POLL: When Will Humanity Truly Find an Alien Earth?

[StarRider1701]

Because, for all indication, at one time Mars wasn't tectonically dead. And Venus hadn't yet choked to death. And there are a LOT of organisms right here on earth that DO enjoy hell very much.

Yeah, but WE ain't one of those organisms. I interpret "Alien Earth" as a place where HUMANS might want to go and live. Sorry to be so selfish, but I don't really care how happy some tube worm is living off a volcanic vent in the bottom of the ocean. That don't do much for me, other than the fact that that might be where life originated way back when. But that is another topic.

To me, finding an Alien Earth is finding a planet that is about the right size and placement in orbit around its star to make it likely to be a life world - a place where humans will likely be able to live. Neither Venus nor Mars fit that discription, and we should be able to make such a determination even from many light years away. To me, a planet meeting those specific conditions would be worth the effort of sending a probe to investigate.

 

[StarRider1701]

After reading parts of the book "Rare Earth" and analysing the exo planet data i voted for a "slam dunk" nr 3. Our solar system is the exeption not the rule. Hot Jupiters, 5 day orbits, chaotic binary star systems is the way of the universe.

Oooh, a slam dunk!!! Gee, we've been able to see planets around other star for how long? Oh yeah, about a decade. Ten whole years. And until very recently, the only planets we have had the ability to see are the Gas Giants (like Jupiter and Saturn.) Oh yeah, that makes it a slam dunk alright! We've only had the capability to SEE the Jupiters of the Galaxy, so of course those just MUST be the only planets out there! We haven't found anything else! Except that now we have a little better technology searching and are beginning to find other things besides gas giant planets.

Slam dunk - NOT! You missed. The net, the rim, the backboard, everything! After only 10 or 12 years of being able to see planets, the only real thing that can be said about earthlike planets in other solar systems is - we haven't got a clue! But we're still looking and we'll find several good candidates fairly soon.

 

[kk434]

The nr3 choice doesn't mean that there are no habitable exo planets, only that current telescopes won't find them. Neither Kepler,Corot or HARPS can find and confirm a habitable world. To do that you need a Terrestial Planet Finder class telescope. Too bad it is cancelled but a lot of candidates found by Kepler may just revive it.

 

[MeteorWayne]

The discussion of alien messages received by Voyager has been split off to the Unexplained here:

viewtopic.php?f=17&t=25948

 

[3488]

I did think about doing that, but was not sure & was going to ask.

Andrew.

 

[Yuri_Armstrong]

After reading parts of the book "Rare Earth" and analysing the exo planet data i voted for a "slam dunk" nr 3. Our solar system is the exeption not the rule. Hot Jupiters, 5 day orbits, chaotic binary star systems is the way of the universe.

I voted the middle option because planet hunting is a pick them off one by one process, and finding Earth-like planets with good conditions will be difficult to do with today's instruments. I expect to see an exponential increase in planet finding technology though.

It really is a stretch to say that our solar system is a rare exception. There are plenty of sun-like stars in our galaxy alone, and binary stars can possess Earth-like planets as well. Also remember it's a lot easier to find super gas giant planets than it is smaller terrestrial ones that could be Earth like. The current data is simply not good enough to make a sound prediction either way. The key here will be patience as missions like the Terrestrial Planet Finder and ESA's Darwin hopefully come to fruition.

 

[ZenGalacticore]

Can we all agree that one, central characteristic that would define an "alien Earth" is an abundance of liquid water? Which of course, would indicate favorable temperatures for life as we know it.

 

[adrenalynn]

Can we all agree that one, central characteristic that would define an "alien Earth" is an abundance of liquid water? Which of course, would indicate favorable temperatures for life as we know it.

Yes - but given again the 't' factor - wouldn't that appear to include Mars? All signs, especially of the last few years, seem to suggest it had some pretty awesome conditions, ie. standing water, before its core seized up and it shed its atmosphere.

 

[ZenGalacticore]

Can we all agree that one, central characteristic that would define an "alien Earth" is an abundance of liquid water? Which of course, would indicate favorable temperatures for life as we know it.

Yes - but given again the 't' factor - wouldn't that appear to include Mars? All signs, especially of the last few years, seem to suggest it had some pretty awesome conditions, ie. standing water, before its core seized up and it shed its atmosphere.

It used to include Mars. But liquid water can no longer exist on Mars due not only to the average temps on most of the planet, but the absence of the right atmospheric pressure. Although that doesn't mean we won't find some type of life there. (I'd be happy with fossilized microbes, because hopefully we'd be able to determine whether or not they were DNA-based, among other things.)

