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Assorted Personal Notations, Essays, and Other Jottings

Posts Tagged ‘extraterrestrial life

[BLOG] Some Monday links

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  • The Broadside Blog’s Caitlin Kelly considers old friends.
  • Centauri Dreams considers the search for extraterrestrial civilizations using infrared astronomy, concentrating on Dyson spheres and the like.
  • The Dragon’s Gaze has two links to papers looking at unusual brown dwarfs.
  • The Dragon’s Tales reports on the flora of late Permian Antarctica.
  • Language Log notes a potentially problematic effort at Bangladesh to put hundreds of thousands of Bengali words online with Google, ready for translators. What of quality control, Victor Mair asks?
  • Lawyers, Guns and Money comments on the Burmese slaves in the Thai fisheries and looks at the desperate last efforts of Confederates to persist.
  • Marginal Revolution suggests that air conditioning really didn’t drive much interstate migration in the United States.
  • The Planetary Society Blog observes discoveries and anticipation for more at Ceres and Pluto.
  • Savage Minds looks to the example of Lesotho to point out that giving people land title by no means necessarily helps them out of poverty.
  • Torontoist looks at the Prism music video prize.

[BLOG] Some Thursday links

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  • Centauri Dreams examines different ways in which starships can decelerate.
  • The Dragon’s Gaze links to a paper examining the potential habitability of exomoons orbiting bright white main-sequence stars, between F5 and F9.5. Ultraviolet radiation is key.
  • The Dragon’s Tales notes a Chinese ASAT weapons test.
  • Joe. My. God. notes the Swedish language now has officially added the gender-neutral pronoun hen to its vocabulary.
  • Language Hat notes an ambitious new project to digitize ancient Irish-language documents.
  • The Power and the Money’s Noel Maurer is critical of the Democratic Party’s stance on abortion when it gets in the way of necessary policy, likening it to the Republican Party’s ongoing satisfaction of its base.
  • The Planetary Society Blog notes the final interesting weeks of Messenger‘s survey of Mercury, with photos.
  • Peter Rukavina remembers when in 1995 he was commissioned by the government of Prince Edward Island to set up a provincial website.
  • Torontoist reacts with humour to the impending merger of Postmedia and Sun Media.
  • Towleroad notes a lawsuit brought by a Michigan women against her former gym for being too trans-friendly.
  • Understanding Society examines the mechanisms connecting experiments with policies.
  • The Volokh Conspiracy argues against mandatory voting and mandatory jury service.
  • Window on Eurasia observes a controversial election among Moldova’s Gagauz and looks at the extent to which Islam in Russia is not under the government’s control.
  • Yorkshire Ranter Alex Harrowell goes on at length about the ridiculous Biryani project, a failed dirty tricks effort to sabotage the English Defense League and radical Muslims. Wow.

[BLOG] Some Wednesday links

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  • Gerry Canavan produces his own compendium of interesting links.
  • Centauri Dreams speculates about the colours indicative of extraterrestrial life, and ecologies.
  • Crooked Timber takes a look at Northern Ireland and the legacies of past violence.
  • The Dragon’s Tales reports on a hominid fossil that may indicate a much greater diversity in our ancestral gene pool than we thought.
  • A Fistful of Euros’ Edward Hugh wonders when the European Central Bank will start to taper interest rates.
  • The Frailest Thing warns that the promises of tech giants to free people from the shackles of the past should be seen critically.
  • On St. Patrick’s Day, Joe. My. God. and Michael in Norfolk both note the extent to which attitudes towards GLBT people in Ireland have changed.
  • Lawyers, Guns and Money wonders about the good sense of going off of anti-depressants.
  • Marginal Revolution’s Tyler Cowen proclaims Scarborough to be one of the world’s best food cities.
  • Savage Minds makes the case for anthropologists to aid the post-cyclone people of Vanuatu.
  • Spacing interviews the NDP’s Thomas Mulcair on urban issues.
  • The Volokh Conspiracy’s David Bernstein is unhappy at the consequences for Israel of Netanyahu’s reelection, while Lawyers, Guns and Money looks at income disparities in Israel.
  • Window on Eurasia argues that high inequality and low social mobility in Russia will doom the country, notes the potential for water-driven conflict in Central Asia, and notes Russian interest in acquiring more slots of Muslim pilgrims after Crimea’s annexation.

[NEWS] Three links on the import of the global ocean of Ganymede

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Back on Friday, news that evidence had been found of a subsurface ocean on Ganymede, Jupiter’s largest satellite, was widely propagating. Centauri Dreams’ Paul Gilster (““Evidence Mounts for Ganymede’s Ocean”) was one of the first bloggers on my RSS feed to report this.

