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Dingus McGee
Social climber
Where Safety trumps Leaving No Trace
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Jan 12, 2016 - 04:25am PT
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Even skin will stop Apha particles.
Sounds harmless? The thickness of a skin layer is much much thicker than the thickness of a single skin cell wall membrane where the momentum of the alpha particle would be reduced and molecules destroyed.
Even skin will stop Apha particles. A neat non sense way to look at what the actual mechanics of what collisions are about.
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Ed Hartouni
Trad climber
Livermore, CA
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Jan 12, 2016 - 09:27am PT
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Pu238 is the fuel for deep space flight... though it has a finite decay time...
the triple alpha decay is easy on electronics.
And Dingus is a bit off base on his fear of alpha induced damage on skin... shielding the alphas is pretty effective and straight forward, they loose a lot of energy thanks to Z=2... but it is true you don't want that radionuclide up against lung or gut tissue.
Dingus could review the studies of "energy loss of charged particles" and report back...
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climbski2
Mountain climber
Anchorage AK, Reno NV
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Jan 12, 2016 - 09:38am PT
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Did not seem to hurt Tom Frost. He lugged one of those reactors up Nanda Devi.
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limpingcrab
Trad climber
the middle of CA
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Jan 12, 2016 - 09:54am PT
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Remember when some people thought the earth was flat?
Remember when Barry Marshall got laughed off the stage for saying ulcers were influenced by bacteria, not just stress, and then went on to win the nobel prize?
Remember when people thought if you went faster than 30mph you would explode?
Remember when doctors thought draining blood was helpful and cleaning things with water was harmful?
Sometimes scientists are the least imaginative group because we won't acknowledge how much we don't know.
I bet the future will look way different than we expect! Maybe we'll be doing FAs on asteroids on our way to another galaxy!
BUT, I still don't think we'll ever find any life out there. Maybe that will make mining the crap out of everything a little less offensive, DMT?
DNA may be a complex molecule but it's made of only 5 very common elements.
Hydrogen - Oxygen (water), Carbon, Nitrogen and Phosphorus
Put in (symbolic) pot. Bring to suitable temperature. Mix (thermal currents) for a long time. Millions or billions of years.
The Universe has time. Lots of time.
Will the soup create DNA?
Given the odds (and time) it's highly likely that DNA already exists outside Earth.
Somewhere. Has it "learned" how to self-replicate? Of course. It's "what DNA does".
Has it evolved into life as we know it? Now that's the question. It's all a matter of opportunity, time and chance.
The universe has lots of time to break down those ingredients. Current researchers have basically all admitted that DNA can't form, or do anything useful if formed, in the "primordial soup." That leads them to hypothesize that perhaps RNA was first. Same problem. Now they hypothesize that possibly RNPs were first (see Cech, T. R. 2009. Crawling Out of the RNA World. Cell. 136 (4): 599-602.). Same problem, especially when considered with the probabilities I posted earlier of a simple protein forming (1 in 1 with 75 zeros).
Most are now on the crystal theory bandwagon referred to in my latest post. Eventually the likelihood of that will settle in and they'll start looking for something else.
In other words, we lucked out that there's life on earth and you're more likely to win that $1.4 billion powerball about a million times in a row than to find life anywhere else.
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Lorenzo
Trad climber
Portland Oregon
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Jan 12, 2016 - 09:56am PT
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Pu238 is the fuel for deep space flight... though it has a finite decay time...
Good point. The half life is something like 88 years, and a pile will produce less energy over time. The Pu 238 on Voyager is expected to stop producing useful energy in about 2025, so if it will turn into V-Jer, it will have to start soon.
The 125 watts on Curiosity will be down to 100 watts in about 14 years from landing.
And one of those chunks isn't totally benign. It's refined to about 85% Pu 238 with most of the rest being 239. The 238 is excellent shielding for the 239 present, but I wouldn't sleep with it for warmth. They do shield it with a graphite jacket. The first element Pu 238 breaks down into is U 234.
