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Posts Tagged ‘extraterrestrial life

[NEWS] Some Wednesday links

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  • The Associated Press notes the hostility in many American communities to Muslim cemeteries.
  • Bloomberg explores the revival of watchmaking in East Germany’s Saxony, and touches on the new two-day public work week in Venezuela.
  • Bloomberg View notes Japan’s rising levels of poverty, looks at the politicization of the Brazilian education system, and examines potential consequences of Pakistan-China nuclear collaboration.
  • The CBC reports on the difficulties of the Canada-European Union trade pact, reports on the conviction of an Alberta couple for not taking their meningitis-afflicted child to medical attention until it was too late, and notes that an American-Spanish gay couple was able to retrieve their child from a Thai surrogate mother.
  • MacLean’s examines how Karla Homolka ending up shifting towards French Canada.
  • The National Post‘s Michael den Tandt is critical of the idea of a new Bombardier bailout.
  • Universe Today notes a paper arguing that, with only one example of life, we can say little with assuredness about extraterrestrial life’s frequency.
  • Vice‘s Noisey notes how Prince and Kate Bush ended up collaborating on “Why Should I Love You?”.
  • The Washington Post reports on a study suggesting that root crops like the potato were less suited to supporting complex civilizations than grains.

[BLOG] Some Wednesday links

  • D-Brief reports on Ceres’ bright spots.
  • Dangerous Minds celebrates the video game arcades of the 1980s.
  • The Dragon’s Gaze links to a paper speculating that tightly-packed globular clusters might be good cradles for life.
  • The Dragon’s Tales examines the processes by which gravel is formed on Mars and Titan.
  • The Everyday Sociology Blog wonders about the extent to which college alienates low-income students.
  • Lawyers, Guns and Money is critical of Hillary Clinton’s speech at AIPAC.
  • The LRB Blog features an essay by an American expatriate in Belgium on the occasion of the Brussels attacks.
  • Steve Munro analyses the quality of service on the 6 Bay bus.
  • The NYRB Daily reflects on the films of a Syrian film collective.
  • The Power and the Money’s Noel Maurer points out that the rate of terrorism in Europe now is substantially lower than in the 1970s and 1980s.
  • Savage Minds considers secrecy as it applies to the anthropological writer.
  • Strange Maps reflects on the BBC’s Shipping Forecast weather service.
  • Whatever’s John Scalzi reflects on the prospects of human survival into the future.
  • Window on Eurasia suggests that Uzbekistan and Kyrgyzstan are on the verge of fighting a border war.

[LINK] “Scientists Search for Signatures of Alien Life Hidden in Gas”

Wired‘s Natalie Wolchover reports about the search for life on other planets, through detecting the gases emitted by life into planetary atmospheres. One problem: What should be looked for?

After millennia of wondering whether we’re alone in the universe—one of “mankind’s most profound and probably earliest questions beyond, ‘What are you going to have for dinner?’” as the NASA astrobiologist Lynn Rothschild put it—the hunt for life on other planets is now ramping up in a serious way. Thousands of exoplanets, or planets orbiting stars other than the sun, have been discovered in the past decade. Among them are potential super-Earths, sub-Neptunes, hot Jupiters and worlds such as Kepler-452b, a possibly rocky, watery “Earth cousin” located 1,400 light-years from here. Starting in 2018 with the expected launch of NASA’s James Webb Space Telescope, astronomers will be able to peer across the light-years and scope out the atmospheres of the most promising exoplanets. They will look for the presence of “biosignature gases,” vapors that could only be produced by alien life.

They’ll do this by observing the thin ring of starlight around an exoplanet while it is positioned in front of its parent star. Gases in the exoplanet’s atmosphere will absorb certain frequencies of the starlight, leaving telltale dips in the spectrum.

As Domagal-Goldman, then a researcher at the University of Washington’s Virtual Planetary Laboratory (VPL), well knew, the gold standard in biosignature gases is oxygen. Not only is oxygen produced in abundance by Earth’s flora—and thus, possibly, other planets’—but 50 years of conventional wisdom held that it could not be produced at detectable levels by geology or photochemistry alone, making it a forgery-proof signature of life. Oxygen filled the sky on Domagal-Goldman’s simulated world, however, not as a result of biological activity there, but because extreme solar radiation was stripping oxygen atoms off carbon dioxide molecules in the air faster than they could recombine. This biosignature could be forged after all.

The search for biosignature gases around faraway exoplanets “is an inherently messy problem,” said Victoria Meadows, an Australian powerhouse who heads VPL. In the years since Domagal-Goldman’s discovery, Meadows has charged her team of 75 with identifying the major “oxygen false positives” that can arise on exoplanets, as well as ways to distinguish these false alarms from true oxygenic signs of biological activity. Meadows still thinks oxygen is the best biosignature gas. But, she said, “if I’m going to look for this, I want to make sure that when I see it, I know what I’m seeing.”

