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The Sep. 14, 2019 issue of The Economist has a brief article on exoplanet K2-a8b. It explains briefly how Dr Tsiara &co. spectroscopically detected water in the exoplanet's atmosphere (while admitting that, alone, did not reveal what form the water was in). They also found evidence for lots of hydrogen and helium, which emphasizes that the "Most Earthlike Planet Yet" description is very much grading on a curve.

 

The issue also has articles about a new forensic technique for identifying the source of sand (sand theft is a big thing -- take note, Dark Champions GMs!) and a study proposing that Neanderthals were dangerously prone to ear infections. Because The Economist likes to report on the stranger sides of science to which most mass market publications pay little attention. The sand science article is titled, "Name That Dune."

 

Dean Shomshak

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13 hours ago, tkdguy said:

 

From the article:

 

Quote

Earth has a major global magnetic field thanks to its rotation and churning, iron-rich, liquid outer core...


Unlike Earth, though, Mars got unlucky. Around four billion years ago, its convulsing outer core appears to have seized up, causing a collapse in its global magnetic field. Left with a weak magnetic shield to defend itself, an outpouring of radiation from the sun—known as the solar wind—gradually stripped away much of its ancient atmosphere, turning a potentially life-supporting, water-rich world into a cold desert.

 

 

I particularly dislike the phrase "its convulsing outer core appears to have seized up".

 

< mini-rant >

 

"Seized up" doesn't communicate anything scientifically, the term is a colloquialism for "stopped working". You have to know what the author is trying to say or attempt to research what happened to Mars' outer core in order to understand the author is trying to communicate.

 

A planet's core has to remain a fluid, at least partially, in order to generate a strong magnetohydrodynamic field. There are words in the language which accurately and concisely describe a fluid no longer remaining a fluid.

 

< /mini-rant >

 

I wasted time scouring the internet to see if researchers has discovered something new about what happened to Mars' core because the author couldn't be bothered to accurately convey his thought.

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Agreed. "Seized up" suggests, what, gears turning and getting jammed? Suddenly, perhaps accidentally? The author clearly is trying to sound breezily nontechnical and exciting -- "seized up" sounds more exciting than "stopped,", yes? But it also completely misrepresents what happened.

 

It's the sort of bad writing that results from assuming the readers are idiot children.

 

Dean Shomshak

 

 

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Well, it's not good for the n"Rare Earth" argument that h a bazillion different factors need to be just right for life to appear. Well, OK, the exact argument is that a bazillion factors need to be just right for complex life to evolve -- in their book Ward and Brownlee graciously concede that bacterial life may be common in the universe. But we can only argue so far as there is evidence, and the evidence of the Solar System suggests that the temperate zone for liquid water is fairly wide, and that planets can diverge significantly from Earth in mass and rotation while remaining temperate for extended periods. I'm inclined to suspect there4's a fair bit of "slop" in other habitability factors, too.

 

Dean Shomshak

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On September 21, 2019 at 4:34 PM, Lord Liaden said:

It sounds like Venus, Mars, and Earth are all within the habitable-zone distance from the Sun. It intrigues me to think that, based on cosmic random chance, our solar system could have had three Earth-like worlds.

 

There is solid reason to say that Venus was in the HZ until 3/4 Gyr ago or so, at which time the inevitable increase in solar luminosity drove all the water into vapor form, the thermal structure of the atmosphere changed so that water was exposed to the solar UV, and it got photodissociated and lost.  End of habitability.

 

The outer edge of the HZ is harder to guess.  Mars is low enough mass that its geological activity was able to maintain a circulation of atmosphere gases through the solid part of the planet for a Gyr, tops, and maintain a magnetic field strong enough to stand off the impinging solar wind, for a less-understood amount of time.  In other words, Mars might not be habitable now even if it was now and had always been where Earth is now.  It is a weak candidate.

 

Had Mars been 1 or 2 earth masses, its geology probably would still be going.  In such a case, would an Earth-mass Mars in its current location be habitable now?  And, an important second question arises: would it have been habitable 3.5 Gyr ago when the solar luminosity was substantially lower?  I would need some convincing before I'd say we had any confidence in our ability to answer those questions.

