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  • richardmitnick 9:31 am on November 21, 2014 Permalink | Reply
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    From Science Daily: “How to estimate the magnetic field of an exoplanet” 

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    [Similar material to an earlier post; but a different slant.]

    Science Daily

    November 20, 2014
    Source: Lomonosov Moscow State University

    Scientists developed a new method which allows to estimate the magnetic field of a distant exoplanet, i.e., a planet, which is located outside the Solar system and orbits a different star. Moreover, they managed to estimate the value of the magnetic moment of the planet HD 209458b.The group of scientists including one of the researchers of the Lomonosov Moscow State University (Russia) published their article in the Science magazine.

    2
    Size comparison of HD 209458 b with Jupiter.

    hj
    Artist’s interpretation of Planet HD 209458b. Scientists have now estimated the value of the magnetic moment of the planet HD 209458b.
    Credit: NASA/ESA/CNRS/Alfred Vidal-Madjar

    In the two decades which passed since the discovery of the first planet outside the Solar system, astronomers have made a great progress in the study of these objects. While 20 years ago a big event was even the discovery of a new planet, nowadays astronomers are able to consider their moons, atmosphere and climate and other characteristics similar to the ones of the planets in the Solar system. One of the important properties of both solid and gaseous planets is their possible magnetic field and its magnitude. On Earth it protects all the living creatures from the dangerous cosmic rays and helps animals to navigate in space.

    Kristina Kislyakova of the Space Research Institute of the Austrian Academy of Sciences in Graz together with an international group of physicists for the first time ever was able to estimate the value of the magnetic moment and the shape of the magnetosphere of the exoplanet HD 209458b. Maxim Khodachenko, a researcher at the Department of Radiation and computational methods of the Skobeltsyn Institute of Nuclear Physics of the Lomonosov Moscow State University, is also one of the authors of the article. He also works at the Space Research Institute of the Austrian Academy of Sciences.

    Planet HD 209458b (Osiris) is a hot Jupiter, approximately one third larger and lighter than Jupiter. It is a hot gaseous giant orbiting very close to the host star HD 209458. HD 209458b accomplishes one revolution around the host star for only 3.5 Earth days. It has been known to astronomers for a long time and is relatively well studied. In particular, it is the first planet where the atmosphere was detected. Therefore, for many scientists it has become a model object for the development of their hypotheses.

    Scientists used the observations of the Hubble Space Telescope of the HD 209458b in the hydrogen Lyman-alpha line at the time of transit, when the planet crosses the stellar disc as seen from Earth. At first, the scientists studied the absorption of the star radiation by the atmosphere of the planet. Afterwards they were able to estimate the shape of the gas cloud surrounding the hot Jupiter, and, based on these results, the size and the configuration of the magnetosphere.

    NASA Hubble Telescope
    NASA/ESA Hubble

    “We modeled the formation of the cloud of hot hydrogen around the planet and showed that only one configuration, which corresponds to specific values of the magnetic moment and the parameters of the stellar wind, allowed us to reproduce the observations,” explained Kristina Kislyakova.

    To make the model more accurate, scientists accounted for many factors that define the interaction between the stellar wind and the atmosphere of the planet: so-called charge exchange between the stellar wind and the neutral atmospheric particles and their ionization, gravitational effects, pressure, radiation acceleration, and the spectral line broadening.

    At present, scientists believe that the size of the atomic hydrogen envelope is defined by the interaction between the gas outflows from the planet and the incoming stellar wind protons. Similarly to Earth, the interaction of the atmosphere with the stellar wind occurs above the magnetosphere. By knowing the parameters of an atomic hydrogen cloud, one can estimate the size of the magnetosphere by means of a specific model.

    Since direct measurements of the magnetic field of exoplanets are currently impossible, the indirect methods are broadly used, for example, using the radio observations. There exist a number of attempts to detect the radio emission from the planet HD 209458b. However, because of the large distances the attempts to detect the radio emission from exoplanets have yet been unsuccessful.

    “The planet’s magnetosphere was relatively small being only 2.9 planetary radii corresponding to a magnetic moment of only 10% of the magnetic moment of Jupiter,” explained Kislyakova, a graduate of the Lobachevsky State University of Nizhny Novgorod. According to her, it is consistent with the estimates of the effectiveness of the planetary dynamo for this planet.

    “This method can be used for every planet, including Earth-like planets, if there exist an extended high energetic hydrogen envelope around them,” summarized Maxim Khodachenko.

    Journal Reference:

    K. G. Kislyakova, M. Holmstrom, H. Lammer, P. Odert, M. L. Khodachenko. Magnetic moment and plasma environment of HD 209458b as determined from Ly observations. Science, 2014; 346 (6212): 981 DOI: 10.1126/science.1257829

    See the full article here.

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  • richardmitnick 11:46 am on November 20, 2014 Permalink | Reply
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    From WIRED: “War of the Worlds” 

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    Wired

    No Date posted
    Lee Billings

    Two teams of astronomers may have found the first earth-like planet in outer space. So who truly discovered Gliese 667C

    g
    Artist’s impression of Gliese 667 Cb with the Gliese 667 A/B binary in the background

    No one knows what the planet Gliese 667Cc looks like. We know that it is about 22 light-years from Earth, a journey of lifetimes upon lifetimes. But no one can say whether it is a world like ours, with oceans and life, cities and single-malt Scotch. Only a hint of a to-and-fro oscillation in the star it orbits, detectable by Earth’s most sensitive telescopes and spectrographs, lets astronomers say the planet exists at all. The planet is bigger than our world, perhaps made of rocks instead of gas, and within its star’s “habitable zone”—at a Goldilocks distance that ensures enough starlight to make liquid water possible but not so much as to nuke the planet clean.

    That’s enough to fill the scientists who hunt for worlds outside our own solar system—so-called exoplanets—with wonder. Gliese 667Cc is, if not a sibling to our world, at least a cousin out there amid the stars. No one knows if it is a place we humans could someday live, breathe, and watch triple sunsets. No one knows whether barely imagined natives are right now pointing their most sensitive and far-seeing technology at Earth, wondering the same things. Yet regardless, to be the person who found Gliese 667Cc is to be the person who changes the quest for life beyond our world, to be remembered as long as humans exist to remember—by the light of the sun or a distant, unknown star.

    Which is a problem. Because another thing no one knows about Gliese 667Cc is who should get credit for discovering it.

    Gliese 667Cc is at the center of an epic controversy in astronomy—a fight over the validity of data, the nature of scientific discovery, and the ever-important question of who got there first.

    In late 1995 Swiss astronomer Michel Mayor and his student Didier Queloz found 51 Pegasi b, the first known exoplanet orbiting a sunlike star. It was orbiting far too close to its sun to allow the formation of water, but the discovery made Mayor’s European team world famous anyway.

    Soon, though, they lost their lead in the planet-hunting race to a pair of American researchers, Geoff Marcy and Paul Butler. The two men had been looking for exoplanets for almost a decade; they bagged their first two worlds a couple of months after Mayor’s announcement.

    The two teams evolved into fiercely competitive dynasties, fighting to have the most—and most tantalizing—worlds to their names. Their rivalry was good for science; within a decade, each had found on the order of a hundred planets around a wide variety of stars. Soon the hunt narrowed to a bigger prize. The teams went searching for smaller, rocky planets they could crown “Earth-like.”

    w
    The Spectral fluctuations of a star with an exoplanet create a sine wave.

    Most planet hunters aren’t looking for exoplanets, per se. Those worlds are too small and dim to easily see. They’re looking instead for telltale shifts in the light of a star, “wobbles” in its spectral identity caused by the gravitational pull of an unseen orbiting exoplanet. When that force tugs a star toward Earth, the Doppler effect ever so slightly compresses the waves of light it emits, shifting them toward the blue end of the spectrum. When the star moves away from Earth, its waves of starlight stretch to reach us, shifting toward the red. You can’t see those shifts with the naked eye. Only a spectrograph can, and the more stable and precise it is, the smaller the wobbles—and planets—you can find.

