Planet Gliese 581 g - Could it support life?

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How do you find life on an alien planet?
By Mike Wall
updated 10/1/2010 1:39:01 PM ET

After spending decades searching for alien planets capable of harboring life, astronomers may have found one. So how can they check to see if life actually exists on this alien world?
On Wednesday, a team of researchers announced the discovery of Gliese 581g, a rocky, roughly Earth-size planet in its parent star's so-called "habitable zone" a just-right range that can allow liquid water to exist.
One of the planet's discoverers said during a briefing that, in his personal opinion, "the chances of life on this planet are 100 percent." To determine if this is true, researchers will have to scrutinize Gliese 581g from afar, searching its atmosphere for certain telltale molecules.But it might be a while before they have the tools to do this properly.
Gliese 581g isn't far from Earth in the great scheme of things — only 20.5 light-years or so. But that translates to about 120 trillion miles (194 trillion kilometers) — 500 million times farther away from us than the moon. [ Tour the six Gliese 581 planets]
So human-built probes won't be getting out there anytime soon. But one way to look for life on Gliese 581g is to turn our radio telescopes toward the planet, searching for patterns in emissions of electromagnetic radiation.
Such patterns could indicate the presence of intelligent life, according to Seth Shostak of the SETI Institute in Mountain View, Calif. The Gliese 581 star system has intrigued researchers for a while, so they've already taken a few looks. During SETI's Project Phoenix, which surveyed almost 1,000 star systems from 1995 to 2005, astronomers looked at Gliese 581 twice, Shostak said.
"No signal was found during these observations," he told Space.com.

What's in your air?
Life doesn't have to be intelligent and advanced for astronomers to pick it up. Studying Gliese 581g's atmosphere, for example, could theoretically reveal the presence of organisms as simple as microbes.
This method assumes the alien planet has an atmosphere, likely a necessity for life to take hold. Gliese 581g's discoverers reported that the planet's gravity is probably strong enough to hold onto an atmosphere, but they didn't definitively detect one.
"The first thing is, you've got to have an atmosphere," said Bill Borucki of NASA's Ames Research Center, the science principal investigator for NASA's planet-hunting Kepler mission. "If there is one, then what's the composition of that atmosphere?"
If astronomers detect the signatures of large, complicated compounds like chlorofluorocarbons, which people have manufactured to use as refrigerants and propellants life is likely, according to Borucki.
"You're looking for chemicals like that," he told Space.com. "If they're there, somebody's making them."
But other, simpler chemicals could also be strong evidence for life, as long as their ratios are right.
"Ideally, you'd be looking for a complement of compounds that normally don't exist in chemical equilibrium," said Jon Jenkins of the SETI Institute, the analysis lead for the Kepler mission.
As an example, both Jenkins and Borucki pointed to methane and oxygen.
"You typically don't have both gases present in significant quantities unless life is present," Jenkins told Space.com. But scientists would have to be careful how they interpreted such information, he added, because we don't know much about how other planetary systems tick.
"Though scientists get excited about these discoveries just like the public does, we also tend to be pretty cautious," Jenkins said

Tough job for today's tech
So scanning Gliese 581g's atmosphere, if it has one, would give us a good idea if the planet harbors life or not. But it'll probably be a few decades before we can do this properly.
Astronomers have characterized the atmospheres of alien planets before. But those other worlds are bigger and much hotter, meaning they throw off lots of radiation for our instruments to pick up. Gliese 581g is relatively close to Earth, but its other traits make it a tough read.
It's only about three to four times as massive as Earth, for example, with an average surface temperature between minus 24 and 10 degrees Fahrenheit (minus 31 to minus 12 degrees Celsius).
"Because they are cool and small, planets like this are very difficult to study," Jenkins said. "It's easier to detect something than to characterize it in detail."
Jenkins said that Gliese 581g also apparently doesn't transit its parent star, meaning it doesn't cross in front of it from our perspective on Earth. Astronomers can learn a lot about a planet's atmosphere by studying starlight that passes through it, but this technique is likely not an option with Gliese 581g.
As a result, the tools astronomers currently have at their disposal likely can't determine what's in Gliese 581g's air, according to Borucki and Jenkins. So researchers will have to wait for new instruments to come into play.

