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Space

Webb Telescope Will Look for Signs of Life Way Out There (nytimes.com) 56

Posted by msmash from the moving-forward dept.
This month will mark a new chapter in the search for extraterrestrial life, when the most powerful space telescope yet built will start spying on planets that orbit other stars. Astronomers hope that the James Webb Space Telescope will reveal whether some of those planets harbor atmospheres that might support life. New York Times: Identifying an atmosphere in another solar system would be remarkable enough. But there is even a chance -- albeit tiny -- that one of these atmospheres will offer what is known as a biosignature: a signal of life itself. "I think we will be able to find planets that we think are interesting -- you know, good possibilities for life," said Megan Mansfield, an astronomer at the University of Arizona. "But we won't necessarily be able to just identify life immediately."

So far, Earth remains the only planet in the universe where life is known to exist. Scientists have been sending probes to Mars for almost 60 years and have not yet found Martians. But it is conceivable that life is hiding under the surface of the Red Planet or waiting to be discovered on a moon of Jupiter or Saturn. Some scientists have held out hope that even Venus, despite its scorching atmosphere of sulfur dioxide clouds, might be home to Venusians. Even if Earth turns out to be the only planet harboring life in our own solar system, many other solar systems in the universe hold so-called exoplanets. In 1995, Swiss astronomers spotted the first exoplanet orbiting a sunlike star. Known as 51 Pegasi b, the exoplanet turned out to be an unpromising home for life -- a puffy gas giant bigger than Jupiter, and a toasty 1,800 degrees Fahrenheit. In the years since, scientists have found more than 5,000 other exoplanets. Some of them are far more similar to Earth -- roughly the same size, made of rock rather than gas and orbiting in a "Goldilocks zone" around their star, not so close as to get cooked but not so far as to be frozen.
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Webb Telescope Will Look for Signs of Life Way Out There More

Webb Telescope Will Look for Signs of Life Way Out There

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  • Atmospheric biosignatures (Score:3)

    by Immerman ( 2627577 ) on Monday July 04, 2022 @06:02PM (#62673492)

    So, anyone have any ideas on exactly what atmospheric biosignatures Webb could be looking for?

    Free oxygen is an obvious one - Webb is capable of very high resolution spectroscopy, and oxygen is so volatile that it gets bound into minerals almost immediately, and can't accumulate to significant levels without some process continuously producing more of it. Life (via photosynthesis) is the only such process we know of. (Of course life doesn't necessarily mean oxygen, as proven by the first billion or so years of life on Earth, but oxygen seems to mean life)

    Another I've heard of is to look for net circular polarization of light - there's good reason to expect life to produce molecules with a preferred chirality, which will then impart a net circular polarization (which can be seen by, e.g. shining flashlight through a tank of sugar-water). Purely chemical reactions in contrast produce equal numbers of left- and right-handed molecules, which combine to impart no net polarization. It sounds like Webb has some sensors capable of detecting polarization, though I'm not clear on whether they're the right kind for this task.

    Any other ideas?

      • An interesting tidbit, I tracked down the actual paper here [acs.org]

        However, my understanding is that oxygen already isn't regarded as impossible to generate without life - just very difficulty to generate at a rate greater than surface weathering can strip from the atmosphere so that it can actually accumulate to significant levels.

        A cautionary finding for sure, but their experiments don't actually seem to generate a very large amount of oxygen, and need pretty extreme conditions to do so. A planet would need to b

        • I was mainly reacting to your unnuanced confidence about life being the only source. My search threw up several links on the issue, but it's well outside my actual knowledge, just a memory of hearing that Oxygen isn't a definite life marker.

          • Yeah, the universe is a big, weird place. I doubt there's any single *definite* life marker, aside from clearly intelligent signals. Just highly probable ones worth further investigation. And at interstellar distances I'm not sure there's anything we could do to confirm things for sure, short of sending a probe at immense expense. Or at least a powerful signal to see if there's any intelligent life that might want to chat.

            Heck, even with Mars being right next door we can't get a straight answer. Our ear

      • Yes oxygen gas does not necessarily need life processes; however, life as we know it requires the continuous generation of oxygen. It is not a binary flag where the presence of it automatically means life but as an indicator any planet that has it should get priority of further investigation.

        • > life as we know it requires the continuous generation of oxygen.

          Hardly. Life as we know it spent 2 to 3 billion years (the start date is still an open question) evolving on an oxygen-free planet before photosynthesis caught on in a big way, and it took another billion years at trace levels (2-4%) before mineral oxidation stopped stripping it out of the air as fast as it was produced. https://en.wikipedia.org/wiki/... [wikipedia.org]

          And most life on Earth today could still do just fine without it. Including all plant

    • Re: (Score:2)

      by rossdee ( 243626 )

        "Free oxygen is an obvious one"

      But if there is a civilization there they will probably charge for it.