    By late 2003 the European team had a very precise instrument, the [ESO] High Accuracy Radial velocity Planet Searcher, or Harps. Mounted to a 3.6-meter telescope on a mountaintop in Chile, Harps could detect wobbles of less than a meter per second. (Earth moves the sun just a tenth that amount.) The Americans had to make do with an older instrument called the [Keck]High Resolution Echelle Spectrometer, or Hires—less precise but paired with a more powerful telescope.

    ESO HARPS
    ESO HARPS at the ESO La Silla 3.6m telescope

    Keck HIRES
    HIRES at Keck Observatory

    As the two teams continued to fight for preeminence, trouble was brewing among the Americans. Marcy, a natural showman as well as a brilliant scientist, regularly appeared on magazine covers, newspaper front pages, and even David Letterman’s late-night show. His far more taciturn partner, Butler, preferred the gritty tasks of refining data pipelines and calibration techniques. Having devoted years of their lives to the planet-hunting cause, Butler and another member of the team, Marcy’s PhD adviser, Steve Vogt (the mastermind behind Hires), began to feel marginalized and diminished by Marcy’s growing fame. The relationships hit a low in 2005, when Marcy split a $1 million award with their archrival Mayor. Marcy credited Butler and Vogt in his acceptance speech and donated most of the money to his home institutions, the University of California and San Francisco State University, but the damage was done. Two years later, the relationship disintegrated. Butler and Vogt formed their own splinter group; Butler and Marcy have barely spoken since.

    It was a risky move. Harps and Hires remained the best planet-hunting spectrographs available, and Butler and Vogt now lacked easy access to fresh data from either one. The American dynasty was shattered, and Marcy was forced to find new collaborators. Meanwhile, the ever-expanding European team continued to wring planets from Harps even though Mayor had formally retired in 2007. The search for Earth 2.0, long seen as a struggle between two teams, became a more crowded and open contest.

    Then a seeming breakthrough: In the spring of 2007, the Europeans announced that they’d spotted a potentially habitable world, Gliese 581d.1 It was a blockbuster—a “super-Earth”—on the outer edge of the habitable zone, eight times more massive than our own world.

    Three years later, in 2010, Butler and Vogt scored their own big find around the same star—Gliese 581g. It was smack in the center of the habitable zone and only three or four times the bulk of Earth, so idyllic-seeming that Vogt poetically called it Zarmina’s World, after his wife, and said he thought the chances for life there were “100 percent.” Butler beamed too, in his own subdued way, saying “the planet is the right distance from the star to have water and the right mass to hold an atmosphere.” They had beaten Marcy, laid some claim to the first potentially Earth-like world, and bested their European competitors.

    But to a chorus of skeptics, Zarmina’s World seemed too good to be true. The European group said the signals the Americans had seen were too weak to be taken seriously. The fight was getting ugly; entire worlds were at stake.

    Plotted on a computer screen, a stellar wobble caused by a single planet looks like a sine wave, though real measurements are rarely so clear. A centimeters-per-second wobble in a million-kilometer-wide ball of seething, roiling plasma isn’t exactly a bright beacon across light-years. Spotting it takes hundreds to thousands of observations, spanning years, and even then it registers as a fractional offset of a single pixel in a detector. Sometimes a signal in one state-of-the-art spectrograph will fail to manifest in another. Researchers can chase promising blips for years, only to see their planetary dreams evaporate. Finding a stellar wobble caused by a habitable world requires a volatile mix of scientific acumen and slow-simmering personal obsession.

    A Spanish astronomer named Guillem Anglada-Escudé certainly meets that description. Now a lecturer at Queen Mary University in London, he began working with the American breakaways Butler (a friend and collaborator) and Vogt not long after they announced Gliese 581g.

    Today, Anglada-Escudé’s name is on the books next to between 20 and 30 exoplanets, many found by scraping public archives in search of weak, borderline wobbles. The European Southern Observatory, which funds Harps, mandates that the spectrograph’s overlords release its data after a proprietary period of a year or two. That gives other researchers access to high-quality observations and potential discoveries that the Harps team might have missed. Scavenging scraps from the European table, it turns out, can be almost as worthwhile as being invited to the meal.

    In the summer of 2011, Anglada-Escudé was a 32-year-old postdoc at the end of a fellowship, looking for a steady research position in academia. With Butler’s help he had developed alternative analytic techniques that he used to scour public Harps data. In fact, Anglada-Escudé argued that his approach treated planetary data sets more thoroughly and efficiently, harvesting more significant signals from the noise.

    One late night that August, he picked a new target: nearly 150 observations of a star called Gliese 667C2 taken by the Harps team between 2004 and 2008. He sat before his laptop in a darkened room, waiting impatiently as his custom software slowly crunched through possible physically stable configurations of planets within the data.

    The first wobble to appear suggested a world in a seven-day orbit—the faster the orbit, the closer to the star the planet must be. A weeklong year is about enough time to get roasted to an inhospitable cinder—and anyway the Harps team had announced that one in 2009, as the planet Gliese 667Cb. But Anglada-Escudé spied what looked suspiciously like structure in the residuals of the stellar sine wave snaking across his screen. He ran his software again and another signal emerged, a strong oscillation with a 91-day period—possibly a planet, possibly a pulsation related to the estimated 105-day rotation period of the star itself.

    1 Astronomer Wilhelm Gliese cataloged hundreds of stars in the 1950s. The lowercase letter marks the order in which astronomers discovered the planets orbiting a star.

    2 The capital C indicates a trinary system, with A and B stars.

    See the full article here.

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  • richardmitnick 6:13 pm on November 10, 2014 Permalink | Reply
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    From astrobio.net: “Preparing for Alien Life” 

    Astrobiology Magazine

    Astrobiology Magazine

    Nov 10, 2014
    Johnny Bontemps

    At a recent event sponsored by NASA and the Library of Congress, a group of scientists and scholars explored how we might prepare for the inevitable discovery of life beyond Earth.

    In 1960, the astronomer Francis Drake pointed a radio telescope located in Green Bank, West Virginia, toward two Sun-like stars 11 light years away. His hope: to pick up a signal that would prove intelligent life might be out there. Fifty years have gone by since Drake’s pioneering SETI experiment, and we’ve yet to hear from the aliens.

    NRAO GBT
    NRAO/Green Bank Radio Telescope

    But thanks to a host of discoveries, the idea that life might exist beyond Earth now seems more plausible than ever. For one, we’ve learned that life can thrive in the most extreme environments here on Earth — from deep-sea methane seep and Antarctic sea ice to acidic rivers and our driest deserts.

    We’ve also found that liquid water isn’t unique to our planet. Saturn’s moon Enceladus and Jupiter’s moons Ganymede and Europa harbor large oceans beneath their icy surfaces. Even Saturn’s largest moon, Titan, could spawn some kind of life in its lakes and rivers of methane-ethane.

    And then there’s the discovery of exoplanets, with more than 1800 alien worlds beyond our Solar System identified so far. In fact, astronomers estimate there may be a trillion planets in our galaxy alone, one-fifth of which may be Earth-like. As Carl Sagan famously said: “The Universe is a pretty big place. If it’s just us, seems like an awful waste of space.”

    NASA Kepler Telescope
    NASA/Kepler exoplanet hunter

    Now some scientists believe the hunt for life beyond Earth may well pay off in our lifetimes. “There have been 10,000 generations of humans before us. Ours could be the first to know,” said SETI astronomer Seth Shostak.