Yesterday’s discussion of hydrothermal activity inside Saturn’s moon Enceladus reminds us how much we can learn about what is inside an object by studying what is outside it. In Enceladus’ case, Cassini’s detection of tiny rock particles rich in silicon as the spacecraft arrived in the Saturnian system led to an investigation of how these grains were being produced inside Enceladus through interactions between water and minerals. If correctly interpreted, these data point to the first active hydrothermal system ever found beyond Earth.

Now Ganymede swings into the spotlight, with work that is just as interesting. Joachim Saur and colleagues at the University of Cologne drew their data not from a spacecraft on the scene but from the Hubble Space Telescope, using Ganymede’s own auroral activity as the investigative tool. Their work gives much greater credence to something that has been suspected since the 1970s: An ocean deep within the frozen crust of the moon.

The early work on a Ganymede ocean grew out of computer models of the interior, but the Galileo spacecraft was able to measure the moon’s magnetic field in 2002, offering enough evidence for an ocean to keep the idea in play. The problem was that the Galileo measurements were too brief to produce an overview of the field’s long-term cyclical activity.

It was Saur’s idea to look at the idea afresh. Given that Ganymede is deeply embedded in Jupiter’s magnetic field, the aurorae that are produced in its polar regions are going to be influenced by any changes to that field, changes that produce a ‘rocking’ movement in the aurorae. These movements, Saur reasoned, would be a useful marker, one that, like the silica grains near Enceladus, could tell a story about activity deep below the surface. Says Saur:

“I was always brainstorming how we could use a telescope in other ways. Is there a way you could use a telescope to look inside a planetary body? Then I thought, the aurorae! Because aurorae are controlled by the magnetic field, if you observe the aurorae in an appropriate way, you learn something about the magnetic field. If you know the magnetic field, then you know something about the moon’s interior.”

The ‘rocking’ of the aurorae on Ganymede depends upon what’s inside the moon, and by the researchers’ calculations, a saltwater ocean would create a secondary magnetic field that would act against Jupiter’s field, tamping down the motion of the aurorae. The Hubble data show us that this is happening, for Saur’s models indicate the auroral activity is reduced to 2 degrees as opposed to the 6 we would expect if an ocean were not present. Ganymede thus joins Europa and Enceladus as an outer planet moon with increasing evidence for an ocean.

In “An internal ocean on Ganymede: Hooray for consistency with previous results!“, the Planetary Society Blog’s Emily Lakdawalla noted that this discovery fits with our understanding of Ganymede’s inner workings.

The Hubble results don’t precisely pin down the size and depth of an ocean at Ganymede, but the range of possible ocean thicknesses and depths is small. The observed behavior of the aurorae at Ganymede are consistent with a liquid ocean that is a relatively small fraction of Ganymede’s radius. Of course, Ganymede is a very big world, so “relatively small” in this case can mean an ocean up to about 100 kilometers deep. According to the paper, some possible oceans that are consistent with the results include, but are not limited to:
•A liquid layer from 150 to 250 kilometers depth with relatively low salinity
•A liquid layer from 190 to 210 kilometers depth with relatively high salinity
•A liquid layer below 330 kilometers depth with relatively high salinity

Water in one form or another at Ganymede goes from the surface to a depth of about 720 kilometers, at which point you reach Ganymede’s rocky outer core. So I think we can generalize these all to say: there is an ocean of less than 100 kilometers thickness located within a few hundred kilometers of the surface of Ganymede. In all possible cases, the liquid layer would be perched within the solid icy mantle, with solid ice above it of the form we have on Earth, and ice below it in a high-pressure crystalline form. [. . .]

That is a lot of liquid water, but it’s in a very different place within Ganymede than the liquid water that we think exists at Europa and Enceladus. Europa has a much higher proportion of rock to ice than Ganymede does, and is also warmer because of greater tidal friction; the same physics that predicted Ganymede’s perched-ocean-within-an-icy-mantle predicts that Europa’s liquid water ocean is in direct contact with its warm rocky core. Warm liquid water percolating among warm rocks is, by definition, hydrothermal activity. Hydrothermal zones are places that exobiologists imagine life might happen, because you have lots of energy and you have rich chemistry created in all that warm liquid water eating away at rocks. Earlier this week, one of the Cassini instrument teams announced that they had detected rock particles from just such an environment that originated within Enceladus.

At Discover‘s Out There blog, Corey S. Powell noted in “Looking for Life in All the Wrong Places?” that the existence of liquid water oceans has implications for the search for extraterrestrial life generally, and for the dispatch of space probes more specifically.

The story used to be all about Mars. Now it is clear that most of the water, most of the organic chemistry, and by extension most of the potentially habitable territory in the solar system resides on or in ice moons. If that’s true in our solar system, there’s a good chance it’s true around other stars across our galaxy and beyond.

