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Don J
2013-Mar-12, 07:00 PM
http://phys.org/news/2013-03-earth-sized-planets-habitable-zones-common.html
"We now estimate that if we were to look at 10 of the nearest small stars we would find about four potentially habitable planets, give or take," said Ravi Kopparapu, a post-doctoral researcher in geosciences. "
Excerpts


The number of potentially habitable planets is greater than previously thought, according to a new analysis by a Penn State researcher, and some of those planets are likely lurking around nearby stars.

"We now estimate that if we were to look at 10 of the nearest small stars we would find about four potentially habitable planets, give or take," said Ravi Kopparapu, a post-doctoral researcher in geosciences. "That is a conservative estimate," he added. "There could be more.

If intelligent life having millions of years of technological advance from us exist on planets orbiting nearby stars the possibility of them visiting Earth seem less farfetched.

neilzero
2013-Mar-12, 11:50 PM
I have not seen any convincing details of how ET can visit Earth, except with magic. Magic is any science we cannot rationally imagine with present science. That does not prove ET can't visit Earth. Neil

Don J
2013-Mar-13, 01:55 AM
I have not seen any convincing details of how ET can visit Earth, except with magic. Magic is any science we cannot rationally imagine with present science. That does not prove ET can't visit Earth. Neil
Certainly,and the "proximity" of another intelligent specie can play a major role, because until recently it was believed that such civilization may only exist thousand(s) or million(s) of years from Earth.

Finally the space travel route chart below may not be so farfetched from an acceptable possibility.
http://commons.wikimedia.org/wiki/File:Zeta_reticuli.png

eburacum45
2013-Mar-13, 05:05 PM
"We now estimate that if we were to look at 10 of the nearest small stars we would find about four potentially habitable planets, give or take," said Ravi Kopparapu, a post-doctoral researcher in geosciences.

Habitable in this context only means planets that might hold liquid water. It does not mean planets with life, or planets with intelligent life, or planets that would be habitable for humans. There are no estimates for any of these quantities, and the last two might be vanishingly rare.

Finally the space travel route chart below may not be so farfetched from an acceptable possibility.
http://commons.wikimedia.org/wiki/File:Zeta_reticuli.pngThis is garbage. The Betty and Barney Hill map was debunked long ago; you only have to look at the gap between Zeta1 and Zeta2 Reticuli to see that it bears no relation to reality.

Don J
2013-Mar-13, 06:37 PM
I have not seen any convincing details of how ET can visit Earth, except with magic. Magic is any science we cannot rationally imagine with present science. Neil
There exist actually here on Earth interesting interstellar space propulsion proposal.Imagine if we were not limited by money about research and development we may have the possibility to visit other nearby stars system already.
http://www.boomslanger.com/images/egps2007.pdf
Current Research in Gravito-Electromagnetic Space Propulsion
Excerpts


in March 2006 the European Space Agency (ESA) announced credible experimental results, reporting on the measurement of artificial gravitational fields (termed gravito-magnetic fields), generated by a rotating Niobium superconductor ring that was subjected to angular acceleration.

These experiments were performed by M. Tajmar and colleagues from ARC Seibersdorf, Austria and C. de Matos from ESA, and recently were repeated with increased accuracy.

Electrodynamic Field Generator pdf (507Kb) U.S. Patent 6,404,089
http://www.boomslanger.com/images/edfg.pdf

Website Introduction Statement:


Extraordinary new potential for our world exists in a revolutionary and patented new propulsion technology that may soon enable true interstellar travel — an all-electric reactionless space drive which is technically capable of breaking the light barrier!!

Don J
2013-Mar-13, 06:51 PM
Habitable in this context only means planets that might hold liquid water. It does not mean planets with life, or planets with intelligent life, or planets that would be habitable for humans. There are no estimates for any of these quantities, and the last two might be vanishingly rare.
This is garbage. The Betty and Barney Hill map was debunked long ago; you only have to look at the gap between Zeta1 and Zeta2 Reticuli to see that it bears no relation to reality.
If we were able to visit other stars system it is logical that we start our exploration to nearby stars system where there exist planets in the habitable zone.
http://commons.wikimedia.org/wiki/File:Zeta_reticuli.png

eburacum45
2013-Mar-13, 10:00 PM
Note that Kopparapu is mostly concerned with the likelihood of 'habitable' planets orbiting red dwarf stars; these planets would be tidally locked, and therefore very different in many ways from any Earth-like environment. I am reasonably optimistic thatsome tidally locked planets could support life, and possibly even intelligent life; but these worlds are so different from ours that I doubt that we'd have much in common.

neilzero
2013-Mar-13, 10:50 PM
I really hope the reactionless drive proves practical, but some of the details suggest technabable to me, but perhaps that is the best way to get things patented with minimum hastle.
I agree much of the twilight zone of tide locked planets can have liquid surface water, but not nearly enough light for photo synthesis without the help of high tech, so colony perhaps, but life evolving there seems unlikely except far below the surface. Neil

Don J
2013-Mar-14, 01:33 AM
Note that Kopparapu is mostly concerned with the likelihood of 'habitable' planets orbiting red dwarf stars; these planets would be tidally locked, and therefore very different in many ways from any Earth-like environment. I am reasonably optimistic thatsome tidally locked planets could support life, and possibly even intelligent life; but these worlds are so different from ours that I doubt that we'd have much in common.
The kind of difference which may result in a intelligent saurian or reptilian race ...Who knows what would have happened on Earth if the dinosaurs have not being destroyed?

Don J
2013-Mar-14, 01:40 AM
I really hope the reactionless drive proves practical, but some of the details suggest technabable to me, but perhaps that is the best way to get things patented with minimum hastle.
I agree much of the twilight zone of tide locked planets can have liquid surface water, but not nearly enough light for photo synthesis without the help of high tech, so colony perhaps, but life evolving there seems unlikely except far below the surface. Neil
That environment seem perfect for the development of an intelligent reptilian based life...and the capacity to hibernate make them even more suitable for long interstellar space travel.


so colony perhaps

That is a possibility.
Note also that although most class-M stars are red dwarfs, the class also hosts most giants and some supergiants such as Antares and Betelgeuse, as well as Mira variables.

Here another study about the possibility of life on planets in the habitable zone of M-dwarfs.
http://www.astrobio.net/interview/1694/m-dwarfs-the-search-for-life-is-on

eburacum45
2013-Mar-14, 05:44 PM
I should point out that there are no reptiles anywhere in the universe except on Earth, unless thy have been taken from Earth at some time in the past. There may be reptile-like organisms, but they will be different from Earth reptiles in some, many, or most ways, and so should be assigned to different taxonomic categories.

Don J
2013-Mar-14, 06:08 PM
I should point out that there are no reptiles anywhere in the universe except on Earth, unless thy have been taken from Earth at some time in the past. There may be reptile-like organisms, but they will be different from Earth reptiles in some, many, or most ways, and so should be assigned to different taxonomic categories.
Yep!A better wording would have been saurian-like or reptilian-like to take into account that difference.
If dinosaurs have not become extinct on Earth,would some evolved to resemble bipedal intelligent humanoids?
http://www.serpo.org/r30pics/Dinosaur_14.jpg
Smartasaurus
http://scienceblogs.com/tetrapodzoology/2008/03/24/dinosauroids-2008/

eburacum45
2013-Mar-14, 07:51 PM
I doubt very much that an intelligent species derived from a dinosaur would have an erect bipedal stance- they would be able to operate just fine with a cantilever spine.

