Help us improve our products. Sign up to take part. A Nature Research Journal. Our inventory of the molecular universe is continually progressing. Our understanding of the astrochemistry behind it will flourish if we are mindful of funding experimental and theoretical efforts as well as observational. Of the remaining 0.
All the other elements are squeezed into the remaining 0. These range in size from the first species ever discovered in space, methylidyne CH, in to the largest molecule thus far detected, C 70 , a buckyball in , and includes alcohols, primitive sugars, amino acids and more.
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The versatility of carbon in its chemical bonding drives the complexity of the chemistry in the Universe. In this October issue of Nature Astronomy , we announce a development in our knowledge of this chemical complexity. Consistently we are discovering new chemical species in space at the rate of four per year. However, here we reveal not only the detection of a new molecule, but also that this molecule is the first molecule in a new family of extraterrestrial molecules.
There are also hints in the ALMA data of a further organohalogen, fluoromethane. It is the circumstances in which chloromethane has been found that add interest to the situation: two separate detections, one around a forming star, and another in a comet in a mature planetary system, our own. It seems possible. The logical follow-up question to this is whether organic molecules can then be delivered intact by comets to terrestrial planets through impacts, and here there is still work to be done. However, the consequences are important because they may have implications for the development of life on early Earth.
When we think about organic molecules in space, and particularly prebiotic molecules such as amino acids and simple sugars, our thoughts inevitably turn towards the possibility of life in the wider Universe. The only known examples of life are found on our planet, but of course one of the big questions of our technological generation is whether we might detect signs of life elsewhere, and intelligent life in particular.
All of them were positive that life must exist elsewhere in the Universe: statistically it is extremely likely. There are many crucial factors that can play a role, though, among which coincidental timescales is perhaps the most staggering — as a race, will the fleetingly short period in cosmic history that belongs to us overlap with that of another race? Nevertheless, they are still an important part of the chemical cosmos.
Only discovering and examining possible martian life could answer this question with certainty.hostmaster.chodaugia.com.vn/any-way-you-want-it-an.php
Scientists measure half-life of element that’s longer than the age of the universe
There is now strong evidence that Europa harbors an ocean of liquid water beneath its extremely cold outermost layer of ice Figure 5. Data from the magnetometer on the Galileo spacecraft not only supports the existence of the ocean, but suggests that it is very salty and that the overlying ice may be only 10 kilometers thick, or even thinner. Could there be life in this ocean? Speculative studies suggest that the energy sources needed to support life should be present.
Abundance of the chemical elements
But whether the origin of life could have occurred in an ocean that was beneath kilometers of ice—so likely cutoff from sunlight—is an open question. It is much harder for Earth and Europa to successfully exchange microorganisms via meteorites than is the case for Earth and Mars, so if there is life on Europa, it is likely due to a separate origin from life on. But because of the liquid water ocean, Europa may be the most intriguing site for extraterrestrial life in our solar system. Still farther out from the Sun, the planet Saturn hosts at least two intriguing worlds.
Farther out from Saturn lies the Mercury-sized world Titan, with its dense atmosphere of nitrogen and methane. There is some evidence that Titan, too, may harbor a subsurface liquid water ocean. All of these worlds need much more exploration and should receive it later this century. Missions to the outer solar system take time the travel time to Jupiter is 3 years from Earth and are expensive. But a balanced program of solar system exploration, especially one emphasizing astrobiology, must systematically explore the Jovian and Saturnian systems as well as Mars.
An important issue in planetary exploration is planetary protection. It was Lederberg who, during the IGY in , wrote to the president of the National Academy of Sciences to raise this as an issue, and the Academy worked with the International Council of Scientific Unions to create an international study group on this question. The concern is scientifically well founded. The organisms freeze-dry, or lyophilize, in the cold vacuum, but when introduced to liquid water they revive. Most NASA Mars mission spacecraft are constructed in class, clean rooms, which means they have thousands of viable sporulating bacteria present per square meter of spacecraft surface, and probably ten or more times as many other types of bacteria.
Since it takes less than a year to get to Mars, this means that Mars spacecraft carry a viable bioload of microorganisms with them to the Red Planet. The first question becomes, then, whether any of these organisms could find their way from the martian surface into habitable niches with liquid water in the subsurface, and if so, whether they could grow in that new environment.
The odds are long, but not impossible. The second. Image EL A recent report that I chaired for the National Research Council NRC , Preventing the Forward Contamination of Mars , looked at these questions and concluded that NASA needs to better understand the numbers and types of microorganisms that currently fly on its spacecraft and take more stringent steps to reduce spacecraft bioload. The current international interpretation of the Outer Space Treaty requirement is that microorganisms carried to other planets must not be allowed to take hold on that world in a way that would render it difficult or impossible to determine if a truly alien biosphere might be present.
So far we have discussed in situ investigation of the solar system, in which spacecraft land on other bodies and conduct experiments at the surface to look for life. Closely related is the biological examination, in terrestrial laboratories, of samples from other worlds.
