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  • richardmitnick 8:58 pm on March 8, 2019 Permalink | Reply
    Tags: A new study explores whether magnetic fields cause this odd reversal, , , , , , Exoplanets, Exoplanets HAT-P-7b and CoRoT-2b have westward winds, Reversing Winds on Hot Jupiters, The majority of hot Jupiters have eastward equatorial winds   

    From AAS NOVA: “Reversing Winds on Hot Jupiters” 

    AASNOVA

    From AAS NOVA

    8 March 2019
    Susanna Kohler

    1
    Artist’s illustration of the hot Jupiter CoRoT-2b, with a hostspot that is offset westward. [NASA/JPL-Caltech/T. Pyle (IPAC)]

    Exoplanets HAT-P-7b and CoRoT-2b have an unusual quirk: instead of having eastward equatorial winds, like the majority of hot Jupiters, these two hot Jupiters have westward winds. A new study explores whether magnetic fields cause this odd reversal.

    Blowing the Wrong Way

    You might think that the hottest — and therefore brightest — part of a tidally locked hot Jupiter should be the part that directly faces its nearby host star. Surprisingly, our observations of hot Jupiters have generally revealed an offset for the peak brightness that’s slightly east of the point directly facing the host. These observations suggest that hot Jupiters host strong eastward-blowing winds near their equators that can displace their hottest point.

    Two planets break this rule, however: HAT-P-7b and CoRoT-2b. Observations of both of these hot Jupiters instead reveal hotspots that lie west of the point facing the host. Astronomers have generally interpreted this to imply that these two planets have westward-blowing equatorial winds — but why?

    There are a number of proposed explanations for this odd apparent reversal:

    1.The planet may not be tidally locked as expected; if it rotates on its axis slightly slower than it orbits its host, this could drive westward winds.
    2.The apparent offset hotspot location could be an illusion caused by asymmetric cloud distribution.
    3.Interactions of the planet’s magnetic field with its atmosphere could modify its wind pattern.

    In a new study led by Alexander Hindle (Newcastle University, UK), a team of scientists explores the feasibility of this third option.

    2
    Plot of the geopotential, which traces temperature, in the authors’ simulations, with (bottom) and without (top) the presence of magnetic fields. The hotspot (marked with a white cross) displaces to the east for the hydrodynamic case and to the west for the magnetohydrodynamic case. [Hindle et al. 2019]

    Magnetic Waves

    Hindle and collaborators use both analytic models and simulations to show what happens in the atmosphere of a planet with a strong magnetic field. They explore a layer of atmosphere that can behave like shallow water, developing planetary-scale waves. Without a magnetic field, these waves will naturally travel eastward. But in the presence of a strong toroidal magnetic field, the wave shears as it travels, resulting in westward-tilting eddies. This drives the winds to switch direction to the west.

    The authors next calculate the minimum magnetic field strength needed to create this equatorial wind reversal for planets with the properties of HAT-P-7b and CoRoT-2b. They find that an inflated hot Jupiter like HAT-P-7b would need a field strength above just 6 Gauss (for comparison, the Earth’s magnetic field is ~1 G). Estimated field strengths for inflated hot Jupiters lie in the 50–100 G range, so attributing HAT-P-7b’s wind reversal to magnetic fields is well within reason.

    For an ordinary hot Jupiter like CoRoT-2b, however, a field strength of 3,000 G is needed. The maximum expected field strength for a hot Jupiter like CoRoT-2b is 250 G, which isn’t sufficient to drive the reversal. Hindle and collaborators conclude that a different mechanism is likely at work on this planet.

    More observations of hot Jupiters in the future — as well as three-dimensional simulations — will help us to further understand the wind behavior in the atmospheres of these toasty planets.

    Citation

    “Shallow-water Magnetohydrodynamics for Westward Hotspots on Hot Jupiters,” A. W. Hindle et al 2019 ApJL 872 L27.
    https://iopscience.iop.org/article/10.3847/2041-8213/ab05dd/meta

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    1

    AAS Mission and Vision Statement

    The mission of the American Astronomical Society is to enhance and share humanity’s scientific understanding of the Universe.

    The Society, through its publications, disseminates and archives the results of astronomical research. The Society also communicates and explains our understanding of the universe to the public.
    The Society facilitates and strengthens the interactions among members through professional meetings and other means. The Society supports member divisions representing specialized research and astronomical interests.
    The Society represents the goals of its community of members to the nation and the world. The Society also works with other scientific and educational societies to promote the advancement of science.
    The Society, through its members, trains, mentors and supports the next generation of astronomers. The Society supports and promotes increased participation of historically underrepresented groups in astronomy.
    The Society assists its members to develop their skills in the fields of education and public outreach at all levels. The Society promotes broad interest in astronomy, which enhances science literacy and leads many to careers in science and engineering.

    Adopted June 7, 2009

     
  • richardmitnick 12:22 pm on January 5, 2019 Permalink | Reply
    Tags: , , , ‘Following the Water’, , , , Exoplanets, Fingerprinting Life, , , , , The habitable zone serves as a target selection tool, , , UCO Lick Observatory Mt Hamilton in San Jose California, UCR’s Alternative Earths Astrobiology Center   

    From UC Riverside: “Are We Alone?” 

    UC Riverside bloc

    From UC Riverside

    May 24, 2018
    Sarah Nightingale

    1
    Illustration by The Brave Union

    Forty years ago, the Voyager 2 spacecraft launched from Florida’s Cape Canaveral. Over the next decade, it swept across the solar system, sending back images of Jupiter’s volcanoes, Saturn’s rings, and for the first time, the icy atmospheres of Uranus and Neptune.

    NASA/Voyager 2

    2
    UCR’s Tim Lyons, left, and Stephen Kane are some of the only researchers in the world using Earth’s history as a guide to finding life in outer space. (Photo by Kurt Miller)

    The mission was more than enough to encourage Stephen Kane, a teenager growing up in Australia, to study planetary science in college. By the time he’d graduated, scientists had detected the first planet outside our solar system, known as an exoplanet, inspiring him to join the hunt and look for more.

    Over the past two decades, Kane, now an associate professor of planetary astrophysics at UC Riverside, has discovered hundreds of alien planets. At first, he focused on identifying giant Jupiter-like planets, which he describes as “low-hanging fruit” due to their large sizes. But in 2011, the Kepler Space Telescope identified the first rocky planet — Kepler 10b. Unlike gas giants such as Jupiter, rocky planets could potentially harbor life.

    NASA/Kepler Telescope

    With the discovery of more Earth-sized planets on the horizon, Kane realized that astrophysicists would struggle to understand the data they were receiving about terrestrial planets and their atmospheres.

    “During the course of the ongoing Kepler mission, I sought out planetary and Earth scientists because they’ve spent hundreds of years studying the solar system and how the Earth’s atmosphere has been shaped by biological and geophysical processes, so they have a lot to bring to the table,” Kane said.

    In 2017, Kane formalized that collaboration by joining an interdisciplinary research group led by Tim Lyons, a distinguished professor of biogeochemistry in the Department of Earth Sciences and director of UCR’s Alternative Earths Astrobiology Center. Backed by roughly $7.5 million from NASA, the center, one of only a handful like it in the world, brings together geochemists, biologists, planetary scientists, and astrophysicists from UCR and partner institutions to search for life on distant worlds using a template defined by the only known planet with life: Earth.

    3
    Astrobiology researchers study areas on Earth that hold evidence of ancient life, such as these stromatolites at the Hamelin Pool Marine Nature Reserve in Shark Bay, Australia. The rocky, dome-shaped structures formed in shallow water through the trapping of sedimentary grains by communities of microorganisms. (Photo by Mark Boyle)

    Fingerprinting Life

    Since its formation more than 4.5 billion years ago, Earth has undergone immense periods of geological and biological change.

    When the first life appeared — in the form of simple microbes — the sun was fainter, there were no continents, and there was no oxygen in the atmosphere. A new kind of life emerged around 2.7 billion years ago: photosynthetic bacteria that use the sun’s energy to convert carbon dioxide and water into food and oxygen gas. Multicellular life evolved from those bacteria, followed by more familiar lifeforms: fish about 530 million years ago, land plants 470 million years ago, and mammals 200 million years ago.

    “There are periods in the Earth’s past that are as different from one another as Earth is from an exoplanet,” Lyons said. “That is the concept of alternative Earths. You can slice the Earth’s history into chapters, pages, and even paragraphs, and there has been life evolving, thriving, surviving, and dying with each step. If we know what kind of atmospheres were present during the early stages of life on Earth, and their relationships to the evolving continents and oceans, we can look for similar signposts in our search for life on exoplanets.”

    While it might seem impossible to characterize ancient oceans and atmospheres, scientists can glean hints by studying rocks formed billions of years ago.