    • I maintain a general uneasiness that life is a process that may be quite different than what we are familiar with on this planet. Discovering other planets in our galaxy with chemical processes we are familiar with here on our planet may indeed generate similar life forms but perhaps examining the nature of life for characteristics other than local chemistries may discover what may be alien forms of what may be called life. There is a current consensus that denies our own developments in AI can be regarded

      • Yeah, life as we don't know it is a fascinating topic, and there's almost certainly tons of kinds out there that we would have no idea how to spot. There is however a lot of thought going into dreaming up ways to recognize life that doesn't conform to our preconceptions. I believe the search for imbalanced chiralities via polarization is one such product of that - it makes no assumptions about what chemistry is involved, instead it just looks for the likely optimization around one molecular handedness.

        As

        • I appreciate your comment which accepts my uneasiness at the general vagueness of what might positively indicates life. I also wonder why you assume that the random interactions of accidental forces could not join to create life which must carry some sort of message. That one variety of life enslaves a different form for it's own purposes is such a common occurrence on this planet that I wonder why you feel it is a negative phenomenon. It has happened many times that life forms merge to the benefit of both

          • Are you familiar with the concept of spontaneous generation? It's a once-popular concept that life could arise spontaneously - e.g. leave out some meat and maggots would spontaneously appear on it, not descended from any other organism. There were once many "recipes" for how to "create" a wide range of different living organisms from non-living ingredients, until eventually more rigorous experimentation proved that it was not the meat that created the maggots, but the flies that landed on the meat.

            That is

            • The concept of slavery is the use of a form of life without proper compensation, Our whole economic system is forcing of one sector of social organization to work for a smaller sector called the elite where the value of the work is greater than the compensation which can be a form of slavery, I have heard it said that the overlords of our economic system were upset because there was a danger of full employment (which, in fairness, could see to it that everybody could provide themselves with enough compensat

              • >The concept of slavery is the use of a form of life without proper compensation
                No.

                The concept of slavery is the use of a being without giving it a choice in the matter. If you can't quit, then you're a slave, no matter how good the compensation. You're no less a prisoner just because your cage is gilded.

                More specifically it's the treatment of a person as *property* - which usually grants the owner the right to do whatever they want to that property as they see fit, including taking all their stuff (p

                • I appreciate your demand for seeking absolutes and on that score I agree totally, It nicely fits military service where symbolic requirements such as saluting continually reminds you of your absolute subjugation and and one that shoves the shit in your face. I fully accepted that back in 1944 in the USAF but there was only the alternate of Nazi Germany and it was a bargain well worth accepting. But alternates of freedom to starve and suffer huge losses for one's self and one's family for the freedom to reje

  • Total waste of expensive instrument time. What idiot decided this?

    • This.

      If life was self-forming, we'd be swimming in signals from across the universe.

      If the UK couldn't put a lid on pirate radio, there's no way any single civilization could stop it. Let alone the quadrillions we should expect if life was self forming.

      • If life was self-forming, we'd be swimming in signals from across the universe.

        I think you have confused the availability of signals and our ability to detect such signals. It has only been since the 1900s that humans have looked at other parts of the spectrum besides visible light.

        If the UK couldn't put a lid on pirate radio, there's no way any single civilization could stop it. Let alone the quadrillions we should expect if life was self forming.

        I do not understand why you would think anyone would want to "stop it" as much as detecting an intelligent radio signal is just harder to detect as a signal because they are the least energetic part of the spectrum. Radio waves start at 124 neV (nano-electron volt) and decrease.

        • Right ! There isn't any motivation to stop it. Which means all the more reason we should see alien signals if life was self forming.

          We can see objects 13.5 billion miles away. There's supposedly 100 billion planets in our galaxy alone. That's a lot of territory we could detect signals from.

          And humans aren't just broadcasting one kind of EM signature. We are blasting it in all kinds of ways. Even if an alien civilization was limiting it somehow to 90% of the spectrum, we'd see that for sure.

          It's not

          • And humans aren't just broadcasting one kind of EM signature. We are blasting it in all kinds of ways. Even if an alien civilization was limiting it somehow to 90% of the spectrum, we'd see that for sure.

            Signals that we humans are "blasting" into space becomes noise the further out it goes [wikipedia.org]. Things like TV broadcasts do not have the strength to reach the end of this solar system without a lot of amplification on the receiver end. Even communication with space craft like Voyager it takes a lot of equipment and we know where they are and what frequencies to listen. For example, the DSN [nasa.gov] is designed specifically to talk to space craft like Voyager and it consists of multiple locations and antenna.

            If an alien civ

            • I keep seeing new fallacies trotted out, like gods getting added to a pantheon. "Socrates ! Come watch the torch races of a new foreign god, Bendis with us !"

              There's a reason CEOs are not hired on their basis to label different views fallacies. It's because this is not a practical way of accomplishing anything. In a court room if they can't find evidence against someone, no prosecutor is going to say, "Your honor, absence of evidence is not evidence of absence." If the government (or opposing side in a c

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