[larens (OP)]

Earlier on there were repeated changes in the format of the forum that tended to hide my posts followed by their revocation, so I am not sure of how much of a consensus there is now.

Could you be specific about what happened? I am not aware of any format changes since you registered here, nor any revocation of your posts.
Have you posted here before using a different identity?

The New Theories icon and link disappeared from The Lighter Side menu and the New Theories list was reduced to one page. This happened more than once. By "revocation" I was referring to the changes being removed within an hour, not to my posts being removed. I have never posted here under a different identity.

I wonder if a general discussion on the likelihood of life originating on a nearby asteroid, and the conditions necessary for that to happen, might be be more productive.

If I had known the opposition to naming the specific asteroid I was to receive, I might have done that. As I explained in my last reply to Bored Chemist the specific location was important to my pursuing my research. Before the Dawn spacecraft visited Vesta I was thinking that an asteroidal location for the origin of life was likely, but I needed a specific location to know what its insolation was and what materials it received from the solar nebula. When I saw the announcement of the detection of hydroxl radicals on Vesta's surface, I immediately understood the scenario and proceeded to research the astrobiology.

[larens (OP)]

 

[it's also  unfortunate that you are saying that hard radiation will generate HCN  and HCHO when, in fact, it will destroy them.

Take a look at the high fraction of HCN and HCHO generated by hard UV in the nebulas of molecular clouds. They can also be generated by harder radiation.

[Kryptid]

I would like to take another look at panspermia.

Oumuamua was an interstellar asteroid, and a pretty fast one (travelling at about 26 kilometers per second before it entered the Solar System). If we use that as an example velocity, then we can calculate how long it would take to travel one light-year. A light-year is 9.46 x 10¹² kilometers, so:

Travel Time = 9.46 x 10¹² kilometers / 26 kilometers per second = 3.64 x 10¹¹ seconds
Travel Time = 3.64 x 10¹¹ seconds / 60 = 6.06 x 10⁹ minutes
Travel Time = 6.06 x 10⁹ minutes / 60 = 1.01 x 10⁸ hours
Travel Time = 1.01 x 10⁸ hours / 24 = 4.21 x 10⁶ days
Travel Time = 4.21 x 10⁶ days / 365.25 = 11,529.5 years

I wrote those calculations out so that anyone can report errors if they find them. That sounds like a long time, but it's very short on a geological time scale. If an asteroid (or even a rogue planet) was large enough, its internal temperature should remain high enough to allow for the existence of liquid water even if it was away from a star. The idea here is that hydrothermal vents would be able to supply enough heat to create pockets of liquid water even if the surface of the rogue planet was frozen. Even 4.54 billion years after its formation, the Earth has enough internal heat left over to operate hydrothermal vents. So an ecosystem of chemotrophic microbes could presumably survive in this environment for billions of years.

So the scenario I'm looking at is this: life develops in another star system. Where or how can be the subject of speculation, but the idea is that it eventually ends up on a planet with hydrothermal vents and bodies of water. Once microbial communities become established on this planet, interactions with other planets in the system cause it to be ejected into interstellar space. The surface freezes, but subsurface water remains liquid due to hydrothermal vents. The ecosystems there survive. If we allow for a (conservative) travel time of one million years before the hydrothermal vents give out, then that would allow for a maximum distance of travel of 1,000,000 years / 11,530 years = 86.73 light-years.

There are quite a few star systems much closer than 86.73 light-years, including Alpha Centauri, Vega, Barnard's star, Sirius and Procyon. So I think it is plausible for life from another star system to reach us. The next step would then require impacts from asteroids in the Solar System to drive material from the rogue planet as it passed through our Solar System. Then those microbe-contaminated samples land in an ocean on Earth and life is jump-started here.

Improbable? Certainly.

Impossible? Hardly.

[larens (OP)]

The next step would then require impacts from asteroids in the Solar System to drive material from the rogue planet as it passed through our Solar System. Then those microbe-contaminated samples land in an ocean on Earth and life is jump-started here.

Improbable? Certainly.

Impossible? Hardly.

I think that the problem of whether interstellar panspermia is significantly probable or improbable may be an intractable problem. It is easy enough to debunk the optimists. One paper I read assumed that a vacuum tight fusion crust had formed on a rock. The problem is that when the crust cooled it would be under tension so would fracture under the slightest impact. On the other hand there are so many possibilities that it is difficult or impossible to show that one has considered all the relevant possibilities.