    But what happens once we do? How would we handle the discovery? And what would be its impact on society?

    pls
    This artist’s concept illustrates the idea that rocky, terrestrial worlds like the inner planets in our Solar System may be plentiful, and diverse, in the Universe. Image Credit: NASA/JPL–Caltech/

    This was the focus of a conference organized last September by the NASA Astrobiology Program and the Library of Congress. For two days, a group of scientists, historians, philosophers and theologians from around the world explored how we might prepare for the inevitable discovery of life — microbial or intelligent — elsewhere in our Universe.

    The symposium was hosted by Steven J. Dick, the second annual Chair in Astrobiology at the Library of Congress. The video presentations can be viewed here.

    “Three Horse Races”

    Of course, the impact of discovery will depend on the specific scenario. In a talk titled Current Approaches to Finding Life Beyond Earth, and What Happens If We Do, Shostak described three ways — or three “horse races” — for finding life in space.

    First, we could find it nearby, in our Solar System. NASA’s Curiosity Rover is currently surveying the Martian surface for signs of past or present life. And Europa Clipper, a mission to Jupiter’s icy moon, is now under consideration.

    NASA Mars Curiosity Rover
    Curiosity

    NASA Europa Clipper
    Europa Clipper schematic

    Second, we could “sniff it out” of the atmosphere of an exoplanet, using telescopes to look for gases such as methane and oxygen that might hint at a biosphere. The James Webb Space Telescope, to be launched in 2018, will be able to carry out that kind of work.

    NASA James Webb Telescope
    NASA/Webb

    And of course we can pursue the kind of SETI work pioneered by Frank Drake, and keep listening for radio signals among the stars.

    eur
    This illustration of Europa (foreground), Jupiter (right) and Io (middle) is an artist’s concept. Image credit: NASA/JPL-Caltech

    Finding life in our Solar System, which likely would be microbial, might not have as great an impact as hearing from an intelligent civilization far away. We’d have to worry about issues like contamination. We might also discover some alternative biochemistry, perhaps uncovering new insights about the nature of life. But that kind of discovery wouldn’t affect us as much as the prospect of communicating with intelligent life.

    Then again it’d take hundreds, if not thousands of years for a signal to travel back and forth, Shostak pointed out. So that third scenario would only teach us a very few things right away, such as their location or what kind of star they orbit.

    However, picking a signal might have other tantalizing implications about the nature of alien intelligence.

    Alien Minds & Artificial Intelligence

    Several researchers, including Shostak, put forward the following premise: “That once a society creates the technology that could put them in touch with the cosmos, they are only a few hundred years away from changing their paradigm from biology to artificial intelligence.”

    The idea is based on the so-called “time scale argument” or “short window observation.” Many researchers predict we’ll have developed a strong artificial intelligence by 2050 here on Earth — about a hundred years after the invention of computers, or a hundred and fifty years after the invention of radio communication.

    “The point is that, going from inventing radios to inventing thinking machines is very short — a few centuries at most,” Shostak said. “The dominant intelligence in the cosmos may well be non-biological.”

    In a talk titled Alien Minds, Susan Schneider, a philosophy professor at the University of Connecticut, explored that idea further. The concept of “whole brain emulation” is becoming increasingly popular among certain researchers, she explained. So are other far-fetched sounding ideas like “mind uploading” and “immortally.” So, to her, a civilization capable of radio communication would likely be “super-intelligent” by the time we hear from them.

    bra
    According to the “short window observation” idea, a civilization capable of radio communication would likely have developed artificial intelligence by the time we hear from them.
    No image credit

    She also argued that alien super-intelligence would be conscious in principle, since the neural code is akin to a computational code, and thoughts could well be embedded in a silicon-based substrate. A silicon-based intelligence would also have tremendous implications for long distance space travel.

    But again, a recurring theme throughout the conference was to be aware of our anthropocentric tendencies. There’s been a huge gap between microbial life and intelligent life on Earth, and even intelligent life has even evolved on a spectrum.

    Lori Marino, a neuroscientist and current director of the Kimela Center for Animal Advocacy, argued as such in a talked titled The Landscape of Intelligence. We have a lot to learn from other intelligent beings here on Earth (such as dolphins) before even thinking about communicating with aliens.

    Philosophical Impact

    Ultimately, the greatest implications might be philosophical. Whether it turns out to be microbial, complex or intelligent, finding life elsewhere will raise intriguing questions about our place in the cosmos.

    A couple of presentations, by theologian Robin Lovin and Vatican astronomer Guy Consolmagno, even addressed the potential impact on the world’s religions.

    But what if we don’t find anything soon, or even at all?

    The search itself can give us a sense of direction, and help us forge a planetary identity, argued the philosopher Clement Vidal in a talk titled Silent Impact. And if we’re truly alone, then we should start taking better care of life here on Earth, and contemplate our duty of colonization, he added.

    ear
    The search itself can help us forge a planetary identity, said philosopher Clement Vidal. Image credit: NASA

    In the meantime, astrobiology can help narrow the gap between the sciences and humanities, as many presenters emphasized. And it can be a step toward integrating our knowledge across a wide range of disciplines.

    So, how do we prepare for something we know so little about? We do so “by continuing to do good science, but also by realizing that science is not metaphysically neutral,” concluded the conference host Steven Dick.

    He added: “We prepare by continuing to question our assumptions about the nature of life and intelligence.”

    See the full article here.

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  • richardmitnick 9:13 pm on November 7, 2014 Permalink | Reply
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    From NASA: “NASA’s TESS Mission Cleared for Next Development Phase” 

    NASA

    NASA

    November 7, 2014
    Claire Saravia
    NASA’s Goddard Space Flight Center, Greenbelt, Maryland

    NASA has officially confirmed the Transiting Exoplanet Survey Satellite (TESS) mission, clearing it to move forward into the development phase. This marks a significant step for the TESS mission, which would search the entire sky for planets outside our solar system, known as exoplanets.

    NASA TESS
    NASA/TESS

    Designed as the first all-sky survey, TESS would spend two years of an overall three-year funded science mission searching both hemispheres of the sky for nearby exoplanets. “This is an incredibly exciting time for the search of planets outside our solar system,” said Mark Sistilli, the TESS program executive from NASA Headquarters, Washington. “We got the green light to start building what is going to be a spacecraft that could change what we think we know about exoplanets.”

    “During its first two years in orbit, the TESS spacecraft will concentrate its gaze on several hundred thousand specially chosen stars, looking for small dips in their light caused by orbiting planets passing between their host star and us,” said TESS Principal Investigator George Ricker of the Massachusetts Institute of Technology, Cambridge, Massachusetts. During the third year, ground-based astronomical observatories would continue monitoring exoplanets identified earlier by the TESS spacecraft.

    TESS is expected to find more than 5,000 exoplanet candidates, including 50 Earth-sized planets. It will also find a wide array of exoplanet types, ranging from small, rocky planets to gas giants. Some of these planets could be the right sizes, and orbit at the correct distances from their stars, to potentially support life.

    “The most exciting part of the search for planets outside our solar system is the identification of ‘earthlike’ planets with rocky surfaces and liquid water as well as temperatures and atmospheric constituents that appear hospitable to life,” said TESS Project Manager Jeff Volosin at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Although these planets are small and harder to detect from so far away, this is exactly the type of world that the TESS mission will focus on identifying.”

    Now that NASA has confirmed TESS, the next step is the Critical Design Review in 2015. This would clear the mission to build the necessary flight hardware for launch.

    “After spending the past year building the team and honing the design, it is incredibly exciting to be approved to move forward toward implementing NASA’s newest exoplanet hunting mission,”Volosin said.

    TESS is designed to complement several other critical missions in the search for life on other planets. Once TESS finds nearby exoplanets to study and determines their sizes, ground-based observatories and other NASA missions, like the James Webb Space Telescope, would make follow-up observations on the most promising candidates to determine their density and other key properties. By figuring out a planet’s characteristics, like its atmospheric conditions, scientists could determine whether the targeted planet has a habitable environment.

    webb
    NASA/Webb

    “TESS should discover thousands of new exoplanets within two hundred light years of Earth,” Ricker said. “Most of these will be orbiting bright stars, making them ideal targets for characterization observations with NASA’s James Webb Space Telescope.”