A few decades away
One promising tool mentioned by Borucki, Jenkins and Shostak is NASA's proposed Terrestrial Planet Finder (TPF) mission, which would use an array of telescopes orbiting Earth to generate detailed images of alien planets.
TPF would employ advanced techniques to reduce the glare of the exoplanets' parent stars, allowing the mission to pick up faint radiation coming from planets. The mission could theoretically detect chemicals like methane and oxygen in the atmospheres of alien worlds such as Gliese 581g.
The TPF mission, however, is in limbo. It is currently unfunded, with no launch date set. So researchers will probably have to wait a while before they can see what Gliese 581g's atmosphere is made of.
Whenever TPF, or something like it, comes along, it may have a long list of planets to check out, Jenkins said.
"I would predict that [Gliese 581g] is just the tip of the iceberg," he said. "Fifteen or 20 years ago, very few people thought we'd be discovering such extrasolar planets anytime soon. This find just shows how far we've come."

My wishful thinking is off the charts. :D But of course I'm pretty skeptical. Who wouldn't be?
 
I've always subscribed to the theory that there is such an unfathomable amount of planets and star systems in our universe, it makes the probability of alien life almost 99.99999%. Hopefully someday aliens will visit and we can have sex with them, like Will Riker did when those aliens kidnapped him.
 
I think we will discover alien life in my lifetime. Whether it's intelligent, evolved life is another matter.

I hope they name the planet "Goldilocks" BTW.
Then, they could be called "Goldlockians"--which sounds cool.
 
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This size of the universe is something I like considering, our knowledge or theories about it keep changing (evolving).

I think it is a forgone conclusion that life exists on other bodies in space.
Our water (or most of it) may have been brought to earth by asteroids.

Complex life, or even intelligent life out there, someplace? Yes, very likely.
That we will even encounter it. Very, very unlikely.

This new planet, how far away is it?

The star Gliese 581 is in the constellation Libra. It is one of one-hundred stars that are closest to the Earth. Its distance of 20.5 light-years (LYs) away makes it about 123 trillion miles (205 trillion kilometers) from the Earth. (One light-year is the distance that light travels in vacuum in one year—a distance of about 6 trillion miles, or 10 trillion kilometers.) In addition, the star is about one third the size of the Sun.
 
Been over this one before, but our own galaxy is what, 100,000 light years across? We are stuck out in the boondocks on a fairly minor spiral arm. If, hypothetically, some comparable species arose in a star system near the opposite edge, any contact physical or otherwise between them and us would take at least 100,000 years from the time at which they reached a suitable level of advanced civilisation. This is a problem because although we don't know anything about (hypothetical) aliens, right here on Earth it remains to be seen whether functioning high technology civilisation can escape its own bottlenecks and last for 100,000 - let alone 20,000 - years. Sure, the aliens would be unimaginably more advanced than we are (yeah, sure, take it as given! or not), but it takes resources to get up that first mountain, no matter who you are.

We could be one of the older species, or we could be one of the latterday species. Either way others could have done their dash, risen and fallen, long before us... or still exist at a microbial level (and there's nothing to demand that life will always get beyond that; don't they speculate that a couple of the ice moons in our own system might host such life?)

All of which is to say, meh.

And even the twenty light years to Gliese 581g? Notwithstanding some of the more wild and wacky predictions, on any forseeable human technology the colonisation of that star system would create a permanent alien civilisation of our own. It would be comparable to the isolation of Australian, American and Eurasian peoples in our own deep past. And we all know how well that worked out.

Well alright, there's always a forty-year round trip of lightspeed communication, there's that. But what's to say the folks at the other end might not develop their own differing priorities. Forty years is a while.
 
I find it funny how we assume they're in some way like us.

As if life cant exist in another manner. As if it needs H2O. As if they need the same conditions as us. As if they need oxygen. As if they would produce CFC's. As if our habitable zone is equivalent to their habitable zone. As if they understand what we understand.

The development of our lives is so incredibly complex. Perhaps not nearly as complex as the universe is vast, but none the less incredibly complex. Do I doubt that life exists outside of our planet? Of course it does. The universe is seemingly infinite. Do I think there is any species or race of life that is human out there? Not without a God, no sir.