But if you told a travel agent in the far future that you wanted to spend some time on an abundantly wet, temperate world, and he secured spacecraft tickets to Mars for you, I think you'd be a bit irate.

It is a darn shame that Mars didn't turn out 7 or 8 times more massive than it is, since if it was, the odds are good that we would be occupying a system with two living worlds.

 

[adrenalynn]

Right - but that's exactly my point. Potentially "alien-earth-like" worlds likely come and go in a virtual blink of the proverbial eye.

By the time we observe one, and ship some probe off to it, it's likely to be deader'n a doornail. Or we overlook one that is going to be alive tomorrow today.

 

[Sycamorefan]

Some very good points Adrenalynn! If Aliens From the Andromeda galaxy were viewing our solar system today, they would see 2 potentially habitable worlds with lots of liquid water. Sadly, Earth wouldn't be one of them. Earth would still be a Volcanic Hell, reeling from the impact of the 2 lesser planets that created it. In as little as 50,000 years, both Mars and Venus Probably lost both their magnetic fields and it all went downhill quickly from there due to Solar Wind Erosion. This is why NASA needs to look much closer for habitable worlds than 10,000 light years away!

 

[Sycamorefan]

My Wife says I'm Slamming NASA too much on my posts... Ok, I probably am. It's just frustrating to know that if NASA could REALLY find an Alien world that had liquid water on it's surface, Methane & Oxygen in the Atmosphere & ANY detectable traces of Chlorophyll, it would stop ALL the budget cuts NASA has had to endure recently. Nothing would excite the public imagination more than a living alien world actually found, except meeting Intelligent ET's. We already have the resources and technology built to do this. Hubble CAN do this already( Spectragraphic Analysis ), it would just need to be re-tasked!

I think my next post will be a check list of what I think a Habitable Alien world/solar system will look like!

 

[MeteorWayne]

What an optimist. I doubt the public would care at all, nor give up any of their tax money to support such investigation,

 

[3488]

Right - but that's exactly my point. Potentially "alien-earth-like" worlds likely come and go in a virtual blink of the proverbial eye.

By the time we observe one, and ship some probe off to it, it's likely to be deader'n a doornail. Or we overlook one that is going to be alive tomorrow today.

Very true adrenalynn. BTW welcome back to SDC, hopefully you can stay with us.

A truly Earthlike planet may indeed last for only a very short period of geological time as compared to the age of it's solar system. Chemical balances in siad atmosphere is vital. Too little O2, then only creatures with very low metabolisms could survive, too much, there is a risk of global firestorms as lightning strikes vegetation or a lava flow makes contact with vegetation in a very oxygen rich atmosphere, etc.

Or planet like Earth but is the love child of Io, i.e an oceanic world, but so geologically active that mega tsunamis are forever crashing across continents & gigantic volcanoes are causing ash clouds that induce dramatic climatic swings on short timescales, or has no large moon to stabilise, so the planet's axial tilt is all over the place over short time periods, etc.

Welcome to SDC Sycamorefan,

You too raise excellent points. I certainly think the Rare Earth hypothesis is the corrext one. It does NOT mean that Earth is unique, but it means that they are extremely rare in the planetary zoo.

I do not think we will find a TRULY Earthlike planet any time soon, possibly not in any of our lifetimes. We will find planets that are the same sort of mass & size of Earth very soon, before this year is out maybe or certainly next year, but an Earth 'clone', I reckon not for at least 50 or so years yet, due to the fact that there are so many candidate sunlike like G type stars, many of which have planets, but then most of those are likely to have hot Jupiters, hot Saturns, hot Neptunes, etc, or giant planets is vastly elliptical orbits, or have gigantic asteroid belts, providing many impactors, etc.

We'll see.

Andrew Brown.

 

[3488]

What an optimist. I doubt the public would care at all, nor give up any of their tax money to support such investigation,

I am afraid you are correct there Wayne. All too correct there.

There must be a huge push into the investment of science, this being a big part of it.

Andrew Brown.

 

[adrenalynn]

Agreed. Finding candidates is one thing. If we want to robotically _go there_, we really need world-wide contribution. And it's hard to get the patriotic rah-rahs that we needed to have to go to the moon on a world-wide scale. With the world economy in a tail-spin and the general consensus [that I observe in my personal life] of just wanting to lynch anyone with a brain - I find it unlikely that we'd fund such a venture. Sorry, Sycamore. I really wanted to agree with you.

It's kinda twisted. We live in probably one of the greatest ages of discovery imaginable - but "no one" cares.

[thanks for the welcome-back! I only stopped in for a minute, and ended-up building a summer home... Intelligent discourse always traps me!]

 

[ZenGalacticore]

It's kinda twisted. We live in probably one of the greatest ages of discovery imaginable - but "no one" cares.