Don J
2013-Mar-14, 08:14 PM
I doubt very much that an intelligent species derived from a dinosaur would have an erect bipedal stance- they would be able to operate just fine with a cantilever spine.
That is a point of view.Here another one:
Dale Russell, discoverer of Stenonychosaurus (now called Troodon), then of the National Museum of Natural Sciences in Ottawa, Canada, postulated that late Cretaceous dinosaurs were well on the way to becoming intellectual animals, and would have succeeded if the dinosaurs had not suffered extinction. Stenonychosaurus had an opposable thumb, stood upright about three feet tall and had binocular vision.
More
http://www.cosmosmagazine.com/features/smartasaurus/

Picture
http://scienceblogs.com/tetrapodzoology/wp-content/blogs.dir/471/files/2012/04/i-9fdaedb12b6696e75625f387f733bfd0-Hecht%20smartasaurus%2023-3-2008.jpg

eburacum45
2013-Mar-14, 08:18 PM
Troodon is not erect; see this reconstruction.
http://en.wikipedia.org/wiki/File:Troodon_skeletal.jpg

Don J
2013-Mar-14, 08:25 PM
Troodon is not erect; see this reconstruction.
http://en.wikipedia.org/wiki/File:Troodon_skeletal.jpg
The point postulated was that giving time if they were not became extinct they may have developed an intelligence and an erect position.
Like great apes which humans are supposed to descend from were not erect standing.

Intelligence is a good thing that contributed to the evolutionary success of our species. What’s good for humans should then have been good for dinosaurs.
Interesting description here.
http://www.cosmosmagazine.com/features/smartasaurus/


Russell discovered the first Troodon skull, which revealed that its brain, relative to its body size, was unusually large for a dinosaur. To ascertain just how big its brain was compared to other dinosaurs, he calculated its EQ. What he found was telling.

Russell calculated that Troodon had an EQ that was small compared to modern humans, but was nearly six times larger than the known dinosaur average. Russell extrapolated that if Troodon had survived and retained the same body size, its modern-day descendants might have a brain volume of 1,100 cm3 — comparable to that of a small human.

Troodon also had a couple of the advanced traits that may have given ancestral primates a leg-up in the mammalian evolutionary race. The placement of its large eyes suggests that it had binocular vision, and the outer two of its three fingers also appear to be opposable.

eburacum45
2013-Mar-14, 09:53 PM
Note that we evolved from erect biped apes which were similar in intelligence to chimpanzees or gorillas. Erect apes seem to have evolved an upright stance long before tool use. Troodon would not need to evolve an upright stance, as it already has its forelimbs free.

Don J
2013-Mar-14, 10:56 PM
Note that we evolved from erect biped apes which were similar in intelligence to chimpanzees or gorillas. Erect apes seem to have evolved an upright stance long before tool use. Troodon would not need to evolve an upright stance, as it already has its forelimbs free.
These details are effectively part of the discussion among palaeontologists as presented in the page linked.But one thing for sure if the dinosaurs have not became extinct we will not have that discussion... but maybe some Troodon descendants, be it in a upright stance or not.
http://www.cosmosmagazine.com/features/smartasaurus/

neilzero
2013-Mar-15, 12:25 AM
I will sumarize what I think is mainstream on this topic. Please correct, comment, or add details. All or most proto stars begin life in a stellar nursery = giant dust cloud, so only the outer edges can be observed except infrared cuts thought the dust somewhat. Some of the protostars start out with as little as 1% of the mass of our sun. The first billion years is pretty much independent of the mass = very hot due to gravitational compaction. fusing lithium, the bigger ones fusing some deuterium, then main sequence begins small scale for the first billion years = fusing hydrogen to helium, unless the mass is less than 7% that of our sun. The under 7% (These are brown dwarfs) cool very slowly but steadly over the the next twenty billion years or so. These light weights can have planets, and colonists could live there, but life evolving there seems unlikely due to the steadilly falling temperatures. The planets are also cooling as their internal heat decreases. The 0.07 to 0.1 solar mass stars will have about a trillion years of constant temperature, and the somewhat more massive almost that long. Ideal for planets with life if the orbits are close to circular and don't shrink or expand much. Planets with one g or a bit more surface gravity and a magnetic field can likely retain their thick to medium atmosphere very long term. Life can evolve below the surface, and possibly on the surface, if portions of the planet are near the middle of the temperature of liquid water. The planets within a few million kilometers of their sun will be too hot where the Sun is over head, but tide lock (or resonant rotation like Mercury) is likely, so there will be a twilight band with liquid water and comfortable temperatures, but not enough light for photo sythesis, unless plants can evolve to use near infrared light/ are any known on Earth? Have we confirmed liberation on any body other than Earth's Moon? Neil

Don J
2013-Mar-15, 03:41 AM
These light weights can have planets, and colonists could live there, but life evolving there seems unlikely due to the steadilly falling temperatures. The planets are also cooling as their internal heat decreases. The 0.07 to 0.1 solar mass stars will have about a trillion years of constant temperature, and the somewhat more massive almost that long. Ideal for planets with life if the orbits are close to circular and don't shrink or expand much. Planets with one g or a bit more surface gravity and a magnetic field can likely retain their thick to medium atmosphere very long term. Life can evolve below the surface, and possibly on the surface, if portions of the planet are near the middle of the temperature of liquid water. The planets within a few million kilometers of their sun will be too hot where the Sun is over head, but tide lock (or resonant rotation like Mercury) is likely, so there will be a twilight band with liquid water and comfortable temperatures, but not enough light for photo sythesis, unless plants can evolve to use near infrared light/ are any known on Earth? Have we confirmed liberation on any body other than Earth's Moon? Neil
There is a discussion which address the tidal lock aspect about planets in the habitable zone of M dwarfs.Here the text from the link in post 10 that you have possibly missed.(Discussion text down the 2/3 of the page)
http://www.astrobio.net/interview/1694/m-dwarfs-the-search-for-life-is-on


Todd Henry (TH): The big argument has always been that to put a planet in the so-called habitable zone [of an M dwarf], you have to move it in so close to the star - because the star is so much cooler and has less radiation - that it locks, just like the moon tidally locks to the Earth. And so you have the same face of the planet facing the star all the time. And if you do that, it has been said, that you'd be boiling away any atmosphere or ocean on the side facing the star and it would be trapped on the dark side and would freeze out.

It turns out that's probably not right. The locking would occur. But it doesn't take that much atmosphere to redistribute the heat. So if you have a little bit more than the Earth's atmosphere - I think that is what's required, but it depends on what molecules are in the atmosphere - you can actually stir the atmosphere up enough and move the heat around the planet. So it doesn't matter if it's tidally locked or not. You still have a good temperature on the whole surface. Some of it's faced toward the star, some of it's facing away from the star, and it doesn't seem to matter. That was the biggest hurdle to get over.

Then there were all kinds of details that go along with that. Not all planets would be tidally locked. There could be another planet in the system that forces it to be in some sort of resonance that would keep it spinning. You could have a slightly eccentric orbit that makes it wobble and librate like the moon does, back and forth. So the details can get you out of a lot of problems.

