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Brokedownclimber
Trad climber
Douglas, WY
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Feb 13, 2016 - 07:28pm PT
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I've stated my thoughts on Panspermia, but what tests can we think of for confirmation, should we find "life" elsewhere--in a recognizable form? There are a couple thing which are possible: optical activity of classes of compounds, both amino acids (proteins) and carbohydrates. All living forms of life we know of on Earth are L-amino acid based, and D-carbohydrate based. If we find a life form which exhibits the same optical rotatory properties as our L & D configurations, that's supportive of the Panspermia concept but not conclusive; it's a necessity, but not a sufficiency. There are actually four combinations possible: L & D as we have on Earth, then the possibilities of L & L, D & L, then D & D. So--if we find another life form elsewhere with one of the other isomeric configuration pairs, it definitely argues AGAINST Panspermia.
Just for those not technically aware of what I'm talking about: L stands for Levorotatory, and D stands for Dextrorotatory. It takes a device known as a Polarimeter to do these measurements.
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High Fructose Corn Spirit
Gym climber
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Feb 13, 2016 - 07:49pm PT
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bdc, tfpu the zubrin video, I'm half way through, hope to get the rest tonight. It's very good, apparently he delivers an inspiring subspeech toward the end. I look forward to it.
Folks here by and large don't know about enantiomers. No sense playing to an audience you don't have?
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Brokedownclimber
Trad climber
Douglas, WY
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Feb 13, 2016 - 08:01pm PT
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HFCS-
Yeah--I try to simplify the concept as much as possible, but you're right. I'm not much of a statistician, though. I'm curious as to how many "samples," that's to say, different new life forms discovered to get a 95 % confidence level that Panspermia would be validated?
My strong suit was always experimental design and execution.
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jstan
climber
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Feb 13, 2016 - 09:02pm PT
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Could you answer those questions first, before we speculate some more?
1. Did life start in one place?
1a. Was it a a comet or a bigger body?
2. Was it cellular, or just a precursor of life (DNA, RNA, peptides, something else)?
3. How did/does it propagate? Be specific, please.
1. Maybe. Maybe not.
1a. That's a definte possibility.
2. Yes.
3. ST rules prevent us from talking about this here.
Moose: I thought your questions excellent and that they deserved an answer.
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WBraun
climber
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Feb 13, 2016 - 09:20pm PT
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Life was never ever started.
It was always already there.
Only the material machines to put life into where started because they are fools number one and want to lord it over and be independent.
Thus the were given this material creation to suffer in.
They spend every waking moment in illusion fighting off suffering and trying to enjoy.
Now they are suffering so badly from their foolish past karmic actions they think going to other planets will help.
Stoopid gross materialists can't get no respect ......
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Brokedownclimber
Trad climber
Douglas, WY
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Feb 13, 2016 - 09:52pm PT
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Moose really got right down to the nitty gritty questions, didn't he?
The easy way out is to simply feign ignorance, which is actually the REAL answer.
The concept of Panspermia is life creation took place once and was then spread throughout the galaxy by debris from the source planet being destroyed. I personally think it would arise on a planetary surface and not a comet. Temperature and basic components both lacking.
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Ed Hartouni
Trad climber
Livermore, CA
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Feb 13, 2016 - 10:25pm PT
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Will someone please explain why you disagree and suspect life to be scattered across the universe? Sorry, I just don't get it.
there is a concept called "naturalness" in physics
http://en.wikipedia.org/wiki/Naturalness_(physics);
in the case of life, if it is highly unlikely, then we wouldn't be here. For us to be here in that case would require a degree of "fine tuning" that is improbable (or perhaps impossible) in a physical system.
so given that we are here, life cannot be so uncommon that our existence is improbable.
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Brokedownclimber
Trad climber
Douglas, WY
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Feb 14, 2016 - 08:13am PT
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Moose-
I neglected to address one of your questions, re: was it first by synthesis of components (amino acids, DNA, RNA, Peptides, etc.) or did "living organisms spontaneously arise?"My take is it had to be synthesis of the building blocks first. Amino acids, then peptides and nucleic acids. Thus, the importance of Urey-Miller type experiments. I'm wondering about the true composition of the "junk" in the Urey-Miller reactor, and whether they had the thought to look for any diketopiperazines? Diketopiperazine itself is another "easy candidate" for formation from the starting components utilized, and partial hydrolysis (rupture of one bond internally) leads to glycyl-glycine. Ta Da! Dipeptide.
I sure wish I weren't retired without access to a laboratory, at times! I may need to resurrect my ancient laptop with my Chemdraw Program, to make a few illustrations for others to follow my thoughts here.