Meanwhile, Sara Seager, a dogged hunter of “twin Earths” at the Massachusetts Institute of Technology who is widely credited with inventing the spectral technique for analyzing exoplanet atmospheres, is pushing research on biosignature gases in a different direction. Seager acknowledges that oxygen is promising, but she urges the astrobiology community to be less terra-centric in its view of how alien life might operate—to think beyond Earth’s geochemistry and the particular air we breathe. “My view is that we do not want to leave a single stone unturned; we need to consider everything,” she said.

Written by Randy McDonald

March 18, 2016 at 12:00 pm

[BLOG] Some Tuesday links

  • blogTO profiles a couple who live on a houseboat near the foot of the Scarborough Bluffs.
  • Centauri Dreams hosts an argument making the case for eventual human emigration in interstellar directions.
  • Dangerous Minds celebates Brian Eno.
  • The Dragon’s Gaze shares a paper considering what “habitability” means.
  • The Dragon’s Tales notes a study suggesting Neanderthals were omnivores.
  • Joe. My. God. shares a collaboration between Jean-Michel Jarre and Peaches.
  • The NYR Daily considers the ethics of drone killings.
  • The Power and the Money’s Noel Maurer (here) and Crooked Timber (here) appear to have opposite perspectives on the threat posed by Trump to liberal democracy.
  • Discover‘s Seriously Science notes the recent study suggesting that at least one bird species’ calls have syntax.
  • The Search explores CUNY-TV’s efforts to create durable archives.
  • Strange Maps notes that Tokelau is an Internet superpower, based in terms of the number of sites it hosts.
  • Transit Toronto maps the proposed route for the Downtown Relief Line, which would stretch from City Hall over to Pape.
  • The Volokh Conspiracy considers the context in which it could, or could not, be a crime for a speaker to encourage an audience to attack hecklers.
  • Arnold Zwicky looks at the social import of clothes.

[BLOG] Some Thursday links

  • Anthropology.net notes a finding suggesting that Neanderthals deliberately used rocks rich in manganese dioxide to start fires.
  • Centauri Dreams considers what could be false signs of life.
  • The Crux notes the stone-throwing chimpanzees.
  • D-Brief suggests that a fungus was the first form of life to make it onto land.
  • The Dragon’s Gaze notes exceptionally eccentrically-orbiting gas giant HD 7449Ab.
  • The Dragon’s Tales notes Russian competition to build India a new aircraft carrier.
  • Language Hat notes the complexities of literary translation.
  • Lawyers, Guns and Money points to a Robert Farley article imagining an Anglo-American war in the early 1920s.
  • The Map Room Blog links to a map of Euroskepticism in the United Kingdom.
  • Marginal Revolution tries to map European place names with the word saint in them.
  • The NYRB Daily despairs for the American party system.
  • The Power and the Money’s Noel Maurer notes the indirect ways in which repealing NAFTA could pay for a US-Mexican border wall.
  • Spacing notes how parks can change cities.
  • Arnold Zwicky considers a variety of geographic areas with indeterminate boundaries, like the South and northeast Asia.

[LINK] “Exoplanet Census Suggests Earth Is Special after All”

Scientific American‘s Shannon Hall reports on this study, “Terrestrial Planets Across Space and Time”.

More than 400 years ago Renaissance scientist Nicolaus Copernicus reduced us to near nothingness by showing that our planet is not the center of the solar system. With every subsequent scientific revolution, most other privileged positions in the universe humans might have held dear have been further degraded, revealing the cold truth that our species is the smallest of specks on a speck of a planet, cosmologically speaking. A new calculation of exoplanets suggests that Earth is just one out of a likely 700 million trillion terrestrial planets in the entire observable universe. But the average age of these planets—well above Earth’s age—and their typical locations—in galaxies vastly unlike the Milky Way—just might turn the Copernican principle on its head.

Astronomer Erik Zackrisson from Uppsala University and his colleagues created a cosmic compendium of all the terrestrial exoplanets likely to exist throughout the observable universe, based on the rocky worlds astronomers have found so far. In a powerful computer simulation, they first created their own mini universe containing models of the earliest galaxies. Then they unleashed the laws of physics—as close as scientists understand them—that describe how galaxies grow, how stars evolve and how planets come to be. Finally, they fast-forwarded through 13.8 billion years of cosmic history. Their results, published to the preprint server arXiv and submitted to The Astrophysical Journal, provide a tantalizing trove of probable exoplanet statistics that helps astronomers understand our place in the universe. “It’s kind of mind-boggling that we’re actually at a point where we can begin to do this,” says co-author Andrew Benson from the Carnegie Observatories in California. Until recently, he says, so few exoplanets were known that reasonable extrapolations to the rest of the universe were impossible. Still, his team’s findings are a preliminary guess at what the cosmos might hold. “It’s certainly the case that there are a lot of uncertainties in a calculation like this. Our knowledge of all of these pieces is imperfect,” he adds.