Astrobiology Magazine (AM): You said that having an atmosphere a little thicker than Earth's could overcome the tidal-locking problem. But wouldn't being closer to the star mean that stellar radiation would be more likely to blow out the atmosphere completely?

TH: That is one of the big problems we came up with. I think that is the largest dragon-head that we saw, that you can sputter away the whole atmosphere - in about a billion years, was the back-of-the-envelope calculation. That really needs to be cleared up. That may be the biggest danger.

But you can get away from that as well. If you have a lot of radiation hitting a planetary surface and there's liquid on it, you're going to be creating atmosphere really quickly, as well. So you may sputter a lot away, but you might just keep regenerating it, so it's not a problem.

They address also the problem of solar flares and other things about radiation and they conclude that:


The best argument against the UV rays and the X-rays in particular is that an M dwarf emits most of that in the first billion years of its life. And once you're through that, then it gets pretty nice. So all the bad stuff happens early. So you just wait. You just wait for your habitable zone to stabilize and your star to stabilize. And then you've got billions of years to play around with the chemistry on the surface.

eburacum45
2013-Mar-16, 03:38 AM
One interesting suggestion there is that a tidally locked planet in an eccentric orbit would librate sufficiently to expose a greater proportion of it's surface to the sun. This is true, but the eccentricity itself can be a signifficant effect on the planet's climate in such a case. The planet will have a short, hot summer and a long cool winter, with various parts of the planet exposed to the sun at different times of year.

Once again, not an environment we are familiar with, but an intriguing prospect none-the-less.

Don J
2013-Mar-17, 01:22 AM
One interesting suggestion there is that a tidally locked planet in an eccentric orbit would librate sufficiently to expose a greater proportion of it's surface to the sun. This is true, but the eccentricity itself can be a signifficant effect on the planet's climate in such a case. The planet will have a short, hot summer and a long cool winter, with various parts of the planet exposed to the sun at different times of year.

Once again, not an environment we are familiar with, but an intriguing prospect none-the-less.
Still a good place for the development of a reptilian/lizard-like life adapted to their planet environment.
What happened on Earth have also a good chance to happen somewhere else with the adequate condition.
Other prehistoric life ...before the dinosaurs.
http://dinosaurs.about.com/od/otherprehistoriclife/a/beforedinos.htm


For approximately 120 million years--from the Carboniferous to the middle Triassic periods--terrestrial life was dominated by the pelycosaurs, archosaurs, and therapsids (the so-called "mammal-like reptiles") that preceded the dinosaurs.

Githyanki
2013-Mar-19, 12:40 PM
Great news ppl; back to research.


I have not seen any convincing details of how ET can visit Earth, except with magic. Magic is any science we cannot rationally imagine with present science. That does not prove ET can't visit Earth. Neil

So you must be an alien in hiding. How long have you been an alien in hiding?

Don J
2013-Mar-21, 01:44 AM
I really hope the reactionless drive proves practical, but some of the details suggest technabable to me, but perhaps that is the best way to get things patented with minimum hastle.
Neil
-see post #5 for context.-
Here another one: warp drive design based on Heim quantum theory.
http://www.1000planets.com/papers/hqtforspacepropphysicsaip2005.pdf

For those interested about Heim quantum theory.
http://en.wikipedia.org/wiki/Heim_theory

eburacum45
2013-Mar-21, 01:16 PM
-see post #5 for context.-
Here another one: warp drive design based on Heim quantum theory.
http://www.1000planets.com/papers/hqtforspacepropphysicsaip2005.pdf

For those interested about Heim quantum theory.
http://en.wikipedia.org/wiki/Heim_theory

Particularly interesting is this list of reasons why Heim theory is garbage;
http://en.wikipedia.org/wiki/Talk:Heim_theory/Archive_2#Arguments_contra_HT
I like this one
9.Use of the exact area "1 meter^2" as a fundamental physical constant (not just as a convenient normalization factor: physical predictions of Heim theory such as the "initial size of the universe" change if you use a different value like "2 meter^2" instead. I have seen no explanation from Heim theory workers of why the arbitrary human unit of "meters" would show up in a fundamental theory this way).

The square metre is a fundamental feature of the Universe? This isn't physics, it's pyramidology.

Don J
2013-Mar-21, 06:41 PM
Particularly interesting is this list of reasons why Heim theory is garbage;
http://en.wikipedia.org/wiki/Talk:Heim_theory/Archive_2#Arguments_contra_HT
I like this one
9.Use of the exact area "1 meter^2" as a fundamental physical constant (not just as a convenient normalization factor: physical predictions of Heim theory such as the "initial size of the universe" change if you use a different value like "2 meter^2" instead. I have seen no explanation from Heim theory workers of why the arbitrary human unit of "meters" would show up in a fundamental theory this way).

The square metre is a fundamental feature of the Universe? This isn't physics, it's pyramidology.
I went to your link and they seem to mix Podkletnov theory as if it is Heim theory .That is not the same thing
http://en.wikipedia.org/wiki/Talk:Heim_theory/Archive_2#Arguments_contra_HT


Podkletnov claims
Regarding Podkletnov theory
......Of course Podkletnov's experimetn has nothing to do with Heim, as the predicted Heim-Lorentz force only produces noticeable effects at very high magnetic field strengths of at least 15 Tesla. Podkletnov was using a weaker magnet: but how weak? I saw one report of an attempt to reproduce his effect using a 1 Tesla magnet - still a bit too weak for an effect. --hughey 22:17, 23 February 2006 (UTC)

Apparently Heim theory was verified by Martin Tajmar who has recently found additional support from Gravity Probe B results.[34]
http://www.ilsb.tuwien.ac.at/~tajmar/
Eta
Martin Tajmar Paper here:
http://arxiv.org/ftp/arxiv/papers/0707/0707.3806.pdf
Predictions for a quantum gravity force
http://en.wikipedia.org/wiki/Heim_theory


In the 1950s, Heim had predicted what he termed a 'contrabary' effect whereby photons, under the influence of a strong magnetic field in a certain configuration, could be transformed into 'gravito-photons', which would provide an artificial gravity force. This idea caused great interest at the time.[30] A recent series of experiments by Martin Tajmar et al., partly funded by European Space Agency, may have produced the first evidence of artificial gravity [31] (about 18 orders of magnitude greater than what General Relativity predicts). As of late 2006, groups at Berkeley and elsewhere were attempting to reproduce this effect. By applying their 'gravito-photon' theory to bosons, Dröscher and Hauser were able to predict the size and direction of the effect. A further prediction of Heim-Dröscher theory shows how a different arrangement of the experiment by Tajmar et al. could produce a vertical force against the direction of the Earth's gravity.