I don't wear my dad's radium dial watch, either.
We did sent a reactor into space in 1965 (SNAP 10A) it lasted 43 days before component failure caused it to go dead.
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climbski2
Mountain climber
Anchorage AK, Reno NV
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Jan 12, 2016 - 10:41am PT
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Those plutonium reactors for use in space are not very efficient though. (like the one Tom Frost helped the CIA try to instal) Just simple direct heat transfer systems.
Need a much better reactor for colonization. Hotter I would think. Something more like what is in our nuclear subs perhaps. But then it gets pretty heavy..which causes significant issues for space travel.
Interesting problems.
Someone mentioned life in the universe.. Hard to imagine we are a singularity. Wanna talk about winning a lottery? that's just ridiculous.
Even if I cannot fathom how Ribosomes and tRNA happened or what it's precursor would have been.
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Lorenzo
Trad climber
Portland Oregon
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Jan 12, 2016 - 10:57am PT
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Those plutonium reactors for use in space are not very efficient though. (like the one Tom Frost helped the CIA try to instal) Just simple direct heat transfer systems.
The computed energy available is currently about .54 watts per gram. There is an effort to quadruple that with better semiconductors. And the energy decreases at .787% per year.
Here are some units the Soviets had in the Arctic to power lighthouses.
Energy in space is for sure one of the biggest problems. I wish those guys in Utah would get cold fusion off the ground...
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limpingcrab
Trad climber
the middle of CA
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Jan 12, 2016 - 11:33am PT
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Someone mentioned life in the universe.. Hard to imagine we are a singularity. Wanna talk about winning a lottery? that's just ridiculous.
Why? So many people seem to think there's life elsewhere but few want to really consider the likelihood.
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climbski2
Mountain climber
Anchorage AK, Reno NV
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Jan 12, 2016 - 11:46am PT
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I seem to recall this question/discussion regarding planets around other stars and do black holes exist? Glad I have been around long enough to see a few of these things answered.
With a little investment in better radio receivers we just might get the life thing answered in my lifetime. I would be much more shocked if there is not than if there is.
Of course no one knows..it's just speculation. Unless you want to invest seriously in getting the question answered.
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Norton
Social climber
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Jan 12, 2016 - 12:03pm PT
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Why? So many people seem to think there's life elsewhere but few want to really consider the likelihood.
Limpingcrab, I read your probability of life post with particular interest
can you expand some more on how life on earth started/differs in comparison ?
habitable zone.....
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jonnyrig
climber
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Jan 12, 2016 - 02:00pm PT
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If there is life off earth, and if it has developed at a similar pace as us, then we are all still in the relative dark ages when it comes to space travel and communications. To effectively communicate anything with an alien race either they would have to have broadcast a few hundred years ago, or our technology would need improvement. Either way, we,d either terrify them or be their future target. Maybe both.
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Dingus McGee
Social climber
Where Safety trumps Leaving No Trace
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Jan 12, 2016 - 04:53pm PT
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Ed,
I am not actually talking about thick skin, but hinting at the cell membrane of one celled animals. Are you going to say no effect here with alpha particles hitting their cell wall membrane? A skin layer, maybe a thousand times thicker?
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Ed Hartouni
Trad climber
Livermore, CA
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Jan 12, 2016 - 06:54pm PT
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do the math Dingus...
how thick is skin (this includes stuff that isn't living anymore)?
and what is the range of a 5.6 MeV alpha particle (the maximum energy)?
it's about 40 microns... the epidermis of a thin-skinned person is about 100 to 150 microns...
so those alphas are pretty much gone before they get to any live cells...
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rbord
Boulder climber
atlanta
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Jan 12, 2016 - 07:06pm PT
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No let's spend our time calculating the likelihood of life on other planets using whatever Incompletely incomplete information we have and then convince ourselves that really our conclusions are spot on because you know we have all of this information and what better use might we make of our time given this incomplete information which we're sure is just really almost complete information right? so we'd better spend our time contemplating that rather than Donald's wacky facial expressions, I mean, shouldn't we? Yes definitely, it is so, and when we look around at we humans, that's we do. Or not.
