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Astronomy and Biology
They meet in Mars exploration.
Since quite a time, humans are roving the planet, "looking for life". Sadly, I think that this is not the case. Biology has taken the smallest part of exploration, with Geology getting the headlines. There are no specific sensors looking for life in those machines (there isn't even a microscope), and all information comes from side effects of other observations. Anyway, it is better than nothing of course. Life has metabolism, and the effects of that metabolism are gases that are produced as side effects of being alive. Methane is one such a gas. Methane is detected regularly in Mars and has a seasonal pattern. Curiosity, the U.S. rover wandering around in Mars, detected a spike in methane concentration that surpassed greatly the almost inexistent background concentration of that gas. Did the rover turn around and return to the hot spot to investigate this matter? No. It just went on wandering around. Two peer reviewed journals publish articles from micro-biologists that identify fossils in the ground. Did the rover turn around and investigate what really those things are? No, it just keep on going, wandering about. In desperation I wrote in an ISS astronaut's web site a letter to him. Please Sir, can you tell anybody to turn those rovers around and investigate that? Never got any answer. NASA is driving those rovers, and it is not looking for any life. A Viking lander engineer remarked that the rock in front of the camera changed color in spring. Spectral analysis gave similar spectra to lichens. Magnetite is found in Mars meteorites, photographs of small worms are published, etc. Humans have acquired a lot of data, but no conclusions are drawn. Life in Mars exists, and it is very similar to earth life. Is this a new planetary genesis? Or both Mars and Earth life have a common origin? We will get an answer to this question when we examine the genetic code of Mars life. If it is the same code, odds are high that it is a common origin. If the code used is different, the common origin becomes more improbable. Farther away we have the biggest ocean of the solar system in Europa. Colored, red material is detectable in the surface. We know that life can thrive in total darkness, as sea floor bacterial communities testimony here on earth. In all those places, we could find life as we know it, since the temperatures are mostly earth like. Titan, however, is much more a challenge for life. Methane is there in BIG quantities, and there is a very complex organic chemistry happening in the atmosphe an orange haze that clouds the whole satellite. There is a fluid cycle, with lakes of methane and ethane, rivers, rain, etc, at around -200 Celsius. That would be life as we do not know it. Water is rock solid at those temperatures, and methane and ethane are the universal solvents. Recently, researchers proved that a membrane can be constructed in those solutions. Those beings would be radically different from us. Life as we do not know it. Farther away we have evidence of molecular clouds with complex organic compounds. Organic molecules are discovered in huge quantities. OK. Microbes. But aliens? Intelligent beings? Life can evolve intelligence, symbolic language, and even astronomy. We are the product of natural evolution. Physical laws are the same here and elsewhere. There are billions and billions of planets in our galaxy. Why aren't "they" talking to us? Where is everybody? said von Neuman. Well, in any case they do not use radio waves, why should they? Neutrinos are much better for communications since they aren't deflected by matter as photons are. But we are unable to listen to anything using neutrinos, so we do not hear anything. Scientific work implies a belief. This sounds preposterous but it is at the base of every scientific observation. You make the hypothesis that this or that phenomena exist, and you try to figure out and measure the consequences. To find something, you have to believe it exists. For instance dark matter. Many astronomers believe this thing exists and they try (with no success so far) to measure a consequence of that hypothetical object. We have to get to the same level when looking for alien life. If you are convinced that it doesn't exist, you will never find it. |
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Astronomy and Biology
jacobnavia
They meet in Mars exploration. Since quite a time, humans are roving the planet, "looking for life". Sadly, I think that this is not the case. Biology has taken the smallest part of exploration, with Geology getting the headlines. There are no specific sensors looking for life in those machines (there isn't even a microscope), and all information comes from side effects of other observations. I believe there is a specific bio test being performed right now. Anyway, it is better than nothing of course. Life has metabolism, and the effects of that metabolism are gases that are produced as side effects of being alive. Methane is one such a gas. Methane is detected regularly in Mars and has a seasonal pattern. Curiosity, the U.S. rover wandering around in Mars, detected a spike in methane concentration that surpassed greatly the almost inexistent background concentration of that gas. There is ample evidence for abiotic methane. This has been suspected for quite some time. I believe first proposed by Soviet Geologists in the 1950's. Here's a link to a new open access paper detailing a process for abiotic methane. /https://www.nature.com/articles/ncomms14134 |
#3
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Astronomy and Biology
Le 10/01/2018 =C3=A0 22:09, brad a =C3=A9crit=C2=A0:
There is ample evidence for abiotic methane. This has been suspected for quite some time. I believe first proposed by Soviet Geologists in the 1950's. Here's a link to a new open access paper detailing a process for abiotic methane. /https://www.nature.com/articles/ncomms14134 1) The process of abiotic methane production occurs at great depth and pressures on earth. Earth has tectonic plate movements, Mars doesn't. Since in Mars everything is fixed since aeons, this process should have finished long ago. 2) Why would an abiotic process have seasonal variations? 3) An abiotic process would yield a fixed methane concentration in the planet, what is not observed. [[Mod. note -- Volcanos are an abiotic phenomenon which can lots of methane, with amounts varying across time/space. I (myself) don't know if we (the scientific community) know enough about Martian "geology" (areology??) to rule out current (ongoing) subduction and/or volcanism. Another abiotic process would be solar heating causing underground deposits to melt/vaporize/sublimate. We'd expect this to vary seasonally. -- jt]] |
#4
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Astronomy and Biology
In article ,
jacobnavia writes: There are no specific sensors looking for life in [Mars rovers] (there isn't even a microscope), [[Mod. note -- Some experiments specifically designed to look for life were landed on Mars in 1976. They found some surprising chemistry, but no unambiguous evidence of life: https://en.wikipedia.org/wiki/Viking_program The underlying engineering problem is that while detecting macroscopic life is fairly easy (take pictures of it), detecting *microscopic* life requires fairly heavy/bulky equipment which is normally designed to be operated directly by skilled humans. So doing this by remote control from 45 light-minutes away (and with zero ability for a human to fix anything that doesn't work) is hard, i.e., difficult to develop and make work properly. That difficulty means lots and lots of engineering person-years to develop the mission, which makes the mission very expensive (on a scale of planetary-science budgets). Given a budget of (say) 5e9 {US$,Euro}/year, one could do some very sophisticated searches for life on Mars. But the actual worldwide budget for all Martian exploration is well under 0.5e-9 {US$,Euro}/year, so progress is slow. And despite what optimists like Zubrin/Musk might say, sending (living) humans to Mars wouldn't be cheap, either. -- jt]] There's no high-magnification microscope, probably because preparing samples for one would have required complex and heavy instrumentation. MAHLI has a resolution of around 25 microns https://msl-scicorner.jpl.nasa.gov/Instruments/MAHLI/ but I don't know how useful it has been in practice. Life has metabolism, and the effects of that metabolism are gases that are produced as side effects of being alive. Methane is one such a gas. I wouldn't mind seeing a chiral labeled release experiment sent to Mars, but so far it hasn't ranked high enough in the priority lists. In desperation I wrote in an ISS astronaut's web site a letter to him. The human spaceflight program is quite separate from the planetary science program. See nasa.gov for contact addresses for the latter. Even for human spaceflight, the astronauts do not make policy, though they certainly influence it. Where is everybody? said von Neuman. Fermi. The Fermi Paradox is a good argument against intelligent extraterrestrial life, though it is far from conclusive. Well, in any case they do not use radio waves, why should they? Neutrinos are much better for communications since they aren't deflected by matter as photons are. Neutrinos are hard to detect. You might want to compare the respective energy requiremets. To find something, you have to believe it exists. Yes, that's why Galileo never found sunspots or the moons of Jupiter: he had no pre-existing conception that they existed. ... Oh, wait... For instance dark matter. No doubt Fritz Zwicky found dark matter only because he believed it existed and was looking for it. Actually, the history is the other way around: astronomers were unwilling to accept dark matter -- despite strong evidence -- until the evidence became overwhelming. Many astronomers believe this thing exists and they try (with no success so far) to measure a consequence of that hypothetical object. Galaxy cluster velocity dispersions? Galaxy rotation curves? Microwave background fluctuations? Gravitational lensing? Dwarf galaxy velocity dispersions? We have to get to the same level when looking for alien life. If you are convinced that it doesn't exist, you will never find it. I don't think anyone -- perhaps barring a few cranks -- is convinced extraterrestrial life doesn't exist. There are active searches in progress and more planned for the future. What priority to give potential searches, in comparison to other projects competing for funding, is a difficult judgment question. -- Help keep our newsgroup healthy; please don't feed the trolls. Steve Willner Phone 617-495-7123 Cambridge, MA 02138 USA |
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Astronomy and Biology
On 12/01/2018 11:27, Steve Willner wrote:
In article , jacobnavia writes: There are no specific sensors looking for life in [Mars rovers] (there isn't even a microscope), [[Mod. note -- Some experiments specifically designed to look for life were landed on Mars in 1976. They found some surprising chemistry, but no unambiguous evidence of life: https://en.wikipedia.org/wiki/Viking_program The underlying engineering problem is that while detecting macroscopic life is fairly easy (take pictures of it), detecting *microscopic* life requires fairly heavy/bulky equipment which is normally designed to be operated directly by skilled humans. So doing this by remote control from 45 light-minutes away (and with zero ability for a human to fix anything that doesn't work) is hard, i.e., difficult to develop and make work properly. That difficulty means lots and lots of engineering person-years to develop the mission, which makes the mission very expensive (on a scale of planetary-science budgets). I thought there was a project underway to send a small stable isotope mass spectrometer to look for any variation of deltaC13 or deltaS34 in the rocks that would be indicative of life. Life preferentially concentrates the lighter isotopes making inorganic materials have a higher concentration of the heavier isotopes. eg. https://ntrs.nasa.gov/archive/nasa/c...9890016972.pdf The challenge is making one that can survive the stresses of launch without being to heavy and do its own sample prep. Increasing AI power will make it possible sooner rather than later but I expect there may be a few disappointments along the way. Mars with its very thin atmosphere is particularly hard to do a soft landing on. Some of the historic articles about what the Viking mission achieved with its mass spectrometers is online at: http://onlinelibrary.wiley.com/doi/10.1002/jms.396/full Given a budget of (say) 5e9 {US$,Euro}/year, one could do some very sophisticated searches for life on Mars. But the actual worldwide budget for all Martian exploration is well under 0.5e-9 {US$,Euro}/year, so progress is slow. And despite what optimists like Zubrin/Musk might say, sending (living) humans to Mars wouldn't be cheap, either. -- jt]] Sending humans to Mars would be more like "Big Brother" with teeth. You would also have to send a substantial robotic automated medical facility there to give them rehab when they arrived. Easier, cheaper and much less risky all around to send smart autonomous robust robotic probes. Life has metabolism, and the effects of that metabolism are gases that are produced as side effects of being alive. Methane is one such a gas. I wouldn't mind seeing a chiral labeled release experiment sent to Mars, but so far it hasn't ranked high enough in the priority lists. I think there were plans to send something using stable isotope labelled likely foods and look for the characteristic signs of life in the waste gasses. The challenge is as ever in distinguishing between inorganic peroxide soil reactions and actual life metabolic processes. The idea was that the observed isotope ratios would be different. It would be extremely exciting to find independent life evolved anywhere else in the solar system - although we need to take great care not to contaminate pristine planetary environments with our own form of life. ISTR some bacteria on the lunar lander Surveyor 3 that Apollo 12 visited were still viable after 3 years on the moon. https://science.nasa.gov/science-new.../ast01sep98_1/ -- Regards, Martin Brown |
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Astronomy and Biology
Le 07/01/2018 à 16:52, jacobnavia a écrit :
We have to get to the same level when looking for alien life. If you are convinced that it doesn't exist, you will never find it. The answers I got weren't really satisfying. Why can't that dammed rover turn around and look if there is anything breathing in the soil? I said: To find something, you have to believe it exists. Steve answered: Yes, that's why Galileo never found sunspots or the moons of Jupiter: he had no pre-existing conception that they existed. ... Oh, wait... Look, he did not look away when they appeared before his eyes. The problem with Mars life is that we do not look for it and our rover goes on. No further investigation is needed, humans look away. In another post, Brad answered: There is ample evidence for abiotic methane. This has been suspected for quite some time. I believe first proposed by Soviet Geologists in the 1950's. Here's a link to a new open access paper detailing a process for abiotic methane. /https://www.nature.com/articles/ncomms14134 Of course, it could be abiotic methane. But isn't worth investigating that? Why would abiotic methane, produced at great depths and temperatures here on earth as that paper explains, have a seasonal appearence? In spring... that looks suspicious to me. If it is abiotic it would be at least an answer. But it is not deemed necessary just to investigate! We just look away. |
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Astronomy and Biology
[[Mod. note -- This article arrived in my moderation inbox with the
quoting a little bit confused. I have fixed this up by hand editing. I apologise if I've mistakenly misattributed anyone's words to someone else. -- jt]] jacobnavia wrote: The answers I got weren't really satisfying. In another post, Brad answered: There is ample evidence for abiotic methane. This has been suspected for quite some time. I believe first proposed by Soviet Geologists in the 1950's. Here's a link to a new open access paper detailing a process for abiotic methane. /https://www.nature.com/articles/ncomms14134 Of course, it could be abiotic methane. But isn't worth investigating that? Why would abiotic methane, produced at great depths and temperatures here on earth as that paper explains, have a seasonal appearence? In spring... that looks suspicious to me. If it is abiotic it would be at least an answer. But it is not deemed necessary just to investigate! We just look away. I guess my response is obscure. So I'll elucidate. The Curiosity rover is designed to look for signs of life. Specifically methane. Your post seemed to imply that biogenic methane was the only type. So I offered a link to a paper on abiogenesis. So why is it relevant? Because ultra mafics on earth are deep