habitability on tidally locked planets: never surrender!

[h2ouniverse]

An article on newscientist:<br />http://space.newscientist.com/article/dn13030-twilight-zones-on-scorched-planets-could-support-life.html<br /><br />Tidally locked planets orbiting quickly on elliptical orbit around red dwarves should be relatively common... And were thought desperately unsuitable for life-as-we-know-it. Apparently, another too quick opinion, that should be thought about twice.<br /><br />Although I can imagine some issues with the atmosphere, the suggestion in this article is another example of the sound (and refreshing) "never say never" approach.

 

[qso1]

When they say unsuitable for life as we know it...that is leaving open the possibility for life as we do not know it...so IMO, they never said never to begin with. I doubt any astronomer or scientist would ever say no life is possible without some kind of disclaimer. Life as we know it has been one of the more popular disclaimers.<br /><br />As for the possibility itself, I would expect to find microbiological organisms thriving along the terminator line...and note my wording, I would expect being the key words. Meaning I do not rule out life all over such a world. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[robnissen]

Life would also be more likely is the planet had a thick atmosphere because the temperature would even out as winds would take heat from the light side to the dark side of the planet. <br /><br />Which also raises a question, if the atmosphere was thick enough to create a massive greenhouse effect, could an earth-mass planet be far enough away from a red dwarf to not be tidally locked, but still have liquid water?

 

[keermalec]

I would say most probably. Also note that if the atmospheric pressure is higher than on Earth, the boilling point of water goes up. So liquid water and presumably life can exist even at higher temperatures than on Earth. <div class="Discussion_UserSignature"> <p><em>“An error does not become a mistake until you refuse to correct it.” John F. Kennedy</em></p> </div>

 

[h2ouniverse]

When I mentioned the issue with the atmosphere, I was thinking to the following:<br />the atmosphere should condensate on the part of the ultra-cold face that is always in the night (as what occurs on Mars for water wapor on alternatively one pole and another), unless it is very very thick...

 

[qso1]

I wouldn't be surprised to find that an earthlike world can exist under the conditions you mention. It would even be considered more earthlike than say mars, or venus considering it would have water in liquid form and the necessary conditions to allow water to exist in that state. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[thebigcat]

I recall reading in one of the early Star Wars universe novels (yeah, I know...I was bored) something interesting. It was obviously based on what we had just learned about Mercury and the writer was trying to show off. (Alan Dean Foster, maybe?) It had a small planet close in, very slow rotation (see...Mercury) In the book, someone, maybe one of Jabba's associates, had a Star Destroyer mounted on the backs of a bunch of Walkers like the ones in <i>TESB</i> for a hidden headquarters. The walkers bore the Destroyer westward at a rate matching the terminator at that lattitude, just ahead of the sunrise. That allowed it to stay on the solid surface (midday temps melted rock) and still use solar panels for power generation.<br /><br />I realize that there are probably a dozen way it could have been done better, maybe more.<br /><br />Okay...planet tidally locked...But what's the orbital eccentricity and the rotational angle. If the planet did have these then there would be a variance in the terminator band, the "twilight zone" if you will, places where the star rose as much as 5 to 10 deg above the horizon. Think of that as the tidal pools of old Precambrian Earth. <div class="Discussion_UserSignature"> </div>

 

[qso1]

Thats correct. Life along the terminator line more or less would mean life developing in large concentrations perhaps as far from the exact terminator as 20 degrees and that life may vary in population depending on what could be seen as seasons. I'd have to work out an actual planet concept to see exactly how this might work. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[3488]

Hi TheBigCat,<br /><br />In reply to:<font color="yellow">Okay...planet tidally locked...But what's the orbital eccentricity<br />and the rotational angle. If the planet did have these then there would be a <br />variance in the terminator band, the "twilight zone" if you will, places where the <br />star rose as much as 5 to 10 deg above the horizon. Think of that as the tidal <br />pools of old Precambrian Earth</font> <br /><br />I like that comment. Such a zone in theory, dependent on thermal properties of the surface<br />& / or atmosphere, would be a pleasantly temperate place to be, a hospitable<br />zone between thew furnace of the permanenlty day portion & the potentially <br />cryonically cold permanent night portion. <br /><br />A very plausible situation IMO.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[3488]

Hi eburacum45,<br /><br />Another good point. Ther main concern I have with a planet with libration in excess of <br />90 degrees, would be the huge eccentricity required, resulting in very different <br />Periastron & Apastron distances, perhaps causing temperature swings that may<br />cancel out the effect of libration?<br /><br />Unless the atmosphere is dense I suppose, that would cause a lag effect that may neutralise <br />the effect over the short term of an orbit?<br /><br />Andrew Brown.<br /> <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[h2ouniverse]

in reply to<br />-----------<br />Basically the planet behaves almost as if it faces the empty focus of the ellipse<br />-----------<br /><br />So the cold face would be opposite to the star at periapsis and at apapsis.<br />= /> This makes two winters per year!<br />amusing...<br />

 

[qso1]

eburacum45:<br />If the eccentricity of the planet's orbit is large enough the twilight zone moves a full 90 degrees over the course of the year...<br /><br />Me:<br />In such a case, I would expect the spread of life to be much more uniform with perhaps more complex life concentrated in the ideal locations if there are any better than the planet has to offer overall. I'd hate to have to make the astronomical charts for that world. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>