    “The chemical compositions of rocks are determined by the chemistry of the oceans and their life, and many of the gases in the atmosphere, through exchange with the oceans, are controlled by the same processes,” Lyons said. “These atmospheric fingerprints of life in the underlying oceans, or biosignatures, can be used as markers of life on other planets light years away.”

    The search for alien biosignatures typically centers on the gases produced by living creatures on Earth because they’re the only examples scientists have to work with. But Earth’s many chapters of inhabitation reveal the great number of possible gas combinations. Oxygen gas, ozone, and methane in a planet’s biosignature could all indicate the presence of life — and seeing them together could present an even stronger argument.

    The center’s search for life is different from the hunt for intelligent life. While those researchers probe for signs of alien civilizations, such as radio waves or powerful lasers, Lyons’ team is essentially looking for the byproducts of simple lifeforms.

    “As we’re exploring exoplanets, what we’re really trying to do is characterize their atmospheres,” he said. “If we see certain profiles of gases, then we may be detecting microbial waste products that are accumulating in the atmosphere.”

    The UCR team must also account for processes that produce the same gases without contributions from life, a phenomenon researchers call false positives. For example, a planetary atmosphere with abundant oxygen would be a promising biosignature, but that evidence could be misleading without fully addressing where it came from. Similarly, methane is a key biosignature, but there are many nonbiological ways to produce this gas on Earth. These distinctions require careful considerations of many factors, including seasonal patterns, tectonic activity, the type of planet and its star, among other data.

    False negatives are another concern, Lyons said. In previous research on ancient organic-rich rocks collected in Western Australia and South Africa, his group showed that about two billion years passed between the moment organisms first started producing oxygen on Earth and when it accumulated at levels high enough to be detectable in the atmosphere. In that scenario, a classic biosignature, oxygen, could be missed.

    “It’s also entirely possible that on some planets oxygen is produced through photosynthesis in pockets in the ocean and you’d never see it in the atmosphere,” Lyons said. “We have to be very clever to consider the many possibilities for biosignatures, and Earth’s past gives us many to choose from.”

    3
    Illustration by The Brave Union

    ‘Following the Water’

    With several hundred terrestrial planets confirmed and many more awaiting discovery, the search for life-bearing worlds is an almost overwhelming task.

    Astronomers are narrowing down their search by focusing on habitable zones — the orbital region around stars where it’s neither too hot nor too cold for liquid water to exist on the surface.

    “We know that liquid water is essential for life as we know it, and so we’re beginning our search by looking for planets that are capable of having similar environments to Earth. We call this approach ‘following the water,’” Kane said.

    While the habitable zone serves as a target selection tool, Kane said a planet nestled in this region won’t necessarily show signs of life — or even liquid water. Venus, for example, occupies the inner edge of the Sun’s habitable zone, but its scorching surface temperature has boiled away any liquid water that once existed.

    “We are extremely fortunate to have Venus in our solar system because it reminds us that a planet can be exactly the same size as Earth and still have things go catastrophically wrong,” Kane said.

    Equally important, being in the habitable zone doesn’t mean a planet will boast other factors that make Earth ideal for life. In addition to liquid water, the perfect candidate would have an insulating atmosphere and a protective magnetic field. It would also offer the right chemical ingredients for life and ways of recycling those elements over and over when continents collide, mountains lift up and wear down, and nutrients are swept back to the seas by rivers.

    “People question why we focus so intently on Earth, but the answer is obvious. We only know what we know about life because of what the Earth has given us,” said Lyons, who has spent decades reconstructing the conditions during which life evolved.

    “If I asked you to design a planet with the perfect conditions for life, you would design something just like Earth because it has all of these essential features,” he added. “We are studying how these building blocks have been assembled in different ways during Earth’s history and asking which of them are essential for life, which can be taken away. From that vantage point, we ask how they could be assembled in very different ways on other planets and still sustain life.”

    Kane said a distant planetary system called TRAPPIST-1, which NASA scientists discovered in 2017, could provide clues about the ingredients that are necessary for life.

    A size comparison of the planets of the TRAPPIST-1 system, lined up in order of increasing distance from their host star. The planetary surfaces are portrayed with an artist’s impression of their potential surface features, including water, ice, and atmospheres. NASA

    The TRAPPIST-1 star, an ultracool dwarf, is orbited by seven Earth-size planets (NASA).

    ESO Belgian robotic Trappist National Telescope at Cerro La Silla, Chile


    ESO Belgian robotic Trappist National Telescope at Cerro La Silla, Chile

    Although miniature compared to our own solar system — TRAPPIST-1 would easily fit inside Mercury’s orbit around the sun — it boasts seven planets, three of which are in the habitable zone. However, the planets don’t have moons, and they may not even have atmospheres.

    “We are finding that compact planetary systems orbiting faint stars are much more common than larger systems, so it’s important that we study them and find out if they could have habitable environments,” Kane said.

    4
    An artist’s illustration of the possible surface of TRAPPIST-1f, one of the planets in the TRAPPIST-1 system.

    Remote Observations

    At about 40 light-years (235 trillion miles) from Earth, the TRAPPIST-1 system is relatively close, but we’re never going to go there.

    “The fascinating thing about astronomy as a science is that it’s all based on remote observations,” Kane said. “We are trying to squeeze every piece of information we can out of photons that we are receiving from a very distant object.”

    While scientists have studied the atmospheres of several dozen exoplanets, most are too distant to probe with current instruments. That situation is changing. In April, NASA launched its Transiting Exoplanet Survey Satellite, known as TESS, which will seek Earth-sized planets around more than 500,000 nearby stars.

    NASA/MIT TESS

    In May 2020, NASA plans to launch the James Webb Space Telescope, which will perform atmospheric studies of the rocky worlds discovered by TESS.

    NASA/ESA/CSA Webb Telescope annotated

    Like Kepler, TESS detects exoplanets using the transit method, which measures the minute dimming of a star as an orbiting planet passes between it and the Earth.

    Planet transit. NASA/Ames

    Because light also passes through the atmosphere of planets, scientists will use the Webb telescope to identify the blanket of gases surrounding them through a technique called spectroscopy.

    Kane and Lyons are working with NASA to design missions that will directly image exoplanets in ways that will ensure that interdisciplinary teams such as theirs can properly interpret a wide variety of planetary processes.

    “As we design future missions, we must make sure they are equipped with the right instruments to detect biosignatures and geological processes, such as active volcanoes,” Kane said.

    UCR’s astrobiology team is one of only a few groups in the world studying ancient Earth to create a catalog of biosignatures that will inform mission design in NASA’s search for life on distant worlds. With quintillions — think the number of gallons of water in all of our oceans — of potentially habitable planets in the universe, Lyons said he is optimistic that we’ll find signs of life in the future.

    “Just like the Voyager missions were important because of what they taught us about our solar system — from the discovery of Jupiter’s rings to the first close-up glimpses of Uranus and Neptune — the TESS and James Webb missions, and more importantly the next generation of telescopes planned for the coming decades, are very likely to change our understanding of distant space,” Lyons said. And perhaps nestled in those discoveries will be an answer to the most fundamental of all questions, ‘are we alone?’

    Alternative Earths Astrobiology Center

    Founded in 2015

    One of 12 research teams funded by the NASA Astrobiology Institute, and one of only two using Earth’s history to guide exoplanet exploration

    Awarded $7.5 million over five years to cultivate a “search engine” for life on planets orbiting distant stars using Earth’s evolution over billions of years as a template

    Builds on existing UCR strengths in biogeochemistry, Earth history, and astrophysics

    Unites 66 researchers and staff at 11 institutions around the world, including primary partners led by former UCR graduate students now on the faculty at Yale and Georgia Tech

    4
    A NASA illustration of TESS monitoring stars outside our solar system.

    Through the Looking Glass

    In April, the Transiting Exoplanet Survey Satellite (TESS) Mission launched with the goal of discovering new Earths and super-Earths around nearby stars. As a guest investigator on the TESS Mission, Stephen Kane will use University of California telescopes, including those at the Lick Observatory in Mt. Hamilton to help determine whether candidate exoplanets identified by TESS are actually planets.

    UCSC Lick Observatory, Mt Hamilton, in San Jose, California, Altitude 1,283 m (4,209 ft)

    UCSC Lick Automated Planet Finder telescope, Mount Hamilton, CA, USA

    The UCO Lick C. Donald Shane telescope is a 120-inch (3.0-meter) reflecting telescope located at the Lick Observatory, Mt Hamilton, in San Jose, California, Altitude 1,283 m (4,209 ft)

    UC Santa Cruz Shelley Wright at the 1-meter Nickel Telescope NIROSETI


    NIROSETI team from left to right Rem Stone UCO Lick Observatory Dan Werthimer UC Berkeley Jérôme Maire U Toronto, Shelley Wright UCSD Patrick Dorval U Toronto Richard Treffers Richard Treffers Starman Systems. (Image by Laurie Hatch)

    By studying the planet mass data obtained from the ground-based telescopes and planet diameter readings from spacecraft observations, Kane will also help determine the overall composition of the newly identified planets.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    UC Riverside Campus

    The University of California, Riverside is one of 10 universities within the prestigious University of California system, and the only UC located in Inland Southern California.