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rick sumner
Trad climber
reno, nevada/ wasilla alaska
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Jan 12, 2016 - 07:45pm PT
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We live around a typical star with, and as we are finding out, a pretty typical planetary makeup. So why do some of you think yourselves and the evolution of life on earth are so damn special?
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jonnyrig
climber
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Jan 12, 2016 - 07:48pm PT
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No let's spend our time calculating the likelihood of life on other planets using whatever Incompletely incomplete information we have and then convince ourselves that really our conclusions are spot on because you know we have all of this information and what better use might we make of our time given this incomplete information which we're sure is just really almost complete information right? so we'd better spend our time contemplating that rather than Donald's wacky facial expressions, I mean, shouldn't we? Yes definitely, it is so, and when we look around at we humans, that's we do. Or not.
As opposed to posting on the internet?
If we are the pinnacle of life in the universe, well.... sh#t.
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Lorenzo
Trad climber
Portland Oregon
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Jan 12, 2016 - 08:02pm PT
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Ed,
I am not actually talking about thick skin, but hinting at the cell membrane of one celled animals. Are you going to say no effect here with alpha particles hitting their cell wall membrane? A skin layer, maybe a thousand times thicker?
I'm pretty sure we won't be overly concerned about single cell animals, except perhaps to keep them in check on a Mars Colony. And anyway, just putting the pile outside solves that issue. The one on Curiosity is a separate box attached to the vehicle. The Apollo 14 mission just dumped it on the ground. They have to be placed where they can dump their heat for the peltier effect to work. Eventually the Alpha particles attract electrons and become Helium. That's how Rutherford proved what they were.
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Mike Bolte
Trad climber
Planet Earth
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Jan 12, 2016 - 08:58pm PT
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Hi Rick:
We live around a typical star with, and as we are finding out, a pretty typical planetary makeup. So why do some of you think yourselves and the evolution of life on earth are so damn special?
I agree with your sentiment here completely, but just to be accurate, with all the planet systems we have discovered in the last 10 years, it is clear that the Solar System is not even close to typical. This is one of the reasons we were slow to discover extra-solar planets. We were looking for solar system analogues.
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limpingcrab
Trad climber
the middle of CA
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Jan 12, 2016 - 09:12pm PT
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Limpingcrab, I read your probability of life post with particular interest
can you expand some more on how life on earth started/differs in comparison ?
I wish I knew. I try to keep up on the subject and it's a cycle of one group mathematically and chemically disproving the previous hypothesis in favor of their own, only to be disproven by the next. In the words of one of my undergrad evolution professors, "the beginning of life is a fascinating topic because there are so many contradictions in the research." One way of saying that it's so unlikely that we haven't even gotten close to figuring out how it could happen, much less taking it for granted that it happened elsewhere.
With a little investment in better radio receivers we just might get the life thing answered in my lifetime. I would be much more shocked if there is not than if there is.
It might be wise to consider the odds of life developing elsewhere before we invest millions/billions in trying to detect it.
We live around a typical star with, and as we are finding out, a pretty typical planetary makeup. So why do some of you think yourselves and the evolution of life on earth are so damn special?
If I won the lottery a million times in a row I would think that was pretty special and I wouldn't necessarily expect to meet other people with the same experience.
I just think with the info we have now it would be wise to spend time/money solving problems on earth or looking into space travel and resources rather than banking on finding life elsewhere. It's math, though ambiguous, still based on math. Might be wrong, I often am, but from what I've learned in my short time I think we'll need many more than a billion planets to have any hope of finding life.
PS: reading what you guys write about the physics of space travel and energy is fascinating. I started out hoping to be a physicist and wish I had the mind and time to also follow that topic closely. Keep it going!
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