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  • richardmitnick 2:13 pm on July 28, 2017 Permalink | Reply
    Tags: , , , , , Titan   

    From ALMA: “ALMA Confirms Complex Chemistry in Titan’s Atmosphere: Saturn’s Moon Offers Glimpse of Earth’s Primordial Past” 

    ESO/NRAO/NAOJ ALMA Array
    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres
    ALMA

    28 July, 2017

    Nicolás Lira
    Education and Public Outreach Coordinator
    Joint ALMA Observatory, Santiago – Chile
    Phone: +56 2 2467 6519
    Cell phone: +56 9 9445 7726
    nicolas.lira@alma.cl

    Charles E. Blue
    Public Information Officer
    National Radio Astronomy Observatory Charlottesville, Virginia – USA
    Phone: +1 434 296 0314
    Cell phone: +1 202 236 6324
    cblue@nrao.edu

    Richard Hook
    Public Information Officer, ESO
    Garching bei München, Germany
    Phone: +49 89 3200 6655
    Cell phone: +49 151 1537 3591
    rhook@eso.org

    Masaaki Hiramatsu
    Education and Public Outreach Officer, NAOJ Chile
    Observatory
, Tokyo – Japan
    Phone: +81 422 34 3630
    hiramatsu.masaaki@nao.ac.jp

    Saturn’s frigid moon Titan has a curious atmosphere. In addition to a hazy mixture of nitrogen and hydrocarbons like methane and ethane, Titan’s atmosphere also contains an array of more complex organic molecules, including vinyl cyanide, which astronomers recently uncovered in archival ALMA data. Under the right conditions, like those found on the surface of Titan, vinyl cyanide may naturally coalesce into microscopic spheres resembling cell membranes.

    Saturn’s largest moon, Titan, is one of our solar system’s most intriguing and Earth-like bodies. It is nearly as large as Mars and has a hazy atmosphere made up mostly of nitrogen with a smattering of organic, carbon-based molecules, including methane (CH4) and ethane (C2H6). Planetary scientists theorize that this chemical make-up is similar to Earth’s primordial atmosphere.

    The conditions on Titan, however, are not conducive to the formation of life as we know it; it’s simply too cold. At ten times the distance from the Earth to the sun, Titan is so cold that liquid methane rains onto its solid icy surface, forming rivers, lakes, and seas.

    1
    Archival ALMA data have confirmed that molecules of vinyl cyanide reside in the atmosphere of Titan, Saturn’s largest moon. Titan is shown in an optical (atmosphere) infrared (surface) composite from NASA’s Cassini spacecraft. In a liquid methane environment, vinyl cyanide may form membranes. Credit: B. Saxton (NRAO/AUI/NSF); NASA.

    These pools of hydrocarbons, however, create a unique environment that may help molecules of vinyl cyanide (C2H3CN) link together to form membranes, features resembling the lipid-based cell membranes of living organisms on Earth.

    Astronomers using archival data from the Atacama Large Millimeter/submillimeter Array (ALMA), which was collected over a series of observations from February to May 2014, have found compelling evidence that molecules of vinyl cyanide are indeed present on Titan and in significant quantities.

    “The presence of vinyl cyanide in an environment with liquid methane suggests the intriguing possibility of chemical processes that are analogous to those important for life on Earth,” said Maureen Palmer, a researcher at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and lead author on a paper published in Science Advances.

    Previous studies by NASA’s Cassini spacecraft, as well as laboratory simulations of Titan’s atmosphere, inferred the likely presence of vinyl cyanide on Titan, but it took ALMA to make a definitive detection.

    NASA/ESA/ASI Cassini-Huygens Spacecraft

    By reviewing the archival data, Palmer and her colleagues found three distinct signals – spikes in the millimeter-wavelength spectrum – that correspond to vinyl cyanide. These telltale signatures originated at least 200 kilometers above the surface of Titan.

