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Posts Tagged ‘extraterrestrial life

[BLOG] Some Friday links

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  • At Acts of Minor Treason, Andrew Barton is very unhappy with the misuse of the Hugo Award.
  • Anthropology.net notes that DNA has been retrieved from an ancient and mostly fossilized Neanderthal fossil.
  • Centauri Dreams examines the early history of the Milky Way Galaxy.
  • Crooked Timber looks at the controversies over religious liberty.
  • The Dragon’s Gaze considers how extraterrestrial life can be detected through disequilibria in exoplanet atmosphere and notes the recent Alpha Centauri B study.
  • The Dragon’s Tales notes that by 2018 a laser will be deployed on a drone.
  • Geocurrents shares slides from a recent lecture on Yemen.
  • Language Hat examines the Yiddish word “khnyok”.
  • Lawyers, Guns and Money considers the Republican race.
  • Marginal Revolution notes the unpopularity of political jobs among young Americans.
  • The Planetary Society Blog notes SpaceX’s problem with retrieving the first stages of its rockets.
  • Torontoist looks at beekeeping in Toronto.
  • Towleroad notes a Kickstarter fundraiser for Emil Cohen’s photos of queer life in Providence.
  • Transit Toronto notes the expansion of free WiFi throughout the subway system.
  • The Volokh Conspiracy notes that divorce papers can be served via Facebook if it is the most practical alternative.
  • Window on Eurasia fears a summertime Russian attack on Ukraine, notes Russian fears of rebellion at home, and looks at Russian Internet censorship.
  • The World’s Gideon Rachman wonders if the Greek demand for Second World War reparations will bring the Eurozone crisis to a head.
  • Yorkshire Ranter Alex Harrowell notes the essential lack of difference on government spending between Labour and the Tories and looks at flawed computer databases.

[BLOG] Some Monday links

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  • blogTO shares some wacky and unusual maps of the Toronto subway system.
  • The Broadside Blog’s Caitlin Kelly describes her reason why she did not want to have children.
  • Gerry Canavan has another post of links.
  • Centauri Dreams looks at Earth-like planets with circumbinary orbits and considers a new model of gas giant formation that explains Jupiter.
  • Crooked Timber examines the ongoing controversy over the Hugo awards for science fiction, as captured by American right-wing authors.
  • The Dragon’s Gaze links to a paper examining the habitability of water worlds.
  • The Dragon’s Tales notes the delay of China’s Mars exploration program.
  • Far Outliers looks at different systems for representing vowels with consonant symbols in the languages of the Pacific Islands.
  • Geocurrents has some posts–1, 2, 3–looking at ways in which the state system does not reflect the reality of the Middle East.
  • Language Hat looks at the revival of Manx.
  • Lawyers, Guns and Money notes that the United States’ Endangered Species Act is important for saving not just individual species but entire ecosystems.
  • Marginal Revolution tells readers how to find good Iranian food.
  • Steve Munro is dubious about the economics of the Union-Pearson Express.
  • pollotenchegg looks at changing industrial production in Ukraine in 2013, finding that the east was doing poorly.
  • The Power and the Money’s Noel Maurer looks at the military situation in eastern Ukraine.
  • Cheri Lucas Rowlands shares beautiful pictures of Bermuda.
  • Peter Rukavina continues mapping airplanes flying above Prince Edward Island.
  • The Russian Demographics Blog reports on the results of the famine in 1930s Ukraine.
  • Window on Eurasia argues that the Belarusian language is still endangered, quotes a Putin confidant on eastern Ukraine’s separation, looks at the impact of the Internet on Karelia, and looks at ethnogenesis as two small nations of the North Caucasus merge.

[BLOG] Some Wednesday links

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  • blogTO notes the opening of a Detroit-style pizzeria in Toronto’s Leslieville.
  • The Dragon’s Gaze links to a paper claiming that circumbinary Earth-like worlds can exist.
  • The Dragon’s Tales notes the American military’s mysterious X-37b space plane.
  • Joe. My. God. notes the opposition of Walmart to an anti-gay bill in Arkansas.
  • Language Hat argues that, at least in the recent past, English has displaced local languages in India. This may be changing.
  • Marginal Revolution seems to warn that too many Chinese are getting into stock speculation.
  • Window on Eurasia notes the overly-close relationship between the Russian Orthodox Church and the Russian state and observes the closing of Crimean Tatar news media.

[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

  • 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

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

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