General simplicity strongly supports the Unique Earth Hypothesis. That along with Fermi's Paradox works against interstellar panspermia being highly probable. Neither, however, prohibits the existence of there being some microbial colonies. The Anthropic Principle makes it difficult to determine the probability that it occurred with Earth.

[Bored chemist]

Take a look at the high fraction of HCN and HCHO generated by hard UV in the nebulas of molecular clouds. They can also be generated by harder radiation.

Even a large fraction if a very good vacuum isn't much actual material.

You complain that it would be too dilute on Earth yet are happy to source it where there is nothing but "space".

[Bored chemist]

I would like to take another look at panspermia.

OK, lets have a look.
How does anything survive getting "launched"?
Throwing a rock through the atmosphere at escape velocity subjects it to conditions that look worse than reentry.

How come it doesn't get fried?

[larens (OP)]

Take a look at the high fraction of HCN and HCHO generated by hard UV in the nebulas of molecular clouds. They can also be generated by harder radiation.

Even a large fraction if a very good vacuum isn't much actual material.

You complain that it would be too dilute on Earth yet are happy to source it where there is nothing but "space".

Looking at the photodissociation zones between nebulas and their molecular clouds gives one empirical data for modeling the chemistry of the Solar nebula when it got blasted by a beam of gamma rays from a neutron star merger. The solar nebula was orders of magnitude denser so got useful concentrations and fugacities of HCN, HCHO, and NS. These were absorbed onto smoke from the evaporation of rock. CN was absorbed onto transition metal atoms. The latter chemicals formed polymers on grain surfaces. HCHO mostly formed on surfaces, rather than in the gas phase. NS hydrolized  to ammonium sulphate, which is a grain aggregator and ferroelectric. (Half of the sulfur is also oxidized or reduced in the process.)

This dust was herded by light pressure, pebble dynamics, and electrostatic levitation to pile up over the asteroidal spring where liquid water activated the chemicals. HCN and HCHO formed polypeptides which were electrically separated through temperature variation of the ferroelectric. Many other reactions, of course, were going on in parallel.

[Bored chemist]

You can have liquid water or you can have ferroelectric ammonium sulphate.
You can't have both. The ferroelectric transition is somewhere near -50C.
And I'm not convinced you can have liquid water until you have something big enough to have an atmosphere to stop it boiling off into space.
And once you have liquid water, and a dense atmosphere, you might as well be on Earth.

[Kryptid]

OK, lets have a look.
How does anything survive getting "launched"?
Throwing a rock through the atmosphere at escape velocity subjects it to conditions that look worse than reentry.

How come it doesn't get fried?

The outside presumably does get vaporized, but the inside can remain cold (at least if the meteorite is large enough): https://wtamu.edu/~cbaird/sq/2012/12/13/what-makes-meteorites-so-hot-that-you-cant-touch-them/

[larens (OP)]

You can have liquid water or you can have ferroelectric ammonium sulphate.
You can't have both. The ferroelectric transition is somewhere near -50C.
And I'm not convinced you can have liquid water until you have something big enough to have an atmosphere to stop it boiling off into space.
And once you have liquid water, and a dense atmosphere, you might as well be on Earth.

In a 3:2 resonance orbit with the early Earth the average black body temperature was a bit above the ferroelectric transition temperature. With day/nighttime variation the transition point would have been crossed every day. The average noon time temperature would have been about 20 C, so the ice/water transition point would have also been crossed. The spring was radioactively heated, so there was a zone near the spring in which the temperature variation centered around 0 C thus making desalination by freezing, the concentration of boron, and water/formamide separation occur every day. Conditions were thus appropriate for the ribose reaction and the winding and unwinding of RNA and DNA.

The UV polymerization of alkanes provided a seal at the surface above the spring. When this was punctured by micrometeorites another layer formed as fluid permeated the dust that had accumulated above it. The new layer was temporarily self sealed by nonvolatile soluble materials. When vapor pressure lifted the layers, fluid spread to the edges and added to the layered area. Water vapor pressure was low because temperatures were near freezing. The hydrological system was thus self regulating.

[Bored chemist]

You can have liquid water or you can have ferroelectric ammonium sulphate.
You can't have both. The ferroelectric transition is somewhere near -50C.
And I'm not convinced you can have liquid water until you have something big enough to have an atmosphere to stop it boiling off into space.
And once you have liquid water, and a dense atmosphere, you might as well be on Earth.