    Titan’s atmosphere is a veritable chemical factory, harnessing the light of the sun and the energy from fast-moving particles that orbit around Saturn to convert simple organic molecules into larger, more complex chemicals.

    “As our knowledge of Titan’s chemistry grows, it becomes increasingly apparent that complex molecules arise naturally in environments similar to those found on the early Earth, but there are important differences,” said Martin Cordiner, also with NASA’s Goddard Space Flight Center and a co-author on the paper.

    For example, Titan is much colder than Earth at any period in its history. Titan averages about 95 kelvins (-290 degrees Fahrenheit), so water at its surface remains frozen. Geologic evidence also suggests that the early Earth had high concentrations of carbon dioxide (CO2); Titan does not. Earth’s rocky surface was also frenetically active, with extensive volcanism and routine asteroid impacts, which would have affected the evolution of our atmosphere. In comparison, Titan’s icy crust appears quite docile.

    “We are continuing to use ALMA to make further observations of Titan’s atmosphere,” concluded Conor Nixon, also with NASA’s Goddard Space Flight Center and a co-author on the paper. “We are looking for new and more complex organic chemicals as well as studying this moon’s atmospheric circulation patterns. In the future, higher-resolution studies will shed more light on this intriguing world and hopefully give us new insights into Titan’s potential for prebiotic chemistry.”

    Additional Information

    These results are in a paper titled ALMA Detection and Astrobiological Potential of Vinyl Cyanide on Titan, M. Palmer et al., appearing in Science Advances [see above].

    See the full article here .

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    The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organization for Astronomical Research in the Southern Hemisphere (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan.

    ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

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  • richardmitnick 12:47 pm on March 1, 2017 Permalink | Reply
    Tags: , , Peeking Through the Haze: A Look at Titan’s Bright Surface Features, Principal Component Analysis (PCA), Titan   

    From astrobites: “Peeking Through the Haze: A Look at Titan’s Bright Surface Features” 

    Astrobites bloc

    Astrobites

    Mar 1, 2017
    Kerrin Hensley

    Title: Compositional Similarities and Distinctions Between Titan’s Evaporitic Terrains
    Authors: S.M. MacKenzie and Jason W. Barnes
    First Author’s Institution: University of Idaho
    1
    Status: Published in the Astrophysical Journal, open access

    Titan, Saturn’s largest moon, is the only solar system object other than the Earth to have a thick atmosphere and standing surface liquid. When the Cassini spacecraft began observing Titan, it even discovered lakes and seas dotting the northern hemisphere.

    NASA/ESA/ASI Cassini Spacecraft
    NASA/ESA/ASI Cassini Spacecraft

    Don’t fire up your rocket just yet, though—because Titan is so cold, the lakes and seas are filled with liquid methane and ethane rather than water.

    1
    Wikipedia

    Titan’s thick, methane-rich atmosphere makes it difficult to observe the surface at visible wavelengths. Luckily, there are several windows in the near-infrared through which light can pass and reveal the surface. Seven of these windows overlap with the wavelength range covered by Cassini’s Visual and Infrared Mapping Spectrometer (VIMS). By looking at how the brightness of the surface changes with wavelength, we can learn about the composition of the surface material. Figure 1 depicts a three-color map of Titan’s surface made with VIMS. The pinkish regions show where the surface reflects strongly at 5 microns.

    3
    Figure 1. Map of Titan’s surface from Cassini. Red is 5 microns, green is 2 microns, and blue is 1.3 microns. Many of the major geographic regions are labeled. Some of the regions selected for this study are indicated with the white arrows.

    The 5-micron-bright regions are found circling lakes in the northern hemisphere, in dry lake beds in both hemispheres, and in the desert-like equatorial regions. The bright rings around the lakes are believed to be evaporites—solid material left behind after the liquid it was dissolved in evaporates. This explains the presence of the bright material surrounding the lakes and the dry lake beds, but what about the desert? Linking 5-micron-bright regions in what is today a desert to the bright rings around the lakes could provide evidence that the equatorial regions of Titan were once covered with liquid.