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Brokedownclimber
Trad climber
Douglas, WY
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Feb 14, 2016 - 08:40am PT
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I just did a Google search on the Urey-Miller experiment, and the above comment (Limpingcrab) that "the results have been discredited." That appears to be a creationist wishful thinking, wet dream. Apparently, re-analysis of the original Miller samples using newer instrumentation than that available in the 1950s, when the experiments were carried out, has revealed even more amino acids and other complex organic compounds than reported. Redesign of the experiments with lower oxygen levels and introduction of Sulfur or Sulfur compounds (note one of my earlier posts suggesting this!), has yielded even more encouraging results. For me to further comment on this topic professionally, I need to get some of the original papers and subsequent journal articles. The idea now involves oceanic volcanic vents as possible sources of the reactions leading to life. Stand by for a later update!
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WBraun
climber
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Feb 14, 2016 - 08:42am PT
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Life comes from life and never comes from matter .......
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Brokedownclimber
Trad climber
Douglas, WY
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Feb 14, 2016 - 09:48am PT
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Moose-
That's a fair summary of the basics.
Back to the Urey-Miller experiments. The major group crowing that the Urey-Miller experiment has been "discredited" are generally extreme creationists. Nothing has been discredited, other than perhaps the incorrect choice of presumed conditions. The experiment is still under investigation by none other than Distinguished Professor Jeffrey L. Bada at UCSD. Considering the original experiments were done in 1952, the analytical tools available were primitive. Bada also was given Miller's original sample vials from the experiments, which under re-analysis by modern instrumentation, revealed 30 different compounds synthesized, instead of the 13 different amino acids found by Miller. Bada is tossing in some Sulfur to the mixture. I haven't progressed beyond the following report: http://www.chemheritage.org/about/news-and-press/chf-in-the-media/2010-7-1-weapos;re-history-back-to-the-future.
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High Fructose Corn Spirit
Gym climber
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Feb 14, 2016 - 10:10am PT
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Here's the four min clip from the Robert Zubrin piece bdc posted in response to 'Why?'
He had me at hello.
Actually he had me at the science, the challenge and at 1492...
[Click to View YouTube Video]
http://youtube/yRVEd1q2cS4
"They will remember what we do to make their civilization possible." R. Zubrin
In the words of our beloved Jeb...
Please clap.
We go to Mars (1) for the science, (2) for the challenge, (3) for the future.
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Brokedownclimber
Trad climber
Douglas, WY
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Feb 14, 2016 - 10:16am PT
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BITD, when the Urey-Miller experiments were done (1952), Watson and Crick had not yet published the papers on the Double Helix, and very little thought was given to Nucleic Acid chemistry. The analytical tools were just not available then, either. But you are indeed correct, in that strands of RNA are fundamental to this chemistry. So...we're back to a chicken or the egg situation, as to which came first. Amino acid chemistry is considerably easier to do than nucleic acid work, so the amino acid studies came first. Having viable strands of RNA are the key to replication, one of the major keys--if not the main key--to origins of life.
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Ed Hartouni
Trad climber
Livermore, CA
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Feb 14, 2016 - 11:15am PT
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We go to Mars (1) for the science, (2) for the challenge, (3) for the future.
there is better science to be done without sending a person... I think it is disingenuous to continue to make that particular claim. The science boards that advise NASA all believe that and the record of science on manned space flights supports the case that little science (outside of human physiological response to space flight) has been accomplished that couldn't have been done, much better, on an unmanned mission (challenge to proponents: name one).
The ISS is pretty much a disaster for science, imagine Pig Pen circling in LEO... plus all the vibrations, the heating, the maneuvering, etc... basically the science packages are in a compromised setting to accommodate the humans.
manned spaceflight is all about (2) above...
Columbus did not sail to do science. He sailed for economic gain, and was supported by the possibility of political gain. The US space program was launched mainly for political gain.
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Brokedownclimber
Trad climber
Douglas, WY
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Feb 14, 2016 - 11:35am PT
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I would agree with Ed on one of his above points: the ISS has been an enormous waste to NASA's (and our) money. The description as a "floating Pig Pen" is probably correct. Hell, I know it's correct; nothing of any scientific value has come from it. But...I DO know that a robotic golfer could not have done any better than Al Shepard at hitting a golf ball on the lunar surface...