I care.

 

[adrenalynn]

If I've told you once, I've told you a million times:

Don't criticize my rhetorical devices! :lol:

 

[Sycamorefan]

OK, here it is! This is what a star system with 2 HABITABLE MOONS should look like by the numbers:
Main Star Choices: M1V (Red Dwarf) or a K4V (Orange) Note, both of these star classes Together are 14 TIMES more plentiful than Yellow Stars
Planet: #1 -A gas giant/Brown Dwarf with a mass 14x bigger than Jupiter, that orbits the star in an eccentric orbit of 20%, thats .32AU-0.4AU or 41.6M Km - 52.08M Km. Yeah, I know 0.4 AU is just slightly outside the habitable zone of these star types, but I factored in the gravitational tidal effects of this body on my moons and it raised the average surface temp a little!
Planet: #2 - another gas giant 2x larger than Jupiter, that orbits with 15% eccentric at 2.75 AU - 3.16 AU. This planet serves as a asteriod/ comet shield for the exomoons
Planet: #3 - Yes, another gas giant the same size as Saturn, that orbits with a 10% eccentric at 5 AU - 5.5AU. This planet also helps to block out those pesky life killing space rocks!
Planet #4 - I know its getting old, but yes, ANOTHER Gas Giant! This one is appx. the size of Neptune with a 5 % Eccentric at 7 AU - 7.25 AU. Do I really need to Explain this one any further!

Exomoon A around Planet#1: Is a little bigger than mars, but nearly twice the mass. it 4100Km in Diameter, has a Density of 3000Kg/M Sq., A surface gravity of .57G, Has a Mag. Field Strength of .0002 Tesla, Orbits Planet#1 at .011AU (1432200Km) in a nearly circular orbit 22 degrees Inclination N of Planet#1 Equator. It has changing seasons a lot like the Earth and the average day cycle here( on the outward facing side ) is 28 hours, 14 hours of daylight every day!

Exomoon B around Planet#1: Is a little smaller than Venus, 9200 Km Diameter, 4400Kg/ M Sq Density, .7G Gravity, A Mag Field Strength of 0.00015 Tesla ( Earth's is 0.0005 ), Orbits Planet#1 at .02 AU (2604000Km) in a nearly circular orbit at 37 Degree Inclination S of Planet#1 Equator. The average day cycle here is 46 Hours, 23 hours of daylight and seasons like the other exomoon! :mrgreen:

 

[Smersh]

What exactly do you mean by "alien earth" anyway?

Something with vegetation? Microbial life?

Good question I think and perhaps Tariq should have clarified exactly what he meant by that. I've taken it to mean a planet with oxygen, land, oceans, clouds and perhaps signs of vegetation. Very similar to the way our own planet would appear, if viewed with similar equipment from a similar distance in fact.

I voted for option 1 anyway. I'm optimistic that with the rate we are discovering exo-planets at the moment, and the speed we are improving our technology to be able to do so, we won't have too long to wait before we detect a planet that appears very similar to our own.

 

[Yuri_Armstrong]

OK, here it is! This is what a star system with 2 HABITABLE MOONS should look like by the numbers:
Main Star Choices: M1V (Red Dwarf) or a K4V (Orange) Note, both of these star classes Together are 14 TIMES more plentiful than Yellow Stars
Planet: #1 -A gas giant/Brown Dwarf with a mass 14x bigger than Jupiter, that orbits the star in an eccentric orbit of 20%, thats .32AU-0.4AU or 41.6M Km - 52.08M Km. Yeah, I know 0.4 AU is just slightly outside the habitable zone of these star types, but I factored in the gravitational tidal effects of this body on my moons and it raised the average surface temp a little!
Planet: #2 - another gas giant 2x larger than Jupiter, that orbits with 15% eccentric at 2.75 AU - 3.16 AU. This planet serves as a asteriod/ comet shield for the exomoons
Planet: #3 - Yes, another gas giant the same size as Saturn, that orbits with a 10% eccentric at 5 AU - 5.5AU. This planet also helps to block out those pesky life killing space rocks!
Planet #4 - I know its getting old, but yes, ANOTHER Gas Giant! This one is appx. the size of Neptune with a 5 % Eccentric at 7 AU - 7.25 AU. Do I really need to Explain this one any further!

Exomoon A around Planet#1: Is a little bigger than mars, but nearly twice the mass. it 4100Km in Diameter, has a Density of 3000Kg/M Sq., A surface gravity of .57G, Has a Mag. Field Strength of .0002 Tesla, Orbits Planet#1 at .011AU (1432200Km) in a nearly circular orbit 22 degrees Inclination N of Planet#1 Equator. It has changing seasons a lot like the Earth and the average day cycle here( on the outward facing side ) is 28 hours, 14 hours of daylight every day!

