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Researchers Create 'Habitability Index' For Exoplanets
hypnosec writes: The Kepler Space Telescope has allowed astronomers to detect and catalog thousands of exoplanets and exoplanet candidates. With more powerful telescopes like the James Webb Space Telescope scheduled for launch, scientists will be able to check if any of these exoplanets are habitable. But these space telescopes are expensive to create, and access time is coveted. This means simply pointing telescopes to random exoplanets isn't a practical proposition. That's why researchers have created what they call a "habitability index for transiting planets," with which astronomers will be able to prioritize the use of space telescopes for finding habitable planets. Their paper is available at the arXiv.
The most habitable worlds, of course, are class M.
Don't ever forget 'climate change', you insensitive clod!
Will likely be invaded by freeloading yuppies the following year.
We can tell how habitable it is by how much it causes a start to warble
Chirp chirp chirp, triiiiiiiiiiiillll, triiiiiiiiiiiiiiiilllll! Chirp triiiiiiiiiiiiiiiiiiillll! Coooo-oooo! Cooooo-oooo! Chirp chirp chirp!!!
The human body can be drained of blood in 8.6 seconds given adequate vacuuming systems.
I think it's silly in the regards that we have precisely one datapoint about the sort of environments in which life may exist, which is pretty terrible in terms of making any sort of definitive statement. I'd much rather they keep their options open, check out a wide range of environments, and just look for signs of "things that are hard to explain", whatever they may be. "Hmm, this body has both a strong oxidizer and a strong reducing agent in its atmosphere - how is that happening?"
I'm not saying "check planets in random order" or anything of that nature. Just that I don't think it's critical to obsess over being sure to examine them in order of "earthishness" from highest to lowest. We need to be looking at a diversity of worlds.
Heck, we don't even know whether the surface of a body is the best place to look, most life in the universe might be in sub-crustal layers for all we know. Certainly would partially help explain the Fermi paradox, if it were such that we rare "surface dwellers" have a far easier route to the cosmos than something that needs to be under gigapascals of pressure to survive and whose radiating transmissions, if any, would be blocked by their planet's crust.
The human body can be drained of blood in 8.6 seconds given adequate vacuuming systems.
Yes, there's only one data point of a planet supporting life. While we can't draw conclusions from that about which planets are habitable, it's very important for at least a couple of reasons:
1) We have no evidence that any planets of any other types are capable of supporting life. We've only seen one planet known to support life, especially intelligent life. That is, of course, Earth. Why not start by looking at planets like the only one we are certain is capable of supporting intelligent life?
2) If life evolves on other types of planets, it may well not at all be like our own. This is a good place to look first because we have some idea of what to look for by looking at how life has evolved on our own planet. We have a relatively good chance of being able to identify and understand life like that on our own planet.
With respect to the diversity of life in the universe, we see it on Earth in the form of extremophiles. There is truly bizarre life that has adapted to survive in virtually every environment anywhere near the surface of the Earth. There is no reason to assume that this couldn't happen elsewhere. However, we may be able to place some limits on where we think it is most likely to develop.
Your example is subterranean beings, an example that I'm not convinced is likely. In order for life to perform the functions that make it life, it consumes a lot of energy. Much energy is also lost to the environment through heat. This seems like a limitation of the universe that can't be circumvented. In order to sustain life, the energy that is lost must be replaced. There are many ways this can be accomplished. Photosynthetic organisms convert light into chemical energy. Organisms in the deep oceans tend to rely on geothermal energy. There are bacteria that use redox reactions to harness energy from chemicals in their environment. And there are predators that obtain energy by consuming other organisms. Regardless, it's essential that there be a continuous influx of energy in order to sustain life. In the case of subterranean beings, this seems most likely to be in the form of geothermal energy or, perhaps, the decay of radioactive isotopes if present in sufficient quantity. That said, it doesn't seem to be the most likely place.
However, just because there's abundant energy to consume doesn't mean it's a favorable place for life. There's a tremendous amount of energy in the sun, but it doesn't seem to be the most likely place for complex organisms to develop because of its composition. Although Jupiter doesn't produce energy through fission like the sun does, there's also a vast amount of energy from the extreme winds and pressures in its atmosphere. Again, because of the composition, it seems unlikely that complex life would develop to use this energy.
The problem with extremophiles becoming complex and intelligent is that only a small portion of life actually does this. Most life is very simple. It takes a lot of energy to for complexity and intelligence, and is only worth it if a survival advantage occurs as a result. One of the driving forces of evolution is random mutations and the resulting natural selection. If a greater diversity of life exists in a region, it seems more likely that those mutations might eventually evolve into an intelligent being. On the other hand, extremophiles must be highly adapted for their particular conditions, which don't really support diversity and may not provide sufficient energy to allow for complexity and intelligence. The less harsh conditions in relatively close to the surface of bodies of water and also on land seem much more likely to lead to intelligent life.
So, although it's possible that life exists in very different forms, perhaps likely, there are reasons to believe that those aren't the most likely places for complex or intelligent life to evolve.
I have no clue where you're coming from. You rightly point out that life takes energy, but then proceed to consider internal sources of energy as worthless, when in reality in the universe far more things are exposed to internal energy than external. And radioactive decay-driven energy sources are only one. For example, Encelaldus's heat seems to be driven by the serpentization of rock, which also releases hydrogen, a potential food source to microorganisms. There are numerous chemical means which can release vast amounts of energy - yes, nuclear energy is many orders of magnitude more dense, but non-radioactive elements are also orders of magnitude more common.
