

None of them are "people selling overpriced miracle cures".  Nor is Behavioral Brain Research some fly-by-night journal. 

Does the existence of hacks somewhere trying to hawk a questionable product invalidate peer-reviewed research unconnected to said people?  Does all of the people trying to hawk vitamin supplements to people who don't need them render all of the research on human vitamin needs invalid?
« Last Edit: 04/19/2016 01:34 pm by Rei »

Offline Hanelyp

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Re: Deuterium
« Reply #22 on: 04/19/2016 10:40 pm »
Regarding the reliability of peer review: http://theweek.com/articles/618141/big-science-broken

Offline Rei

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Re: Mars/Venus colonization calculations - Deuterium
« Reply #23 on: 04/19/2016 11:34 pm »
And the alternative is?

Peer review is not perfect, but it's the best thing we have.  Because the alternative is flat assertion.  And given the choice between a paper having been gone over by a group of experts in the field, versus someone arbitrary just declaring "X is true, Y is false" without any review, which do you think is going to give the right answer the most often?

I for one do not long for a return to the Dark Ages, of truth declared by fiat.
« Last Edit: 04/19/2016 11:35 pm by Rei »

Offline Chris Bergin

Re: Mars/Venus colonization calculations - Deuterium
« Reply #24 on: 04/19/2016 11:37 pm »
Right so I don't understand the thread (my fault) but I do see a mod report about anti-science rhetoric being off-topic, per Hanley's post, so let's....not.

I have given the thread a better thread title (I think), because a single word thread title is no help.
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