Currently there are five orbiters and two surface robots exploring Mars. Here are the equivalent numbers for the four moons: Europa, 0. Ganymede, 0. Enceladus, 0. Titan, 0. It seems like we may have been looking for life in all the wrong places.

That’s the bad news. Now that good part. The Cassini spacecraft orbiting Saturn is performing local observations and occasional flybys of Enceladus and Titan. Archived information from NASA’s Galileo probe, along with new data from the Hubble Space Telescope, are deepening our understanding of Enceladus and Ganymede. Europe is working on a spacecraft called JUICE, which will examine Ganymede in detail. And the Obama administration is poised to approve the Europa Clipper, the first mission dedicated entirely to one of these icy moons; it could launch as early as 2022. In short, our explorations are starting to catch up with our fast-changing knowledge.

Getting to the next stage of understanding won’t be easy. The icy moons are far away, making them time-consuming and costly to reach. A trip to Mars takes about 8 months. Galileo needed 6 years to reach Jupiter, and Cassini’s voyage to Saturn was a 7-year undertaking. NASA also has a whole planetary-science bureaucracy built around the exploration of Mars. There are a lot of careers tied to the Red Planet.

At the same time, it’s hard to ignore the contrast. This past week, a group of researchers reported that the Red Planet probably had a vast ocean covering its northern hemisphere. It was an encouraging discovery, one that got quite a bit of news coverage. That ocean on Mars dried up about 4 billion years ago, however. The oceans of Enceladus and Europa are calling to us right now. If we want answers—if we want to find life, or the processes leading up to life—those are the places where we have to go.

Written by Randy McDonald

March 16, 2015 at 7:13 pm

[BLOG] Some Monday links

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  • blogTO takes a look at the reasons for the failure of the Toronto Sushi Festival, a failure that included the blog’s own misrepresentation of the event’s success.
  • The Broadside Blog’s Caitlin Kelly argues that, in our media-saturated environment, paying attention to everything is exhausting.
  • Centauri Dreams and D-Brief react to Dawn’s arrival at Ceres.
  • The Crux notes that Enceladus’ seas appear to be driven by tectonic activity, suggesting they may support life.
  • The Dragon’s Gaze looks at the remarkably eccentric orbit of exoplanet HD 8673Ab, links to a paper suggesting that hot Jupiters disrupt their planetary systems as they migrate inwards, and suggests that planetary systems discovered by Kepler with only one or two planets are the remnants of much denser systems.
  • The Dragon’s Tales and The Power and the Money discuss the idea of military unity in the European Union.
  • A Fistful of Euros compares the recent trajectories of Greece and Iceland following their
  • Joe. My. God. notes an Irish bishop who made an odd comparison of gay people to people with Down’s syndrome.
  • Language Hat notes that the Parisian journals of Russian exiles from the Soviet Union are online and notes the South Arabian language of the Yemeni island of Socotra.
  • Lawyers, Guns and Money considers if rudeness can be a firing offense.
  • Marginal Revolution criticizes the Greek government, and argues that Krugman’s criticism of the Trans-Pacific Partnership is misfounded.
  • The Planetary Society Blog calls for a return to Venus.
  • Otto Pohl observes that just over 62 years after his death, Stalin remains a popular figure in Russia.
  • The Power and the Money’s Noel Maurer notes worsening American-Venezuelan relations and argues that Venezuela’s PetroCaribe scheme hasn’t achieved its geopolitical goals.
  • Registan considers the controversy surrounding the disappearance of Vladimir Putin.
  • Peter Rukavina notes how, by tweaking an inexpensive Raspberry Pi computer, he can detect aircraft incoming to Charlottetown.
  • Spacing Toronto notes gendered violence on mass transit.
  • Towleroad observes the conviction of a California man on charges of intentionally trying to infect others with HIV.
  • The Volokh Conspiracy considers the legal issues surrounding an Indian state’s ban on beef, by comparison to California’s horse meat ban.
  • Window on Eurasia notes one Russian’s call to partition Ukraine, observes Russian irredentism towards the Baltics, considers the consequences of Russia’s statements about Crimea, looks at Hungarian irredentism towards western Ukraine, argues that a new Yalta is impossible, and compares the position of Vladimir Putin to that of Khrushchev afte the humiliating Cuban Missile Crisis.

[LINK] On the possible extensive water oceans of early Mars

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The New York Times‘ Marc Kaufman reported on the controversial new suggestion, described in the new Science paper “Strong water isotopic anomalies in the martian atmosphere: Probing current and ancient reservoirs”.

After six years of planetary observations, scientists at NASA say they have found convincing new evidence that ancient Mars had an ocean.

