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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 
5 weeks ago 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 
8 weeks ago 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 
9 weeks ago by briansholis
Twitter
RT : Our latest star chart with all the stars with known potentially habitable worlds.
astrobiology  exoplanets  from twitter_favs
12 weeks ago 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
Twitter
This is where the real ✨magic✨ happens! (Turning lab work into papers!)
astrobiology  internabby  from twitter_favs
june 2018 by jeffharbert

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