    “The Webb telescope and other teams will focus on understanding the atmospheres and surfaces of these distant worlds, and someday, hopefully identify the first signs of life outside of our solar system,” Volosin said.

    TESS will use four cameras to study sections of the sky’s north and south hemispheres, looking for exoplanets. The cameras would cover about 90 percent of the sky by the end of the mission. This makes TESS an ideal follow-up to the Kepler mission, which searches for exoplanets in a fixed area of the sky. Because the TESS mission surveys the entire sky, TESS is expected to find exoplanets much closer to Earth, making them easier for further study.

    NASA Kepler Telescope
    NASA/Kepler

    In addition, Ricker said TESS would provide precision, full-frame images for more than 20 million bright stars and galaxies.

    “This unique new data will comprise a treasure trove for astronomers throughout the world for many decades to come,” Ricker said.

    Now that TESS is cleared to move into the next development stage, it can continue towards its goal of being a key part of NASA’s search for life beyond Earth.

    “I’m still hopeful that in my lifetime, we will discover the existence of life outside of our solar system and I’m excited to be part of a NASA mission that serves as a key stepping stone in that search,” Volosin said.

    TESS is an Explorer-class mission overseen by the Astrophysics Division at NASA Headquarters. It is being developed jointly by Massachusetts Institute of Technology, in Cambridge, Massachusetts and NASA Goddard. Additional partners include NASA’s Ames Research Center in Moffett Field, California; the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, and the Space Telescope Science Institute in Baltimore. More than a dozen universities and observatories worldwide are participating in the scientific planning for the mission.

    See the full article here.

    The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.

    President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

    Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.

    NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate’s Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories [Hubble,
    Chandra, Spitzer ]and associated programs. NASA shares data with various national and international organizations such as from the Greenhouse Gases Observing Satellite.


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  • richardmitnick 2:59 pm on November 7, 2014 Permalink | Reply
    Tags: , , , , , Exoplanets   

    From SPACE.com: “European Spacecraft Could Find 70,000 New Alien Worlds” 

    space-dot-com logo

    SPACE.com

    November 06, 2014
    Mike Wall

    A European spacecraft that launched late last year could eventually discover 70,000 exoplanets, helping researchers better understand the number and characteristics of alien worlds throughout the galaxy, a new study reports.

    The European Space Agency’s star-monitoring Gaia mission, which launched in December 2013, should find about 21,000 alien planets over the course of its five-year mission and perhaps 70,000 distant worlds if it keeps operating for 10 years, the study found.

    ESA Gaia satellite
    ESA/Gaia

    “It’s not just about the numbers. Each of these planets will be conveying some very specific details, and many will be highly interesting in their own way,” lead author Michael Perryman of Princeton University said in a statement. “If you look at the planets that have been discovered until now, they occupy very specific regions of discovery space. Gaia will not only discover a whole list of planets, but in an area that has not been thoroughly explored so far.”

    The first alien world around a sunlike star was spotted in 1995. Since then, astronomers have found nearly 2,000 exoplanets, with more than half of the discoveries made by NASA’s Kepler space telescope.

    NASA Kepler Telescope
    NASA/Kepler

    But there are many more out there, waiting to be discovered. Astronomers think that, on average, every star in the Milky Way hosts at least one planet, meaning the galaxy probably teems with more than 100 billion alien worlds.

    The $1 billion Gaia mission operates from a gravitationally stable spot 930,000 miles (1.5 million kilometers) from Earth called the Earth-Sun Lagrange Point 2. The spacecraft’s main goal is to catalog and closely monitor 1 billion Milky Way stars, helping researchers create a detailed 3D map that should shed light on the galaxy’s structure and evolution.

    But Gaia’s precise tracking work should also reveal the presence of many alien planets by noting how their gravity tugs the stars slightly this way and that, researchers say.

    Perryman and his colleagues wanted to get a better idea of just how many alien worlds Gaia could be expected to find. They arrived at their estimates after integrating a number of sources of information, including a comprehensive model of Milky Way star and planet positions, the latest exoplanet-distribution data (much of it from Kepler) and details of Gaia’s measurement capabilities, researchers said.

    “Our assessment will help prepare exoplanet researchers for what to expect from Gaia,” Perryman said. “We’re going to be adding potentially 20,000 new planets in a completely new area of discovery space. It’s anyone’s guess how the field will develop as a result.”

    The new study has been accepted for publication in The Astrophysical Journal and is available now on the preprint site arXiv.

    See the full article, with further material, here.
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  • richardmitnick 2:20 pm on October 19, 2014 Permalink | Reply
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    From astrobio.net: “Rediscovering Venus to Find Faraway Earths “ 

    Astrobiology Magazine

    Astrobiology Magazine

    Oct 19, 2014
    fa
    Contact:
    Lyndsay Meyer
    The Optical Society
    +1.202.416.1435
    lmeyer@osa.org

    New optical device designed to measure gravitational pull of a planet should speed the search for Earth-like exoplanets.

    Astronomers Chih-Hao Li and David Phillips of the Harvard-Smithsonian Center for Astrophysics want to rediscover Venus—that familiar, nearby planet stargazers can see with the naked eye much of the year.

    Granted, humans first discovered Venus in ancient times. But Li and Phillips have something distinctly modern in mind. They plan to find the second planet again using a powerful new optical device installed on the Italian National Telescope that will measure Venus’ precise gravitational pull on the sun. If they succeed, their first-of-its-kind demonstration of this new technology will be used for finding Earth-like exoplanets orbiting distant stars.

    Italian National Telescope Galileo
    Italian National Telescope Galileo Internal
    Galileo Italian National Telescope

    “We are building a telescope that will let us see the sun the way we would see other stars,” said Phillips, who is a staff scientist at the Harvard-Smithsonian Center for Astrophysics. He and Li, a research associate at the Center for Astrophysics, will describe the device in a paper to be presented at The Optical Society’s (OSA) 98th Annual Meeting, Frontiers in Optics, being held Oct. 19-23 in Tucson, Arizona, USA. Li is the lead author of the paper, which has 12 collaborators.

    Astronomers have identified more than 1,700 exoplanets, some as far as hundreds of light years away. Most were discovered by the traditional transit method, which measures the decrease in brightness when a planet orbiting a distant star transits that luminous body, moving directly between the Earth and the star. This provides information about the planet’s size, but not its mass.

    Li and Phillips are developing a new laser-based technology known as the green astro-comb for use with the “radial velocity method,” which offers complementary information about the mass of the distant planet.

    From this information, astronomers will be able to determine whether distant exoplanets they discover are rocky worlds like Earth or less dense gas giants like Jupiter. The method is precise enough to help astronomers identify Earth-like planets in the “habitable zone,” the orbital distance “sweet-spot” where water exists as a liquid.

    Better Precision with a Laser

    The radial velocity method works by measuring how exoplanet gravity changes the light emitted from its star. As exoplanets circle a star, their gravitation tugs at the star changing the speed with which it moves toward or away from Earth by a small amount. The star speeds up slightly as it approaches Earth, with each light wave taking a fraction of a second less time to arrive than the wave before it.

    To an observer on Earth, the crests of these waves look closer together than they should, so they appear to have a higher frequency and look bluer. As the star recedes, the crests move further apart and the frequencies seem lower and redder.

    astro
    The astro-comb calibrates the Italian National Telescope’s HARPS-Nspectrograph using an observation of the asteroid Vesta. The top figure is a colorizedversion of the raw HARPS-N spectrum, showing the astro-comb calibration dottedlines and the sun’s spectrum reflected off Vesta as mostly solid vertical lines.The middle figure shows the raw data converted to a very precise standard one-dimensionalplot of spectral intensity vs. wavelength. The very regular astro-comb calibrationspectrum is below below. Credit: David Phillips

    This motion-based frequency change is known as the Doppler shift. Astronomers measure it by capturing the spectrum of a star on the pixels of a digital camera and watching how it changes over time.

