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From: Jeroen Belleman <jeroen@nospam.please>
Newsgroups: sci.electronics.design
Subject: Re: Expedition to Europa
Date: Fri, 28 Jun 2024 20:01:20 +0200
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On 6/28/24 09:01, Jeff Layman wrote:
> On 28/06/2024 02:41, john larkin wrote:
>> On Fri, 28 Jun 2024 03:22:04 +0200, "Carlos E.R."
>> <robin_listas@es.invalid> wrote:
>>
>>> On 2024-06-27 20:39, Joe Gwinn wrote:
>>>>
>>>> Excerpted from Aviation Week, June 3-16 2024, page 38:
>>>>
>>>> Located more than five times farther away from the Sun than Earth,
>>>> Europa seems an unlikely place to look for life. Surface temperatures
>>>> on the ice-shrouded moon of Jupiter average |-260F, and radiation
>>>> levels are high enough to kill a human being in one day.
>>>
>>> Being that far from the sun, where comes that radiation from?
>>
>> Our sun is friendly. The universe is deadly.
>>
>> It's a miracle that Earth is shielded.
> 
> Indeed. It's a point often ignored by exoplanet life-seekers. It's one 
> thing to find suitable conditions which might create life, it's another 
> thing entirely to find conditions which could sustain life. Take this 
> very recent review on Gliese 12 b:
> <https://ras.ac.uk/news-and-press/news/rare-exo-venus-earth-temperature-discovered>
> 
> Note this comment:
> "..."Although we don't yet know whether it possesses an atmosphere, 
> we've been thinking of it as an exo-Venus, with similar size and energy 
> received from its star as our planetary neighbour in the solar system."
> 
> An important factor in retaining an atmosphere is the storminess of its 
> star. Red dwarfs tend to be magnetically active, resulting in frequent, 
> powerful X-ray flares.
> 
> However, analyses by both teams conclude that Gliese 12 shows no signs 
> of such extreme behaviour, raising hopes that Gliese 12 b's atmosphere 
> may still be intact."
> 
> So a red dwarf tends to have frequent powerful x-ray flares, yet the 
> only comment is that there were no signs of this extreme behaviour. 
> Firstly, how can it be "extreme" if it's frequent, and how long have 
> they been observing this star anyway? Secondly, did nobody consider what 
> an x-ray flare would do to any life which might have formed on the 
> planet? Never mind the planet's surface temperature and presence - or 
> not - of an atmosphere. A blast of x-rays and probably other radiation 
> isn't exactly know for its life-sustaining properties.
> 
> And that's even supposing a red dwarf would be capable of providing 
> "suitable" radiation levels capable of supporting an earth-like planet 
> in the first place. See:
> <https://ras.ac.uk/news-and-press/research-highlights/earth-biospheres-other-planets-may-be-rare>
> 

Oh well. Earth has a toxic, oxidizing atmosphere, with free oxygen and
worse, ozone. And yet life thrives.

Don't take all these "extreme" conditions too seriously. What seems
extreme for us may be balmy for them. That is, if there is a 'them';
We have yet to find any.

Jeroen Belleman