but, on Mars they are on the surface. Basalt. As evidenced by only shield volcanoes on Mars. The surface of mars is basalt, whereas, basalt underlies oceans or continents on earth. So it seemed reasonable to look for near surface processes near volcanoes on Mars, and where any exposed carbonates may be present. An impact crater near a volcanic province. That's where it is. ie: look for water, basalt, some source of carbon and assume shallow genesis. Serpentinization (water reacting with basalt) releases (at low ~100C temp)H2 which in turn reacts with CO2 associated with hydrothermal intrusions associated with volcanism. In any endeavor one must first develop a plan of action. Then that plan must be followed. Any deviation obscures the results and adds chaos more than any perceived temporary gain. That rover carries instrumentation to do exactly what you want. My opinion, let them follow their plan. My understanding is the 2020 rover will have the instrumentation to detect the C12/C13 ratio in the methane to give a more definitive answer to the type being released. See here. http://exploration.esa.int/mars/46038-methane-on-mars/ Sorry for my original disjointed post. Brad |
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Astronomy and Biology
In article ,
Martin Brown writes: I thought there was a project underway to send a small stable isotope mass spectrometer to look for any variation of deltaC13 or deltaS34 in the rocks that would be indicative of life. Life preferentially concentrates the lighter isotopes making inorganic materials have a higher concentration of the heavier isotopes. eg. https://ntrs.nasa.gov/archive/nasa/c...9890016972.pdf Distinguishing between life and abiotic chemistry is the reason for doing _chiral_ labeled release. Life should prefer one enantiomer over the other, while abiotic processes should show little or no preference. Anybody know when or why 'stereoisomers' became 'enantiomers'? -- Help keep our newsgroup healthy; please don't feed the trolls. Steve Willner Phone 617-495-7123 Cambridge, MA 02138 USA |
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Astronomy and Biology
[[Mod. note -- My apologies for the delay in processing this article;
which arrived in my moderation inbox on 2018-01-19. -- jt]] On 17/01/2018 22:59, Steve Willner wrote: In article , Martin Brown writes: I thought there was a project underway to send a small stable isotope mass spectrometer to look for any variation of deltaC13 or deltaS34 in the rocks that would be indicative of life. Life preferentially concentrates the lighter isotopes making inorganic materials have a higher concentration of the heavier isotopes. eg. https://ntrs.nasa.gov/archive/nasa/c...9890016972.pdf Distinguishing between life and abiotic chemistry is the reason for doing _chiral_ labeled release. Life should prefer one enantiomer over the other, while abiotic processes should show little or no preference. Not sure you need to use chiral labelled reagents. You could feed the critters a racemic mixture and then measure any change in the angle of rotation of plane polarised light if there was any difference in the rate of reaction for the two forms. I suspect there may well be some abiotic reactions on clay surfaces that do show a preference for handedness if that is how life got started. Anybody know when or why 'stereoisomers' became 'enantiomers'? They were called D and L optical isomers first because of the effect their solutions had on rotating plane polarised light. Essentially materials with the same chemistry but different effect on light. Some crystals, sugars and naturally occurring amino acids solutions first observed to do this in 1813 by Biot and explained in 1874 by Hoff as being due to an asymmetric tetrahedral carbon atom in the molecule. I think the preferred names are down to IUPAC. Enantiomers are strictly non superposable mirror images of each other whilst (dia)stereoisomers can include other things as well. http://goldbook.iupac.org/html/D/D01679.html Still chiral molecules but not related as exact mirror images. -- Regards, Martin Brown |
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Astronomy and Biology
[I thought I'd replied before, but it seems not to have gotten
through. Apologies if it shows up twice.] [[Mod. note -- I don't recall seeing it. -- jt]] In article , Martin Brown writes: Not sure you need to use chiral labelled reagents. You could feed the critters a racemic mixture and then measure any change in the angle of rotation of plane polarised light if there was any difference in the rate of reaction for the two forms. Sorry, but I can't visualize how that would work. What would be needed to prepare the sample? Viking had a labeled release experiment (which showed positive results based on pre-flight criteria), and a similar experiment with chiral reagents should be only a little more complex. I suspect there may well be some abiotic reactions on clay surfaces that do show a preference for handedness if that is how life got started. Have those been seen anywhere? I think the preferred names are down to IUPAC. Enantiomers are strictly non superposable mirror images of each other whilst (dia)stereoisomers can include other things as well. http://goldbook.iupac.org/html/D/D01679.html Still chiral molecules but not related as exact mirror images. Thanks! As far as I can tell, "stereoisomers" is the general term, which includes both enantiomers and diastereoisomers. The latter have more than one stereocenter and are mirror images in some but not all. I've learned something. -- Help keep our newsgroup healthy; please don't feed the trolls. Steve Willner Phone 617-495-7123 Cambridge, MA 02138 USA |
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