These samples could arrive on Earth in an uncontrolled way, via meteorites that originated as debris blown off another world by a big impact, or in a controlled way, as samples brought back by a dedicated spacecraft. But both cases involve hands-on investigations for the presence of life in the solar system. A third way to search for life is to examine the light coming from the atmospheres of other worlds—i. This has been done for Mars and other planets in our solar system for decades and has just become possible for certain giant exoplanets—planets in orbit around a star other than our Sun.
With the Kepler mission that will launch in the next few years, we should soon know the statistics of the presence of Earth-sized planets around other stars.
With knowledge of the stars, we will know which, if any, of these worlds lie in the right range of distances for liquid water oceans to be possible on their surfaces. This is an extraordinary moment. Humans have speculated for millennia about whether other planets like ours could exist—for example, Aristotle asked and answered, on theoretical grounds this question in his book On the Heavens. In a few years we will no longer have to speculate. We should not let human civilization sleepwalk through this remarkable transition in our knowledge about our place in the universe.
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Some decades further on we will be able to observe these planets from dedicated satellites in space, and determine the composition of their atmospheres. The hope is that we might detect some combination of gases in some atmospheres that equilibrium chemistry would seem to forbid, but which biology might just generate. This could imply that there are biospheres on these worlds. Or maybe not. The evidence would be circumstantial, and as soon as such data were reported, scientists would rightly, and conservatively, search for non-biological explanations.
Indeed, we have seen this already at Mars: it is now clear that the martian atmosphere, a highly oxidizing atmosphere flooded with ultraviolet light that should not permit organics to exist for long, contains patches of the simple organic molecule methane—at about the 10 parts per billion level. The methane must be produced by localized sources at the surface; it is well out of equilibrium with the existing atmosphere.
It could be the product of a martian version of the methanogenic bacteria we know on Earth. But already there have also been published papers suggesting explanations in terms of martian geochemistry. Atmospheric chemistry consistent with biological sources may provide hints of life, but it evidently it does not in itself provide decisive arguments for the existence of life. Besides the three techniques for searching for extraterrestrial life so far discussed—in situ investigations, examination of samples delivered to Earth, and remote sensing of planetary atmospheres—there is one other.
Chyba and Kevin P. This is the search for extraterrestrial intelligence or, rather, technology , or SETI. SETI need make no assumptions about the biochemical or other makeup of extraterrestrial life. It must, on the other hand, rely on the existence of technology capable of communicating across interstellar distances. Radio frequencies are the natural frequency to use for interstellar communications, because of the so-called microwave window where galactic background noise is lowest.
For each target star, Project Phoenix examined billions of frequencies. Algorithms assumed that the frequency would drift, as a real transmission certainly would due to the motion of the source of the transmission relative to Earth. To be a credible detection, any signal received had to stand up against multiple tests, including a check against all known confounding signals e. No source has ever passed through all of these filters. It is sometimes said that humanity has looked and looked and looked for extraterrestrial radio transmissions without finding any, so it must be that we are alone.
Superficially, this might seem to follow from the fact that SETI radio searches have been carried out since the first search was conducted by Frank Drake nearly 50 years ago. But in fact, even Project Phoenix has only scratched the surface. The nearly 1, stars it has searched account for just a ten-millionth of the stars in our galaxy.
This array will. Once completed, the ATA should examine around a million stars in a decade of observing. But even this will represent just a hundred-thousandth of the stars in our galaxy. If technical civilizations beaming signals across interstellar distances are more rare than one in every hundred thousand stars, even the ATA will not be successful anytime soon. But in the absence of any mature theory about the prevalence of intelligent life and technology, the search is the best that we can do.
Nevertheless, arguments have been put forward regarding the likelihood of extraterrestrial intelligence. On the face of it, this assertion also seems consistent with the Copernican principle, the idea that Earth has no unique status in the universe. But in fact, this line of reasoning does not hold up.
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The reason is that we do not know the probability of the origin of life, and then intelligence, and then technology, on an Earth-like world. If this probability were extremely small—say, less than one in a hundred billion—then Earth could be the only planet in the galaxy harboring an intelligent civilization. There could still be a hundred million other Earth-like worlds, but only one would have hit the jackpot. This would be like rolling six identical dice and having only one came up with a six. There is nothing special about that particular die; any one of them could have rolled a six but statistically most of them would not.
The Copernican principle is not violated, but Earth could still be unique. The Drake equation summarizes this way of looking at the problem. Obviously this equation is not an equation analogous to, say, the ideal gas law equation. The ideal gas law hypothesizes a relationship among the pressure, volume, and temperature of gases in the laboratory, so is subject to empirical test. The Drake equation does not pose this kind of testable hypothesis. Rather it is. But in fact, by breaking the calculation down into a product of numbers that may be estimated such as the population of Chicago, the number of people per family, the fraction of families that own pianos, how often pianos have to be tuned, and so on one can make a reasonable estimate of the correct answer.
