Hydrogen dominated terrestrial worlds

[granpa]

At room temp you obviously need at least 1000 bar to get liquid density.

As for heat, thats why I pointed out that its transparent

[Moontanman]

At room temp you obviously need at least 1000 bar to get liquid density.

As for heat, thats why I pointed out that its transparent

 

 

There you run into more of a mini neptune than a super earth. Such planets are called by some Ice Giants due to the deep layers of pressure ice at the bottom of the hydrogen, I am not sure that on Neptune's you get liquid hydrogen much less on mini neptunes.

 

[granpa]

I didnt say liquid hydrogen

[Moontanman]

I didnt say liquid hydrogen

 

 

You don't get metallic gaseous hydrogen, it's liquid metallic hydrogen, not sure about metallic helium but neither Uranus or Neptune have pressure high enough to create them.

[granpa]

Neptunes "atmosphere" is liquid hydrogen and liquid helium

[Moontanman]

Neptunes "atmosphere" is liquid hydrogen and liquid helium

 

 

Citation please! The sites I have visited disagree with you! But it's not relevant to the OT...

[granpa]

Air? At that depth?

[Moontanman]

Air? At that depth?

 

 

a dense gas at best, the atmospheres of the ice giants diffuse into liquid ices like water ammonia and methane then into possibly liquid carbon then a rocky core hotter than the surface of the sun by a significant margin...

 

But this thread is not about ice giants, it's about super terrestrials that retain a hydrogen helium atmosphere... but with a rocky surface with oceans, the paper suggest 30 bar may be the limit but it could work at less pressure as well but far far from the atmosphere of our ice giants...

[granpa]

Before it will hold hydrogen it will hold water.

Then its no longer a rocky surface

[Moontanman]

Before it will hold hydrogen it will hold water.

Then its no longer a rocky surface

 

 

That is a potential problem with the concept, although ending up a water world is a potential problem for Earth sized terrestrial planets as well. As I indicated earlier Earth may have shed much water in the collision that formed the Moon. The specifics is nothing more than speculation, the possibility is real...

[jimmydasaint]

Moontanman, this evidence about something unusual on Titan is six years old. Is there any update?

Strobel found a disparity in the hydrogen densities that lead to a flow down to the surface at a rate of about 10,000 trillion trillion hydrogen molecules per second. This is about the same rate at which the molecules escape out of the upper atmosphere.

"It's as if you have a hose and you're squirting hydrogen onto the ground, but it's disappearing," Strobel said. "I didn't expect this result, because molecular hydrogen is extremely chemically inert in the atmosphere, very light and buoyant. It should 'float' to the top of the atmosphere and escape."

Strobel said it is not likely that hydrogen is being stored in a cave or underground space on Titan. The Titan surface is also so cold that a chemical process that involved a catalyst would be needed to convert hydrogen molecules and acetylene back to methane, even though overall there would be a net release of energy. The energy barrier could be overcome if there were an unknown mineral acting as the catalyst on Titan's surface.

 

http://www.nasa.gov/topics/solarsystem/features/titan20100603.html

 

Artistic rendering of Titan's surface. Awe inspiring!

Edited August 7, 2016 by jimmydasaint

[Moontanman]

Moontanman, this evidence about something unusual on Titan is six years old. Is there any update?

http://www.nasa.gov/topics/solarsystem/features/titan20100603.html

 

Artistic rendering of Titan's surface. Awe inspiring!

 

 

Since we have little to no new data the ideas are speculative. This one somewhat less so:

 

http://phys.org/news/2015-10-kind-life-titan.html

[jimmydasaint]

From that paper Moontanman,

If some form of life exists on Titan, whether sea monster or (more likely) microbe, it would almost certainly need to have a cell membrane, just like every living thing on Earth does. Could phospholipid bilayer membranes form in liquid methane on Titan? The answer is no. Unlike water, the methane molecule has an even distribution of electrical charges. It lacks water's polar qualities, and so couldn't attract the polar heads of phospholipid molecule. This attraction is needed for the phospholipids to form an Earth-style cell membrane.

Read more at: http://phys.org/news/2015-10-kind-life-titan.html#jCp

The Cornell investigators saw nitriles and amines as potential candidates for their Titanian cell membranes. Both are polar molecules that might stick together to form a membrane in non-polar liquid methane due to the polarity of nitrogen containing groups found in both of them. They reasoned that candidate molecules must be much smaller than phospholipids, so that they could form fluid membranes at liquid methane temperatures. They considered nitriles and amines containing strings of between three and six carbon atoms. Nitrogen containing groups are called 'azoto' –groups, so the team named their hypothetical Titanian counterpart to the liposome the 'azotosome'.