    Widely recognized as one of the most ethnically diverse research universities in the nation, UCR’s current enrollment is more than 21,000 students, with a goal of 25,000 students by 2020. The campus is in the midst of a tremendous growth spurt with new and remodeled facilities coming on-line on a regular basis.

    We are located approximately 50 miles east of downtown Los Angeles. UCR is also within easy driving distance of dozens of major cultural and recreational sites, as well as desert, mountain and coastal destinations.

     
  • richardmitnick 12:57 pm on November 1, 2018 Permalink | Reply
    Tags: , , , , Exoplanets, , , ,   

    From Many Worlds: “The Kepler Space Telescope Mission Is Ending But Its Legacy Will Keep Growing” 

    NASA NExSS bloc

    NASA NExSS

    Many Words icon

    From Many Worlds

    2018-11-01
    Marc Kaufman

    NASA/Kepler Telescope

    As of October 2018, the planet-hunting spacecraft has been in space for nearly a decade. (NASA via AP)

    The Kepler Space Telescope is dead. Long live the Kepler.

    NASA officials announced on Tuesday that the pioneering exoplanet survey telescope — which had led to the identification of almost 2,700 exoplanets — had finally reached its end, having essentially run out of fuel. This is after nine years of observing, after a malfunctioning steering system required a complex fix and change of plants, and after the hydrazine fuel levels reached empty.

    While the sheer number of exoplanets discovered is impressive the telescope did substantially more: it proved once and for all that the galaxy is filled with planets orbiting distant stars. Before Kepler this was speculated, but now it is firmly established thanks to the Kepler run.

    It also provided data for thousands of papers exploring the logic and characteristics of exoplanets. And that’s why the Kepler will indeed live long in the world of space science.

    “As NASA’s first planet-hunting mission, Kepler has wildly exceeded all our expectations and paved the way for our exploration and search for life in the solar system and beyond,” said Thomas Zurbuchen, associate administrator of NASA’s Science Mission Directorate in Washington.

    “Not only did it show us how many planets could be out there, it sparked an entirely new and robust field of research that has taken the science community by storm. Its discoveries have shed a new light on our place in the universe, and illuminated the tantalizing mysteries and possibilities among the stars.”

    1
    The Kepler Space Telescope was focused on hunting for planets in this patch of the Milky Way. After two of its four spinning reaction wheels failed, it could no longer remain steady enough to stare that those distant stars but was reconfigured to look elsewhere and at a different angle for the K2 mission. (Carter Roberts/NASA)

    Kepler was initially the unlikely brainchild of William Borucki, its founding principal investigator who is now retired from NASA’s Ames Research Center in California’s Silicon Valley.

    3
    William Borucki, originally the main champion for the Kepler idea and later the principal investigator of the mission. His work at NASA went back to the Apollo days. (NASA)

    When he began thinking of designing and proposing a space telescope that could potentially tell us how common distant exoplanets were — and especially smaller terrestrial exoplanets like Earth – the science of extra solar planets was at a very different stage.

    “When we started conceiving this mission 35 years ago we didn’t know of a single planet outside our solar system,” Borucki said. “Now that we know planets are everywhere, Kepler has set us on a new course that’s full of promise for future generations to explore our galaxy.”

    The space telescope was launched in 2009. While Kepler did not find the first exoplanets — that required the work of astronomers using a different technique of observing based on the “wobble” of stars caused by orbiting planets — it did change the exoplanet paradigm substantially.

    Not only did it prove that exoplanets are common, it found that planets outnumber stars in our galaxy (which has hundreds of billions of those stars.)

    In addition it found that small, terrestrial-size planets are common as well, with some 20 to 50 percent of stars likely to have planets of that size and type. And what menagerie of planets it found out there.

    Among the greatest surprises: The Kepler mission provided data showing that the most common sized planets in the galaxy fall somewhere between Earth and Neptune, a type of planet that isn’t present in our solar system.

    It found solar systems of all sizes as well, including some with many planets (as many as eight) orbiting close to their host star.

    The discovery of these compact systems, generally orbiting a red dwarf star, raised questions about how solar systems form: Are these planets “born” close to their parent star, or do they form farther out and migrate in?

    So far, more than 2,500 peer-reviewed papers have been published using Kepler data, with substantial amounts of that data still unmined.

    Natalie Batalha was the project and mission scientist for Kepler for much of its run, and I asked her about its legacy.

    2
    Astrophysicist Natalie Batalha was the Kepler project and mission scientist for a decade. She left NASA recently for the University of California at Santa Cruz “to carry on the Kepler legacy” by creating an interdisciplinary center for the study of planetary habitability.

    “When I think of Kepler’s influence across all of astrophysics, I’m amazed at what such a simple experiment accomplished,” she wrote in an email. “You’d be hard-pressed to come up with a more boring mandate — to unblinkingly measure the brightnesses of the same stars for years on end. No beautiful images. No fancy spectra. No landscapes. Just dots in a scatter plot.

    “And yet time-domain astronomy exploded. We’d never looked at the Universe quite this way before. We saw lava worlds and water worlds and disintegrating planets and heart-beat stars and supernova shock waves and the spinning cores of stars and planets the age of the galaxy itself… all from those dots.”

    4
    The Kepler-62 system is but one of many solar systems detected by the space telescope. The planets within the green discs are in the habitable zones of the stars — where water could be liquid at times. (NASA)

    While Kepler provided remarkable answers to questions about the overall planetary makeup of our galaxy, it did not identify smaller planets that will be directly imaged, the evolving gold standard for characterizing exoplanets. The 150,000 stars that the telescope was observing were very distant, in the range of a few hundred to a few thousand light-years away. One light year is about 6 trillion (6,000,000,000,000) miles.

    Nonetheless, Kepler was able to detect the presence of a handful of Earth-sized planets in the habitable zones of their stars. The Kepler-62 system held one of them, and it is 1200 light-years away. In contrast, the four Earth-sized planets in the habitable zone of the much-studied Trappist-1 system are 39 light-years away.

    Kepler made its observations using the the transit technique, which looks for tiny dips in the amount of light coming from a star caused by the presence of a planet passing in front of the star. While the inference that exoplanets are ubiquitous came from Kepler results, the telescope was actually observing but a small bit of the sky. It has been estimated that it would require around 400 space telescopes like Kepler to cover the whole sky.

    What’s more, only planets whose orbits are seen edge-on from Earth can be detected via the transit method, and that rules out a vast number of exoplanets.

    The bulk of the stars that were selected for close Kepler observation were more or less sun-like, but a sampling of other stars occurred as well. One of the most important factors was brightness. Detecting minuscule changes in brightness caused by transiting planet is impossible if the star is too dim.

    Four years into the mission, after the primary mission objectives had been met, mechanical failures temporarily halted observations. The mission team was able to devise a fix, switching the spacecraft’s field of view roughly every three months. This enabled an extended mission for the spacecraft, dubbed K2, which lasted as long as the first mission and bumped Kepler’s count of surveyed stars up to more than 500,000.

    But it was inevitable that the mission would come to an end sooner rather than later because of that dwindling fuel supply, needed to keep the telescope properly pointed.

    Kepler cannot be refueled because NASA decided to place the telescope in an orbit around the sun that is well beyond the influence of the Earth and moon — to simplify operations and ensure an extremely quiet, stable environment for scientific observations. So Kepler was beyond the reach of any refueling vessel. The Kepler team compensated by flying considerably more fuel than was necessary to meet the mission objectives.

    The video below explains what will happen to the Kepler capsule once it is decommissioned. But a NASA release explains that the final commands “will be to turn off the spacecraft transmitters and disable the onboard fault protection that would turn them back on. While the spacecraft is a long way from Earth and requires enormous antennas to communicate with it, it is good practice to turn off transmitters when they are no longer being used, and not pollute the airwaves with potential interference.”

    And so Kepler will actually continue orbiting for many decades, just as its legacy will continue long after operations cease.

    Kepler’s follow-on exoplanet surveyor — the Transiting Exoplanet Survey Satellite or TESS — was launched this year and has begun sending back data.

    NASA/MIT TESS

    Its primary mission objective is to survey the brightest stars near the Earth for transiting exoplanets. The TESS satellite uses an array of wide-field cameras to survey some 85% of the sky, and is planned to last for two years.

    See the full article here .


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    Please help promote STEM in your local schools.

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    About Many Worlds

    There are many worlds out there waiting to fire your imagination.