However, in July 2007, a group in Canterbury, New Zealand, said that they failed to reproduce Tajmar et al.'s effect, concluding that, based on the accuracy of the experiment, any such effect, if it exists, must be 21 times smaller than that predicted by the theory proposed by Tajmar in 2006.[32] Tajmar et al., however, interpreted a trend in the Canterbury data of the order expected, though almost hidden by noise. They also reported on their own improved laser gyro measurements of the effect, but this time found 'parity breaking' in that only for clockwise spin did they note an effect, whilst for the Canterbury group there was only an anti-clockwise effect .[33] In the same paper, the Heim-Theory explanation of the effect is, for the first time, cited as a possible cause of the artificial gravity. Tajmar has recently found additional support from Gravity Probe B results.[34]

The original Heim theory was later extended


Most notable are the theoretical generalizations put forth by Walter Dröscher, who worked in collaboration with Heim at some length. Their combined theories are also known as "Heim-Dröscher" theories or Extended Heim theory.[11]

There are some differences between the original "Heim Theory" and the extended versions proposed by his successors. For example, in its original version Heim theory has six dimensions, i.e., the 4 of normal space-time with two extra timelike dimensions. Dröscher first extended this to eight and claimed that this yields quantum electrodynamics along with the "particle zoo" of mesons and baryons. Later, four more dimensions were used to arrive at the twelve dimensional version, which involves extra gravitational forces; one of these corresponds to quintessence.[11]
Eta 2
Links to Dröscher, and Häuser papers
http://www.hpcc-space.de/publications/index.html



First and second publication in a peer reviewed scientific journal

Burkhard Heim (1977). "Vorschlag eines Weges einer einheitlichen Beschreibung der Elementarteilchen (Recommendation of a Way to a Unified Description of Elementary Particles)". Zeitschrift für Naturforschung 32a: 233–243. Bibcode 1977ZNatA..32..233H.
Hauser, J., Dröscher, W., Emerging Physics for Novel Field Propulsion Science
Paper presented at the Space, Propulsion & Energy Sciences International Forum SPESIF-2010, Johns Hopkins - APL, Laurel, Maryland, 23–25 February 2010, published by the American Institute of Physics. [5]

Swift
2013-Mar-21, 08:32 PM
-see post #5 for context.-
Here another one: warp drive design based on Heim quantum theory.
http://www.1000planets.com/papers/hqtforspacepropphysicsaip2005.pdf

For those interested about Heim quantum theory.
http://en.wikipedia.org/wiki/Heim_theory
This has absolutely nothing to do with probability of Earth-sized planets in habitable zones. Even if you did start this thread, you cannot hijack to discuss any topic you like. If you wish to discuss reptile lifeforms or warp drive, start threads in appropriate forums.

Any further off-topic posts will be infracted.

Grant Hatch
2013-Mar-22, 03:11 AM
http://phys.org/news/2013-03-earth-sized-planets-habitable-zones-common.html
"We now estimate that if we were to look at 10 of the nearest small stars we would find about four potentially habitable planets, give or take," said Ravi Kopparapu, a post-doctoral researcher in geosciences. "
Excerpts

If intelligent life having millions of years of technological advance from us exist on planets orbiting nearby stars the possibility of them visiting Earth seem less farfetched.

The methods used to detect extrasolar planets are skewed by their very nature (methodology) towards the detection of larger, more massive, stellar proximate planets..... It's little wonder that the bulk of the planets discovered to date are UN-earthlike. As the field advances and "higher resolution" methodology becomes available we will undoubtedly find more and more approx earth sized and type planets residing in the "goldilocks" zone of other stellar systems.

I am not convinced that intelligent life even needs to evolve in "our" conception of a goldilocks zone. It wouldn't suprise me in the least if life "finds a way" in temperatures and chemistries deadly to us..... I would even go so far as to predict we find life (though not neccessarily "intelligent") WITHIN the solar system in places such as Mars, Titan, Europa, the clouds of Jupiter, etc.... It's possible that the only thing that life needs is a biosphere of sufficient energetic disequilibrium to exploit. http://www.ncbi.nlm.nih.gov/pubmed/18163875

Don J
2013-Mar-22, 06:39 PM
I am not convinced that intelligent life even needs to evolve in "our" conception of a goldilocks zone. It wouldn't suprise me in the least if life "finds a way" in temperatures and chemistries deadly to us..... I would even go so far as to predict we find life (though not neccessarily "intelligent") WITHIN the solar system in places such as Mars, Titan, Europa, the clouds of Jupiter, etc.... It's possible that the only thing that life needs is a biosphere of sufficient energetic disequilibrium to exploit. http://www.ncbi.nlm.nih.gov/pubmed/18163875
From the abstract you linked.


Data from the Galileo Near-Infrared Mapping Spectrometer were used to constrain the surface abundance of CO(2) to 0.036% by number relative to water. Laboratory results indicate that radiolytically processed CO(2)-rich ices yield CO and H(2)CO(3); the reductants H(2)CO, CH(3)OH, and CH(4) are at most minor species. We analyzed chemical sources and sinks and concluded that the radiolytically processed surface of Europa could serve to maintain an oxidized ocean even if the surface oxidants (O(2), H(2)O(2), CO(2), SO(2), and SO(4) (2)) are delivered only once every approximately 0.5 Gyr.
If delivery periods are comparable to the observed surface age (30-70 Myr), then Europa's ocean could reach O(2) concentrations comparable to those found in terrestrial surface waters, even if approximately 10(9) moles yr(1) of hydrothermally delivered reductants consume most of the oxidant flux. Such an ocean would be energetically hospitable for terrestrial marine macrofauna.
The availability of reductants could be the limiting factor for biologically useful chemical energy on Europa.

Do you have access to a free copy of the paper you linked?
If so, are they elaborating more about what they means by macrofauna ,it must be bigger than micro-organism?
Eta


I would even go so far as to predict we find life (though not neccessarily "intelligent") WITHIN the solar system in places such as Mars,

Dr. Gilbert V. Levin the man who have conceived the method to seek microorganisms life on NASA’s 1976 Viking Mission to Mars. is convinced that the results were positive but other scientists were not so convinced,but new data from recent missions seem to give more weight to Levine conclusion.
Details +Many good links.... here:
http://www.gillevin.com/mars.htm
Excerpts


Originally named “Gulliver,” for the Lilliputians (microorganisms) it was seeking, it was renamed the “Labeled Release (LR)” experiment by NASA to indicate the technology used – the release of radioactive gas from radio-labeled compounds in the event they were metabolized by microorganisms in the Martian soil. Simply put, the LR squirted a drop of carefully designed radioactive food onto a tiny cup of Martian soil and monitored the air above the soil to detect radioactive gas that any microorganisms present might breathe out. Levin and his co-workers, notably Dr. Patricia Ann Straat, then spent the next decade developing the experiment and instrument, and in analyzing the results obtained from its successful operation on Mars. At both landing sites, some 4,000 miles apart, the LR returned evidence of living microorganisms. Initially discounted by NASA and most space scientists, the results of this milestone project have, nonetheless, been causing excitement and controversy ever since. In 1997, after 21 years of study of the Mars LR results, of new information scientists obtained about environmental conditions on Mars, and of the extreme environments in which life was found on Earth, Dr. Levin published his conclusion that the LR had, indeed, discovered living microorganisms on the Red Planet.

Grant Hatch
2013-Mar-23, 04:05 PM
No, sorry, Just the abstract. I assume "macrofauna" would include everything from microfauna on up since the macrofauna would need something to eat...... I remember the original Viking findings as well. I was always curious as to why they initially thought it was a positive result but then backed down. If memory serves "they" decided it could have been just a chemical reaction having nothing to do with life.....