But this can not be done with the Drake equation. L, in particular, moves us into the realm of extraterrestrial sociology and political science, which remain less developed fields. At its lower end it could be as short as the interval between, say, the invention of radio and the mass production of thermonuclear weapons; based on our experience, this interval could be as short as decades. The average value of L in the galaxy might well be anywhere in this interval, although even a small number of very long-lived civilizations could make the average quite long indeed.
In the face of the uncertainties the Drake equation reveals, the large-numbers argument cannot resolve questions about the frequency of civilizations in our galaxy. Another way to assess the prospects for other intelligent life is to extrapolate from the history of life on Earth. There is a set of arguments bearing on this question that have been rehearsed for a full century, beginning in with Alfred Russel Wallace, the co-discoverer of the theory of evolution, and being revived at intervals since by a series of authors.
Gould wrote in The evolution of human intelligence, after all, depended on a series of contingent factors, including the collision of a major asteroid with Earth 65 million years ago. The counterarguments are equally familiar: convergence is frequently observed in evolutionary history, and nature has evolved complex phenomena such as eyesight and flight many times, so that even though any given evolutionary line might be highly contingent, a large number of parallel paths may lead to the same functional outcome.
To this the reply is made that technical intelligence has only evolved once on Earth, so evidently convergence was not operating in this particular case. Marino and her colleagues begin with a reproducible measurement that correlates with what is meant by intelligence, and that can be employed with the fossil record as well as contemporary organisms. There is at least one such measure, called encephalization. Animals with EQs above 1 are brainier than average; those with EQ values below 1 are less brainy than expected for their body size. There is strong evidence that EQ among primates correlates with the ability to innovate, social learning and tool use; among birds it correlates with behavioral flexibility.
In well-controlled studies, dolphins have been shown to be capable of mirror self-recognition, an ability demonstrated only by a few other animals besides humans Figure 5. The highest EQ values on Earth after modern humans are those of four dolphin species, with the highest of the four being about 4. Great apes have EQs lower than this, with a mean around 1. This is about the same as that of the human ancestor.
Among our more recent ancestors, the tool-users Homo erectus and the earlier Homo habilis had EQ values of about 5. These results suggest that the evolution of human intelligence on Earth is not an entirely exceptional phenomenon. With a sufficiently large database of EQ measurements for fossil whale species, one can go further, and begin to test other long-standing assertions about intelligence, such as the claim that increases in encephalization should be pervasive because of the selective advantage that is conferred by bigger brains.
Marino and her colleagues have done this analysis, applying statistical tests to data for modern and fossil whales going back 50 million years. They show that while the overall trend in encephalization has been increasing, at any given speciation event, the successor species was as statistically likely to have a lower EQ as a higher one.
That is, encephalization was not pervasively advantageous; the increase in intelligence at the high end of encephalization seems better modeled as a random walk rather than a pervasive selection pressure favoring bigger brains. But it should be emphasized that the size of the data set here is so far very small, and nearly no funding is available for this kind of work.
These results are those of only a nascent research program, but they emphasize that there are reproducible, quantitative methods that can be applied to begin to address some long-standing assertions about the likelihood of the evolution of intelligence in the universe. Just as studies of microscopic life on Earth inform thinking about the prospects for microorganisms elsewhere, so can rigorous exploration of the evolution of intelligence on Earth inform our thinking about the prospects for intelligence elsewhere.
But since they are not here, they must not exist! The paradox obviously does not hold in a strict logical sense, since each of its assertions is at best a claim of probability, but it has been a powerful force on thinking about the prospects for extraterrestrial intelligence. Whatever the rigor of the Fermi paradox, there have been many solutions proposed for it. The challenge to most of these solutions is the large-number assertion: while this or that explanation might explain the failure of some, even most, civilizations to colonize the galaxy, the timescale for colonization is putatively so short that unless the total number of civilizations in galactic history were quite small, the galaxy would indeed have been colonized.
These colonization scenarios have posited exponential reproduction and paid little attention to ecological factors, such as the evolution of predation or other behavior that could have the effect of reducing the rate of expansion of a space-faring population. What parameters does one choose in predator-prey modeling to depict accurately the expansion timescales of competing technical civilizations?
It is hard to make such parameter choices with a feeling of confidence. And it is close to impossible to know whether such simple analogies from life on Earth are or are not applicable. Various practical arguments against galactic spaceflight being commonplace have been countered by invoking either genetic engineering or artificial intelligence in the form of self-replicating and evolving machines.
It is hard to know what comes after this exponential lift-off. It may prove generally true that there is only a brief interval during which a species is technically intelligent yet still retains its biologically evolved form. If so, we should expect that any civilization with which we make contact through SETI or otherwise is unlikely to resemble its biological predecessor species.
But well before biotechnology permits the reengineering of the human species, it will put great power for extremely dangerous manipulations of microorganisms into the hands of small groups of the technically competent. Indeed, it is doing so already. The National Academies has already convened two committees to examine this issue.
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