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SpaceIL lunar lander mission - 2019
JRehling
post Aug 10 2019, 01:17 AM
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It turns out this crash may have added some tardigrades to the Moon.

https://blogs.scientificamerican.com/life-u...dy-on-the-moon/
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Phil Stooke
post Aug 10 2019, 06:00 AM
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There has been a lot of chatter about tardigrades surviving UV radiation and vacuum, but I am not at all sure about them surviving the temperature extremes.

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marsbug
post Aug 11 2019, 11:08 AM
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From what I read they can, in their hibernated ptotective state, survive lows of - 200 celcius and highs of +145. It's not clear if they were in that state during the crash, or how their tolerance holds up under the assault of the combined factors of the lunar surface. Even in the best case for them, they might stay viable for a while in some buried-by-the-impact nook with lower than average (for that lattitude) temperature swings and some shelter from other factors, but eventually the lunar conditions will get them, as the cannot leave their protective state without dying. I got the temperature tolerance infofrom here' https://www.livescience.com/57985-tardigrade-facts.html. Are webutting up against rule 1.3 here?


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Explorer1
post Aug 11 2019, 03:26 PM
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QUOTE (marsbug @ Aug 11 2019, 07:08 AM) *
Are webutting up against rule 1.3 here?

1.3 says nothing whatsoever about Earth life. Chang'e 4's biological payload and images in the other thread were discussed without issue.
The only terrestrial species we can't discuss on this forum is homo sapiens, obviously (via Rule 1.6) wink.gif
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marsbug
post Aug 11 2019, 04:45 PM
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Ok, hang on: The tardigrades are.in their 'safed' hibernating state, and are not exposed to the lunar environmen, but sealed in layers of epoxy resin, sandwiched between layers of nickel, in an object about the size of a coin. The object is itself expected to have survived impact mostly intact. That bodes much better for their odds of long term survival and eventual recovery: A Wired article on the subject https://www.wired.com/story/a-crashed-israe...s-on-the-moon/:

I can increase the reporyed range of temperature tolerance too, down to pretty much absolute zero, according to this bbc report: http://www.bbc.co.uk/earth/story/20150313-...nimals-on-earth

Interestingly, in this state, tardigrafes do metabolise albeit at 0.01% their normal rate, and so might be argued to be 'alive' on the lunar surface. But I will say that, if I had to find an extant living thing on the lunar surface today, my 'least hugely unlikely' choice would still be to look in the mini greenhouse on the Chang'e 4 lander, assuming it still has pressure - I would bet some extremophile capable of handling the temperature swings (which would be somewhat moderated by the measures taken to keep the lander functioning) might have snuck in and be surviving off the remains of the dead plants. Ok, sorry for the lurch off topic, I'll leave it thete as a faintly amusing thought.


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JRehling
post Aug 11 2019, 05:01 PM
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It seems like a decent future mission would be to go grab these and return them to Earth and establish that they remained viable on the Moon. They won't really have been exposed to the full lunar environment (certainly no UV getting through to them) so the odds are good.

From the telemetry, this was more of a hard landing than an impact so the craft is maybe fairly intact.

Of course, it'd be far easier to have a future return craft carry its own tardigrades (etc?) and eliminate the complicated hardware.

Of course, part two: The interplanetary space between the Earth and the Moon already has basically the same environment as the Moon. Landing on the lunar surface only changes the thermal + radiative factors a bit.
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Thorsten Denk
post Aug 11 2019, 07:45 PM
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QUOTE (JRehling @ Aug 11 2019, 07:01 PM) *
From the telemetry, this was more of a hard landing than an impact so the craft is maybe fairly intact.


Ehem, you think 1km/s impacts are survivable?
Asking for both, the craft and the tardigrades...

Thorsten
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marsbug
post Aug 11 2019, 08:08 PM
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It's not my field so I cannot vouch for it, but from what was said by this source.... https://amp.businessinsider.com/tardigrades...alive-2019-89-8
"Tardigrades in dry state can survive pressures up to 74,000 times the pressure we experience at sea level, so the [crash] impact should not be a problem for them," evolutionary zoologist Roberto Guidetti told Business Insider.

As for the vehicle... the retro reflector experiment, a small simple chunk of solid material, is thought to have perhaps survived. So I imagine that other components that are also small and basically solid chunks of material, could have survived. So not the vehicle, but identifiable components of it, perhaps, based on my layman reading of what is being said by engineers on the subject.


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Phil Stooke
post Aug 26 2019, 09:54 PM
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I don't have the time or the desire to investigate tardigrade survival, but I get a sense that there is a bit of tardigrade worship going on around this story, and I am not referring to UMSF here but in the wider media. People are taking it rather for granted that they can survive mind-boggling temperature extremes. All I have done so far is look at the Wikipedia page on tardigrades, and it says that the wee critters can survive temperatures close to absolute zero or up to about 150 C, with citations I have not followed up on. However, the caveat is that they are apparently shown to survive these extremes for 'a few minutes'. The lunar night is not 1 K, but it is a lot longer than a few minutes, and the day would get hotter than 150 C for long periods. I don't think the radiation story is as clear-cut as is sometimes claimed either, particularly if we bring in cosmic rays. Mark me down as skeptical that our little friends have much chance of surviving prolonged exposure to the lunar environment.

Phil


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JRehling
post Aug 27 2019, 04:24 AM
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Near absolute zero, aren't a few minutes and a billion years about the same thing? Extreme cold is the cessation of change, so it seems like anything that would survive (remain viable) a few minutes of it (if the cold is allowed to penetrate all the way through) would survive an arbitrary duration of it.

It seems like it's the freezing and the unfreezing that would do the harm, not the being-at a low temperature.

PS: Though maybe cosmic ray strikes accumulating for a long time, which are not verboten at low temperatures, would fiddle with biology catastrophically.
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marsbug
post Aug 27 2019, 03:12 PM
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This is soooo not my area of expertise, but a wee bit of googleing suggests that the lunar regolith has impressive insulating properties, and within half a meter of the surface the temperature is fairly constant at roughly -130 deg C to -150 deg c (eg, here: https://www.sciencedirect.com/science/artic...94576514004160) even at noon and midnight. Given that something hitting at approx 1km/sec will either smash to bits if it hits stone, or deeply bury if it hits deep, more yielding, regolith (and the lunar surface has little that isn't one or t' other). I'd (very tentatively) suggest that the much worshipped tardigrades are either slam dunk dead or in a situation where the effects of low temperature and radiation dmage accumulation on their survival are more likely relevant than the effects of high temperature.


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nprev
post Aug 28 2019, 01:05 AM
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Might be time to stop beating a dead tardigrade here. (Well...lots of 'em). wink.gif


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marsbug
post Aug 30 2019, 10:30 AM
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I've just started teacher training (physics), and part of it is to teach general science - so we have to get some training in biology. We just did the segment on using microscopes to examine algae and protozoa - we found a tardigrade in our sample. Looking at it it's hard to imagine it's relative made that journey (dead or alive). Not really relevant, but it was very cool and gives me a cool connection to show students how different fields of science can be connected.


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