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  • richardmitnick 11:36 am on May 4, 2019 Permalink | Reply
    Tags: "When it comes to planetary habitability it’s what’s inside that counts", A true picture of planetary habitability must consider how a planet’s atmosphere is linked to and shaped by what’s happening in its interior, , , , , , , , , Planetary Science,   

    From Carnegie Institution for Science: “When it comes to planetary habitability, it’s what’s inside that counts” 

    Carnegie Institution for Science
    From Carnegie Institution for Science

    May 01, 2019

    Which of Earth’s features were essential for the origin and sustenance of life? And how do scientists identify those features on other worlds?

    A team of Carnegie investigators with array of expertise ranging from geochemistry to planetary science to astronomy published this week in Science an essay urging the research community to recognize the vital importance of a planet’s interior dynamics in creating an environment that’s hospitable for life.

    With our existing capabilities, observing an exoplanet’s atmospheric composition will be the first way to search for signatures of life elsewhere. However, Carnegie’s Anat Shahar, Peter Driscoll, Alycia Weinberger, and George Cody argue that a true picture of planetary habitability must consider how a planet’s atmosphere is linked to and shaped by what’s happening in its interior.

    1
    Reprinted with permission from Shahar et. al., Science Volume 364:3(2019).

    For example, on Earth, plate tectonics are crucial for maintaining a surface climate where life can thrive. What’s more, without the cycling of material between its surface and interior, the convection that drives the Earth’s magnetic field would not be possible and without a magnetic field, we would be bombarded by cosmic radiation.

    “We need a better understanding of how a planet’s composition and interior influence its habitability, starting with Earth,” Shahar said. “This can be used to guide the search for exoplanets and star systems where life could thrive, signatures of which could be detected by telescopes.”

    It all starts with the formation process. Planets are born from the rotating ring of dust and gas that surrounds a young star. The elemental building blocks from which rocky planets form—silicon, magnesium, oxygen, carbon, iron, and hydrogen—are universal. But their abundances and the heating and cooling they experience in their youth will affect their interior chemistry and, in turn, things like ocean volume and atmospheric composition.

    “One of the big questions we need to ask is whether the geologic and dynamic features that make our home planet habitable can be produced on planets with different compositions,” Driscoll explained.

    The Carnegie colleagues assert that the search for extraterrestrial life must be guided by an interdisciplinary approach that combines astronomical observations, laboratory experiments of planetary interior conditions, and mathematical modeling and simulations.

    2
    Artist’s impression of the surface of the planet Barnard’s Star b courtesy of ESO/M. Kornmesser.

    “Carnegie scientists are long-established world leaders in the fields of geochemistry, geophysics, planetary science, astrobiology, and astronomy,” said Weinberger. “So, our institution is perfectly placed to tackle this cross-disciplinary challenge.”

    In the next decade as a new generation of telescopes come online, scientists will begin to search in earnest for biosignatures in the atmospheres of rocky exoplanets. But the colleagues say that these observations must be put in the context of a larger understanding of how a planet’s total makeup and interior geochemistry determines the evolution of a stable and temperate surface where life could perhaps arise and thrive.

    “The heart of habitability is in planetary interiors,” concluded Cody.

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Carnegie Institution of Washington Bldg

    Carnegie Institution for Science

    Andrew Carnegie established a unique organization dedicated to scientific discovery “to encourage, in the broadest and most liberal manner, investigation, research, and discovery and the application of knowledge to the improvement of mankind…” The philosophy was and is to devote the institution’s resources to “exceptional” individuals so that they can explore the most intriguing scientific questions in an atmosphere of complete freedom. Carnegie and his trustees realized that flexibility and freedom were essential to the institution’s success and that tradition is the foundation of the institution today as it supports research in the Earth, space, and life sciences.

    6.5 meter Magellan Telescopes located at Carnegie’s Las Campanas Observatory, Chile.
    6.5 meter Magellan Telescopes located at Carnegie’s Las Campanas Observatory, Chile


    Carnegie Las Campanas 2.5 meter Irénée Dupont telescope, Atacama Desert, over 2,500 m (8,200 ft) high approximately 100 kilometres (62 mi) northeast of the city of La Serena,Chile


    Carnegie Institution Swope telescope at Las Campanas, Chile, 100 kilometres (62 mi) northeast of the city of La Serena. near the north end of a 7 km (4.3 mi) long mountain ridge. Cerro Las Campanas, near the southern end and over 2,500 m (8,200 ft) high, at Las Campanas, Chile

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  • richardmitnick 12:25 pm on January 3, 2018 Permalink | Reply
    Tags: , , , , , Planetary Science, Saturn's moon Titan sports Earth-like features, Titan's seas   

    From Cornell Chronicle: “Saturn’s moon Titan sports Earth-like features” 

    Cornell Bloc

    Cornell Chronicle

    January 3, 2018
    Linda B. Glaser
    cunews@cornell.edu

    1

    Using the now-complete Cassini data set, Cornell astronomers have created a new global topographic map of Saturn’s moon Titan that has opened new windows into understanding its liquid flows and terrain. Two new papers, published Dec. 2 in Geophysical Review Letters, describe the map and discoveries arising from it.