Don J
2013-Mar-23, 06:25 PM
No, sorry, Just the abstract. I assume "macrofauna" would include everything from microfauna on up since the macrofauna would need something to eat......

That is what i though they were implying.


I remember the original Viking findings as well. I was always curious as to why they initially thought it was a positive result but then backed down.

A possible explanation maybe that positive results so early in Mars exploration=no more funding for Mars life detection.Think about it!How many probes were send to Mars since the Viking mission?Also why they have never send another probe in the same area of the Viking mission?


If memory serves "they" decided it could have been just a chemical reaction having nothing to do with life.....
If you go to the link below Levin explain that all attempt using chemical reaction failed to reproduce the results.
see page 5 of the PDF doc....On page 13 figure 6 there is an image of snow or frost on the Mars soil.Fig7show an image of possible mud puddle.
The Viking mission and life on Mars. (2011)
http://www.gillevin.com/Mars/THE_VIKING_MISSION_AND_LIFE_ON_MARS.pdf

Source ( links to Dr. Gilbert V. Levin -positive detection of living microorganisms in the soil of Mars.)
http://www.gillevin.com/mars.htm

eburacum45
2013-Mar-24, 03:19 PM
Another thread about Levin and his claims

Levin going a bit too far in his zealotry? (http://cosmoquest.org/forum/showthread.php?12754-Levin-going-a-bit-too-far-in-his-zealotry)

There may be life on Mars; I hope there is. If Curiosity finds evidence for life that wouldn't terminate the Mars Program, but instead it give it a greater urgency, at least until a sample-and-return mission could bring it back to Earth to be analysed. The discovery of life on Mars would be a very important event, and it would be very important to find out whether or not this life is related to Earth life or not.

If life on Mars is related to Earth life, that would provide evidence that life can be transferred from world to world within a solar system. A good thing, but it doesn't say anything useful about the possibility of life in other systems. Our system might be the only system with life in the universe, but that wouldn't stop life being transferred from one planet to another one nearby.

If life on Mars is unrelated to Earth life then that suggests that abiogenesis events are relatively common, since two such events have occurred within a single system. This is the result I would like to see, but it would have certain implications for the future development of humankind, at least if Nick Bostrom is right.
Why I hope the search for extraterrestrial life finds nothing (http://www.sentientdevelopments.com/2008/04/nick-bostrom-why-i-hope-search-for.html).

Grant Hatch
2013-Mar-24, 04:04 PM
I read the Bostrom link and found it unconvincing. Logical errors and assumptions flaw it beyond repair......

eburacum45
2013-Mar-24, 06:09 PM
I read the Bostrom link and found it unconvincing. Logical errors and assumptions flaw it beyond repair......

We've discussed it at some length on this forum, and most people think that. There are a great many possible solutions to the Fermi Paradox.

But if we find that the universe is full of life, and littered with the remains of extinct civilisations, that would be a worrying development. If advanced civilisations always die out, something must be causing that to occur; a Great Filter in our future, which we cannot predict.

Don J
2013-Mar-25, 03:57 AM
Another thread about Levin and his claims

Levin going a bit too far in his zealotry? (http://cosmoquest.org/forum/showthread.php?12754-Levin-going-a-bit-too-far-in-his-zealotry)

If you go at page 5 of the PDF document you will notice that Levin is addressing adequately all the objections cited in the thread you linked.
http://www.gillevin.com/Mars/THE_VIKING_MISSION_AND_LIFE_ON_MARS.pdf
For example post 23 of your linked thread.


A lot has indeed changed since Viking. We also have the experimental evidence that superoxide (O3.) is produced by the action of UV radiation on Martian regolith.

Levin said that the theory ie(chemical reaction vs biological reaction causing positive LR detection) from the oxidation of the Martian soil caused by the UV factor was quickly put forward by some astrobiologists during the mission. However that theory was quickly eliminated after they have moved a rock at dawn and testing the soil underneath.It was fully active. (see figure 2 PDF)
Eta
More recently,the Rover Opportunity confirmed that the surface of Mars is not highly oxidizing.Its analysis of the soil supported the Viking Magnetic Properties experiment in that the majority of the iron is less than fully oxidized.

Other point covered by Levin
Why "Viking GCMS didn't get a positive response." Hint... the sensitivity of the GCMS instrument was eight order of magnitude lower than the LR.That the GCMS even frequently obtained negative results with live soils on Earth.See reference number(12)(13)PDF doc
http://www.gillevin.com/Mars/THE_VIKING_MISSION_AND_LIFE_ON_MARS.pdf

That important "detail" about the in-sensitivity of the GCMS is also well described by RG Clark in post 22 and 26 of your linked thread .
To resume, the sensitivity of GCMS on Viking was set to detect organic content "in the kinds of soils you might have in your backyard or in arable land."but totally unable to detect organic content "in samples taken from Antarctica and from Siberia with active life that had the organic content of a few million cells per gram."

http://cosmoquest.org/forum/showthread.php?12754-Levin-going-a-bit-too-far-in-his-zealotry


There may be life on Mars; I hope there is. If Curiosity finds evidence for life that wouldn't terminate the Mars Program, but instead it give it a greater urgency, at least until a sample-and-return mission could bring it back to Earth to be analysed. The discovery of life on Mars would be a very important event, and it would be very important to find out whether or not this life is related to Earth life or not.

If life on Mars is related to Earth life, that would provide evidence that life can be transferred from world to world within a solar system.
Don't you think that there is some danger of contamination with a sample-and-return mission of biological active microorganisms from the Martian soil?
As Levin point out in the space.com article
http://www.space.com/209-life-mars-scientist-claims.html


If indeed Mars is rife with life, care should be taken in hauling back to Earth specimens of rock and surface materials from the red planet. NASA has indicated that, next decade, robotic craft could be dispatched to gather and return to Earth select samples of Mars for detailed laboratory study.

Could those bits of Mars, perhaps laden with martian microbes, act as dangerous cargo?

As a precaution, Levin advocates a kind of bio-shield strategy for Earth - but using the Moon.

The new NASA vision to reestablish a human presence on the Moon is good timing, Levin said. "Bring samples of Mars not to Earth but to the Moon," he said. "There we would have built a scientific laboratory in which scientists could examine the samples and determine whether or not there is a hazard."

eburacum45
2013-Mar-25, 02:09 PM
Levin said. "Bring samples of Mars not to Earth but to the Moon," he said. "There we would have built a scientific laboratory in which scientists could examine the samples and determine whether or not there is a hazard." .
An excellent idea, if it encourages the use of the Moon for research purposes. Dangerous genetic engineering, nanotech weapons development, and quarantine arrangements could all be handled on the Moon, or perhaps more easily in orbiting research stations closer to Earth. Quite a few potentially dangerous processes might be best handled off the surface of the Earth; another reason to expand research operations into space.

MaDeR
2013-Mar-25, 05:14 PM
A possible explanation maybe that positive results so early in Mars exploration=no more funding for Mars life detection.
Wrong, wrong, wrong. This conspiracy thery does not hold. Look below.


How many probes were send to Mars since the Viking mission?
If life would be unquestionably discovered by Viking, we probably would be on Mars by now personally, in addition to untold bilions of $ poured in robotic exploration and research order of magnitude greater than we have now.


Also why they have never send another probe in the same area of the Viking mission?
Because we have entire planet to explore?