    In this paper, the authors searched for a compositional link between the bright regions in the desert and the evaporites around the lakes and seas. They used an absorption feature at 4.92 microns in order to investigate whether or not the 5-micron-bright material in each of these regions is the same. The 4.92-micron absorption feature has been observed previously in the desert region, but no one has been able to definitively say what compound causes it. Because of this, finding the same feature in the desert and around the lakes can indicate that the regions are geologically similar, but can’t yet tell us about the chemical makeup of the material.

    The authors used Principal Component Analysis (PCA) to isolate the weak 4.92-micron absorption feature. PCA is a mathematical method that separates the individual components that make up an observed signal. In this case, the main contributors to the signal (i.e. the “principal components”) could be changes in the surface reflectivity, instrumental noise, or compositional variations. Once the components have been separated, the unwanted contributors can be removed. As a result, PCA can be used to isolate a signal that is much smaller than the background noise. (PCA is also used in the direct detection of exoplanets and is described in more detail here.) After applying PCA, the authors observed the 4.92-micron absorption feature in both the desert and around the lakes, strengthening the hypothesis that the desert once had liquid. However, they also found that not all of the lake regions had the absorption feature, and some of the regions that did have it didn’t have it in every observation. They suggested that material with a crystalline structure that reflects light more strongly at some angles or transient effects like methane rain could cause the absorption feature to appear intermittently.

    What causes some lake regions to have the absorption feature while others don’t? The authors suggested that the material that causes the 4.92-micron absorption feature could be just one of several solids that are left behind as the lakes evaporate away. Whether or not a lake rim has the absorption feature could be a function of how far the evaporation has progressed. As evaporation proceeds, materials that are more soluble precipitate out in sequence. We could see a 5-micron-bright evaporite ring without the absorption feature if the lake hasn’t evaporated enough for the material causing the absorption to precipitate out. The authors even have a suggestion for why this might happen to some lakes in the northern hemisphere but not others—lakes closest to the north pole might experience more methane rainfall than more southern lagoons, periodically halting the evaporation before the absorbing material can crystallize.

    Although the authors posit many explanations for the mysterious behavior of the 4.92-micron absorption feature, they can’t yet settle on one cause. It’s not surprising that Titan, an inhospitable but strangely familiar world with complex geology and weather systems, presents a challenge to astronomers. In the future, by modeling how Titan’s climate changes over time, we can hope to learn more about what causes the distribution of evaporites on Titan’s surface.

    See the full article here .

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    What do we do?

    Astrobites is a daily astrophysical literature journal written by graduate students in astronomy. Our goal is to present one interesting paper per day in a brief format that is accessible to undergraduate students in the physical sciences who are interested in active research.
    Why read Astrobites?

    Reading a technical paper from an unfamiliar subfield is intimidating. It may not be obvious how the techniques used by the researchers really work or what role the new research plays in answering the bigger questions motivating that field, not to mention the obscure jargon! For most people, it takes years for scientific papers to become meaningful.
    Our goal is to solve this problem, one paper at a time. In 5 minutes a day reading Astrobites, you should not only learn about one interesting piece of current work, but also get a peek at the broader picture of research in a new area of astronomy.

     
  • richardmitnick 1:43 pm on February 12, 2015 Permalink | Reply
    Tags: , , , Titan   

    From JPL: “A New Way to View Titan: ‘Despeckle’ It” 

    JPL

    February 11, 2015
    Preston Dyches
    Jet Propulsion Laboratory, Pasadena, Calif.
    818-354-7013
    preston.dyches@jpl.nasa.gov

    During 10 years of discovery, NASA’s Cassini spacecraft has pulled back the smoggy veil that obscures the surface of Titan, Saturn’s largest moon.

    NASA Cassini Spacecraft

    Cassini’s radar instrument has mapped almost half of the giant moon’s surface; revealed vast, desert-like expanses of sand dunes; and plumbed the depths of expansive hydrocarbon seas. What could make that scientific bounty even more amazing? Well, what if the radar images could look even better?

