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Orbital Period

Could Chance for Life on Gliese 581g Actually Be “100%”?

30 Sep , 2010

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The announcement yesterday of the discovery of the closest Earth-sized planet found so far that also exists in the habitable zone around its star is certainly exciting (read our previous article for all the details). Gliese 581g is surely a potential habitable planet where liquid water could exist on the planet‘s surface, and many are touting the old adage of where there’s water, there’s life. However, some quotes from one of the scientists involved in the discovery might be feeding some wild speculation about the potential for life on this extrasolar planet and elsewhere. “Personally, given the ubiquity and propensity of life to flourish wherever it can, I would say, my own personal feeling is that the chances of life on this planet are 100 percent,” said discoverer and astronomer Steven Vogt during a press briefing yesterday. “I have almost no doubt about it.”

Yes, that is an exact quote. He really used those words. He also said that it would be pretty hard to imagine that water wouldn’t exist on the planet, given the ubiquity of water in our solar system and beyond, and the habitable region in which this planet orbits.

Also participating in the briefing was Paul Butler of the Carnegie Institution of Washington, which provided funds for the observations at the Keck I telescope, and his comments were more tempered.

“Any discussion of life on at this point is purely speculative,” Butler said. “What we know is that this planet exists at the right distance for liquid water it has the right amount of mass to hold on to its atmosphere and any liquid water on the surface. So any subsequent discussion of life there is purely speculative. That being said, on the Earth anywhere you find liquid water you find life in overwhelming abundance. The question should be, if this planet has liquid water, how can you rule out life doesn’t exist? It is pretty probable that anywhere you find liquid water pooling, that you would find life existing.”

Are Vogt’s claims too extreme, or were they made in exhilaration during an exciting announcement? This has been a topic of debate on Twitter this morning. Some wondered if Vogt had been misquoted, and many expressed that Vogt’s words may fuel off-the-deep-end speculation about the certainty of life on another world.

“Until we know more about this planet and the origin of life itself, any claim of certain habitation is idiotic and does not serve science,” said Dr. Stuart Clark (@DrStuClark), author and astronomy journalist. To clarify, he wanted others to know that he thinks just the claim is idiotic, not the discovery or the people involved.

“As cool as it is, please realize that right now *all* we really know about it is its orbit and estimated mass. That’s it.” said Lee Billings (@leebillings), editor at Seed Magazine. “In other words, barring observational evidence that may still be a generation away, Gliese 581g is ‘Earth-like’ only in terms of mass/orbit.”

From our pal Phil Plait, the Bad Astronomer (@badastronomer): “I understand what he meant – he thinks it *could* have life – but it was phrased unfortunately, and the media have jumped on it, of course.”

From David Masten (@dmasten), CEO of the commercial space company Masten Space Systems: “I have an opinion or 3 about life on anything in Gliese 581! And I’d dare say much closer to zero chance. But I’m not an astrobiologist.”

“Claiming a 100% chance of life on Gliese 581g is definitely an overreach,” said astrophysicist Juan Cabanela (@Juan_Kinda_Guy) at Minnesota State University Moorhead, “given we currently have a sample of 1 planet with life.”

“Vogt’s extrapolation was certainly quite a leap. On the other hand, the media might finally get it that some scientists really do think life everywhere is possible – but not bug-eyed aliens” said Robert Cumming, (@maltesk), journalist at the Swedish magazine “Populär Astronomi.“. “Then we can also discuss why there might not be life everywhere after all.”

Mark Thompson (@PeoplesAstro), Astronomy presenter on BBC’s the One Show said the Vogt’s quote was “absolutely and totally inappropriate. We can’t even be 100% sure it’s made of rock!!!”

From astronomer, educator and journalist Nicole Gugliucci (@noisyastronomer): “The public seems to have enough trouble trusting science these days without scientists making bold statements like that.”

“100% is ridiculous,” Tweeted frequent image contributor to Universe Today, Stu Atkinson (@mars_stu). “No *possible* way anyone could know that, surely?”

Many expressed excitement over the discovery, and Stu articulated perhaps the most colorful, which was re-tweeted several times yesterday: “Ah, a PROPER planet!” Not a great fat bloated sweaty “Who ate all the pies” ‘hot Jupiter’ tearing insanely around its star.”

What are your views?