Don J
2013-Mar-25, 06:06 PM
Wrong, wrong, wrong. This conspiracy thery does not hold. Look below.

That is not a conspiracy theory that is a fact.
How do you interpret the reaction of the Biology Team Leader of the Viking mission when he saw the positive results of the LR and dismissed them by saying "Too much too soon"?see Page 6 point c, of the PDF.


If life would be unquestionably discovered by Viking, we probably would be on Mars by now personally, in addition to untold bilions of $ poured in robotic exploration and research order of magnitude greater than we have now.

Billions have been actually spend in the search for Martian life after the Viking mission while only one or two robotic missions would have been needed to collect sample from the 2 Viking site(s) which given positive LR results.


Because we have entire planet to explore?
Why not concentrate the efforts where the data showed LR positive results in an area where snow or frost on the surface of Mars was imaged by a Viking camera?see page 13 of the Pdf doc.
http://www.gillevin.com/Mars/THE_VIKING_MISSION_AND_LIFE_ON_MARS.pdf

beskeptical
2013-Mar-25, 06:34 PM
No, sorry, Just the abstract. I assume "macrofauna" would include everything from microfauna on up since the macrofauna would need something to eat...... I remember the original Viking findings as well. I was always curious as to why they initially thought it was a positive result but then backed down. If memory serves "they" decided it could have been just a chemical reaction having nothing to do with life.....
Phil Plait wrote about this explaining just what you are asking. But I can't easily find it. Maybe someone else knows the link.

Swift
2013-Mar-25, 06:41 PM
That is not a conspiracy theory that is a fact.
When probes were sent to Mars may be a fact, but your implication that somehow positive results for life from Viking were suppressed to obtain more funding is a conspiracy theory.

In any case, it once again has nothing to do with the OP, about the probability of Earth-sized planets in habitable zones of other stars.

This is strike 2 Don; if you drive this thread off topic again you will be infracted and the thread will be closed.

lpetrich
2013-Mar-26, 05:37 PM
Getting back to the original subject, I must say that I'm somewhat skeptical. It was about planets of *red dwarfs*, the planets that are easiest to detect with our techniques -- radial velocity and transit. It also helps that habitable-zone planets of red dwarfs orbit their stars relatively fast, allowing for faster discovery.

But can these results be reasonably extrapolated to the planets of Sunlike stars?

Systems like Gliese 581's don't look that much like the Solar System -- they are several super-Earths with no Jovian planets. So if they are typical, there will be some difficulty. But it could be that our Solar System is atypical.

Don J
2013-Mar-27, 06:23 AM
Getting back to the original subject, I must say that I'm somewhat skeptical. It was about planets of *red dwarfs*, the planets that are easiest to detect with our techniques -- radial velocity and transit. It also helps that habitable-zone planets of red dwarfs orbit their stars relatively fast, allowing for faster discovery.

But can these results be reasonably extrapolated to the planets of Sunlike stars?

I have provided a link in post 10 to a discussion page about that.
http://www.astrobio.net/interview/1694/m-dwarfs-the-search-for-life-is-on
"Astrobiology Magazine: So your odds of finding a planet in the habitable zone around any specific M dwarf are slim, but the total amount of habitable zone around all M dwarfs combined is equal to the total amount around sun-like stars."

"Todd Henry (TH): Right. And the bonus is that the M dwarfs, on average - if you had to look at 100 M dwarfs or 100 G dwarfs - are so much closer. So my bet is that we're going to find life on something going around an M dwarf before we find it around a G dwarf."

"AM: And the Sun is a G type star?"

"TH: Right. The sun is a G dwarf. G stars account for about 5 percent of all the stars in the Universe. And M dwarfs are at least 70 percent."

MaDeR
2013-Mar-27, 03:37 PM
Because it is OT, I will say only this:


That is not a conspiracy theory that is a fact.
You suggest conspiracy that is inclined to dismiss, downplay and hide evidence of life on Mars. While we have dozen of this kind of conspiracies, your variant is even less sane than usual - as apparently you think discovery of life on Mars would got NASA less money than non-discovery. This is completely nonsensical.

If you want to continue discussion, pelase create thread in "Conspiracy Theories" subforum. I can reply there.

Don J
2013-Mar-27, 04:06 PM
Because it is OT, I will say only this:


You suggest conspiracy that is inclined to dismiss, downplay and hide evidence of life on Mars. While we have dozen of this kind of conspiracies, your variant is even less sane than usual - as apparently you think discovery of life on Mars would got NASA less money than non-discovery. This is completely nonsensical.

If you want to continue discussion, pelase create thread in "Conspiracy Theories" subforum. I can reply there.
That is not what i have said at all.Reread post 38 for the context.
Here what i wrote:
-Billions have been actually spend in the search for Martian life after the Viking mission while only one or two robotic missions would have been needed to collect sample from the 2 Viking site(s) which given positive (life detection) LR results.-

Swift
2013-Mar-27, 05:19 PM
MaDer and Don J

When I say to stop an off-topic line of discussion, I mean stop it. There is no "last word" or "I just have to respond" exception to this. You are both getting "friendly reminder" infractions for this. Next time you get points.

If either of you want to discuss the topic, start a thread in the CT forum.

lpetrich
2013-Mar-27, 09:56 PM
I have provided a link in post 10 to a discussion page about that.
http://www.astrobio.net/interview/1694/m-dwarfs-the-search-for-life-is-on
A big problem with the habitability of Earthlike planets orbiting red dwarfs is that they will get tidally locked, and that may make their far sides cold enough to freeze out the ocean and at least some of the atmosphere. That would turn the entire near side into a desert.

However, some exoplanet climate modelers recent report that such a planet's far side will not get that cold if the atmosphere is thick enough to carry lots of heat to the far side.

But my main concern was whether one could reasonably extrapolate from red dwarfs to Sunlike stars. The planet statistics may be very different.

lpetrich
2013-Mar-27, 11:28 PM
Ten New and Updated Multiplanet Systems and a Survey of Exoplanetary Systems - Abstract - The Astrophysical Journal - IOPscience (http://m.iopscience.iop.org/0004-637X/693/2/1084?rel=sem&relno=9)
Abstract:

We present the latest velocities for ten multiplanet systems, including a re-analysis of archival Keck and Lick data, resulting in improved velocities that supersede our previously published measurements. We derive updated orbital fits for 10 Lick and Keck systems, including two systems (HD 11964, HD 183263) for which we provide confirmation of second planets only tentatively identified elsewhere, and two others (HD 187123 and HD 217107) for which we provide a major revision of the outer planet's orbit. We compile orbital elements from the literature to generate a catalog of the 28 published multiple-planet systems around stars within 200 pc. From this catalog we find several intriguing patterns emerging: (1) including those systems with long-term radial velocity trends, at least 28% of known planetary systems appear to contain multiple planets; (2) planets in multiple-planet systems have somewhat smaller eccentricities than single planets; and (3) the distribution of orbital distances of planets in multiplanet systems and single planets are inconsistent: single-planet systems show a pileup at P ~ 3 days and a jump near 1 AU, while multiplanet systems show a more uniform distribution in log-period. In addition, among all planetary systems we find the following. (1) There may be an emerging, positive correlation between stellar mass and giant-planet semimajor axis. (2) Exoplanets with M sin i > 1 M Jup more massive than Jupiter have eccentricities broadly distributed across 0 < e < 0.5, while lower mass exoplanets exhibit a distribution peaked near e = 0.
In Section 3.6. Multiplicity versus Stellar Mass:

... It appears that planets around M dwarfs may be found preferentially in multiplanet systems rather than singly. This trend, if it is not simply Poisson noise and should hold up as more M dwarf systems are discovered, is especially surprising since M dwarfs have a lower-than-average planet occurrence rate (Endl et al. 2006; Johnson et al. 2007a; Mayor et al. 2009).