Exomoon B around Planet#1: Is a little smaller than Venus, 9200 Km Diameter, 4400Kg/ M Sq Density, .7G Gravity, A Mag Field Strength of 0.00015 Tesla ( Earth's is 0.0005 ), Orbits Planet#1 at .02 AU (2604000Km) in a nearly circular orbit at 37 Degree Inclination S of Planet#1 Equator. The average day cycle here is 46 Hours, 23 hours of daylight and seasons like the other exomoon! :mrgreen:

Those are some very precise numbers sycamore! A system with TWO habitable moons but 4 gas giants... it does sound plausible. Whoever lived there would have quite the view

Good question I think and perhaps Tariq should have clarified exactly what he meant by that. I've taken it to mean a planet with oxygen, land, oceans, clouds and perhaps signs of vegetation. Very similar to the way our own planet would appear, if viewed with similar equipment from a similar distance in fact.

I voted for option 1 anyway. I'm optimistic that with the rate we are discovering exo-planets at the moment, and the speed we are improving our technology to be able to do so, we won't have too long to wait before we detect a planet that appears very similar to our own.

By earth like I think it should be defined as habitable by humans. If conditions were right for us, then it would be good for a huge ecosystem of life like we have here on Earth.

We've already found a potential one, Gliese 581 d. Trouble is our technology isn't good enough to say that it's definitely probable, but chances look good. I'm betting 10 years tops until we find another earth-like world, be it planet, moon, or "dwarf" planet. Hopefully we will find more potential planets like Gliese and will study their characteristics in better detail.

Someone mentioned the time effect that what we are seeing in these other stars is from the past, but in our neighborhood of about 30 light years that is practically nothing on the gelogical time scale. If we were discussing thousands of light years then yes that would be a concern but at 20 light years it's not that big of a deal.

Then after we find these candidates and determine that they are earth like, the next step is to attempt to detect light that could possibly be coming from cities on those worlds. This may have a better chance of locating extraterrestrial life than SETI. The next 10-20 years of planet hunting will be very exciting. I'm looking forward to this mission:

http://en.wikipedia.org/wiki/Terrestrial_Planet_Finder

I was a bit dissapointed to see that Gliese 581 was not on their list of top stars to study, but hopefully they will be sure to check out that system in addition to the others. The Rigil Kent system should definitely be the first one to investigate though, since it is so close to us. I await many fascinating discoveries by the TPF if they ever get it off the ground, and hoepfully the ESA will eventually launch something like the Darwin mission.

 

[Sycamorefan]

I strongly suspect that Gliese 581d will have life forms on it, but the hellish conditions on most of the planet will probably prevent it from becoming home to anything but simple life forms (Sponges, Jellyfish & etc). Class M (red dwarf) stars have 3 major problems that a stand alone terrestrial Planet can't overcome:
1. The Habitable Zone is so close to the star that any planet in that zone is Tidally Locked, Which means that they can't rotate on their axis like earth does, one side always faces the star and cooks, and the other gets no sunshine and freezes. Sort of like our moon.
2. Red Dwarf stars tend to have violent outbursts of Solar Flares, with lots of deadly radiation, if any Gas Giants are within 0.12 AU Due to gravitational Tidal forces of the Planet. Gliese 581b is just big enough and just close enough to be that kind of problem.
3. A tidally locked world would have no seasons, therefore one less important avenue to prevent thermal runaway like the greenhouse effect gone wrong( Like Venus ).
I very sorry to rain on parade like this, but stand alone Terrestrial worlds are going to be very, very, very rare and only found around certain K (orange) and G (Yellow) class stars. There are just too many factors that have to be almost perfect for them to exist. Think Exomoons like Pandora, Endor or Yavin 4. Little imperfections of Gravity, Tidal locking, eccentricity, Solar flares and gas giants in the habitable zone aren't problems, if fact, there needed!

 

[Sycamorefan]

Oops, I made a mistake on the diameter of the smaller exomoon! I put it in miles, not Km! So instead of 4100 MILES, it should have been 5740 KM. Glad I caught that, I wouldn't want those guys from NASA pointing that out for me!

 

[StarRider1701]

I agree that we are finding some really great looking moons in terms of numbers. On paper they may look good, BUT...

How many moons are in our solar system? How many of them might look good on paper from another solar system using our current technology? I will be VERY skeptical about any moon being considered habitable, especially from this distance. I would be much happier about an actual planet considered habitable using those statistics and much liklier to expend funds for a probe to a possible habitable planet rather than a maybe moon.

 

[phaze]

I think we'll find one just about as soon as our technology allows us to.