The abstract?

The study of cosmology, galaxy formation and exoplanetary systems has now advanced to a stage where a cosmic inventory of terrestrial planets may be attempted. By coupling semi-analytic models of galaxy formation to a recipe that relates the occurrence of planets to the mass and metallicity of their host stars, we trace the population of terrestrial planets around both solar-mass (FGK type) and lower-mass (M dwarf) stars throughout all of cosmic history. We find that the mean age of terrestrial planets in the local Universe is 8 ± 1 Gyr and that the typical planet of this type is located in a spheroid-dominated galaxy with total stellar mass about twice that of the Milky Way. We estimate that hot Jupiters have depleted the population of terrestrial planets around FGK stars at Redshift z = 0 by no more than 10%, and predict that 1/3 of the terrestrial planets in the local Universe are orbiting stars in a metallicity range for which such planets have yet to be been detected. When looking at the inventory of planets throughout the whole observable Universe (i.e. in all galaxies on our past light cone) we argue for a total of 2×1019 and 7×1020 terrestrial planets around FGK and M stars, respectively. Due to the hierarchical formation of galaxies and lookback-time effects, the average terrestrial planet on our past light cone has an age of just 1.7 ± 0.2 Gyr and is sitting in a galaxy with a stellar mass a factor of 2 lower than that of the Milky Way. These results are discussed in the context of cosmic habitability, the Copernican principle and the prospects of searches for extraterrestrial intelligence at cosmological distances.

Written by Randy McDonald

February 21, 2016 at 5:48 pm

[LINK] Two links from The Dragon’s Gaze about dying Venus and Mars

The Dragon’s Gaze recently-ish had two interesting links examining Venus and Mars, two worlds in our solar system’s youth which could have been rather more Earth-like than at present. The first link was to the paper “Exploring the Inner Edge of the Habitable Zone with Fully Coupled Oceans”.

Rotation in planetary atmospheres plays an important role in regulating atmospheric and oceanic heat flow, cloud formation and precipitation. Using the Goddard Institute for Space Studies (GISS) three dimension General Circulation Model (3D-GCM) we investigate how the effects of varying rotation rate and increasing the incident stellar flux on a planet set bounds on a planet’s habitable zone with its parent star. From ensemble climate simulations we identify which factors are the primary controllers of uncertainty in setting these bounds. This is shown in particular for fully coupled ocean (FCO) runs — some of the first that have been utilized in this context. Results with a Slab Ocean (SO) of 100m mixed layer depth are compared with a similar study by Yang et al. 2014, which demonstrates consistency across models. However, there are clear differences for rotations rates of 1-16x present Earth sidereal day lengths between the 100m SO and FCO models, which points to the necessity of using FCOs whenever possible. The latter was recently demonstrated quite clearly by Hu & Yang 2014 in their aquaworld study with a FCO when compared with similar mixed layer ocean studies and by Cullum et al. 2014.

We also show how these results have implications for Venus in the early history of our Solar System since even at this time Venus received more solar flux than Earth does today while it may still have had a slow retrograde rotation. The Venus runs utilize a 2.9Gya solar spectrum generated with the code of Claire et al. 2012, a modern Venus topography with an ocean filling the lowlands (giving an equivalent depth of 310 meters if spread across the entire surface), atmosphere of 1 bar N2, CO2=0.4mb, CH4=0.001mb and present day orbital parameters, radius, & gravity. We demonstrate that ancient Venus could have had quite moderate surface temperatures given these assumptions.

The second link was to “The early geodynamic evolution of Mars-type planets”.

It is not clear whether Mars once possessed active tectonics, yet the question is critical for understanding the thermal evolution of Mars, and the origin and longevity of its early dynamo. To address these issues, we have coupled mantle flow simulations, together with parameterized core evolution models, to simulate the early evolution of Mars-like planets, and constrain the influence of early mobile-lid tectonics on core evolution. We have explored a wide parameter suite, encapsulating a range of uncertainties in initial conditions, rheological parameters, and surface strength. We present successful models that experience early mobile-lid behaviour, with a later transition into a stagnant-lid mode, which reproduce core dynamo histories similar to the magnetic history of early Mars.

Written by Randy McDonald

February 10, 2016 at 7:30 pm


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