    Thanks to a recently developed technique for handling noise in Cassini’s radar images, these views now have a whole new look. The technique, referred to by its developers as “despeckling,” produces images of Titan’s surface that are much clearer and easier to look at than the views to which scientists and the public have grown accustomed.

    Typically, Cassini’s radar images have a characteristic grainy appearance. This “speckle noise” can make it difficult for scientists to interpret small-scale features or identify changes in images of the same area taken at different times. Despeckling uses an algorithm to modify the noise, resulting in clearer views that can be easier for researchers to interpret.

    Antoine Lucas got the idea to apply this new technique while working with members of Cassini’s radar team when he was a postdoctoral researcher at the California Institute of Technology in Pasadena.

    “Noise in the images gave me headaches,” said Lucas, who now works at the astrophysics division of France’s nuclear center (CEA). Knowing that mathematical models for handling the noise might be helpful, Lucas searched through research published by that community, which is somewhat disconnected from people working directly with scientific data. He found that a team near Paris was working on a “de-noising” algorithm, and he began working with them to adapt their model to the Cassini radar data. The collaboration resulted in some new and innovative analysis techniques.

    “My headaches were gone, and more importantly, we were able to go further in our understanding of Titan’s surface using the new technique,” Lucas said.

    As helpful as the tool has been, for now, it is being used selectively.

    “This is an amazing technique, and Antoine has done a great job of showing that we can trust it not to put features into the images that aren’t really there,” said Randy Kirk, a Cassini radar team member from the U.S. Geologic Survey in Flagstaff, Arizona. Kirk said the radar team is going to have to prioritize which images are the most important to applying the technique. “It takes a lot of computation, and at the moment quite a bit of ‘fine-tuning’ to get the best results with each new image, so for now we’ll likely be despeckling only the most important — or most puzzling — images,” Kirk said.

    Despeckling Cassini’s radar images has a variety of scientific benefits. Lucas and colleagues have shown that they can produce 3-D maps, called digital elevation maps, of Titan’s surface with greatly improved quality. With clearer views of river channels, lake shorelines and windswept dunes, researchers are also able to perform more precise analyses of processes shaping Titan’s surface. And Lucas suspects that the speckle noise itself, when analyzed separately, may hold information about properties of the surface and subsurface.

    “This new technique provides a fresh look at the data, which helps us better understand the original images,” said Stephen Wall, deputy team lead of Cassini’s radar team, which is based at NASA’s Jet Propulsion Laboratory in Pasadena, California. “With this innovative new tool, we will look for details that help us to distinguish among the different processes that shape Titan’s surface,” he said.

    Details about the new technique were published recently in the Journal of Geophysical Research: Planets.

    The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology, Pasadena, manages the mission for NASA’s Science Mission Directorate in Washington. The VIMS team is based at the University of Arizona in Tucson. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the US and several European countries.

    More information about Cassini:

    http://www.nasa.gov/cassini

    http://saturn.jpl.nasa.gov

    Despeckling Ligea Mare

    1
    Presented here are side-by-side comparisons of a traditional Cassini Synthetic Aperture Radar (SAR) view and one made using a new technique for handling electronic noise that results in clearer views of Titan’s surface. The technique, called despeckling, produces images that can be easier for researchers to interpret.

    The view is a mosaic of SAR swaths over Ligeia Mare, one of the large hydrocarbons seas on Titan. In particular, despeckling improves the visibility of channels flowing down to the sea.

    Perspective on Kraken Mare Shores

    2
    This Cassini Synthetic Aperture Radar (SAR) image is presented as a perspective view and shows a landscape near the eastern shoreline of Kraken Mare, a hydrocarbon sea in Titan’s north polar region. This image was processed using a technique for handling noise that results in clearer views that can be easier for researchers to interpret. The technique, called despeckling, also is useful for producing altimetry data and 3-D views called digital elevation maps.