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On 9/23/2019 at 12:27 PM, Lord Liaden said:

Me, I'm still hoping we discover some methane-breathers on the gas giant planets.


Speaking of which, I finally got around to scanning this satiric fable from Feinberg and Shapiro's Life Beyond Earth (published 1980) -- in this case, making fun of what they considered prematurely pessimistic interpretations of the Viking lander test results:

 

Fable 3

 

The results of the fifth space probe of minor planetoid three were being described at the Jovian Conference on Space Research. Sarpedon, the chief scientist in charge of the probe, reported on it:

 

The probe passed through the thin atmosphere of planetoid three successfully. From the experience that we gained by previous unsuccessful probes, we were able to construct this probe out of special materials that could resist the extreme environment at the gasliquid interface of the planetoid. The highly' oxidized outer coating of the probe enabled it to avoid the fate of probes number one through four, which rapidly combined with a toxic gas in the planetoid's atmosphere. When the probe reached the interface, it was subjected to the chemical action of the hydrogen-oxygen liquid compound that forms the main component of the interface. This gradually removed the oxidized protective coating of the probe and so exposed the inner machinery to the toxic atmosphere. As a result, only seventy-two minutes of data were obtained. But this data is enough to confirm the previous opinion of the best scientists— that life is impossible on such planetoids.

 

If the toxic atmosphere and liquid surface were not enough to show this, an immense flux of deadly radiation of optical light was detected at the surface, which was hardly screened by the thin atmosphere. This radiation can dissociate many chemical compounds that are essential to life, and is more intense at the interface of planetoid three even than in outer space near our planet. Also, the temperature at the interface is as low as that in the uppermost levels of our planet. This means that chemical reactions proceed very slowly, and life processes would be extremely sluggish, if indeed there has been time enough for life to evolve there. Finally, none of the complex molecules with which we associate life could be detected at the interface. A sample of the liquid region showed the overwhelming part of its composition to be oxide of hydrogen, with small amounts of dissolved sodium chloride and other metallic salts. There are minor traces of dissolved oxide of carbon, as well as traces of volatile carbon compounds of a type not known on Jupiter. One mobile subprobe was lost in an unknown way, apparently falling into a floating mixture of hydrogen oxide with solidified and nitrogenized carbon compounds. The high temperature of the probe eventually melted this mixture, but not until the probe had been dissolved and oxidized. Small amounts of solid material from the interface were recovered by' another subprobe and placed in a nutrient solution containing essentials of life such as hydrogen cyanide, at an absolute temperature twice the normal value at the interface. At first, the solid material reacted chemically with the nutrients, liberating various gases. But after a short time, the reactions stopped and no further activity was observed. The unwillingness of any hypothetical organism to use rich nutrients is a serious blow to the belief that planetoid three is a home of life.

 

On the basis of these results, it appears safe to conclude that planetoid three is not a place where life can exist, and no further biological probes of that planetoid are warranted. Our future studies of the minor planetoids should concentrate on planetoid two, whose thick atmosphere and high temperature at the interface make conditions there much more similar to those on our own world, the only one that we know is hospitable to life. Perhaps life, as we know it, can exist (if only in an attenuated form) on the second planetoid from the central star, but surely not in the wholly alien conditions of the third planetoid.

 

Sarpedon stopped burping spurts of hydrogen sulfide, which was his method of communicating with his fellow scientists. They, in turn, signaled their approval of his conclusions by producing small pulses of heat, intense enough to boil some of the magnesium chloride crystals contained in parts of their bodies. The result was a small train of bubbles in the dense hydrogen surrounding them all, forming a beautiful but transient pattern pleasing to the speaker and audience alike.

 

On planetoid three, known to a few of its inhabitants as Earth, countless living things were being born, existing, and dying every second, unaware of the negative verdict about their possible existence which had been rendered by Jupiter's leading scientists.

-----

Feinberg and Shapiro tried to think outside the box to identify every imaginable habitat for Life As We Don't Know It. One critic said they thought so far outside the box they lost sight of the box completely. But they provide some excellent ideas for SF.

 

Dean Shomshak
 

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