We are so incredibly complex. That needs to be understood. Even under the exact same conditions, atmosphirically, planet-wise, etc. humans could not be replicated. That needs to be understood. In fact, that applies to any complex species. Or even one-cell organisms.

If life exists, which I'd say it more than likely does, it's not like us(which isnt to say it's not intellegent). Even the concept of male and female is questionable. Unless a Godly being made it happen, I really do not think life exists as we know it.
 
All the planets that are unlike ours, that we're able to relatively closely observe, dont contain life. therefore, it's not unreasonable to assume that it takes the same conditions that made life on Earth possible to make life on other planets possible. I dont think anyone is assuming they would look anything like us. Those comments are mostly made in jest.
That's not to say it would be impossible to find life on a very different environment, but if we're going to be looking, we might as well explore the more obvious avenues first
 
How is that statement valid (I mean this in no disrespect)?

"All planets that are unlike ours, that we're able to relatively closely observe, dont contain life. "

Well at the same time... all planets that are similar to ours, that we're able to relatively closely observe... also do not contain life.

Well I mean... both statements are true. Because we've never found life!

The point I'm making is that we're making so many things 'common sense' if you will... when in reality even the smartest of scientists appear to not think outside the box.

I'm always told of how unfathomable the size of the universe is. And that we cannot comprehend it. I mean... infinite. I get it. Never ending. Always expanding. So if that's the case... how is it not the case that even the very real laws of physics, or the laws of sustaining life as we know it, are not different elsewhere in the universe? I mean... if it's really infinite... who is to say that 1000000000 light years away (excuse my exaggerations) the laws of physics are the same?

We assume too much. Temperature seems ideal for us between 0 and 100 farenheit. But temperature is just a measure based upon our life forms. Who is to say 5000 farenheit to 6000 farenheit is not the ideal temperature for living being x?

Think about stuff like this.

Time as we know it... a year is a long time. What about a dog? Does everything go slower in a dog's life, or do they just live shorter live as a whole? Hell we'd never know considering we can neither communicate with a dog on an intellegent level nor could we ever be a dog. It sounds stupid, but keeping an open mind is important.

Time as we know it could be completely upside down to another species of life. With a never ending universe, there are never ending possibilities. And I think that's what is so incomprehensible.
 
Well no, the laws of physics are consistent (or consistently weird) across this universe. That's kind of how scientists can say anything meaningful about it. That can't rule out under what odd conditions some other lifeform might find itself able to flourish. Oxygen might not be a prerequisite, in fact it was toxic to the earliest forms of Earth life, but I suspect that water above freezing would be.
 
See that's just the point. I'm fully aware that the laws of physics are consistent. As to well regarded theory.

But excuse me... have we even left our solar system? I think not.

I'm not serious in claiming that the laws of physics may not apply elsewhere in the Universe. I'm just making a point that we wouldn't know because we will never, ever in our lives or our children's children's (500 times over) lives be able to experience what the 'other side' if you will (take that for what its worth), of the universe is like.

Again, I'm not claiming that the laws of physics would be different elsewhere. I'm just pointing out that we are assuming stuff based upon theory. Stuff that is not even proven fact. It is assumed fact.

I would suspect that life as we know it requires water.

I would not suspect that life as we do not know it, which is a very real possibility, requires water.
 
forgive me if i'm wrong, but isn't it at least a necessity to have water for life (as we know it, i won't bother thinking about all the what-ifs) to exist at all? the atacama desert springs to mind as there are some parts of the desert with no life whatsoever. again, like i said sure there may be some aliens on planet x that live off mercury and plutonium instead, but we don't know for sure so i personally am not going to bother stressing over that stuff.

but anyway, water is a bit of a necessity. while the universe is seemingly infinite, sure, if it's too ridiculously cold or hot or the atmosphere isn't right then there can't be any water. no water, no life.
 
Scientists have been sending out radio signals since the eary 1950s.

Everybody knows the rest of the galaxy has been using satellite radio for centuries, they haven't touched the AM or FM dial since B.C.

Is this really the basis for your belief? Or is yours a religious one?
 
How is that statement valid (I mean this in no disrespect)?