    Scientists have used a technique called radargrammetry to determine the altitude of surface features in this view at a resolution of approximately half a mile, or 1 kilometer. The altimetry reveals that the area is smooth overall, with a maximum amplitude of 0.75 mile (1.2 kilometers) in height. The topography also shows that all observed channels flow downhill.

    The presence of what scientists call “knickpoints” — locations on a river where a sharp change in slope occurs — might indicate stratification in the bedrock, erosion mechanisms at work or a particular way the surface responds to runoff events, such as floods following large storms. One such knickpoint is visible just above the lower left corner, where an area of bright slopes is seen.

    The image was obtained during a flyby of Titan on April 10, 2007. A more traditional radar image of this area on Titan is seen in PIA19046.

    Titan Despeckled Montage

    3
    This montage of Cassini Synthetic Aperture Radar (SAR) images of the surface of Titan shows four examples of how a newly developed technique for handling noise results in clearer, easier to interpret views. The top row of images was produced in the manner used since the mission arrived in the Saturn system a decade ago; the row at bottom was produced using the new technique.

    The three leftmost image pairs show bays and spits of land in Ligea Mare, one of Titan’s large hydrocarbon seas. The rightmost pair shows a valley network along Jingpo Lacus, one of Titan’s larger northern lakes.

    North is toward the left in these images. Each thumbnail represents an area 70 miles (112 kilometers) wide.

    Leilah Fluctus Despeckled

    4
    Presented here are side-by-side comparisons of a traditional Cassini Synthetic Aperture Radar (SAR) view, at left, and one made using a new technique for handling electronic noise that results in clearer views of Titan’s surface, at right. The technique, called despeckling, produces images that can be easier for researchers to interpret.

    The terrain seen here is in the flow region named Leilah Fluctus (55 degrees north, 80 degrees west). With the speckle noise suppressed, the overall pattern of bright and dark in the scene becomes more apparent. In particular, cone-shaped features near lower right stand out, which could be alluvial analogues on Titan — features produced by the action of rivers or floods.

    North is toward right in this image, which shows an area about 50 miles (80 kilometers) wide.

    See the full article here.

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    NASA JPL Campus

    Jet Propulsion Laboratory (JPL) is a federally funded research and development center and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, United States. Although the facility has a Pasadena postal address, it is actually headquartered in the city of La Cañada Flintridge [1], on the northwest border of Pasadena. JPL is managed by the nearby California Institute of Technology (Caltech) for the National Aeronautics and Space Administration. The Laboratory’s primary function is the construction and operation of robotic planetary spacecraft, though it also conducts Earth-orbit and astronomy missions. It is also responsible for operating NASA’s Deep Space Network.

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  • richardmitnick 3:55 pm on September 4, 2014 Permalink | Reply
    Tags: , , , , , , , Titan   

    From Astrobiology: “Icy Aquifers on Titan Transform Methane Rainfall” 

    Astrobiology Magazine

    Astrobiology Magazine

    The NASA and European Space Agency Cassini mission has revealed hundreds of lakes and seas spread across the north polar region of Saturn’s moon Titan. These lakes are filled not with water but with hydrocarbons, a form of organic compound that is also found naturally on Earth and includes methane. The vast majority of liquid in Titan’s lakes is thought to be replenished by rainfall from clouds in the moon’s atmosphere. But how liquids move and cycle through Titan’s crust and atmosphere is still relatively unknown.

    A recent study led by Olivier Mousis, a Cassini research associate at the University of Franche-Comté, France, examined how Titan’s methane rainfall would interact with icy materials within underground reservoirs. They found that the formation of materials called Clathrate changes the chemical composition of the rainfall runoff that charges these hydrocarbon “aquifers.” This process leads to the formation of reservoirs of propane and ethane that may feed into some rivers and lakes.

    clathrate
    Structure of the 3:1 inclusion complex of urea and 1,6-dichlorohexane. The framework is composed of molecules of urea that are linked by hydrogen bonds, leaving approximately hexagonal channels into which align the molecules of the chlorocarbon. Color scheme: oxygen is red, nitrogen is blue, chlorine is green.