    Marc Kaufman is an experienced journalist, having spent three decades at The Washington Post and The Philadelphia Inquirer, and is the author of two books on searching for life and planetary habitability. While the “Many Worlds” column is supported by the Lunar Planetary Institute/USRA and informed by NASA’s NExSS initiative, any opinions expressed are the author’s alone.

    This site is for everyone interested in the burgeoning field of exoplanet detection and research, from the general public to scientists in the field. It will present columns, news stories and in-depth features, as well as the work of guest writers.

    About NExSS

    The Nexus for Exoplanet System Science (NExSS) is a NASA research coordination network dedicated to the study of planetary habitability. The goals of NExSS are to investigate the diversity of exoplanets and to learn how their history, geology, and climate interact to create the conditions for life. NExSS investigators also strive to put planets into an architectural context — as solar systems built over the eons through dynamical processes and sculpted by stars. Based on our understanding of our own solar system and habitable planet Earth, researchers in the network aim to identify where habitable niches are most likely to occur, which planets are most likely to be habitable. Leveraging current NASA investments in research and missions, NExSS will accelerate the discovery and characterization of other potentially life-bearing worlds in the galaxy, using a systems science approach.
    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 [JAXA]Greenhouse Gases Observing Satellite.

     
  • richardmitnick 2:53 pm on October 28, 2018 Permalink | Reply
    Tags: , , , , Exoplanets, ,   

    From JPL-Caltech: “Rocky? Habitable? Sizing up a Galaxy of Planets” 

    NASA JPL Banner

    From JPL-Caltech

    Oct. 25, 2018

    Calla Cofield
    Jet Propulsion Laboratory, Pasadena, Calif.
    626-808-2469
    calla.e.cofield@jpl.nasa.gov

    Alison Hawkes
    Ames Research Center, California’s Silicon Valley
    650-604-0281
    alison.hawkes@nasa.gov

    Written by Pat Brennan​

    1
    Artist’s concept of how rocky, potentially habitable worlds elsewhere in our galaxy might appear. Data gathered by telescopes in space and on the ground suggest that small, rocky planets are common. (Placing them so close together in a line is for illustrative purposes only.) Credits: NASA/JPL-Caltech/R. Hurt (SSC-Caltech)

    The planets so far discovered across the Milky Way are a motley, teeming multitude: hot Jupiters, gas giants, small, rocky worlds and mysterious planets larger than Earth and smaller than Neptune. As we prepare to add many thousands more to the thousands found already, the search goes on for evidence of life – and for a world something like our own.

    And as our space telescopes and other instruments grow ever more sensitive, we’re beginning to zero in.

    The discoveries so far inspire excitement and curiosity among scientists and the public. We’ve found rocky planets in Earth’s size range, at the right distance from their parent stars to harbor liquid water. While these characteristics don’t guarantee a habitable world – we can’t quite tell yet if these planets really do possess atmospheres or oceans – they can help point us in the right direction.

    Future space telescopes will be able to analyze the light from some of these planets, searching for water or a mixture of gases that resembles our own atmosphere. We will gain a better understanding of temperatures on the surface. As we continue checking off items on the habitability list, we’ll draw closer and closer to finding a world bearing recognizable signs of life.

    Among the most critical factors in the shaping and development of a habitable planet is the nature of its parent star. The star’s mass, size and age determine the distance and extent of its “habitable zone” – the region around a star where the temperature potentially allows for liquid water to pool on a planet’s surface.

    Star-mapping the Galaxy

    The European Space Agency’s Gaia satellite, launched in 2013, is becoming one of history’s greatest star mappers.

    ESA/GAIA satellite

    It relies on a suite of high-precision instruments to measure star brightness, distance, and composition. The ambitious goal is to create a three-dimensional map of our Milky Way galaxy. The chart so far includes the positions of about 1.7 billion stars, with distances for about 1.3 billion.

    That has prompted a reassessment of star sizes to learn whether some might be larger, smaller, dimmer or brighter than scientists had thought.

    It turns out that many of the stars were found to be brighter – and larger – than previous surveys estimated. For the team managing the explosion of planet finds from NASA’s Kepler space telescope, beginning in 2009, that also means a revision of sizes for the planets in orbit around them.

    NASA/Kepler Telescope

    If a star is brighter than we thought, it’s often larger than we thought as well. The planet in orbit around it, measured proportionally by the transit method, must also be larger.

    That means some of the planets thought to be of a size and temperature similar to Earth’s are really bigger – and usually, hotter.

    “Gaia has improved distances and has improved assessments of how bright a star is, and how big a planet is,” said Eric Mamajek, the deputy program chief scientist for NASA’s Exoplanet Exploration Program. “The whole issue has always been, how well do we understand the star? This is just another chapter of that ongoing story.”

    The latest scientific data from the Gaia space probe also is prompting a reassessment of the most promising “habitable zone” planets found by observatories around the world, as well as space-based instruments like NASA’s Kepler.

    Habitable planets Current Potential Planetary Habitability Laboratory U Puerto Rico Arecibo

    As scientists iron out both observations and definitions of what we consider a potentially habitable world, better data is bringing us closer to finding such a planet and – maybe just as important – finding our own planet’s place among them.

    Of the 3,700 exoplanets – planets around other stars – confirmed by scientists so far, about 2,600 were found by the Kepler space telescope. Kepler hunts for the tiny eclipse, or dip in starlight, as a planet crosses the face of its star.

    The most recent analysis of Kepler’s discoveries shows that 20 to 50 percent of the stars in the sky are likely to have small, potentially rocky planets in their habitable zones. Our initial estimate of near Earth-sized, habitable-zone planets from the Kepler spacecraft as of June 19, 2017, was 30. Preliminary analysis of newer data, on both those exoplanets and their host stars, shows that the number is likely smaller – possibly between 2 and 12.

    Much more data are needed, including a better understanding of how a planet’s size relates to its composition.

    “We’re still trying to figure out how big a planet can be and still be rocky,” said Jessie Dotson, an astrophysicist at NASA’s Ames Research Center in California’s Silicon Valley. She is also the project scientist for Kepler’s current, extended mission, known as K2.

    At first glance, the latest analysis might seem disappointing: fewer rocky, potentially habitable worlds among the thousands of exoplanets found so far. But that doesn’t change one of the most astonishing conclusions after more than 20 years of observation: Planets in the habitable zone are common.

    More and better data on these far distant planets means a more accurate demographic portrait of a universe of planets – and a more nuanced understanding of their composition, possible atmospheres and life-bearing potential.

    That should put us on more solid ground for the coming torrent of exoplanet discoveries from TESS (the Transiting Exoplanet Survey Satellite), and future telescopes as well. It brings us one step closer in our search for a promising planet among a galaxy of stars.

    “This is the exciting part of science,” Dotson said. “So often, we’re really portrayed as, ‘Now we know this story.’ But I have a theory: Scientists love it when we don’t know something. It’s the hunt that’s so exciting.”

    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, 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.

    Caltech Logo

    NASA image

     
  • richardmitnick 12:43 pm on August 29, 2018 Permalink | Reply
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    From AAS NOVA: “Habitable Moons Instead of Habitable Planets?” 

    AASNOVA

    From AAS NOVA

    29 August 2018
    Susanna Kohler

    1
    Artist’s depiction of an Earth-like exomoon orbiting a gas-giant planet. [NASA/JPL-Caltech]

    One of the primary goals of exoplanet-hunting missions like Kepler is to discover Earth-like planets in their hosts’ habitable zones.

    NASA/Kepler Telescope

    But could there be other relevant worlds to look for? A new study has explored the possibility of habitable moons around giant planets.

    Seeking Rocky Worlds

    Since its launch, the Kepler mission has found hundreds of planet candidates within their hosts’ habitable zones — the regions where liquid water can exist on a planet surface. In the search for livable worlds beyond our solar system, it stands to reason that terrestrial, Earth-like planets are the best targets. But stand-alone planets aren’t the only type of rocky world out there!

    Many of the Kepler planet candidates found to lie in their hosts’ habitable zones are larger than three Earth radii. These giant planets, while unlikely to be good targets themselves in the search for habitable worlds, are potential hosts to large terrestrial satellites that would also exist in the habitable zone. In a new study led by Michelle Hill (University of Southern Queensland and University of New England, Australia; San Francisco State University), a team of scientists explores the occurrence rate of such moons.

    2
    Kepler has found more than 70 gas giants in their hosts’ habitable zones. These are shown in the plot above (green), binned according to the temperature distribution of their hosts and compared to the broader sample of Kepler planet candidates (grey). [Hill et al. 2018]

    A Giant-Planet Tally

    Hill and collaborators combine the known Kepler detections of giant planets located within their hosts’ optimistic habitable zones with calculated detection efficiencies that measure the likelihood that there are additional, similar planets that we’re missing. From this, the authors estimate the frequency with which we expect giant planets to occur in the habitable zones of different types of stars.