    Creating the map took about a year, according to doctoral student Paul Corlies, first author on Titan’s Topography and Shape at the End of the Cassini Mission. The map combines all of the Titan topography data from multiple sources. Since only about 9 percent of Titan has been observed in relatively high-resolution topography, with 25-30 percent of the topography imaged in lower resolution, the remainder of the moon was mapped using an interpolation algorithm and a global minimization process, which reduced errors such as those arising from spacecraft location.

    The map revealed several new features on Titan, including new mountains, none higher than 700 meters. The map also provides a global view of the highs and lows of Titan’s topography, which enabled the scientists to confirm that two locations in the equatorial region of Titan are in fact depressions that could be either ancient, dried seas or cryovolcanic flows.

    The map also revealed that Titan is a little bit flatter – more oblate – than was previously known, which suggests there is more variability in the thickness of Titan’s crust than previously thought.

    “The main point of the work was to create a map for use by the scientific community,” said Corlies; within 30 minutes of the data set being available online, he began to receive inquiries on how to use it. The data set is downloadable in the form of the data that was observed, as well as that data plus interpolated data that was not observed. The map will be important for those modeling Titan’s climate, studying Titan’s shape and gravity, and testing interior models, as well as for those seeking to understand morphologic land forms on Titan.

    Other Cornell authors on the paper are senior author Alex Hayes, assistant professor of astronomy, doctoral candidate Samuel Birch and research associate Valerio Poggiali.

    The second paper, Topographic Constraints on the Evolution and Connectivity of Titan’s Lacustrine Basins, finds three important results using the new map’s topographical data. The team included Hayes, Corlies, Birch, Poggiali, research associate Marco Mastrogiuseppe and Roger Michaelides ’15.

    The first result is that Titan’s three seas share a common equipotential surface, meaning they form a sea level, just as Earth’s oceans do. Either because there’s flow through the subsurface between the seas or because the channels between them allow enough liquid to pass through, the oceans on Titan are all at the same elevation.

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    This colorized mosaic using data from Cassini’s radar instrument shows some of Titan’s northern lakes and seas. (NASA/JPL-Caltech/ASI/USGS)

    “We’re measuring the elevation of a liquid surface on another body 10 astronomical units away from the sun to an accuracy of roughly 40 centimeters. Because we have such amazing accuracy we were able to see that between these two seas the elevation varied smoothly about 11 meters, relative to the center of mass of Titan, consistent with the expected change in the gravitational potential. We are measuring Titan’s geoid. This is the shape that the surface would take under the influence of gravity and rotation alone, which is the same shape that dominates Earth’s oceans,” said Hayes.

    The paper’s second result proves a hypothesis that Hayes advanced in his first paper, in graduate school: that Titan’s lakes communicate with each other through the subsurface. Hayes and his team measured the elevation of lakes filled with liquid as well as those that are now dry, and found that lakes exist hundreds of meters above sea level, and that within a watershed, the floors of the empty lakes are all at higher elevations than the filled lakes in their vicinity.

    “We don’t see any empty lakes that are below the local filled lakes because, if they did go below that level, they would be filled themselves. This suggests that there’s flow in the subsurface and that they are communicating with each other,” said Hayes. “It’s also telling us that there is liquid hydrocarbon stored on the subsurface of Titan.”

    The paper’s final result raises a new mystery for Titan. Researchers found that the vast majority of Titan’s lakes sit in sharp-edged depressions that “literally look like you took a cookie cutter and cut out holes in Titan’s surface,” Hayes said. The lakes are surrounded by high ridges, hundreds of meters high in some places.

    The lakes seem to be formed the way karst is on Earth, in places like the Florida Everglades, where underlying material dissolves and the surface collapses, forming holes in the ground. The lakes on Titan, like Earth’s karst, are topographically closed, with no inflow or outflow channels. But Earth karst does not have sharp, raised rims.

    The shape of the lakes indicates a process called uniform scarp retreat, where the borders of the lakes are expanding by a constant amount each time. The largest lake in the south, for example, looks like a series of smaller empty lakes that have coalesced or conglomerated into one big feature.

    “But if these things do grow outward, does that mean you’re destroying and recreating the rims all the time and that the rims are moving outward with it? Understanding these things is in my opinion the lynchpin to understanding the evolution of the polar basins on Titan,” said Hayes.

    The research was supported by grants from NASA and the Italian Space Agency.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Once called “the first American university” by educational historian Frederick Rudolph, Cornell University represents a distinctive mix of eminent scholarship and democratic ideals. Adding practical subjects to the classics and admitting qualified students regardless of nationality, race, social circumstance, gender, or religion was quite a departure when Cornell was founded in 1865.

    Today’s Cornell reflects this heritage of egalitarian excellence. It is home to the nation’s first colleges devoted to hotel administration, industrial and labor relations, and veterinary medicine. Both a private university and the land-grant institution of New York State, Cornell University is the most educationally diverse member of the Ivy League.

    On the Ithaca campus alone nearly 20,000 students representing every state and 120 countries choose from among 4,000 courses in 11 undergraduate, graduate, and professional schools. Many undergraduates participate in a wide range of interdisciplinary programs, play meaningful roles in original research, and study in Cornell programs in Washington, New York City, and the world over.

     
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