    “We knew that a significant fraction of the lakes on Titan’s surface might possibly be connected with hidden bodies of liquid beneath Titan’s crust, but we just didn’t know how they would interact,” said Mousis. “Now, we have a better idea of what these hidden lakes or oceans could be like.”

    Mousis and colleagues at Cornell University, Ithaca, New York, and NASA’s Jet Propulsion Laboratory, Pasadena, California, modeled how a subsurface reservoir of liquid hydrocarbons would diffuse, or spread, through Titan’s porous, icy crust. They found that, at the bottom of the original reservoir, which contains methane from rainfall, a second reservoir would slowly form. This secondary reservoir would be composed of clathrates.

    cassini
    Cassini

    Clathrates are compounds in which water forms a crystal structure with small cages that trap other substances like methane and ethane. Clathrates that contain methane are found on Earth in some polar and ocean sediments. On Titan, the surface pressure and temperature should allow clathrates to form when liquid hydrocarbons come into contact with water ice, which is a major component of the moon’s crust. These clathrate layers could remain stable as far down as several miles below Titan’s surface.

    One of the peculiar properties of clathrates is that they trap and split molecules into a mix of liquid and solid phases, in a process called fractionation. Titan’s subsurface clathrate reservoirs would interact with and fractionate the liquid methane from the original underground hydrocarbon lake, slowly changing its composition. Eventually the original methane aquifer would be turned into a propane or ethane aquifer.

    “Our study shows that the composition of Titan’s underground liquid reservoirs can change significantly through their interaction with the icy subsurface, provided the reservoirs are cut off from the atmosphere for some period of time,” said Mathieu Choukroun of JPL, one of three co-authors of the study with Mousis.

    Importantly, the chemical transformations taking place underground would affect Titan’s surface. Lakes and rivers fed by springs from propane or ethane subsurface reservoirs would show the same kind of composition, whereas those fed by rainfall would be different and contain a significant fraction of methane. This means researchers could examine the composition of Titan’s surface lakes to learn something about what is happening deep underground, said Mousis.

    The results are published in the Sept. 1, 2014, printed issue of the journal Icarus. The research was funded by the French Centre National d’Etudes Spatiales (CNES) and NASA.

    See the full article here.

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  • richardmitnick 6:56 am on August 14, 2014 Permalink | Reply
    Tags: , , , , , Titan   

    From SPACE.com: “Titan, Saturn’s Largest Moon, Explained” 

    space-dot-com logo

    SPACE.com

    January 14, 2013
    Karl Tate

    Discovered in the year 1655, Titan is the largest of Saturn’s 62 charted moons. Titan is the only moon in the solar system with a dense atmosphere and stable bodies of liquid on its surface.

    titan
    Credit: NASA/JPL/Caltech/Space Science Institute

    The environment on Titan is deadly to human life, with a toxic atmosphere consisting mostly of nitrogen and methane. The surface temperature is minus 290 degrees F (minus 179 degrees C).

    Titan, 3,200 miles (5,150 kilometers) in diameter, is the second-largest moon in the solar system, one-and-a-half times the size of Earth’s moon. Titan is larger than the planet Mercury and is three-quarters the size of Mars. [Amazing Photos of Titan]

    In 2005, the Huygens lander revealed the surface of Titan is a wasteland of water ice and frozen hydrocarbons. Despite its lack of liquid water, some scientists believe Titan may support life, now or in the distant future when the sun’s heat increases.

    A rain of liquid ethane and methane falls to form lakes, making Titan the only planet or moon apart from Earth known to have liquid on its surface. In addition, some scientists think Titan may have large sub-surface oceans of liquid ammonia. Radar images of Titan’s north polar region show presumed lakes of liquid hydrocarbons.

    See the full article here.

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