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Rev. Mod. Phys. 91, 021002 (2019) - Colloquium: Physical constraints for the evolution of life on exoplanets
"Recently, many Earth-sized planets have been discovered around stars other than the Sun that might possess appropriate conditions for life. The development of theoretical methods for assessing the putative habitability of these worlds is of paramount importance, since it serves the dual purpose of identifying and quantifying what types of biosignatures may exist and determining the selection of optimal target stars and planets for subsequent observations. This Colloquium discusses how a multitude of physical factors act in tandem to regulate the propensity of worlds for hosting detectable biospheres. The focus is primarily on planets around low-mass stars, as they are most readily accessible to searches for biosignatures. This Colloquium outlines how factors such as stellar winds, the availability of ultraviolet and visible light, the surface water and land fractions, stellar flares, and associated phenomena place potential constraints on the evolution of life on these planets."
to:NB  physics  astronomy  astrobiology 
11 days ago by cshalizi
Apollo astronauts left their poop on the moon. NASA ought to go back for that shit.
It’s been nearly 50 years since the Apollo 11 moon landing. Neil Armstrong’s iconic footprint is still there, undisturbed; there’s no atmosphere, no wind on the moon to blow it away.

But the bigger human footprint on the moon is, arguably, the 96 bags of human waste left behind by the six Apollo missions that landed there.

Yes, our brave astronauts took dumps on their way to the moon, perhaps even on the moon, and they left behind their diapers in baggies, on humanity’s doorstep to the greater cosmos.

The bags have lingered there, and no one knows what has become of them. Now scientists want to go back, and answer a question that has profound implications for our future explorations of Mars: Is anything alive in them?
by:BrianResnick  from:Vox  astronomy  biology  astrobiology  shit  geo:Moon 
11 weeks ago by owenblacker
Geological and Geochemical Constraints on the Origin and Evolution of Life | Astrobiology
> The Hadean geological record remains on the Mars and Ceres, so the hypothesis of planetary transfer is more testable than origin on the Earth. Origin on a nonsurviving body, including an asteroid or the Moon-forming impactor Theia, is not directly testable. Venus was conceivably habitable (Way et al., 2016), but sampling logistics are not favorable. Transfer from extrasolar planets within the Solar System's open cluster is also conceivable and might even be eventually testable (Valtonen et al., 2008; Belbruno et al., 2012). Later transfer from distant stars (panspermia) is geometrically extremely unlikely (Melosh, 2003; Valtonen et al., 2008). It is a quintessential example of a science stopper, an infinitesimally likely hypothesis involving speculation about unknown features of a distant world, as opposed to potentially knowable features of Solar System objects.
astrobiology  panspermia  LUCA  genetics 
february 2019 by porejide
The moon’s craters suggest Earth hasn’t erased lots of past impacts | Science News
History of now - Snowball earth, moon, craters,

The lack of ancient impact craters on Earth (older than 650 mya) was presumed to be due to erosion, plate tectonics.

New evidence from lunar craters suggest otherwise. The bombardment rate between 650mya and 290mya was low and picked (hence few craters on Earth), with an uptick in bombardment around 290 mya (evidence of which does survive on Earth).

The reason for lack of craters before 650 mya? Snowball Earth ~650mya wiped away evidence of earlier bombardments, not plate tectonics and slow erosion from wind and rain.
History_of_now  moon  Space  astronomy  astrobiology  planets  grade_A 
january 2019 by Marcellus
Rebecca Boyle, "Searching for Life in a Martian Landscape," The Atlantic
This liminal state, between finding and not finding, is characteristic of astrobiology in general. We don’t know whether we’re alone, but we don’t know whether we aren’t. We do know that there is one planet with life, and on this planet, life is everywhere; because of us, we can be sure life in the universe is possible. If we don’t find life on Mars pretty soon, or on Enceladus or Titan or Europa or Trappist-1b, that doesn’t mean we should stop trying. But it’s also possible that life has happened only once. We might be it.
astrobiology  AtacamaDesert  Chile  TheAtlantic  RebeccaBoyle  AlienLife  bacteria 
january 2019 by briansholis
RT : Our latest star chart with all the stars with known potentially habitable worlds.
astrobiology  exoplanets  from twitter_favs
december 2018 by alvar
Meet the Endoterrestrials - The Atlantic
Even as Onstott awaits those results, he is starting to consider an even more radical possibility: that deep-dwelling microbes don’t just feed off of earthquakes, but might also trigger them. He believes that as microbes attack the iron, manganese, and other elements in the minerals that line the fault, they could weaken the rock—and prime the fault for its next big slip. Exploring that possibility would mean doing laboratory experiments to find out whether microbes in a fault can actually break down minerals quickly enough to affect seismic activity. With a scientist’s characteristic understatement, he contemplates the work ahead: “It’s a reasonable hypothesis to test.”
astrobiology  microbiology  told-em-so  it's-a-microbial-world 
october 2018 by Vaguery
Superhabitable planet - Wikipedia
They propose clarifications because a circumstellar habitable zone (HZ) is not enough to define a planet's habitability.[3] Heller and Armstrong state that it is not clear why Earth should offer the most suitable physicochemical parameters to living organisms.
wikipedia  article  astrobiology 
september 2018 by AleatoricConsonance

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