*all Tweets used by permission.

Here’s an article about abiogenesis, theories about how life got started here on Earth.

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SkepticTim
Member
SkepticTim
September 30, 2010 8:53 AM

Perhaps we should remember, during our speculations about the existence of life on planets in the “habitable zone” (i.e. liquid water can exist on the planet), that liquid water may be a necessary condition for the existence of carbon based life like us, but it is not a sufficient condition!

Olaf
Member
Olaf
September 30, 2010 9:12 AM

I think you can rephrase it to “Earth bacterial life could survive on that planet if we drop a bucket in a puddle out there.”

It does not mean that life actually started out there.

CrazyEddieBlogger
Member
September 30, 2010 9:13 AM
People confuse “habitable” with “inhabitated” and with “habitable by humans”. So to clarify. “Habitable” means it doesn’t have show-stoppers for life, and in a more narrow sense, doesn’t have show-stoppers for life-as-we-know-it, meaning anything vaguely similar to what we see on Earth. This is generally taken as “can support liquid water on the surface”, while acknowledging that yes, there could be other types of chemistries and life that are not water-based. To me, higher magnetic fields than we’re used to, for example, do not make a planet non-habitable. “Inhabited” means that life developed there. “habitable by humans” means that you survive on the surface with reasonable means of protection. The “100%” quote was about habitability, the first criteria,… Read more »
Morellio
Member
Morellio
September 30, 2010 9:36 AM

Eh well, his hypothesis is that there is a 100% chance of life. I fully endorse investigation! When will we get spectra of the atmosphere? I’m surprised that hasn’t been done already..

Roen
Member
Roen
September 30, 2010 9:46 AM

Those with Twitter I highly recommend tweeting this article all over the place to combat the over-the-deep-end reactions.

Ted Judah
Member
Ted Judah
September 30, 2010 9:50 AM

Do we have the technology to send a spacecraft 40 LY and still function autonomously to enter Gliesian orbit and beam images back to earth? Will we ever consider such a mission to a super-promissing spectrally-suggestive-of-life planet? Would you support such a mission even if you would not see the results in your lifetime? I think I would.

Olaf
Member
Olaf
September 30, 2010 9:59 AM

Ted Judah, all we need to do is create a worm hole here, ship one of the openings to that planet and we have instant access just like a Stargate. If we can reach 0.5 times the speed of light with that ship.then the portal can be open in 40 years from now. smile

I am just wondering, can we ship a second bigger wormhole through a wormhole?

Olaf
Member
Olaf
September 30, 2010 10:00 AM

But what about the closer stars, do we have signs of planets? I am thinking about Alpha centaury or so.

Lawrence B. Crowell
Member
Lawrence B. Crowell
September 30, 2010 12:56 PM
No *&@^ing way is it 100%. There are a number of things which have to be overcome. The atmosphere can’t be a hothouse CO_2 atmosphere. This planet could easily be a 300C autoclave envirnoment with maybe 100 torr of pressure. If the atmosphere started out with too littlepressure it could have been lost by now. This is intriguing however, and there is a chance for life here. If this could be imaged and found to be a double planet with a quick orbital rotation in a tidal lock I would feel even much better. Much more data is needed, including on the chemistry of the atmosphere and if possible a measurement of its blackbody radiation temperature. It is… Read more »
Uncle Fred
Member
Uncle Fred
September 30, 2010 1:16 PM

Why would it take “another generation” to get more in-depth observations of this planet? Surely we can a spectra of the atmosphere? There must be more we can do too.

As for the comments from some of these scientists, it seems they haven’t been reading Universetoday! What are their thoughts on the dead world scenario? Or a Venusian hurricane planet? Or the weak magnetosphere scenario where water and/or lighter atmospheric elements are gone?

Don Alexander
Member
Don Alexander
September 30, 2010 1:31 PM
As an actual astrophysicist I’m going to leave the speculation as to whether this planet is habitable to people who model atmospheres and stuff. What I AM going to comment on is our ability to obtain observations which can clinch the argument one way or another. IT DOES NOT REPEAT NOT EXIST AT THIS TIME. It took 11 years of measurement with a hi-res spectrograph on one of Earth greatest telescopes to even tease out the radial velocity signal. 1.6 m/s is a value I have never heard of before, it’s incredible. Even confirming the existence of this planet has pushed modern techology to the limit. Remember the definition of a parsec? At one parsec distance (about 3… Read more »
Olaf
Member
Olaf
September 30, 2010 1:35 PM

Don Alexander, how did they discover that it is tidal locked?