    The result: a frequency of 6.5 ± 1.9%, 11.5 ± 3.1%, and 6 ± 6% for giant planets lying in the habitable zones of G, K, and M stars, respectively. This is lower than the equivalent occurrence rate of habitable-zone terrestrial planets — which means that if the giant planets all host an average of one moon, habitable-zone rocky moons are less likely to exist than habitable-zone rocky planets. However, if each giant planet hosts more than one moon, the occurrence rates of moons in the habitable zone could quickly become larger than the rates of habitable-zone planets.

    3
    Distribution of the estimated planet–moon angular separation for known Kepler habitable-zone giant planets. Future missions would need to be able to resolve a separation between 1 and 90 microarcsec to detect potential moons. [Hill et al. 2018]

    Lessons from Our Solar System

    What can we learn from our own solar system? Of the ~185 moons known to orbit planets within our solar system, all but a few are in orbit around the gas giants. Jupiter, in particular, recently upped its tally to a whopping 79 moons! Gas giants therefore seem quite capable of hosting many moons.

    Could habitable-zone moons reasonably support life? Jupiter’s moon Io provides a good example of how radiative and tidal heating by the giant planet can warm a moon above the temperature of its surroundings. And Saturn’s satellite Ganymede demonstrates that large moons can even have their own magnetic fields, potentially shielding the moons’ atmospheres from their host planets.

    3
    NASA’s Galileo spacecraft acquired its highest resolution images of Jupiter’s moon Io on 3 July 1999 during its closest pass to Io since orbit insertion in late 1995. This color mosaic uses the near-infrared, green and violet filters (slightly more than the visible range) of the spacecraft’s camera and approximates what the human eye would see. Most of Io’s surface has pastel colors, punctuated by black, brown, green, orange, and red units near the active volcanic centers. A false color version of the mosaic has been created to enhance the contrast of the color variations.
    3 July 1999
    Source http://photojournal.jpl.nasa.gov/catalog/PIA02308
    Author NASA / JPL / University of Arizona

    4
    True color image of Ganymede, obtained by the Galileo spacecraft, with enhanced contrast.
    8 May 1998 (date of composite release); Galileo image taken on 26 June 1996.
    Source http://photojournal.jpl.nasa.gov/catalog/PIA00716
    Author NASA/JPL (edited by PlanetUser)

    Overall, it seems that the terrestrial satellites of habitable-zone gas giants are a valuable target to consider in the ongoing search for habitable worlds. Hill and collaborators’ work goes on to discuss observational strategies for detecting such objects, providing hope that future observations will bring us closer to detecting habitable moons beyond our solar system.

    Citation

    “Exploring Kepler Giant Planets in the Habitable Zone,” Michelle L. Hill et al 2018 ApJ 860 67. http://iopscience.iop.org/article/10.3847/1538-4357/aac384/meta

    Related journal articles
    _________________________________________________
    See the full article for further references with links.

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    1

    AAS Mission and Vision Statement

    The mission of the American Astronomical Society is to enhance and share humanity’s scientific understanding of the Universe.

    The Society, through its publications, disseminates and archives the results of astronomical research. The Society also communicates and explains our understanding of the universe to the public.
    The Society facilitates and strengthens the interactions among members through professional meetings and other means. The Society supports member divisions representing specialized research and astronomical interests.
    The Society represents the goals of its community of members to the nation and the world. The Society also works with other scientific and educational societies to promote the advancement of science.
    The Society, through its members, trains, mentors and supports the next generation of astronomers. The Society supports and promotes increased participation of historically underrepresented groups in astronomy.
    The Society assists its members to develop their skills in the fields of education and public outreach at all levels. The Society promotes broad interest in astronomy, which enhances science literacy and leads many to careers in science and engineering.

    Adopted June 7, 2009

     
  • richardmitnick 11:02 am on July 9, 2018 Permalink | Reply
    Tags: , , , , Exoplanets,   

    From Many Worlds: “The Architecture of Solar Systems” 

    NASA NExSS bloc

    NASA NExSS

    Many Words icon

    From Many Worlds

    2
    The architecture of planetary systems is an increasingly important factor to exoplanet scientists. This illustration shows the Kepler-11 system where the planets are all roughly the same size and their orbits spaced at roughly the same distances from each other. The the planets are, in the view of scientists involved with the study, “peas in a pod.” (NASA)

    Before the discovery of the first exoplanet that orbits a star like ours, 51 Pegasi b, the assumption of solar system scientists was that others planetary systems that might exist were likely to be like ours.

    1
    This artist’s view shows the hot Jupiter exoplanet 51 Pegasi b, sometimes referred to as Bellerophon, which orbits a star about 50 light-years from Earth in the northern constellation of Pegasus (The Winged Horse). This was the first exoplanet around a normal star to be found in 1995. Twenty years later this object was also the first exoplanet to be be directly detected spectroscopically in visible light. ESO/M. Kornmesser/Nick Risinger (skysurvey.org)

    Small rocky planets in the inner solar system, big gas giants like Jupiter, Saturn and Neptune beyond and, back then, Pluto bringing up the rear.

    But 51 Peg b broke every solar system rule imaginable. It was a giant and hot Jupiter-size planet, and it was so close to its star that it orbited in a little over four days. Our Jupiter takes twelve years to complete an orbit.

    This was the “everything we knew about solar systems is wrong” period, and twenty years later thinking about the nature and logic of solar system architecture remains very much in flux.

    But progress is being made, even if the results are sometimes quite confounding. The umbrella idea is no longer that solar, or planetary, systems are pretty much like ours, but rather that the galaxy is filled with a wild diversity of both planets and planetary systems.

    Detecting and trying to understand planetary systems is today an important focus 0f exoplanet study, especially now that the Kepler Space Telescope mission has made clear that multi-planet systems are common.

    As of early July, 632 multi planet systems have been detected and 2,841 stars are known to have at least one exoplanets. Many of those stars with a singular planet may well have others yet to be found.

    An intriguing newcomer to the diversity story came recently from University of Montreal astronomer Lauren Weiss, who with colleagues expanded on and studied some collected Kepler data.

    What she found has been deemed the “peas in a pod” addition to the solar system menagerie.

    Weiss was working with the California-Kepler Survey, which included a team of scientists pouring over, elaborating on and looking for patterns in, among other things, solar system architectures.

    Weiss is part of the California-Kepler Survey team, which used the Keck Observatory to obtain high-resolution spectra of 1305 stars hosting 2025 transiting planets originally discovered by Kepler.

    From these spectra, they measured precise sizes of the stars and their planets, looking for patterns in, among other things, solar system architectures. They focused on 909 planets belonging to 355 multi-planet systems. By improving the measurements of the radii of the stars, Weiss said, they were able to recalculate the radii of all the planets.

    So Weiss studied hundreds systems and did find a number of surprising, unexpected patterns.

    In many systems, the planets were all roughly the same size as the planet in orbit next to them. (No tiny-Mars-to-gigantic-Jupiter transitions.) This kind of planetary architecture was not found everywhere but it was quite common — more common than random planet sizing would predict.

    “The effect showed up with smaller planets and larger ones,” Weiss told me during last week’s University of Cambridge Exoplanets2 conference. “The planets in each system seemed to know about the sizes of the neighbors,” and for thus far unknown reasons maintained those similar sizes.

    What’s more, Weiss and her colleagues found that the orbits of these “planets in a pod” were generally an equal distance apart in “multi” of three planets or more. In other words, the distance between the orbits of planet A and planet B was often the same distance as between the orbits of planet B and planet C.

    So not only were many of the planets almost the same size, but they were in orbits spaced at distances from each other that were once again much more similar than a random distribution would predict. In the Astronomical Journal article where she and her colleagues described the phenomena, they also found a “wall” defining how close together the planets orbited.

    The architecture of these systems, Weiss said, reflected the shapes and sizes of the protoplanetary in which they were formed. And it would appear that the planets had not been disrupted by larger planets that can dramatically change the structure of a solar system — as happened with Jupiter in our own.

    But while those factors explain some of what was found, Weiss said other astrophysical dynamics needed to be at play as well to produce this common architecture. The stability of the system, for instance, would be compromised if the orbits were closer than that “wall,” as the gravitational pull of the planets would send them into orbits that would ultimately result in collisions.

    The improved spectra of the Kepler planets were obtained from 2011 to 2015, and the targets are mostly located between 1,000 and 4,000 light-years away from Earth.

    2
    The architectures of California-Kepler study multi-planet systems with four planets or more. Each row corresponds to the planets around one and the circles represent the radii of planets in the system. Note how many have lines of planets that are roughly the same size. (Lauren Weiss, The Astronomical Journal.)