    Today’s best spectrographs are only capable of measuring Doppler shifts caused by velocity changes of 1 meter per second or more. Only large gas giants or “super-earths” close to their host stars have enough gravity to cause those changes.

    The new astro-comb Li, Phillips and their colleagues are developing, however, will be able to detect Doppler shifts as small as 10 centimeters per second—small enough to find habitable zone Earth-like planets, even from hundreds of light years away.

    “The astro-comb works by injecting 8,000 lines of laser light into the spectrograph. They hit the same pixels as starlight of the same wavelength. This creates a comb-like set of lines that lets us map the spectrograph down to 1/10,000 of a pixel. So if I have light on this section of the pixel, I can tell you the precise wavelength,” Phillips explained.

    “By calibrating the spectrograph this way, we can take into account very small changes in temperature or humidity that affect the performance of the spectrograph. This way, we can compare data we take tonight with data from the same star five years from now and find those very small Doppler shifts,” he said.

    Seeing Green

    Li and his co-researchers pioneered the astro-comb several years ago, but it only worked with infrared and blue light. Their new version of the astro-comb lets astronomers measure green light—which is better for finding exoplanets.

    “The stars we look at are brightest in the green visible range, and this is the range spectrographs are built to handle,” Phillips said.

    Building the green astro-comb was a challenge, since the researchers needed to convert red laser light to green frequencies. They did it by making small fibers that convert one color of light to another.

    pla
    A slowly rotating planet is not guaranteed to be habitable, as is evident when looking at the inhospitable Venus. Credit: NASA/JPL/Caltech

    “Red light goes in and green light comes out,” Phillips said. “Even though I see it every day and understand the physics, it looks like magic.”

    The researchers plan to test the green astro-comb by pointing it at our sun, analyzing its spectrum to see if they can find Venus and rediscover its characteristic period of revolution, its size, its mass and its composition.

    “We know a lot about Venus, and we can compare our answers to what we already know, so we are more confident about our answers when we point our spectrographs at distant stars,” Li said.

    The Harvard-Smithsonian team is installing this device on the High-Accuracy Radial Velocity Planet Searcher-North (HARPS-N), a new spectrograph designed to search for exoplanets using the Italian National Telescope.

    “We will look at the thousands of potential exoplanets identified by the Kepler satellite telescope by the transit method. Together, our two methods can tell us a lot about those worlds,” Li said.

    And, because he will have already discovered Venus, he will be more certain of the answers.

    See the full article here.

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  • richardmitnick 11:47 am on October 4, 2014 Permalink | Reply
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    From astrobio.net: “Are the world’s religions ready for E.T.?” 

    Astrobiology Magazine

    Astrobiology Magazine

    Oct 4, 2014
    Source: Vanderbilt University
    David Salisbury

    In 1930, Albert Einstein was asked for his opinion about the possibility of life elsewhere in the universe. “Other beings, perhaps, but not men,” he answered. Then he was asked whether science and religion conflict. “Not really, though it depends, of course, on your religious views.”

    Over the past 10 years, astronomers’ new ability to detect planets orbiting other stars has taken this question out of the realm of philosophy, as it was for Einstein, and transformed it into something that scientists might soon be able to answer.

    Realization that the nature of the debate about life on other worlds is about to fundamentally change led Vanderbilt Professor of Astronomy David Weintraub to begin thinking seriously about the question of how people will react to the discovery of life on other planets. He realized, as Einstein had observed, that people’s reactions will be heavily influenced by their religious beliefs. So he decided to find out what the world’s major religions have to say about the matter. The result is a book titled Religions and Extraterrestrial Life (Springer International Publishing) published this month.

    book
    Credit: Springer

    “When I did a library search, I found only half a dozen books and they were all written about the question of extraterrestrial life and Christianity, and mostly about Roman Catholicism, so I decided to take a broader look,” the astronomer said.

    As a result, his book describes what religious leaders and theologians have to say about extraterrestrial life in more than two dozen major religions, including Judaism, Roman Catholicism, the Eastern Orthodox churches, the Church of England and the Anglican Communion, several mainline Protestant sects, the Southern Baptist Convention and other evangelical and fundamentalist Christian denominations, the Religious Society of Friends (Quakers), Seventh Day Adventism and Jehovah’s Witnesses, the Church of Jesus Christ of Latter-Day Saints (Mormons), Islam and several major Asian religions including Hinduism, Buddhism and the Bahá’í Faith.

    Discovery of planets

    The remarkable progress that astronomers have made at detecting exoplanets gives the issue of extraterrestrial life a new sense of immediacy. In 2000, astronomers had detected 50 planets orbiting other stars. Today, the number has grown to more than 1,000. If the rate of discovery keeps up its current pace, astronomers will have identified more than a million exoplanets by the year 2045.

    “If even one exoplanet shows signs of biological activity – and those signs should not be hard to detect, if living things are present – then we will know Earth is not the only place in the universe where life exists,” Weintraub points out. “Although it is impossible to prove a negative, if we have not found any signs of life after a million exoplanets have been studied, then we will know that life in the universe is, at best, exceedingly rare.”

    Public opinion polling indicates that about one fifth to one third of the American public believes that extraterrestrials exist, Weintraub reports. However, this varies considerably with religious affiliation.

    Belief in extraterrestrials varies by religion

    55 percent of Atheists
    44 percent of Muslims
    37 percent of Jews
    36 percent of Hindus
    32 percent of Christians

    Of the Christians, more than one third of the Eastern Orthodox faithful (41 percent), Roman Catholics (37 percent), Methodists (37 percent), and Lutherans (35 percent) professed belief in extraterrestrial life. Only the Baptists (29 percent) fell below the one-third threshold.

    Asian religions would have the least difficulty in accepting the discovery of extraterrestrial life, Weintraub concluded. Some Hindu thinkers have speculated that humans may be reincarnated as aliens, and vice versa, while Buddhist cosmology includes thousands of inhabited worlds.

    Weintraub quotes passages in the Qur’an that appear to support the idea that spiritual beings exist on other planets, but notes that these beings may not practice Islam as it is practiced on Earth. “Islam, like other faiths, has fundamentalist and conservative traditions. All Muslims, however, likely would agree that the prophetically revealed religion of Islam is a set of practices designed only for humans on earth,” Weintraub wrote.

    Weintraub found very little in Judaic scriptures or rabbinical writings that bear on the question. The few Talmudic and Kabbalistic commentaries on the subject do assert that space is infinite and contains a potentially infinite number of worlds and that nothing can deny the existence of extraterrestrial life. At the same time, Jews don’t believe the discovery of extraterrestrial intelligence would have much effect on them. He quotes a Jewish anthropologist and scholar who has addressed this issue and concluded that the relationship beween Jews and God would not be affected in the slightest by “the existence of other life forms, newly discovered scientific realities or pan-human behavioral changes.”

    Christian debate

    Among Christian religions, the Roman Catholics have done the most thinking about the possibility of life on other worlds, the astronomer discovered. In fact, they have had an on-again, off-again theological debate that has gone on for a thousand years.

    dw
    Author David Weintraub (Daniel Dubois / Vanderbilt)

    The crux of the matter is original sin. If intelligent aliens are not descended from Adam and Eve, do they suffer from original sin? Do they need to be saved? If they do, then did Christ visit them and was he crucified and resurrected on other planets? “From a Roman Catholic perspective, if sentient extraterrestrials exist some but perhaps not all such species may suffer original sin and will require redemption,” Weintraub summarizes.