There may be subtle observational selection effects at work here, however. If M dwarfs in general have lower mass planets than F-K stars (and thus require more observations before publication), then we may simply be seeing the already-documented increase in planet occurrence rate amongst low-mass planets. The ongoing RV M dwarf surveys will improve the statistics of these systems, which should help illuminate if the effect is due to selection effects, small numbers, or astrophysics.
So if M dwarfs have planetary-system differences from more massive stars, then it may not be very reasonable to extrapolate from them. So the number of habitable Earthlike planets for M dwarfs may not carry over into the number of habitable Earthlike planets for Sunlike stars. So it will be necessary to get statistics for Earthlike planets of Sunlike stars more directly.

eburacum45
2013-Mar-28, 07:21 AM
A big problem with the habitability of Earthlike planets orbiting red dwarfs is that they will get tidally locked, and that may make their far sides cold enough to freeze out the ocean and at least some of the atmosphere. That would turn the entire near side into a desert.

However, some exoplanet climate modelers recent report that such a planet's far side will not get that cold if the atmosphere is thick enough to carry lots of heat to the far side.


Exactly. A tidally-locked planet orbiting a red dwarf in the habitable zone will be either icy/desert two-face or warm thick atmosphere soup; neither are anything like the Earth, so any life that emerges there will be significantly different to Earth life (i.e., it's not just a matter of the inhabitants resembling an upright Troodon).

TheBrett
2013-Mar-28, 02:48 PM
Exactly. A tidally-locked planet orbiting a red dwarf in the habitable zone will be either icy/desert two-face or warm thick atmosphere soup; neither are anything like the Earth, so any life that emerges there will be significantly different to Earth life (i.e., it's not just a matter of the inhabitants resembling an upright Troodon).

Would all potential habitable planet orbits be close enough to lead to tidal locking around M-class stars? Most of the ones we've found so far that might be habitable were near the inner edge of their projected habitable zones (aside from the dubious Gliese 581g).

Don J
2013-Mar-28, 07:33 PM
A big problem with the habitability of Earthlike planets orbiting red dwarfs is that they will get tidally locked, and that may make their far sides cold enough to freeze out the ocean and at least some of the atmosphere. That would turn the entire near side into a desert.

However, some exoplanet climate modelers recent report that such a planet's far side will not get that cold if the atmosphere is thick enough to carry lots of heat to the far side.

Apparently ,it doesn't take that much atmosphere to redistribute the heat (experts said )..... if you have a little bit more than the Earth's atmosphere - .... that is what's required, but it depends on what molecules are in the atmosphere - you can actually stir the atmosphere up enough and move the heat around the planet. So it doesn't matter if it's tidally locked or not. You still have a good temperature on the whole surface.

More, about all aspects of the tidally locked planet thingy....
http://www.astrobio.net/interview/1694/m-dwarfs-the-search-for-life-is-on
Excerpts


TH: The big argument has always been that to put a planet in the so-called habitable zone [of an M dwarf], you have to move it in so close to the star - because the star is so much cooler and has less radiation - that it locks, just like the moon tidally locks to the Earth. And so you have the same face of the planet facing the star all the time. And if you do that, it has been said, that you'd be boiling away any atmosphere or ocean on the side facing the star and it would be trapped on the dark side and would freeze out.

It turns out that's probably not right. The locking would occur. But it doesn't take that much atmosphere to redistribute the heat. So if you have a little bit more than the Earth's atmosphere - I think that is what's required, but it depends on what molecules are in the atmosphere - you can actually stir the atmosphere up enough and move the heat around the planet. So it doesn't matter if it's tidally locked or not. You still have a good temperature on the whole surface. Some of it's faced toward the star, some of it's facing away from the star, and it doesn't seem to matter. That was the biggest hurdle to get over.

Then there were all kinds of details that go along with that. Not all planets would be tidally locked. There could be another planet in the system that forces it to be in some sort of resonance that would keep it spinning. You could have a slightly eccentric orbit that makes it wobble and librate like the moon does, back and forth. So the details can get you out of a lot of problems.

AM: You said that having an atmosphere a little thicker than Earth's could overcome the tidal-locking problem. But wouldn't being closer to the star mean that stellar radiation would be more likely to blow out the atmosphere completely?

TH: That is one of the big problems we came up with. I think that is the largest dragon-head that we saw, that you can sputter away the whole atmosphere - in about a billion years, was the back-of-the-envelope calculation. That really needs to be cleared up. That may be the biggest danger.

But you can get away from that as well. If you have a lot of radiation hitting a planetary surface and there's liquid on it, you're going to be creating atmosphere really quickly, as well. So you may sputter a lot away, but you might just keep regenerating it, so it's not a problem.

AM: Anything else?

TH: The other big gotcha was the intensity of the solar flares - we've sort of known about this for a while - whether you get X-rays and ultraviolet problems. When you're an organism sitting on a planet's surface, you really care about several things coming at you. One is X-rays, because they can damage any molecular structure that gets established. One is ultraviolet, for the same sort of reason, at slightly lower energies. One is particles that are coming from the star itself. And you might also worry about whether or not the spots on the stars change the overall flux of the radiation, whether you get enough visible or infrared radiation.

pleiades_blue
Blue stars in the Pleiades. These stars produce more UV radiation than red stars.
Credit: DSS and LTImage


Each of those four things could have been a major problem. But we pretty much decided that there were always ways around them. The best argument against the UV rays and the X-rays in particular is that an M dwarf emits most of that in the first billion years of its life. And once you're through that, then it gets pretty nice. So all the bad stuff happens early. So you just wait. You just wait for your habitable zone to stabilize and your star to stabilize. And then you've got billions of years to play around with the chemistry on the surface.

neilzero
2013-Mar-29, 12:13 AM
So far we have found zero planets tide locked to their star= The assumption that they are tide locked is based on math, not results. Have we confirmed any asteroids tide locked to our Sun? Moons tide locked to their planet are common, but possibly that is not the same thing. Neil

lpetrich
2013-Mar-29, 07:24 PM
neilzero, what are you claiming? That every exoplanet ever found rotates with respect to its star? Or that no exoplanet's rotation rate has ever been determined?

The latter assertion is pretty much correct, though there may be indirect evidence of rotation in at least one case: Mysterious 'Hot Spot' Seen on Distant Exoplanet : Discovery News (http://news.discovery.com/space/mysterious-hot-spot-seen-on-distant-exoplanet.htm)

The theory of tidal drag is reasonably well understood, the main problem being finding the dissipation rates of the tidally-distorted materials. Tidal locking - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Tidal_locking) has some of the math.

So a habitable planet of a M dwarf will be tidally locked to its star, unless it has unusually low tidal dissipation or it formed or had a super big collision very recently by astronomical standards.