In a 3:2 resonance orbit with the early Earth the average black body temperature was a bit above the ferroelectric transition temperature. With day/nighttime variation the transition point would have been crossed every day. The average noon time temperature would have been about 20 C, so the ice/water transition point would have also been crossed. The spring was radioactively heated, so there was a zone near the spring in which the temperature variation centered around 0 C thus making desalination by freezing, the concentration of boron, and water/formamide separation occur every day. Conditions were thus appropriate for the ribose reaction and the winding and unwinding of RNA and DNA.

The UV polymerization of alkanes provided a seal at the surface above the spring. When this was punctured by micrometeorites another layer formed as fluid permeated the dust that had accumulated above it. The new layer was temporarily self sealed by nonvolatile soluble materials. When vapor pressure lifted the layers, fluid spread to the edges and added to the layered area. Water vapor pressure was low because temperatures were near freezing. The hydrological system was thus self regulating.

What's the atmospheric pressure here?
Do you know that ammonium sulphate is very soluble in water?

[larens (OP)]

What's the atmospheric pressure here?

The atmosphere is a high vacuum. The gas below the seals is mainly methane.

Do you know that ammonium sulphate is very soluble in water?

Yes, that means it is deposited away from the spring and at a temperature near its ferroelectric point.

[Bored chemist]

How come the seals survive the volume and pressure changes?
At 20C the vapour pressure of water is about 1/40 atmospheres or about a quarter of a tonne per square meter.

[Kryptid]

Is this the genetic study you were speaking about earlier? https://phys.org/news/2013-04-law-life-began-earth.html

[larens (OP)]

How come the seals survive the volume and pressure changes?
At 20C the vapour pressure of water is about 1/40 atmospheres or about a quarter of a tonne per square meter.

How come the seals survive the volume and pressure changes?
At 20C the vapour pressure of water is about 1/40 atmospheres or about a quarter of a tonne per square meter.

Because the organic seals are quite small. What you have is a lot of small grains stuck together with plastic.  Porous material can be quite strong. Think of foamed concrete. There are bubbles so volume change is not a problem. Because the interconnections are plastic, it also deforms well under impacts. Most of the water is just a few degrees above freezing. It would probably only reach 20 C fairly deep in the spring.

Is this the genetic study you were speaking about earlier? https://phys.org/news/2013-04-law-life-began-earth.html

The paper you cite is only a thought exercise which proves that you cannot extend Moore's law back that far. I probably referred to,"The physiology and habitat of the last universal common ancestor":   https://www.nature.com/articles/nmicrobiol2016116
Unfortunately Nature is behind a paywall.

[Bored chemist]

Who put the gas under the plastic?

[Bored chemist]

Most of the water is just a few degrees above freezing. It would probably only reach 20 C fairly deep in the spring.

If all the water boils of "only deep in the spring" then it still all boils off.
At 0C the vapour pressure is still over a hundredweight to the square metre.
And if it has significant volatile organics in it, the pressure may be higher.

[larens (OP)]

Who put the gas under the plastic?

Enthalpy. Methane is the product of exothermic reactions.

Most of the water is just a few degrees above freezing. It would probably only reach 20 C fairly deep in the spring.

If all the water boils of "only deep in the spring" then it still all boils off.
At 0C the vapour pressure is still over a hundredweight to the square metre.
And if it has significant volatile organics in it, the pressure may be higher.

If you put on your scuba gear and dive down to where it is 20 C, you will be able to see that there is enough pressure to keep it from boiling. Be sure to take your wet suit. It's pretty cold at the top. Also take a radiation meter. You are not as radiation tolerant as Deinococcus Radiodurans. Since you are bored, take along Fantastic Voyage with Raquel Welch as entertainment. Fortunately the community of Halloysite nanotube creatures at the top has learned how to regulate the nuclear reactor so that it does not create a geyser. They add chloride as a neutron absorber when they detect radioiodine. This is why we need iodine for our thyroid hormones to regulate our growth.

[Bored chemist]

If you put on your scuba gear and dive down to where it is 20 C, you will be able to see

https://en.wikipedia.org/wiki/Convection

[larens (OP)]

https://en.wikipedia.org/wiki/Convection

https://en.wikipedia.org/wiki/Heat_exchanger