    The inherent diversity of Protestant denominations, where individuals are encouraged to interpret scripture independently, has led to many conflicting approaches to the question of extraterrestrial intelligence. Weintraub determined that the views of Lutheran theologian Paul Tillich appear to represent a viable consensus. Tillich argued that the need for salvation is universal and the “saving power” of God must be everywhere. At the same time, he maintained that God’s plan for human life need not be the same as his plan for aliens.

    Evangelical and fundamental Christians are most likely to have difficulty accepting the discovery of extraterrestrial life, the astronomer’s research indicates. “…most evangelical and fundamentalist Christian leaders argue quite forcefully that the Bible makes clear that extraterrestrial life does not exist. From this perspective, the only living, God-worshipping beings in the entire universe are humans, created by God, who live on Earth.” Southern Baptist evangelist Billy Graham was a prominent exception who stated that he firmly believes “there are intelligent beings like us far away in space who worship God.”

    Weintraub also identified two religions – Mormonism and Seventh-day Adventism – whose theology embraces extraterrestrials. In Mormonism, God helps exalt lesser souls so they can achieve immortality and live as gods on other worlds. And, Ellen White, who co-founded Seventh-Day Adventism, wrote that Got had given her a view of other worlds where the people are “noble, majestic and lovely” because they live in strict obedience to God’s commandments.

    Are we ready?

    In answer to the question “Are we ready?” Weintraub concludes, “While some of us claim to be ready, a great many of us probably are not… very few among us have spent much time thinking hard about what actual knowledge about extraterrestrial life, whether viruses or single-celled creatures or bipeds piloting intergalactic spaceships, might mean for our personal beliefs [and] our relationships with the divine.”

    See the full article, with video, here.

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  • richardmitnick 7:00 pm on October 2, 2014 Permalink | Reply
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    From Ethan Siegel: “Preparing for Alien Life” 

    Starts with a bang
    Starts with a Bang

    Oct 2, 2014
    Ethan Siegel

    “Language… has created the word ‘loneliness’ to express the pain of being alone. And it has created the word ‘solitude’ to express the glory of being alone.” -Paul Tillich

    Recently, the John Templeton Foundation ran a series of articles asking one of the biggest questions of all: Are We Alone in the Universe? One of the articles in particular I was a big fan of, but would have liked to seen go longer and more in-depth. You see, we have every reason to not only believe that some form of life is quite common in the Universe, but that if we get lucky, we’re going to find it in the next two decades, tops.

    Let me explain.

    stars
    Image credit: Robert Gendler of http://www.robgendlerastropics.com/Biography.html, of the Rosette_Nebula.

    Everywhere we look in the Universe, we see evidence that the same cosmic story is unfolding, from nearby stars to neighboring galaxies to distant clusters across the Universe. We see the same laws of physics, the same physical phenomena, and a shared history that cuts across the billions of light years that separate us.

    We see a Universe that began from a hot, dense, expanding state,

    cone
    Image credit: NASA / Goddard Space Flight Center, via http://cosmictimes.gsfc.nasa.gov/universemashup/archive/pages/expanding_universe.html.

    where matter won out over antimatter,

    me
    Image credit: me, with the background by Christof Schaefer.

    where stable atomic nuclei and then neutral atoms formed,

    asdv
    Image credit: Universe Adventure, © 2005 LBNL Physics Division.

    where gravitational collapse caused the first stars to form,

    cor
    Image credit: The Coronet Cluster, X-ray/IR composite, via NASA/CXC/J. Forbrich, NASA/JPL-Caltech L.Allen (Harvard-Smithsonian CfA), IRAC GTO.

    where the heavy elements formed in their cores were recycled back into interstellar space when those stars died in supernova explosions,

    sr
    Image credit: Supernova Remnant 1E 0102.2–7219, via NASA / CXC / MIT / SAO / STScI / J. DePasquale / D.Dewey et al., at http://www.cfa.harvard.edu/imagelist/2009-16.

    where complex molecules arose from multiple generations of stars spilling their innards back into deep space,
    srt
    Image credit: NASA, ESA, CXC, SSC, and STScI.

    where later generations of stars formed with planets, moons, asteroids and comets around them,

    uni
    Image credit: Avi M. Mandell, NASA.

    and where the ingredients essential to life are ubiquitous.

    This is the consistent cosmic story that we see cutting across the entire observable Universe, from nearby stars to distant nebulae to the galactic center to other galaxies, as far as our technology allows us to observe. Over the last two decades, we’ve discovered the first planets around Sun-like stars [exoplanets]. While initially we tended to discover hot, giant planets in close orbits around their stars, that turned out to be solely because those types of planets are the easiest to observe: they causes the largest “rocking motion” (or stellar wobble) of their parent star due to gravitation, and they also block the most amount of light if they happen to have the right alignment to transit in front of their star’s disk relative to our line-of-sight.

    It’s the planets and planetary candidates that are found via this latter method — the planetary transit — that are likely to be the first planets found that harbor life. This isn’t because planets that transit in front of their stars relative to us are more likely to contain life, but rather because it’s easiest to detect a surefire sign of life using this method.

    Even though there are many conceivable chemical reactions that can give rise to life, and many possible signatures that life would leave behind as a by-product, there are a great many abiotic processes that we’d have to rule out. In addition, there are a great many properties of Earth that — although we could see them from a distant star — aren’t necessarily indicators of life.

    From a long distance away, we could find, with a large enough telescope, that Earth contained:

    oceans and continents,
    an active, variable-cloud-cover atmosphere, and
    polar icecaps that grew and shrank with the seasons.

    But none of those are necessarily indicative of life. However, there is a signature that Earth possesses that, as far as we know, couldn’t occur on a planet that didn’t have life.

    readout
    Image credit: Ziurys et al. 2006, NRAO Newsletter, 109, 11.

    You see, every atom and molecule in existence has a signature spectrum that’s unique to that configuration. Hydrogen, helium, lithium and all the elements of the periodic table have specific wavelengths of light that they absorb and emit, corresponding to the atomic transitions that can occur within those atoms, with all other transitions being forbidden. This is true of molecules as well, including the nitrogen, water vapor, carbon dioxide and ozone in the Earth’s atmosphere.

    pt
    Periodic Tbale of elements

    All of those molecules could be the result of either organic or inorganic processes, but there’s one component of Earth’s atmosphere that couldn’t have arisen through inorganic processes, and that’s oxygen.

    gr
    Image credit: Fran Bagenal of Colorado, via http://lasp.colorado.edu/~bagenal/3720/CLASS5/5Spectroscopy.html.

    There are only a few ways to produce oxygen abiotically, mostly from the high-energy dissociation of other molecules, and even then that only produces it in trace amounts. Here on Earth, however, our atmosphere is a tremendous 21% oxygen, and that percentage has been signficant (at 10% or above) for some two billion years. Although not every planet that has life on it will have a large oxygen content in its atmosphere, every planet that has a large oxygen content in its atmosphere has, at the very least, a history of life that gave rise to that oxygen!

    So how, then, would we detect oxygen on a planetary atmosphere?

    gra
    Image credit: H. Rauer et al.: Potential Biosignatures in super-Earth Atmospheres. Astronomy & Astrophysics, February 16, 2011.

    We couldn’t do it the same way we do it here on Earth; the light coming from an individual, rocky planet in another solar system is far too faint to be seen with not only existing telescope technology, but with any of the telescopes proposed to be built over the next generation. But we are expecting huge upgrades in telescope technology over the next decade or two: the largest, most powerful telescope in space will go from Hubble, at 2.4 meters in diameter, to James Webb, which will have a primary mirror that’s 6.5 meters in diameter, with five times the light-gathering power!

    NASA Hubble Telescope
    NASA/ESA Hubble

    NASA Webb Telescope
    NASA/WEbb

    nasa
    Image credit: NASA.