Synthesizing azotosomes for experimental study would have been difficult and expensive, because the experiments would need to be conducted at the cryogenic temperatures of liquid methane. But since the candidate molecules have been studied extensively for other reasons, the Cornell researchers felt justified in turning to the tools of computational chemistry to determine whether their candidate molecules could cohere as a flexible membrane in liquid methane. Computational models have been used successfully to study conventional phospholipid cell membranes.

Acrylonitrile has been identified as a possible basis for cell membranes in liquid methane on Titan. It is known to be present in Titan’s atmosphere at a concentration of 10 parts per million and has been produced in laboratory simulations …more

The group's computational simulations showed that some candidate substances could be ruled out because they would not cohere as a membrane, would be too rigid, or would form a solid. Nevertheless, the simulations also showed that a number of substances would form membranes with suitable properties. One suitable substance is acrylonitrile, which Cassini showed is present in Titan's atmosphere at 10 parts per million concentration. Despite the huge difference in temperature between cryogenic azotozomes and room temperature liposomes, the simulations showed them to exhibit strikingly similar properties of stability and response to mechanical stress. Cell membranes, then, are possible for life in liquid methane.

The scientists from Cornell view their findings as nothing more than a first step towards showing that life in liquid methane is possible, and towards developing the methods that future spacecraft will need to search for it on Titan. If life is possible in liquid methane, the implications ultimately extend far beyond Titan.

When seeking conditions suitable for life in the galaxy, astronomers typically search for exoplanets within a star's habitable zone, defined as the narrow range of distances over which a planet with an Earth-like atmosphere would have a surface temperature suitable for liquid water. If methane life is possible, then stars would also have a methane habitable zone, a region where methane could exist as a liquid on a planet or moon, making methane life possible. The number of habitable worlds in the galaxy would be greatly increased. Perhaps, on some worlds, methane life evolves into complex forms that we can scarcely imagine. Maybe some of them are even a bit like sea monsters.

Read more at: http://phys.org/news/2015-10-kind-life-titan.html#jCp

This seems to bring out hope for some sort of life form. Our cells have a protective useful fat-based (phospholipid membrane). In methane, it is possible that acrylonitrile forms membrane-like structures like bubbles (liposomes) that they called azotosomes at such low temperatures (-180 Celsius or so). the simulations could show a potential cell membrane, which could allow protection for cell reactions, which are useful for life to form. So, the search for life could be much wider than we previously thought. Was that the main aim for the O.P.?

[Moontanman]

From that paper Moontanman,

This seems to bring out hope for some sort of life form. Our cells have a protective useful fat-based (phospholipid membrane). In methane, it is possible that acrylonitrile forms membrane-like structures like bubbles (liposomes) that they called azotosomes at such low temperatures (-180 Celsius or so). the simulations could show a potential cell membrane, which could allow protection for cell reactions, which are useful for life to form. So, the search for life could be much wider than we previously thought. Was that the main aim for the O.P.?

 

Yes, the idea is that potentially we need to use some bigger numbers in parts of the Drake equation if nothing else... But Titan wasn't the real thrust of the OP, it was actual super terrestrial planets with hydrogen atmospheres but a mega super Titan is also possible...

[Phi for All]

Do you think there would be any broad inherent differences in creatures adapted to hydrogen worlds, something that would preclude anything we'd recognize as life?

[Moontanman]

Do you think there would be any broad inherent differences in creatures adapted to hydrogen worlds, something that would preclude anything we'd recognize as life?

 

 

I really can't think of any, higher gravity might seriously change the direction natural selection might drive complex body plans. Higher density atmosphere would change the physical shape of flying creatures, possibly we might see some body plans never favored by evolution, balloon like organisms, air filter feeders a bit more serious than spiders.

 

It is the $64,000,000,000 question....

[Phi for All]

I really can't think of any, higher gravity might seriously change the direction natural selection might drive complex body plans. Higher density atmosphere would change the physical shape of flying creatures, possibly we might see some body plans never favored by evolution, balloon like organisms, air filter feeders a bit more serious than spiders.

 

It is the $64,000,000,000 question....

 

One of my first thoughts was of a jellyfish-like creature in the atmosphere, something that could out-compete plants and ground creatures for sunlight.

[Moontanman]

 

One of my first thoughts was of a jellyfish-like creature in the atmosphere, something that could out-compete plants and ground creatures for sunlight.

 

 

I'm not really sure how dense a 10 to 20 bar atmosphere would be, for sure there could be massive flying creatures. possibly balloon like organisms, secreting pure hydrogen to fill the balloon, metabolically heating it for extra lift.

 

I think I could make a case for a rather bizarre ecosystem with quite a bit more colonization of the air than we see on Earth. Of course a lot of this depends on how successful life is at living on a terrestrial world with a hydrogen atmosphere...

[tigrex]

So, is it implying that we can grow plants on some planets?