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Ed Hartouni
Trad climber
Livermore, CA
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Feb 14, 2016 - 11:47am PT
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Interesting to contemplate the history of life on planet Earth...
teasing evidence of the earliest possible indication, read this article:
Potentially biogenic carbon preserved in a 4.1 billion-year-old zircon
"We report ¹²C/¹³C of graphite preserved in 4.1-Ga zircon. Its complete encasement in crack-free, undisturbed zircon demonstrates that it is not contamination from more recent geologic processes. Its ¹²C-rich isotopic signature may be evidence for the origin of life on Earth by 4.1 Ga."
Interestingly, another way of dating early life is through genomic clocks...
A genomic timescale of prokaryote evolution: insights into the origin of methanogenesis, phototrophy, and the colonization of land
"Discussion
Origin of life on Earth
Neither the time for the origin of life, nor the divergence of archaebacteria and eubacteria, was estimated directly in this study. Nonetheless, one divergence within archaebacteria was estimated to be as old as 4.11 Ga (Node P), suggesting even earlier dates for the last common ancestor of living organisms and the origin of life. This is in agreement with previous molecular clock analyses using mostly different data sets and methodology [28,30]. A Hadean (4.5–4.0 Ga) origin for life on Earth is also consistent with the early establishment of a hydrosphere [31,53]."
and this interesting paper setting the scene for the history:
The habitat and nature of early life
Immediately after the Moon-forming impact, a rock vapour atmosphere would have formed. As this cooled it would have formed an optically thick layer of dust in the high atmosphere. After about 2,000 years, a rind would have begun to form on the magma ocean of the mantle, and for perhaps 2 million years surface temperatures lingered near 100°C, with a steam greenhouse, before beginning to cool. Bombardment on a lesser scale was ongoing, but gradually decaying. Until about 3.8 Gyr, the Earth would have suffered frequent massive meteorite impacts, some sufficiently large to heat the oceans to greater than 110°C, or even to the ~300° C needed to convert the whole ocean to steam. Impacting bodies of a diameter of 500 km or more would have been capable of vaporizing the ocean; bodies of 200 km could have heated it above 100°C. Impacts would have ejected huge quantities of debris, made of basalt or komatiite (a magnesium-rich lava). Planets are active, and the Earth’s ocean is not simply an unchanging puddle. Seawater chemistry would have been controlled by volcanism and by reaction with this debris, such that it is improbable that a long-lived global ‘primeval soup’ could have collected from impacts of organic-rich meteorites and comets.
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Brokedownclimber
Trad climber
Douglas, WY
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Feb 14, 2016 - 03:46pm PT
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Re: The Habitat and Early Nature of Life.
Sounds very erudite, but is also a bit simplistic. The huge amount of water brought by cometary impacts would result in a lot faster cooling than is implied in the referenced paper. Comets are thought of as 'dirty snowballs," but at cryogenic temperatures in their cores. This means I'm "throwing some cold water" on the paper. The research being done at UCSD is strong on the thermal vents in the oceans as possible sites of the necessary abiotic chemical synthesis of pre-biotic molecules.
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High Fructose Corn Spirit
Gym climber
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Feb 14, 2016 - 04:46pm PT
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"challenge to proponents: name one" -ed
Imagine the science we could do and what we could learn if we had a couple guys on Mars growing potatoes, corn, tomatoes, zucchini and rhubarb?
C'mon, where's your imagination today? Did you watch the Zubrin clip? How about the movie, The Martian? That film there is an excellent model that points the way to lots of potential Martian science.
And how about just the continuing science, inclu research and development, of humanity in a martian environment?
How many years of science of humanity in a martian environment do we have right now? Zero.
Why not wait till H sapiens has at least TEN years of science of humanity in a martian environment before dissing the prospects?
Think about it: no way could today's robots grow potatoes on Mars better - and no way could they conduct science on those potatoes growing on Mars better - than a couple guys (preferably a guy and girl, imo) living out of a hab.
and I'm not even a botanist.
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Brokedownclimber
Trad climber
Douglas, WY
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Feb 14, 2016 - 04:57pm PT
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One has to remember---Ed's a physicist, which is all about numbers. There's around 1.4x10^18 metric tons of water on the Earth, which is indeed a small percentage of the Earth's total mass, but comets have undoubtedly brought a lot more in the early stages which simply vaporized and escaped earth's gravity. Also, the mantle is only a few hundred miles thick with a still molten core. So...that puts my argument to bed on that issue. Enough water arrived with potentially organic precursors to life, or indeed, with bacteria spores present.
I'm in agreement with HFCS about the biological experiments on Mars, and running a deep drill rig s Zubrin suggested, is a lot more than a robotic system could ever hope to do, at least not under the weight restrictions of interplanetary travel. Knowing the number of guys I do in the oil patch, if robotics could work, they'd be doing it here instead of on Mars!
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