    In addition to that, the current generation of 8-to-10 meter ground-based telescopes will be superseded by 20-to-35 meter telescopes, providing not only additional light-gathering power but also increased resolution. Examples include the Giant Magellan Telescope, the Thirty Meter Telescope and the European Extremely Large Telescope projects.

    Giant Magellan TelescopeGiant Magellan Interior
    Giant Magellan Telescope

    TMT
    TMT Schematic
    TME

    ESO E-ELT
    ins
    ESO E-ELT

    This improvement in sensitivity means we’re going to be able to detect smaller effects, find smaller planets around larger stars, and many other advances. But perhaps the greatest advance towards finding a planet with oxygen on it — and hence, life — will occur where we have rocky, Earth-sized planets transiting in front of their stars.

    pla
    Image credit: NASA / JPL-Caltech, via http://www.nasa.gov/centers/goddard/news/topstory/2007/cloudy_world.html.

    You see, when a planet passes in front of its star, it not only blocks a fraction of the starlight coming from the star, it also allows a tiny amount of that starlight to pass through the planet’s atmosphere, streaming on into the Universe towards us! Just as the Moon turns red during an eclipse because sunlight passes through the Earth’s atmosphere, so should we be able to see tiny absorption signatures corresponding to different elements when distant starlight passes through a transiting planet’s atmosphere.

    So far, with present technology, we’ve been able to find signatures like water in the atmospheres of Neptune-sized planets.

    star
    Image credit: Harvard Smithsonian Center for Astrophysics, illustration of Planet HAT-P-11b.

    But what the next generation of telescope advances should bring us is the ability to find those same types of signatures around Earth-sized planet, and we should be able to find those signatures around stars up to perhaps 25-to-30 light years away, or conceivably even farther! Given that we have some 300 stars within that conservative distance alone, and given that some of those planetary systems are bound to have a fortuitous alignment with our line-of-sight, we’re going to have the first opportunity, if oxygen-producing life is really abundant in the Universe, to find our first planet with alien life within a single generation.

    pl
    Image credit: NASA / NSF / Lynette Cook. Via http://www.nasa.gov/topics/universe/features/gliese_581_feature.html.

    If the Universe is kind to us, the first signs of life beyond our Solar System will not only teach us that we’re not alone, but that the optimists have it right. Life might not only exist on planets other than Earth, it might be more common than most of us have dared to dream.

    See the full article, with video, here.

    Starts With A Bang! is a blog/video blog about cosmology, physics, astronomy, and anything else I find interesting enough to write about. I am a firm believer that the highest good in life is learning, and the greatest evil is willful ignorance. The goal of everything on this site is to help inform you about our world, how we came to be here, and to understand how it all works. As I write these pages for you, I hope to not only explain to you what we know, think, and believe, but how we know it, and why we draw the conclusions we do. It is my hope that you find this interesting, informative, and accessible.

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  • richardmitnick 5:41 pm on September 30, 2014 Permalink | Reply
    Tags: , , , , , Exoplanets,   

    From SPACE.com: “Search for Alien Life Should Target Water, Oxygen and Chlorophyll” 

    space-dot-com logo

    SPACE.com

    September 30, 2014
    Mike Wall

    The next generation of space telescopes hunting for signs of extraterrestrial life should focus on water, then oxygen and then alien versions of the plant chemical chlorophyll, a new study suggests.

    In the past 20 years or so, astronomers have confirmed the existence of nearly 2,000 worlds outside Earth’s solar system. Many of these exoplanets lie in the habitable zones of stars, areas potentially warm enough for the worlds to harbor liquid water on their surfaces. Astrobiologists hope that life may someday be spotted on such alien planets, since there is life pretty much everywhere water exists on Earth.

    One strategy to discover signs of such alien life involves looking for ways that organisms might change a world’s appearance. For example, chemicals typically shape what are known as the spectra seen from planets by adding or removing wavelengths of light. Alien-hunting telescopes could look for spectra that reveal chemicals associated with life. In other words, these searches would focus on biosignatures — chemicals or combinations of chemicals that life could produce, but that processes other than life could not or would be unlikely to create.

    Astrophysicists Timothy Brandt and David Spiegel at the Institute for Advanced Study in Princeton, New Jersey, sought to see how challenging it might be to conclusively identify signatures of water, oxygen and chlorophyll — the green pigment that plants use to convert sunlight to energy — on a distant twin of Earth using a future off-Earth instrument such as NASA’s proposed Advanced Technology Large-Aperture Space Telescope (ATLAST).

    atlast
    8-meter monolithic mirror telescope (credit: MSFC Advanced Concepts Office)
    again
    16-meter segmented mirror telescope (credit: Northrop Grumman Aerospace Systems & NASA/STScI)
    two conceptual schemes for ATLAST

    The scientists found that water would be the easiest to detect.

    “Water is a very common molecule, and I think a mission to take spectra of exoplanets should certainly look for water,” said Brandt, the lead study author. “Indeed, we have found water in a few gas giants more massive than Jupiter orbiting other stars.”

    In comparison, oxygen is more difficult to detect than previously thought, requiring scientific instruments approximately twice as sensitive as those needed to detect water and significantly better at discriminating between similar colors of light.

    “Oxygen, however, has only been a large part of Earth’s atmosphere for a few hundred million years,” Brandt said. “If we see it in an exoplanet, it probably points to life, but not finding oxygen certainly does not mean that the planet is sterile.”

    Although a well-designed space telescope could detect water and oxygen on a nearby Earth twin, the astrophysicists found the instrument would need to be significantly more sensitive, or very lucky, to see chlorophyll. Identifying this chemical typically requires scientific instruments about six times more sensitive than those needed for oxygen. Chlorophyll becomes as detectable as oxygen only when an exoplanet has a lot of vegetation and/or little in the way of cloud cover, researchers said.

    Chlorophyll slightly reddens the light from Earth. If extraterrestrial life does convert sunlight to energy as plants do, scientists expect that the alien process might use a different pigment than chlorophyll. But alien photosynthesis could also slightly redden planets, just as chlorophyll does.

    “Light comes in packets called photons, and only photons with at least a certain amount of energy are useful for photosynthesis,” Brandt said. Chlorophyll reflects photons that are too red and low in energy to be used for photosynthesis, and it may be reasonable to assume that extraterrestrial pigments would do the same thing, Brandt noted.

    The researchers suggest a strategy for discovering Earthlike alien life that first looks for water, then oxygen on the more favorable planets and finally chlorophyll on only the most exceptionally promising worlds.

    “The goal of a future space telescope will be primarily to detect water and oxygen on a planet around a nearby star,” Brandt said. “The construction and launch of such a telescope will probably cost at least $10 billion and won’t happen for at least 20 years — a lot of technology development needs to happen first — but it could be the most exciting mission of my lifetime.”

    Brandt and Spiegel detailed their findings online Sept. 1 in the journal Proceedings of the National Academy of Sciences.

    See the full article here.

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  • richardmitnick 10:45 am on September 15, 2014 Permalink | Reply
    Tags: , , , , , , Exoplanets   

    From Astrobiology: “Planets with Oddball Orbits Like Mercury Could Host Life” 

    Astrobiology Magazine

    Astrobiology Magazine

    Sep 15, 2014
    Charles Q. Choi

    mercury
    On Mercury a solar day is about 176 Earth days long. During its first Mercury solar day in orbit the MESSENGER spacecraft imaged nearly the entire surface of Mercury to generate a global monochrome map at 250 meters per pixel resolution and a 1 kilometer per pixel resolution color map. Credit: NASA/JHU APL/CIW

    Mercury has an oddball orbit — it takes longer for it to rotate on its axis and complete a day than it takes to orbit the sun and complete a year. Now, researchers suggest photosynthesis could take place on an alien planet with a similarly bizarre orbit, potentially helping support complex life.

    However, the scientists noted that the threat of prolonged periods of darkness and cold on these planets would present significant challenges to life, and could even potentially freeze their atmospheres. They detailed their findings in the International Journal of Astrobiology.