Gomar
2013-Apr-18, 04:20 PM
Still a good place for the development of a reptilian/lizard-like life adapted to their planet environment.
What happened on Earth have also a good chance to happen somewhere else with the adequate condition.
Other prehistoric life ...before the dinosaurs.
http://dinosaurs.about.com/od/otherprehistoriclife/a/beforedinos.htm


The dinosaurs walked the Earth for hundreds of millions of years, without use of fire, the wheel, stone tools, writing, or any form of advanced tech such as electricity, irrigation, construction of brick structures(Pyramids), the internet, or anything beyond using their beaks, claws, and jaws.

Luckily for us, a meteor hit the Earth, the dinos died, and homo sapiens evolved, spread across the planet, etc.
This proves no species (birds, insects, beavers, amphibians, sharks, dolphins) besides primates who walk upright, have a large brain, and 5 fingers could built tech of any kind.
It's either primates, or none at all.

neilzero
2013-Apr-18, 05:06 PM
Evidence Gomar, not proof.

Nuemerious objects in our solar system have resonances with other bodies, so perhaps slow rotation in resonance instead of tide lock may occur frequently for planets very close to their Sun, especially if there is a gas giant planet that is almost as close to their Sun.

lpetrich
2013-Apr-18, 06:07 PM
Most nonhuman-primate species are not bipedal.

I recall Frank Drake proposing a present-day animal that could produce a successor sentient species: squirrels. I don't recall his arguments, however.

eburacum45
2013-Apr-18, 10:47 PM
Most nonhuman-primate species are not bipedal.

I recall Frank Drake proposing a present-day animal that could produce a successor sentient species: squirrels. I don't recall his arguments, however.

I'd go for meerkats, myself. Simples.

But remember, there are no squirrels on any other planet in the universe, unless they have been taken there by deliberate action. There may be creatures that resemble squirrels, but they will not be even remotely related to them, so should be given a different taxonomic label.
(The same goes for meerkats, and reptiles as well, of course).

KABOOM
2013-Apr-19, 05:28 PM
http://www.nasa.gov/home/hqnews/2013/apr/HQ_13-112_Kepler_62_finding.html


The Kepler-62 system has five planets; 62b, 62c, 62d, 62e and 62f. The Kepler-69 system has two planets; 69b and 69c. Kepler-62e, 62f and 69c are the super-Earth-sized planets.

Two of the newly discovered planets orbit a star smaller and cooler than the sun. Kepler-62f is only 40 percent larger than Earth, making it the exoplanet closest to the size of our planet known in the habitable zone of another star.

Very cool!

neilzero
2013-Apr-20, 02:03 AM
Does 40% larger mean 1.4 times Earth's diameter or Earth's surface area, or Earth's volume or Earth's mass? Neil

TheBrett
2013-Apr-20, 04:42 AM
Does 40% larger mean 1.4 times Earth's diameter or Earth's surface area, or Earth's volume or Earth's mass? Neil

It's actually referring to the planet's radius, which is 1.41 times that of Earth (meaning that its diameter is about 80-90% greater than that of Earth, and internal volume is 2.8 times that of Earth).

That actually makes me more optimistic for its possible rockiness and habitability. If it had the same density of Earth, it would only be 2.8 times more massive than Earth. It could even be less than that, if it had a density closer to that of Mars than Earth. I suppose it could be an oceanic planet like Kepler-22b, but it's pretty small compared to that.

lpetrich
2013-Apr-20, 10:37 AM
Kepler 22b now has its own Wikipedia article, and I learned from it that it's described as an ocean planet because its mean density is too low for it to have an Earthlike composition. That's from a radial-velocity upper limit.

galacsi
2013-Apr-20, 07:22 PM
It's actually referring to the planet's radius, which is 1.41 times that of Earth (meaning that its diameter is about 80-90% greater than that of Earth, and internal volume is 2.8 times that of Earth).

hum . . . If the radius is 1.41 times that of earth ,the diameter is also 1.41 times that of Earth !! (And the area is 1.41 squared times that of Earth ie 1.99 ,and the volume is 2.8 times that of Earth , as you said)

TheBrett
2013-Apr-20, 09:32 PM
My mistake. I didn't add that right. In any case, I'm hoping it's a rocky planet. That's pretty small for an oceanic planet or gas dwarf, unless it's basically a "snowball" that drifted in from Kepler-62's outer solar system.

All of this makes me wonder about the planets we can't spot with our current technology. We've spotted the five planets around Kepler-62, but I wonder if it's got outer solar system gas giants like our own that we can't see. Or would that show up in the orbit measurements?

Zwart Gat
2013-Apr-21, 09:43 AM
Mercury is tidally locked, but on an elliptic orbit with a 3:2 resonance, so it rotates anyway. Combined with potential moons and atmosphere, tidal locking doesn't seem to be a big problem. However, the variability of red dwarfs seems worse.

neilzero
2013-Apr-21, 11:39 AM
Our sun is variable, but only slightly and throws moderate CMEs. There are lots more red dwarfs, so possibly we are noticing the ones that are most hostle to planets that are close. Someone posted that red dwarfs are typically less hostile after they age a few billion years, which may be as much as 80% of the the nearby red dwarfs. Neil

Don J
2013-Jul-04, 01:41 AM
New data about Earth sized planets in the habitable zone around red dwarfs:a group of researchers has now doubled that estimate after considering how cloud cover might help an alien planet support life.


Though only about dozen potentially habitable exoplanets have been detected so far, scientists say the universe should be teeming with alien worlds that could support life.
The Milky Way alone may host 60 billion such planets around faint red dwarf stars, a new estimate suggests.
Based on data from NASA's planet-hunting Kepler spacecraft, scientists have predicted that there should be one Earth-size planet in the habitable zone of each red dwarf, the most common type of star. But a group of researchers has now doubled that estimate after considering how cloud cover might help an alien planet support life.
"Clouds cause warming, and they cause cooling on Earth," study researcher Dorian Abbot, an assistant professor in geophysical sciences at the University of Chicago, said in a statement. "They reflect sunlight to cool things off, and they absorb infrared radiation from the surface to make a greenhouse effect. That's part of what keeps the planet warm enough to sustain life."(snip)
....
In the new study, the researchers used 3D simulations to model the way air and moisture would move over a planet tidally locked around a red dwarf. The team found that any surface water would result in water clouds. What's more, highly reflective clouds would build at the point of the star-facing side where it's always high noon. This would have a cooling effect in the inner ring of the habitable zone, meaning the planets there would be able to sustain water on their surfaces much closer to their star, the researchers say.
(snip)...
The findings could give scientists a new way to confirm the presence of liquid water on the surface of alien planets with the James Webb Space Telescope (JWST), a new space-based observatory scheduled for launch in 2018, the researchers say.

"If you look at Brazil or Indonesia with an infrared telescope from space, it can look cold, and that's because you're seeing the cloud deck," Cowan said. "The cloud deck is at high altitude, and it's extremely cold up there."

The same could be true of a habitable exoplanet with a highly reflective cloud cover, the researchers say. If JWST detects a similar cold signal over the dayside of an alien world, Abbot said, "it's almost definitely from clouds, and it's a confirmation that you do have surface liquid water."

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