    Planetary system architecture was a significant topic at the Cambridge Exoplanets2 conference. While the detection of individual exoplanets remains important in the field, it is often treated as a precursor to the ultimate detection of systems with more planets.

    The TRAPPIST-1 system, discovered in 2015 by a Belgian team, is probably the most studied and significant of those discovered so far.

    ESO Belgian robotic Trappist National Telescope at Cerro La Silla, Chile


    ESO Belgian robotic Trappist-South National Telescope at Cerro La Silla, Chile, 600 km north of Santiago de Chile at an altitude of 2400 metres.

    A size comparison of the planets of the TRAPPIST-1 system, lined up in order of increasing distance from their host star. The planetary surfaces are portrayed with an artist’s impression of their potential surface features, including water, ice, and atmospheres. NASA

    The ultra-cool dwarf star hosts seven Earth-sized, temperate exoplanets in or near the “habitable zone.” As described by one of those responsible for the discovery, Brice-Olivier Demory of the Center for Space and Habitability University of Bern, the system “represents a unique setting to study the formation and evolution of terrestrial planets that formed in the same protoplanetary disk.”

    The Trappist-1 architecture features not only the seven rocky planets, but also a resonance system whereby the planets orbits at paces directly related to the planets nearby them. In other words, one planet may make two orbits in exactly the time that it takes for the next planet to make three orbits.

    All the Trappist-1 planets are in resonance to another system planet, though they are not all in resonance to each other.

    The animation above from the NASA Ames Research Center shows the orbits of the Trappist-1 system. The planets pass so close to one another that gravitational interactions are significant, and to remain stable the orbital periods are nearly resonant. In the time the innermost planet completes eight orbits, the second, third, and fourth planets complete five, three, and two respectively.

    The system is very flat and compact. All seven of TRAPPIST-1’s planets orbit much closer to their star than Mercury orbits the sun. Except for TRAPPIST-1b, they orbit farther than the Galilean moons — three of which are also in resonance around Jupiter.

    The distance between the orbits of TRAPPIST-1b and TRAPPIST-1c is only 1.6 times the distance between the Earth and the Moon. A year on the closest planet passes in only 1.5 Earth days, while the seventh planet’s year passes in only 18.8 days.

    Given the packed nature of the system, the planets have to be in particular orbits that keep them from colliding. But they also have to be in orbits that ensure that all or most of the planets aren’t on the same side of the star, creating a severe imbalance that would result in chaos.

    “The Trappist-1 system has entered into a zone of stability,” Demory told me, also at the Exoplanets2 conference. “We think of it as a Darwinian effect — the system survives because of that stability created through the resonance. Without the stability, it would die.

    He said the Trappist-1 planets were most likely formed away from their star and migrated inward. The system had rather a long time to form, between seven and eight billion years.

    The nature of some of the systems now being discovered brings to mind that early reaction to the detection of 51 Pegasi b, the world’s first known exoplanet.

    The prevailing consensus that extra-solar systems would likely be similar to ours was turned on its head by the giant planet’s closeness to its host star. For a time many astronomers thought that hot Jupiter planets would be found to be common.

    But 20 years later they know that hot Jupiters — and the planetary architecture they create — are rather unusual, like the architecture of our own solar system.

    With each new discovery of a planetary system, the understanding grows that while solar systems are governed by astrophysical forces, they nonetheless come in all sizes and shapes. Diversity is what binds them together.

    See the full article here .


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    About Many Worlds

    There are many worlds out there waiting to fire your imagination.

    Marc Kaufman is an experienced journalist, having spent three decades at The Washington Post and The Philadelphia Inquirer, and is the author of two books on searching for life and planetary habitability. While the “Many Worlds” column is supported by the Lunar Planetary Institute/USRA and informed by NASA’s NExSS initiative, any opinions expressed are the author’s alone.

    This site is for everyone interested in the burgeoning field of exoplanet detection and research, from the general public to scientists in the field. It will present columns, news stories and in-depth features, as well as the work of guest writers.

    About NExSS

    The Nexus for Exoplanet System Science (NExSS) is a NASA research coordination network dedicated to the study of planetary habitability. The goals of NExSS are to investigate the diversity of exoplanets and to learn how their history, geology, and climate interact to create the conditions for life. NExSS investigators also strive to put planets into an architectural context — as solar systems built over the eons through dynamical processes and sculpted by stars. Based on our understanding of our own solar system and habitable planet Earth, researchers in the network aim to identify where habitable niches are most likely to occur, which planets are most likely to be habitable. Leveraging current NASA investments in research and missions, NExSS will accelerate the discovery and characterization of other potentially life-bearing worlds in the galaxy, using a systems science approach.
    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 [JAXA]Greenhouse Gases Observing Satellite.

     
  • richardmitnick 2:14 pm on May 2, 2018 Permalink | Reply
    Tags: , , , , Exoplanet WASP-107b, Exoplanets,   

    From NASA/ESA Hubble Telescope: “Hubble Detects Helium in the Atmosphere of an Exoplanet for the First Time” 

    NASA Hubble Banner

    NASA/ESA Hubble Telescope

    NASA/ESA Hubble Telescope

    May 2, 2018

    Jessica Spake
    University of Exeter, Exeter, United Kingdom
    jspake@astro.ex.ac.uk

    David Sing
    University of Exeter, Exeter, United Kingdom
    011-44-13-9272-5652
    sing@astro.ex.ac.uk

    Mathias Jäger
    ESA/Hubble, Garching, Germany
    011-49-1-76-6239-7500
    mjaeger@partner.eso.org

    Ray Villard
    Space Telescope Science Institute, Baltimore, Maryland
    410-338-4514
    villard@stsci.edu

    1
    Ballooning Atmosphere Extends Tens of Thousands of Miles Above a Gas Giant Planet.

    There may be no shortage of balloon-filled birthday parties or people with silly high-pitched voices on the planet WASP-107b. That’s because NASA’s Hubble Space Telescope was used to detect helium in the atmosphere for the first time ever on a world outside of our solar system. The discovery demonstrates the ability to use infrared spectra to study exoplanet atmospheres.

    Though as far back as 2000 helium was predicted to be one of the most readily-detectable gases on giant exoplanets, until now helium had not been found — despite searches for it. Helium was first discovered on the Sun, and is the second-most common element in the universe after hydrogen. It’s one of the main constituents of the planets Jupiter and Saturn.

    An international team of astronomers led by Jessica Spake of the University of Exeter, UK, used Hubble’s Wide Field Camera 3 to discover helium. The atmosphere of WASP-107b must stretch tens of thousands of miles out into space. This is the first time that such an extended atmosphere has been discovered at infrared wavelengths.

    The Full Story

    Astronomers using NASA’s Hubble Space Telescope have detected helium in the atmosphere of the exoplanet WASP-107b. This is the first time this element has been detected in the atmosphere of a planet outside the solar system. The discovery demonstrates the ability to use infrared spectra to study exoplanet extended atmospheres.

    The international team of astronomers, led by Jessica Spake, a PhD student at the University of Exeter in the UK, used Hubble’s Wide Field Camera 3 to discover helium in the atmosphere of the exoplanet WASP-107b. This is the first detection of its kind.

    NASA/ESA Hubble WFC3

    Spake explained the importance of the discovery: “Helium is the second-most common element in the universe after hydrogen. It is also one of the main constituents of the planets Jupiter and Saturn in our solar system. However, up until now helium had not been detected on exoplanets — despite searches for it.”

    The team made the detection by analyzing the infrared spectrum of the atmosphere of WASP-107b. Previous detections of extended exoplanet atmospheres have been made by studying the spectrum at ultraviolet and optical wavelengths; this detection therefore demonstrates that exoplanet atmospheres can also be studied at longer wavelengths.

    The measurement of an exoplanet’s atmosphere is performed when the planet passes in front of its host star. A tiny portion of the star’s light passes through the exoplanet’s atmosphere, leaving detectable fingerprints in the spectrum of the star. The larger the amount of an element present in the atmosphere, the easier the detection becomes.

    “The strong signal from helium we measured demonstrates a new technique to study upper layers of exoplanet atmospheres in a wider range of planets,” said Spake. “Current methods, which use ultraviolet light, are limited to the closest exoplanets. We know there is helium in the Earth’s upper atmosphere and this new technique may help us to detect atmospheres around Earth-sized exoplanets — which is very difficult with current technology.”

    WASP-107b is one of the lowest density planets known: While the planet is about the same size as Jupiter, it has only 12 percent of Jupiter’s mass. The exoplanet is about 200 light-years from Earth and takes less than six days to orbit its host star.

    The amount of helium detected in the atmosphere of WASP-107b is so large that its upper atmosphere must extend tens of thousands of miles out into space. This also makes it the first time that an extended atmosphere has been discovered at infrared wavelengths.

