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Sunset on Mars:  

And Sojourner on Mars, that went with Pathfinder... hey, found a graphic:  

Mankind has sent robot invaders to five celestial bodies so far:  

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Well, when you have a small number of cables supporting a fixed amount of mass, when you lose one cable the strain gets redistributed among the remaining cables, which is sort of a recipe for losing more.  I have seen comments suspecting the anchor points for the cables, not merely the cables themselves, were damaged by the hurricane stresses. 


And, lots of things in Puerto Rico took not-always-obvious damage in the 2017 hurricane, and federal help has not been forthcoming at anything like the level that comes for states.  It is appalling how much of the crucial electrical utility infrastructure in the region around the observatory was rebuilt by observatory staff after the hurricane, because they were on the ground there and had the know-how (though not usually the materials and tools), and in 2017 the federal political apparatus was not interested in sending aid to a Spanish-speaking area, even if it has been a US dependency for over a century.

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1 hour ago, tkdguy said:


Possibly, since our lasers won't reach the nebula for another 7500 years. Not sure what good the experiment will do; I just reported it.

And am I correct in thinking it will be another 7500 years before we learn about any effect it might have had? Does anyone seriously believe homo sapiens will be around that long?

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4 hours ago, tkdguy said:


Possibly, since our lasers won't reach the nebula for another 7500 years. Not sure what good the experiment will do; I just reported it.


So the aliens in the nebula won't think we're attacking them with low-powered lasers for another 7500 years.


Good to know.

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I think that if you knew what was coming, you could detect them with instrumentation.  No chance with the eyeball, no matter how big a telescope.  But you;d need to know something about the lasers being fired at you, at least with 2020 technology.

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On 11/12/2020 at 11:53 PM, tkdguy said:

OMG!  Whoever wrote this article is a mouth-breathing moron.  The astronomers are just using a particular color for a laser guide star.  They're only shooting it into the upper atmosphere to watch how light scatters up there.  This is barely even a story aside from the pretty pictures.


That author should be fired, preferably out of a cannon.

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On 9/14/2020 at 3:12 PM, tkdguy said:

Phosphines found in Venus' atmosphere


Potential signs of life in Venus?


On 9/15/2020 at 11:50 AM, Cancer said:

The technical paper in Nature Astronomy is here.  I managed to get to it this morning without a subscription, so I don't think it's behind a paywall, but YMMV.


This is based on spectroscopic observations of an absorption line at about 1 millimeter wavelength.  The first observation was done with the James Clerke Maxwell Telescope in 2017, and I would call that spectrum suggestive but not compelling that an absorption line was actually present.  The 2019 ALMA spectrum is better but I would still hesitate to make a claim based on that.  The two data sets jointly make something worth putting into the literature.  Even so, it fairly cries out for confirming evidence, which probably will have to come from an atmospheric probe: I don't think it'll be possible to do better with Earthbased data for quite some time.


The best takeaway from this is the whole of their main-text final paragraph ("PH3" here means PH[sub]3[/sub]: the chemical formula for phosphine. )


Terrestrial biology does produce phosphine at a rate adequate to make the feature seen in the millimeter spectra.  Other known photochemical and geochemical processes don't.  That's as strong a statement in favor of life as can be made from these data, IMO.  OTOH, I am not convinced that the identification of this single spectral line as being due to phosphine is bulletproof; and even if it is, while a particularly implausible assumption about a biosphere producing PH3 can produce the observed feature, that's a really bad reason to think of this as evidence for life there.


Earlier this week came a note backpedaling on the phosphine claim; some calibration errors in one dataset, and then it seems that the feature identified as PH3 is perhaps better explained as a blend of a couple of S02 lines ... and SO2 is already known to be important in Venus's atmosphere.  Though I didn't know abotu the calibration issues, the alternative identification for the spectral feature is towards the top of my list of reasons I was pretty skeptical of this stuff in the first place.

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On 11/20/2020 at 5:42 PM, tkdguy said:


You can sum up Herzog's critique as "not an argument". To claim that going to Mars is obscene because fascism and communism existed is completely bonkers. 


Besides, Elon Musk is destined to go to Mars, as the leader of Mars has been called "The Elon" since 1952. 

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