It was probably the size of the Arctic Ocean, larger than previously estimated, the researchers reported on Thursday. The body of water spread across the low-lying plain of the planet’s northern hemisphere for millions of years, they said.

If confirmed, the findings would add significantly to scientists’ understanding of the planet’s history and lend new weight to the view that ancient Mars had everything needed for life to emerge.

“The existence of a northern ocean has been debated for decades, but this is the first time we have such a strong collection of data from around the globe,” said Michael Mumma, principal investigator at NASA’s Goddard Center for Astrobiology and an author of the report, published in the journal Science. “Our results tell us there had to be a northern ocean.”

But other experts said the question was hardly resolved. The ocean remains “a hypothesis,” said Ashwin Vasavada, project scientist of the Curiosity rover mission at the Jet Propulsion Laboratory in Pasadena, Calif.

The Guardian‘s Ian Sample explained the scientists’ methodology.

The scientists used the Keck II telescope and Nasa’s Infrared Telescope Facility, both in Hawaii, and the ESO’s Very Large Telescope in Chile, to make maps of the Martian atmosphere over six years. They looked specifically at how different forms of water molecules in the Martian air varied from place to place over the changing seasons.

Martian water, like that on Earth, contains standard water molecules, made from two hydrogen atoms and one oxygen atom, and another form of water made with a heavy isotope of hydrogen called deuterium. On Mars, water containing normal hydrogen is lost to space over time, but the heavier form is left behind.

When normal water is lost on Mars, the concentration of deuterium in water left behind goes up. The process can be used to infer how much water there used to be on the planet. The higher the concentration of deuterium, the more water has been lost.

The infrared maps show that water near the Martian ice caps is enriched with deuterium. The high concentration means that Mars must have lost a vast amount of water in the past, equivalent to more than six times that now locked up in the planet’s frozen ice caps.

The scientists calculate that the amount of water was enough to create a global ocean that covered the entire surface of Mars to a depth of 137m. But Mars was probably never completely submerged. Based on the Martian terrain today, the scientists believe the water pooled into a much deeper ocean in the low-lying northern plains, creating an ocean that covered nearly a fifth of the planet’s surface. The Atlantic, by comparison, covers about 17% of Earth’s surface.

“Ultimately we can conclude this idea of an ocean covering 20% of the planet which opens the idea of habitability and the evolution of life on the planet,” said Geronimo Villanueva, the first author on the study.

The Vastitas Borealis, the deep and level northern-hemispheric plain, has long been thought of as a possible ancient ocean bed.

The science can be challenged on multiple grounds. For example, are scientists correct in their judgement of Mars’ ancient hydrogen/deuterium ratios? It could go either way if they are wrong. Regardless, this has implications for ancient–and even current?–life on the Red Planet.

Written by Randy McDonald

March 5, 2015 at 11:17 pm

[BLOG] Some Tuesday links

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  • The Big Picture looks at the uses of oil barrels around the world.
  • blogTO wonders if the Annex is ready for a condo boom.
  • Centauri Dreams features a guest post from Andrew Lepage noting how odd spectra on Mars were misidentified as proof of life.
  • Crooked Timber notes a student occupation of the University of Amsterdam’s headquarters.
  • Discover‘s The Crux makes a poor argument that space probe visits to Pluto and Ceres will lead to the redefinition of these worlds as planets.
  • The Dragon’s Gaze looks at an odd pulsating hot subdwarf B star with a brown dwarf.
  • The Dragon’s Tales suggests chemical mechanisms for life on Titan, and explains the differences in water plumes between Europa and Enceladus.
  • A Fistful of Euros notes political conflict in Germany.
  • Discover‘s Inkfist notes that birds from harsher climates are smarters.
  • Joe. My. God. shares Madonna’s critique of ageism.
  • Languages of the World examines the genesis of the English language.
  • Marginal Revolution notes Japanese funerals for robots, suggests Facebook usage makes people less happy, and notes family formation in Europe.
  • John Moyer examines punctuation.
  • Steve Munro maps out routes for a Scarborough subway.
  • The Planetary Society Blog looks at science on Pluto.
  • pollotenchegg maps the distribution of ethnically mixed households in Ukraine.
  • The Power and the Money’s Noel Maurer looks at how Panama successfully made use of price controls, and why.
  • Progressive Download’s John Farrell wonders what is the rush for three-parent IVF therapy.
  • Transit Toronto explains how old TTC tickets can be exchanged.
  • Window on Eurasia notes the importance of Belarus for the Baltic States, notes the newly-debatable borders of the former Soviet Union, suggests Tatarstan is unhappy with Russian federalism, and looks at the small grounds for Russian-Ukrainian hostilities.
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