    Since its atmosphere is so extended, the planet is losing a significant amount of its atmospheric gases into space — between about 0.1 percent to 4 percent of its atmosphere’s total mass every billion years.

    Stellar radiation has a significant effect on the rate at which a planet’s atmosphere escapes. The star WASP-107 is highly active, supporting the atmospheric loss. As the atmosphere absorbs radiation it heats up, so the gas rapidly expands and escapes more quickly into space.

    As far back as the year 2000, it was predicted that helium would be one of the most readily-detectable gases on giant exoplanets, but until now, searches were unsuccessful.

    David Sing, co-author of the study also from the University of Exeter, concluded: “Our new method, along with future telescopes such as NASA’s James Webb Space Telescope, will allow us to analyze atmospheres of exoplanets in far greater detail than ever before.”

    The team’s study appears on May 2, 2018, in the online issue of science journal Nature.

    The international team of astronomers in this study consists of J. Spake (University of Exeter, Exeter, UK), D. Sing (University of Exeter, Exeter, UK; Johns Hopkins University, Baltimore, Maryland), T. Evans (University of Exeter, UK), A. Oklopčić (Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts), V. Bourrier (University Geneva Observatory, Sauverny, Switzerland), L. Kreidberg (Harvard Society of Fellows and Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts), B. Rackham (University of Arizona, Tucson, Arizona), J. Irwin (Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts), D. Ehrenreich and A. Wyttenbach (University of Geneva Observatory, Sauverny, Switzerland), H. Wakeford (Space Telescope Science Institute, Baltimore, Maryland), Y. Zhou (University of Arizona, Tucson, Arizona), K. Chubb (University College London, London, UK), N. Nikolov and J. Goyal (University of Exeter, Exeter, UK), G. Henry and M. Williamson (Tennessee State University, Nashville, Tennessee), S. Blumenthal (Space Telescope Science Institute, Baltimore, Maryland), D. Anderson and C. Hellier (Keele University, Staffordshire, UK), D. Charbonneau (Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts), S. Udry (University of Geneva Observatory, Sauverny, Switzerland), and N. Madhusudhan (University of Cambridge, Cambridge, UK).

    See the full article here .

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    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

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  • richardmitnick 4:47 pm on April 17, 2018 Permalink | Reply
    Tags: Exoplanets, , , Ramp compression, Superearths   

    From Lawrence Livermore National Laboratory: “Ramp compression of iron provides insight into core conditions of large rocky exoplanets” 

    Lawrence Livermore National Laboratory

    April 16, 2018
    Breanna Bishop
    bishop33@llnl.gov
    925-423-9802

    1
    High-power lasers at the National Ignition Facility are focused onto a multi-stepped iron sample at the center of the 10-meter-diameter target chamber. These experiments measure the equation of state of iron under core conditions of large rocky exoplanets.

    In a paper published today by Nature Astronomy , a team of researchers from Lawrence Livermore National Laboratory (LLNL), Princeton University, Johns Hopkins University and the University of Rochester have provided the first experimentally based mass-radius relationship for a hypothetical pure iron planet at super-Earth core conditions.

    This discovery can be used to evaluate plausible compositional space for large, rocky exoplanets, forming the basis of future planetary interior models, which in turn can be used to more accurately interpret observation data from the Kepler space mission and aid in identifying planets suitable for habitability.

    “The discovery of large numbers of planets outside our solar system has been one of the most exciting scientific discoveries of this generation,” said Ray Smith, a physicist at LLNL and lead author of the research. “These discoveries raise fundamental questions. What are the different types of extrasolar planets and how do they form and evolve? Which of these objects can potentially sustain surface conditions suitable for life? To address such questions, it is necessary to understand the composition and interior structure of these objects.”

    Of the more than 4,000 confirmed and candidate extrasolar planets, those that are one to four times the radius of the Earth are now known to be the most abundant. This size range, which spans between Earth and Neptune, is not represented in our own solar system, indicating that planets form over a wider range of physical conditions than previously thought.

    “Determining the interior structure and composition of these super-Earth planets is challenging but is crucial to understanding the diversity and evolution of planetary systems within our galaxy,” Smith said.

    As core pressures for even a 5×-Earth-mass planet can reach as high as 2 million atmospheres, a fundamental requirement for constraining exoplanetary composition and interior structure is an accurate determination of the material properties at extreme pressures. Iron (Fe) is a cosmochemically abundant element and, as the dominant constituent of terrestrial planetary cores, is a key material for studying super-Earth interiors. A detailed understanding of the properties of iron at super-Earth conditions is an essential component of the team’s experiments.

    The researchers describe a new generation of high-power laser experiments, which use ramp compression techniques to provide the first absolute equation of state measurements of Fe at the extreme pressure and density conditions found within super-Earth cores. Such shock-free dynamic compression is uniquely suited for compressing matter with minimal heating to TPa pressures (1 TPa = 10 million atmospheres).

    The experiments were conducted at the LLNL’s National Ignition Facility (NIF).

    NIF, the world’s largest and most energetic laser, can deliver up to 2 megajoules of laser energy over 30 nanoseconds and provides the necessary laser power and control to ramp compress materials to TPa pressures. The team’s experiments reached peak pressures of 1.4 TPa, four times higher pressure than previous static results, representing core conditions found with a 3-4x Earth mass planet.

    “Planetary interior models, which rely on a description of constituent materials under extreme pressures, are commonly based on extrapolations of low-pressure data and produce a wide range of predicated material states. Our experimental data provides a firmer basis for establishing the properties of a super-Earth planet with a pure iron planet,” Smith said. “Furthermore, our study demonstrates the capability for determination of equations of state and other key thermodynamic properties of planetary core materials at pressures well beyond those of conventional static techniques. Such information is crucial for advancing our understanding of the structure and dynamics of large rocky exoplanets and their evolution.”

    Future experiments on NIF will extend the study of planetary materials to several TPa while combining nanosecond X-ray diffraction techniques to determine the crystal structure evolution with pressure.

    Co-authors include Dayne Fratanduono, David Braun, Peter Celliers, Suzanne Ali, Amalia Fernandez-Pañella, Richard Kraus, Damian Swift and Jon Eggert from LLNL; Thomas Duffy from Princeton University; June Wicks from Johns Hopkins University; and Gilbert Collins from the University of Rochester.
    Tags: Lasers / NIF / National Ignition Facility

    See the full article here .

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  • richardmitnick 7:49 am on April 17, 2018 Permalink | Reply
    Tags: , , , , Exoplanets, From NASA Spaceflight: TESS,   

    From NASA Spaceflight: TESS 

    NASA Spaceflight

    NASA Spaceflight

    April 16, 2018
    Chris Gebhardt

    TESS background/overview:

    NASA/TESS

    The original idea for TESS goes back to 2005 when Dr. George Ricker was the Principle Investigator High Energy Transient Explorer (HETE) – the first satellite mission dedicated to the study of gamma-ray bursts. Slowly, the idea evolved in 2008 and 2009, with Dr. Ricker, now TESS’s Principal Investigator at MIT (Massachusetts Institute of Technology), saying “We wanted to initially try to do this as a privately funded system, and MIT was very helpful for us. We had support from Google for some of the studies that were originally going to be done.”

    That led to a collaboration with NASA Ames to create a proposal for a small-class explorer exoplanet mission that was ultimately not selected for flight. That then led to a partnership with Orbital ATK and the Goddard Space Flight Center in Greenbelt, Maryland, for a revised mission proposal over 2011 and 2012.

    TESS was officially selected for inclusion in NASA’s Medium Explorer mission program on 5 April 2013, and with just over five years of design and build operations, now stands ready to launch. “It’s been a long time coming. It’s been 13 years, but for the last five years, basically, pretty much [everything with the mission has been] the same,” said Dr. Ricker.

    1
    TESS undergoes final pre-launch processing at the Kennedy Space Flight Center. Credit: Chris Gebhart for NSF/L2

    While TESS is generally perceived as a follow-on to NASA’s Kepler planet hunting satellite, it will perform a very different kind of mission. Where Kepler was a prolonged, deep, and narrow field observatory that looked continuously at specific stars in one quarter of 1% of the sky at an optimal range of 2,000 to 3,000 light years distance, TESS will perform a wide- and shallow-field survey covering 85% of the sky with an optimal distance stretching to 300 light years.

    TESS will accomplish its observations by using the sole science instrument onboard: a package of four wide-field-of-view CCD cameras with a low-noise, low-power 16.8 megapixel CCD detector. Each camera as a 24° x 24° field of view, a 100 mm (4 in) pupil diameter, a lens assembly with seven optical elements, and a bandpass range of 600 to 1,000 nm.

    When functioning together – as designed – the four cameras have a 24° x 96° field of view.

