Life on another planet

[Kyle Howdyshell]

What are the chances of the newly discovered planet Gliese 581 capable of producing or substaining life?

[Swift]

Hi Kyle, welcome to BAUT.

I moved your thread from Astronomy to Life in Space, I think it a better fit there. I would also suggest you look over this thread, where the topic is already under discussion.

[Somes J]

A Palette of Climates For Gliese 581g:

Gliese 581g is modelled as a world tidally locked to its star like our moon is to Earth (a likely scenario given its orbit). It is found to be capable of supporting relatively Earthlike conditions on the day side with a 1 bar atmosphere and greenhouse effect equivalent to .2 bars CO2 (Earth's atmosphere is 1 bar and .0003 bars CO2). Another possibility is that it may be an icy world with a subsurface liquid water ocean.

Is Gliese 581d habitable? Some constraints from radiative-convective climate modeling:

The recently discovered exoplanet Gl581d is extremely close to the outer edge of its system’s habitable zone, which has led to
much speculation on its possible climate. We have performed a range of simulations to assess whether, given simple combinations
of chemically stable greenhouse gases, the planet could sustain liquid water on its surface. For best estimates of the surface gravity,
surface albedo and cloud coverage, we find that less than 10 bars of CO2 is sucient to maintain a global mean temperature above the
melting point of water. Furthermore, even with the most conservative choices of these parameters, we calculate temperatures above
the water melting point for CO2 partial pressures greater than about 40 bar. However, we note that as Gl581d is probably in a tidally
resonant orbit, further simulations in 3D are required to test whether such atmospheric conditions are stable against the collapse of
CO2 on the surface.

[Canis Lupus]

Is Gliese 581d habitable? Some constraints from radiative-convective climate modeling:

Given the reasonable doubts being cast over the climate modelling done for Earth, despite its proximity, one would be wise to take the above modelling with a grain, if not a planet load, of salt.

[John Jaksich]

Kyle, welcome to BAUTforum!

As computer models come and go -- it is interesting . . . . but as Canis Lupus points out--- it is just one piece of a proverbial puzzle that might not mean anything. There is a factor called the "galactic habitable zone" ---which depending upon how the planet interacts with its neighboring "space-volume"---may push the planet out of the our own habitable--type zone . . . . i.e. --- what is the environment in which this planet exists--are there any sources of "harmful" radiation nearby? --super nova remmants, etc,

[Kyle Howdyshell]

So, given that there is a subsurface liquid water ocean. Does that mean that Gliese 581g atomosphere is very similar and can contain the same components as our own?

[Somes J]

So, given that there is a subsurface liquid water ocean. Does that mean that Gliese 581g atomosphere is very similar and can contain the same components as our own?

Keep in mind the simulation only indicates that a subsurface ocean may be possible, not that it exists. The simulations do indicate a nitrogen-dominated atmosphere is possible (wouldn't collapse on the darkside) and that it could keep darkside temperatures above the frost point of CO2 (-140 C at Earthlike concentrations), so if there was an area where ice was thin enough for light to penetrate plants could theoretically exist.

This planet will probably not be "Earthlike" in the sense of being a place where humans could withstand the surface environment without life support though, going by the paper. If it has an atmosphere like ours, it will be a frozen snowball. If it is warm enough to have Earthlike temperatures on the dayside, it will need CO2 concentrations that would be toxic to humans. Even in the friendliest simulated scenarios, either the garden spot would look like the Arctic or you'd need breathing apparatus.

Given the reasonable doubts being cast over the climate modelling done for Earth, despite its proximity, one would be wise to take the above modelling with a grain, if not a planet load, of salt.

Perhaps, but in the absence of direct observations such hypothesizing is unfortunately the best we have for the moment.

Hopefully we'll soon have telescopes capable of investigating the atmospheres of these planets through spectroscopy. That should let us make more informed conclusions about their nature.

There is a factor called the "galactic habitable zone" ---which depending upon how the planet interacts with its neighboring "space-volume"---may push the planet out of the our own habitable--type zone . . . . i.e. --- what is the environment in which this planet exists--are there any sources of "harmful" radiation nearby? --super nova remmants, etc,

Well, we know approximately what Gliese 581's present neighborhood is like: it is roughly our present neighborhood. 20 light years is a very small distance on the galactic scale; on it Gliese 581 and Sol are basically next-door neighbors. Of course, I imagine they probably have different orbital velocities around the center of the galaxy, so tens or hundreds of millions of years ago they may have been in quite different areas of the galaxy.

Another possible problem with Gliese 581's planets is composition. Given that this is a lower metallicity star than Sol (as per Solstation) that has several rather massive planets, and Gliese 581 b is more like Neptune than Earth in mass, I wouldn't be at all surprised if it ultimately turns out we're looking at several inward-migrated failed gas giant cores here. Such planets, forming beyond the snow line, might have huge volatile inventories; such worlds wouldn't be very Earthlike even if they got the right amount of sunlight.

[MaDeR]

What are the chances of the newly discovered planet Gliese 581 capable of producing or substaining life?

In short: no one knows. Insufficient information.

[Kyle Howdyshell]

Yea! besides our technology is still many years away before we could even think of "starting a new life" on that planet

[Orion's Fan]

Welcome, Kyle.

I think that the most important thing about this new discovery is that, even if the planet is not similar enough to Earth to harbor life, that it continue to give evidence that many, many planets with varying surfaces, atmospheres, etc, exist and that life IS out there somewhere.

I know, I know...we are all anxious to find it!

[icarus5]

well small step to human..lol