Kawarthajon
Member
Kawarthajon
September 30, 2010 3:18 PM
I think that the term “habitable zone” is a misnomer because we have evidence from our solar system that there are 3 planets in this zone, but only one which supports life. As people have mentioned, there are many things that could prevent life from forming – no atmosphere, no water, too much atmosphere, poison in the atmosphere, too hot, too cold, etc… Seems like a huge stretch to say that just because a planet is located in the habitable zone means that it harbours life. Not to mention the fact that each planet system we find destroys all of our models for planetary formation and this planet may be in a form that we haven’t even considered… Read more »
Lawrence B. Crowell
Member
Lawrence B. Crowell
September 30, 2010 4:06 PM

There is another things which needs to be considered. These planets are rather heavy and in close orbits. Take a look at

http://en.wikipedia.org/wiki/Gliese_581

and these bodies are close to each other and gravitaitonally perturb each other. It seems as if these would gravitationally perturb each other in ways that could be quite dramatic. It is possible they rattle each other enough so they might drift in and out of the so called habitable zone.

LC

Torbjorn Larsson OM
Member
Torbjorn Larsson OM
September 30, 2010 4:48 PM
Considering that Gliese 581g lies within the habitable zone and by the tidal lock in a convective atmosphere will have liquid water conditions somewhere on its surface, it is nearly 100 % certainty it is habitable. A convective atmosphere will naturally give a livable annulus, the circulatory systems will be much more stable than here. As we know from Venus a (near) locked planet retain atmosphere. The remaining water content will depend on the starting water content. The two showstoppers of abiogenesis inhibitor is a non-water world (originally or by the hydrogen loss from locking), or a water world (with scant nutrients at livable pressures). But as we move towards the ice line outwards the habitable zone of… Read more »
Torbjorn Larsson OM
Member
Torbjorn Larsson OM
September 30, 2010 4:52 PM

these bodies are close to each other and gravitaitonally perturb each other.

In general planets are found closed packed with respect to disturbances. I believe the orbit circularity of the new planetary fits, as good as our system AFAIU my quick browsing of the paper (it’s on arxiv), rejects that the system is in a disturbed phase.

Torbjorn Larsson OM
Member
Torbjorn Larsson OM
September 30, 2010 4:56 PM

Oops! “The problem likely is not to have life, the problem is _not_ to have life under those circumstances.” – The problem likely is not to have life, the problem is _to not_ have life under those circumstances.

Torbjorn Larsson OM
Member
Torbjorn Larsson OM
September 30, 2010 4:59 PM

Also, re disturbances, I just remembered that the paper has a discussion on how the keplerian tree fit procedure easily exaggerate eccentricities when data is missing.

If so, I would not trust orbital predictions until all or nearly all planets are found, which today seem to take 11 (!) years – or more.

pink
Member
September 30, 2010 9:35 PM

I don’t see the big problem- since we do know only it’s mass and orbit, why not guess that there’s life? It’s just as good as the opposite guess. A percentage chance is not the most meaningful statement, what’s wrong with 100%?

Vogt knows that there’s a habitable zone climate and probably water, and water means extremophiles at the very least (in many people’s opinions). Really I don’t mind his statement, and besides I like optimism…

He also said “my own personal feeling…” He didn’t say “After months of exhaustive calculation…”

Lighten up! Go Gliese581g! xD

Uncle Fred
Member
Uncle Fred
September 30, 2010 5:45 PM
Torbjorn, I had not considered the long life span of these systems. 7 – 11 Billion years would give ample time for life to arise, even if large areas of the planet are unsuitable. I imagine there must be a probability calculation that could be derived from all this. Factors perhaps being: 1. Time since planet formation 2. Stability of star 3. Stability or orbit 4. Size of planet 5. Likelihood and frequency of impact events / time 6. Volume of planet conducive to carbon-based life as a factor of time.i.e. lower value for areas further away from the twilight zone, mapped over geological time (crust cooling etc.) 7. Water volume / time 8. Other atmospheric factors. 8.… Read more »
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