    The overall spacecraft is built on a LEOStar-2 satellite bus by Orbital ATK. The spacecraft bus is capable of three-axis stabilization via four hydrazine thrusters as well as four reaction wheels. This provides TESS’s cameras with greater than three-arc-second fine pointing control – necessary for the sensitive light observations TESS will perform once in its science orbit.

    The data collected during TESS’s observational campaigns – as well as general spacecraft communications – will route through a Ka-band antenna with a 100 Mbit/s downlink capability. The entire craft is powered by two solar arrays capable of generating 400 watts.

    “There’s more than 100 scientists and other personnel cooperating on the mission,” said Dr. Ricker, “and as far as the mission itself is concerned, all the work that was involved in designing, developing, and building the hardware, we’ve estimated that there’s more than a million person-hours that have gone into that over the past five years.”

    Launch and Orbit:

    The launch phase of the mission will see a Falcon 9 deliver TESS into a lunar transfer orbit, sending the craft to a precise point when the moon’s gravity will grab TESS and fling it out into a farther orbit than it’s initially launched into.

    At 350 kg (772 lb), TESS is the lightest-known payload to have ever launched on a Falcon 9. After lifting off from SLC-40 at the Cape Canaveral Air Force Station, FL, the Falcon 9 will fly due east from the pad. The first stage, after 2 minutes 29 seconds of powered flight, will separate from the second stage and perform a landing on the Of Course I Still Love You drone ship in the Atlantic.

    SpaceX will also attempt to recover the payload fairing, but as there is no fairing catching boat – yet – on the east coast, the fairing will parachute into the ocean for intact recovery, serving primarily as a test of the new recovery systems.

    For the launch, after stage separation, the second stage will continue to fire its single MVac (vacuum optimized Merlin engine) until SECO-1 (Stage Engine Cut Off -1) at 8minutes 22 seconds into flight. This will be followed by a 32 minute 33 second coast of the stage and TESS before the second stage engine re-starts for a burn to send TESS into a Lunar Transfer Orbit.

    Shortly after SECO-2, TESS will separate from the top of the Falcon 9 second stage at 48 minutes 42 seconds after launch having been placed into a super synchronous transfer orbit of 200 x 270,000 km (124 x 167,770 mi). The second stage will then perform a third burn to inject itself into a disposal hyperbolic (Earth-escape) orbit.

    Over the first five days, TESS’s control teams will check out the overall health of the spacecraft before activating TESS’s science instruments 7-8 days after launch. TESS will then perform a final lunar flyby on 16 May – one month after launch, a lunar gravity assist which will change the the craft’s orbital inclination to send it into its 13.7 day, 108,000 x 373,000 km (67,000 x 232,000 mi) science orbit of Earth – an orbit that is in perfect 2:1 resonance with the moon.

    2
    The maneuvers and encounters Leading to the final TESS orbit. PLEA and PLEP are the post lunar-encounter-apogee and perigee, respectively. Credit Ricker et al. 2015.

    The specific orbit, referred to as the P/2 lunar resonant orbit, will place TESS completely outside the Van Allen Radiation belts, with TESS’s apogee (farthest point in orbit from the Earth) approximately 90 degrees away from the position of the Moon. This will minimize the Moon’s potential destabilizing effect on TESS and maintain a stable orbit for decades while also providing a consistent, good camera temperature range for the observatory’s operations.

    Moreover, this orbit will provide TESS with unobstructed views of both the Northern and Southern Hemispheres. For almost all of its orbit, TESS will be in data gathering mode, only transmitting its stored data to Earth once per orbit during the three hours of its closest approach to Earth, or perigee. Assuming an on-time launch, TESS will enter operations on 12 June.

    Overall, TESS has daily launch opportunities from 16-21 April, no launch opportunity on the 22nd (per NASA documentation), and then daily opportunities again from 23-26 April. There is no opportunity on 22 April because the amount of time between the consecutive daily opportunities on 21 and 23 April is just slightly longer than 24 hours, thus barely skipping over all times on the 22nd.

    However, if for some reason TESS is not off the ground by 26 April, the exoplanet hunter must stand down launch operations so that NASA’s Launch Services Provider (LSP) group can shift gears to support the agency’s InSight mission launch to Mars from Vandenberg Air Force Base, California.

    The LSP does not have a large enough staff to support two missions from both coasts, and since InSight has a short interplanetary launch window it must launch within, InSight would get priority over TESS. After InSight, TESS has additional launch opportunities in both May and June.

    Mission:

    Once its checkout phase is complete, TESS will begin its 26 observational campaigns (13 for each hemisphere) to survey 85% of the sky for transiting exoplanets near Earth. Observations will start with the Southern Hemisphere, and those 13 campaigns will last approximately one year.

    According to Dr. Ricker, choosing to survey the Southern Hemisphere first was “a function of the follow-up resources that are currently available. Many of the most powerful telescopes that ground-based astronomers use are located in the Southern Hemisphere.”

    TESS will then be re-aimed to perform the 13 observational campaigns needed to cover the Northern Hemisphere. During all 26 campaigns, the entire south and north polar sky regions will receive near-continuous year-long assessments from TESS’s cameras – as each observation campaign for the Southern and Northern Hemispheres overlap completely at their respective pole.

    3
    Dr. Ricker shows the number of exoplanets TESS is predicted to find within 100 parsecs (326 lightyears) of Earth. Credit Ricker et al. for NSF/L2

    Every 13.7 days, when TESS swings closest to Earth, the craft will downlink its observation data to scientists at MIT who will process it and make it available to other scientists and the public. Specifically, TESS’s team will focus on the 1,000 closest red dwarf stars to Earth as well as nearby G, K, and M type stars with apparent magnitudes greater than 12.

    Over its primary 2 year mission, TESS will observe about half a million stars in an area 400 times larger than the Kepler mission and is expected to find 20,000 exoplanets – including 500-1,000 Earth-sized planets and Super-Earths.

    These planets will be added to the growing number of known exoplanets. According to NASA’s Exoplanet Archive hosted by CalTech, as of 12 April 2018, there are 3,717 known exoplanets with 2,652 of those found by the Kepler Space Telescope.

    TESS’s primary mission duration is two years, during which all of its science objectives are scheduled to be completed. While a mission extension is never a guarantee, TESS can be extended for additional observations based on its design and orbit. “We can extend, because the orbit will be operating and aligned for more than two decades,” said Dr. Ricker. “Now, as is the case for many Explorer missions, we fully expect that there will be an extended mission for TESS, so we pre-designed the satellite and the operation so that it can go on for a much longer time.”

    See the full article here .

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    NASASpaceFlight.com, now in its eighth year of operations, is already the leading online news resource for everyone interested in space flight specific news, supplying our readership with the latest news, around the clock, with editors covering all the leading space faring nations.

    Breaking more exclusive space flight related news stories than any other site in its field, NASASpaceFlight.com is dedicated to expanding the public’s awareness and respect for the space flight industry, which in turn is reflected in the many thousands of space industry visitors to the site, ranging from NASA to Lockheed Martin, Boeing, United Space Alliance and commercial space flight arena.

    With a monthly readership of 500,000 visitors and growing, the site’s expansion has already seen articles being referenced and linked by major news networks such as MSNBC, CBS, The New York Times, Popular Science, but to name a few.

     
  • richardmitnick 9:25 am on February 4, 2018 Permalink | Reply
    Tags: Exoplanets, , ,   

    From Universe Today: “For the First Time, Planets Have Been Discovered in ANOTHER Galaxy!” 

    universe-today

    Universe Today

    3 Feb , 2018
    Matt Williams

    1
    Using the microlensing metthod, a team of astrophysicists have found the first extra-galactic planets! Credit: NASA/Tim Pyle

    Gravitational microlensing, S. Liebes, Physical Review B, 133 (1964): 835

    The first confirmed discovery of a planet beyond our Solar System (aka. an Extrasolar Planet) was a groundbreaking event. And while the initial discoveries were made using only ground-based observatories, and were therefore few and far between, the study of exoplanets has grown considerably with the deployment of space-based telescopes like the Kepler space telescope.

    As of February 1st, 2018, 3,728 planets have been confirmed in 2,794 systems, with 622 systems having more than one planet. But now, thanks to a new study by a team of astrophysicists from the University of Oklahoma, the first planets beyond our galaxy have been discovered! Using a technique predicting by Einstein’s Theory of General Relativity, this team found evidence of planets in a galaxy roughly 3.8 billion light years away.

    The study which details their discovery, titled Probing Planets in Extragalactic Galaxies Using Quasar Microlensing, recently appeared in The Astrophysical Journal Letters. The study was conducted by Xinyu Dai and Eduardo Guerras, a postdoctoral researcher and professor from the Homer L. Dodge Department of Physics and Astronomy at the University of Oklahoma, respectively.

    See the full article here .

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