Anywhere that there is heat and fluids (or solids that can undergo solid-state convection) can experience that heat being turned into harvestable forms of chemical energy, because chemical equilibriums are different at different temperatures. For example, at STP conditions, N2 + O2 is favorable, while at high temperatures NO2 is more favorable. N2 + O2 that goes to higher temperatures and forms NO2, which then comes back down to the lower atmosphere, is bringing a source of chemical energy with it.
Since heat differentials can and will be readily converted to chemical energy wherever it's associated with convection of any variety, then any source of heat is a fuel for life - and heat most definitely doesn't only come from nuclear decay - or chemical reactions. It comes also from the rebalancing of layers to a lower gravitational equipotential. It comes from impacts. It comes from tidal heating. It comes from thermal cycling in elongated orbits. It comes from mass loss due to solar wind exposure. There's a vast range of potential heating sources in the universe that can create heat differentials. And heat differentials make exploitable chemical reactions.
You make blind assertions that "these environments wouldn't be likely because of their composition". What do you know about this? You have a sample size of one of chemical processes that have created life. We can't even see deep into our own world to see what other alternatives might exist at higher pressures, let alone in other worlds. Heck, underground doesn't even mean particularly high pressures. Dwarf planets can have Earth-surface pressures at hundreds of meters or even kilometers depth. And life on Earth exists fine in the deep sea, wherever there's energy to support it, where pressures are at over 1000 atmospheres
Deep environments might prove even more prone to organic chemistry. In general, pressure is usually associated with faster reaction rates. You also often have more complex arrangements of possible chemical phases for each compound at higher pressures than with lower pressures. Water for example over its possible temperature range at a particular depth might have 3-5 potential ice phases, a liquid phase, a supercritical fluid phase, and a gas phase. This leads to a much greater range of possibilities for reactions to potentially exploit, because each chemical in each of its phases has the potential it interact with each other chemical in each of its other phases, or in the case of non-metastable forms, at least many of its other phases.
Common theories for the origin of life on Earth usually assume that it wasn't the sun that powered the first forms of life, even though that's the most convenient source of energy on our planet. Photosynthesis is much more complicated than most forms of chemosynthesis. Environments like black smokers, volcanic pools or acidic waters within deep iron-rich minerals seem like far more likely candidates.
Intelligence evolving within creatures that live in liquids? Oh, we've never seen that before! ;) Except, of course, for the fact that the second-most intelligent category of mammals are aquatic (cetaceans), and the most intelligent invertebrates (mollusks) live there too. Rather, the oceans tend to be highly competitive environments, and thus good breeding grounds for intelligence.
The human body can be drained of blood in 8.6 seconds given adequate vacuuming systems.
** I should clarify that when I say "mollusks", I mean like cephlapods, not like snails ;)
The human body can be drained of blood in 8.6 seconds given adequate vacuuming systems.
I thought that said "hitability".
But my analogy is this. Say that you're a pearl diver. You're browsing along a dive forum one day and see a picture from someone on their vacation to a remote tropical island holding a large, rare pearl that they found on a dive. You ask them where they found it, and they tell you they only did one dive and found it in waters of about 15 meter depth off the shore. Wanting to find many of these such pearls, you head out to the island. Now, you have two approaches you could take.
1. Spend a long time carefully doing a geological survey of the water depth around all of the shores of the island. Then do your dives in order of which are most precisely 15 meters deep, regardless of how convenient they are to access. Only move on to areas that are any more or any less than exactly 15 meters deep when you've exhausted all of the known 15-meter depth areas.
2. Go out and start diving wherever the water looks to be at least in the right ballpark of 15 meters depth. Start with the most convenient areas first. Don't obsess over the exact depth - exploring some 10 meter areas, some 20 meter areas, etc, just trying to keep it roughly in the ballpark of 15 meters. Because hey, for all you know, more than 15 meters or less than 15 meters might be an even better diving depth; you've only got one datapoint so far.
Which makes more sense? #2, obviously. Which is the same strategy we should be using with exoplanets in the search for life. We should be "favoring" Earthlike planets, but not obsessing over earthlike-ness in the search. We should be checking out a diverse range that is only "centered" on Earthlike bodies. And we should be focusing on those which lend themselves to easier, more detailed observation first, such as those closer to us and with a more favorable orbital alignment.
The human body can be drained of blood in 8.6 seconds given adequate vacuuming systems.
repeating the same tired space age clichés that will never, ever happen, ever.
I think it is you that is living in fantasyland. You are claiming that it will never happen, which the evidence contradicts.
APK likes to ask for responses to the same things over and over. Maybe he just likes the responses?
Has anyone classified ... (must stop) Ura....NO! (throwing keyboard across room)
That's fine, it implies suitable for humans or similar advanced life as necessary zombie-fodder. It implies a level of non-human sentience too for zombies to vocally express the longing for braaaaaaaiiiiiinnnssssss. Finding a class Z is a win-win
It is certainly within the ability of current human scientific and engineering ability to send an unmanned probe to the nearest three stars in less than two centuries with nuclear fission power alone
There is thriving (non-sentient) life there already, they're called mormons