    Astronomers have discovered more than 1,700 alien planets in the past two decades, raising the hope that at least some might be home to extraterrestrial life. Scientists mostly focus the search for alien life on exoplanets in the habitable zones of stars. These are regions where worlds would be warm enough to have liquid water on their surfaces, a potential boon to life.

    spin
    The 3:2 spin orbit resonance of Mercury and the Sun. Credit: Wikicommons

    Although many exoplanets are potentially habitable, they may differ from Earth significantly in one or more ways. For instance, habitable planets around dim red dwarf stars orbit much closer than Earth does to the Sun, sometimes even closer than Mercury’s distance. Red dwarfs are of interest as possible habitats for life because they are the most common stars in the universe — if life can exist around red dwarfs, then life might be very common across the cosmos. Recent findings from NASA’s Kepler Space Observatory suggest that at least half of all red dwarfs host rocky planets that are one-half to four times the mass of Earth.

    NASA Kepler Telescope
    NASA/Kepler

    Since a planet in the habitable zone of a red dwarf orbits very near its star, it experiences much stronger gravitational tidal forces than Earth does from the Sun, which slows the rate at which those worlds spin. The most likely result of this slowdown is that the planet enters what is technically called a 1:1 spin orbit resonance, completing one rotation on its axis every time it completes one orbit around its star. This rate of rotation means that one side of that planet will always face toward its star, while the other side will permanently face away, just as the Moon always shows the same side to Earth. One recent study suggests that such “tidally locked” planets may develop strange lobster-shaped oceans basking in the warmth of their stars on their daysides, while the nightsides of such worlds are mostly covered in an icy shell.

    However, if a habitable red dwarf planet has a very eccentric orbit — that is, oval-shaped — it could develop what is called a 3:2 spin orbit resonance, meaning that it rotates three times for every two orbits around its star. Mercury has such an unusual orbit, which can lead to strange phenomena. For instance, at certain times on Mercury, an observer could see the Sun rise about halfway and then reverse its course and set, all during the course of one mercurial day. Mercury itself is not habitable, since it lacks an atmosphere and experiences temperatures ranging from 212 to 1,292 degrees Fahrenheit (100 to 700 degrees Celsius).

    “If the Sun were less intense, Mercury would be within the habitable zone, and therefore life would have to adapt to strange light cycles,” said lead study author Sarah Brown, an astrobiologist at the United Kingdom Center for Astrobiology in Edinburgh, Scotland.

    Light is crucial for photosynthesis, the process by which plants and other photosynthetic organisms use the Sun’s rays to create energy-rich molecules such as sugars. Most life on Earth currently depends on photosynthesis or its byproducts in one way or the other, and while primitive life can exist without photosynthesis, it may be necessary for more complex multi-cellular organisms to emerge because the main source for oxygen on Earth comes from photosynthetic life, and oxygen is thought to be necessary for multi-cellular life to arise.

    To see what photosynthetic life might exist on a habitable red dwarf planet with an orbit similar to Mercury’s, scientists calculated the amount of light that reached all points on its surface. Their model involved a planet the same mass and diameter as the Earth with a similar atmosphere and amount of water on its surface. The red dwarf star was 30 percent the Sun’s mass and 1 percent as luminous, giving it a temperature of about 5,840 degrees Fahrenheit (3,225 degrees Celsius) and a habitable zone extending from 10 to 20 percent of an astronomical unit (AU) from the star. (One AU is the average distance between Earth and the Sun.)

    spin
    The 1:1 spin orbit resonance of Earth and the Moon. Credit: Wikicommons

    The scientists found that the amount of light the surface of these planets received concentrated on certain bright spots. Surprisingly, the amount of light these planets receive do not just vary over latitude as they do on Earth, where more light reaches equatorial regions than polar regions, but also varied over longitude. Were photosynthetic life to exist on worlds with these types of orbits, “one would expect to find niches that depend on longitude and latitude, rather than just latitude,” said study co-author Alexander Mead, a cosmologist at the Royal Observatory, Edinburgh, in Scotland.

    The research team found these planets could experience nights that last for months. This could pose major problems for photosynthetic life, which depends on light. Still, the scientists noted that many plants can store enough energy to last through 180 days of darkness. Moreover, some photosynthetic microbes spend up to decades dormant in the dark, while others are mixotrophic, which means they can survive on photosynthesis when light is abundant and switch to devouring food when light is absent.

    Another problem these long spans of darkness pose for life is the cold, which could freeze the atmospheres of these planets. Still, the investigators note that heat can flow from the dayside of such a planet to its nightside and prevent this freezing if that planet’s atmosphere is sufficiently dense and can trap infrared light from the planet’s star. This heat flow could lead to very strong winds, but this does not necessarily make the world uninhabitable, they added.

    “Life having to cope with such tidally driven resonances could be common in the universe,” Mead said. “It changes one’s perception of what habitable planets in the Universe would be like. There are many possibilities that are very un-Earth-like.”

    big
    It is difficult to form Mercury in solar system simulations, suggesting that some of our assumptions about the small planet’s formation might be wrong, a new study suggests. NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

    However, the researchers noted that the strength of a world’s magnetic field depends in large part on how quickly it spins, which suggests that planets with orbits like Mercury’s might have relatively weak magnetic fields. This could mean these worlds are not as good at deflecting harmful electrically charged particles streaming from their red dwarfs and other stars that can damage organisms and strip off the atmospheres of these planets.

    The investigators suggested that dense atmospheres could help keep such planets habitable in the face of radiation from space. They added that life might be confined to certain spots on the surfaces of those planets that experience relatively safe levels of radiation.

    Are astronomers capable of detecting habitable planets with a 3:2 spin orbit resonance?

    “Measuring the day length of extrasolar planets is enormously difficult, and the first day length measurements for any extrasolar planets were only published this year,” Mead said. “Such a measurement for the planets we discuss would be much more difficult due to the fact that they are small, rocky planets around faint stars. This means that we are probably a long way from measuring the spin rates of such habitable worlds.”

    Another problem these long spans of darkness pose for life is the cold, which could freeze the atmospheres of these planets. Still, the investigators note that heat can flow from the dayside of such a planet to its nightside and prevent this freezing if that planet’s atmosphere is sufficiently dense and can trap infrared light from the planet’s star. This heat flow could lead to very strong winds, but this does not necessarily make the world uninhabitable, they added.

    “Life having to cope with such tidally driven resonances could be common in the universe,” Mead said. “It changes one’s perception of what habitable planets in the Universe would be like. There are many possibilities that are very un-Earth-like.”

    It is difficult to form Mercury in solar system simulations, suggesting that some of our assumptions about the small planet’s formation might be wrong, a new study suggests. NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

    It is difficult to form Mercury in solar system simulations, suggesting that some of our assumptions about the small planet’s formation might be wrong, a new study suggests. NASA/Johns Hopkins University

    However, the researchers noted that the strength of a world’s magnetic field depends in large part on how quickly it spins, which suggests that planets with orbits like Mercury’s might have relatively weak magnetic fields. This could mean these worlds are not as good at deflecting harmful electrically charged particles streaming from their red dwarfs and other stars that can damage organisms and strip off the atmospheres of these planets.

    The investigators suggested that dense atmospheres could help keep such planets habitable in the face of radiation from space. They added that life might be confined to certain spots on the surfaces of those planets that experience relatively safe levels of radiation.

    Are astronomers capable of detecting habitable planets with a 3:2 spin orbit resonance?

    “Measuring the day length of extrasolar planets is enormously difficult, and the first day length measurements for any extrasolar planets were only published this year,” Mead said. “Such a measurement for the planets we discuss would be much more difficult due to the fact that they are small, rocky planets around faint stars. This means that we are probably a long way from measuring the spin rates of such habitable worlds.”

    See the full article here.

    NASA

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