"All planets that are unlike ours, that we're able to relatively closely observe, dont contain life. "

Well at the same time... all planets that are similar to ours, that we're able to relatively closely observe... also do not contain life.

Well that's just the thing. What planets have we found that are similar to ours? Is this not the closest we've found yet? It's not a very common situation and we havent really had the opportunity.
I get what you're saying, but it makes more sense to think that, under similar conditions, similar chemical processes may have taken place.
 
Certainly it makes sense to look their first. We should look elsewhere and think big, though.

But going back to my original post, I'm just saying that I find it amusing that everything that we are looking for, the standard, is us, right down to the oxygen that we breath. They seem to want to turn their head if our conditions are not met.
 
Probably because it's not worth spending all the time and money finding if it's not something that our human race can use and eventually exploit. Not saying that's how I feel, but it is a common criticism of space exploration....for all the money, resources, and even the lives lost, what really have we achieved?
 
Probably because it's not worth spending all the time and money finding if it's not something that our human race can use and eventually exploit. Not saying that's how I feel, but it is a common criticism of space exploration....for all the money, resources, and even the lives lost, what really have we achieved?

Unless our neighbors are much closer than we originally thought, I doubt we will ever exploit anybody. Considering matter cannot travel the speed of light, you'd literally have to develop technology that travels almost exactly the speed of light. In which case, it's a 40 year round trip for us to exploit them.

And yes, achieving knowledge. It is the human desire to know more.
 
Probably because it's not worth spending all the time and money finding if it's not something that our human race can use and eventually exploit. Not saying that's how I feel, but it is a common criticism of space exploration....for all the money, resources, and even the lives lost, what really have we achieved?

Know anyone who has had Lasik eye surgery? That's a direct result of our space program.

GPS? Satellite communications? Material science research?

Okay, it's not the cure for cancer (yet), but the beneficial spill-over from space and military tech spending is almost immeasurable at this point.
 
Again, I said that is not how *I* feel about it, but I have heard the space programs criticized MANY times for the amount of money and resources it has exploited trying to get to this, trying to find that to no avail. But, with all the crap going on right in front of us, I think at this point I'd trade in my local Lasik surgeon and GPS unit for, say, basic healthcare and halfway decent primary education for all...
 
Again, I said that is not how *I* feel about it, but I have heard the space programs criticized MANY times for the amount of money and resources it has exploited trying to get to this, trying to find that to no avail. But, with all the crap going on right in front of us, I think at this point I'd trade in my local Lasik surgeon and GPS unit for, say, basic healthcare and halfway decent primary education for all...

Didn't mean for it to come off as an attack.

And yes, basic healthcare versus Reagan's Star Wars program that got us Lasik--absolutely.

There are so many thing our government wastes money on, but any money spent on research is okay in my book. It generally is spent in the U.S. It helps universities' research programs and keeps us ahead of the rest of the world economically.

Anyway, Obama is NOT a space exploration advocate, so there will probably only be minimal spending on it in his tenure.
 
Scientists have been sending out radio signals since the eary 1950s.

A whole lot more than scientists have been sending out radio waves since the 1950's. That's not the point, a radio wave sent out, in the manner in which we Earthlings would do, would dissipate greatly in intensity by the time it reaches the nearest star*.

Yes, that's nearest star. Not even out of our galaxy.

It would take an incredibly strong radio wave to make it to the nearest star and be detected. We could do it but would probably never do such a thing. The point is, they'd need to be listening really closely...and the greater distance traveled, the weaker the signal/wave as it dissipates.

Which is precisely why SETI listens, rather than broadcasts.

You also have to figure the UNFATHOMABLE distances these waves would have to travel to reach one of these Earth-like planets.

I tend to find that skeptics on this issue haven't thought much about the Cosmos. Because we haven't found anything in the year 2010 in our little (less than a) grain of sand in this corner of the Universe, means essentially nothing.

We can't put a man on Mars, which is right next door and you'd wonder how an alien lifeform...anywhere else in the Universe can't contact us? Our receive one of our teeny radio waves and then have to SEND IT BACK?

ETA*
Need to clarify, the radio waves DO make it to the nearest star, it's just...beyond a crapshoot that they would be able to detect something that small. They would have to be listening and looking in the exact right place unless it were something much bigger.
 
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