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  • richardmitnick 10:43 am on May 4, 2018 Permalink | Reply
    Tags: , , , , , Sara Seager,   

    From MIT News: “Ushering in the next phase of exoplanet discovery” 

    MIT News
    MIT Widget

    MIT News

    May 3, 2018
    Lauren Hinkel | Oceans at MIT

    NASA/TESS

    1
    “TESS is trying to take everything that people have already done and do it better and do it across the whole sky,” says Sara Seager, the Class of 1941 Professor at MIT.
    Photo: Justin Knight.

    2
    TESS will survey the sky in a series of 13 observing segments, each 27-days long. It will spend the first year on the southern ecliptic hemisphere and the second year on the northern ecliptic hemisphere. Depending on sky position, TESS targets will be observed for a minimum of 27 days up to a maximum of 351 days. Image: Roland Vanderspek.

    Professor Sara Seager previews a new era of discovery as a leader of the TESS mission, which is expected to find some 20,000 extrasolar planets.


    A SpaceX Falcon 9 rocket lifted off on April 18 from Cape Canaveral Air Force Station carrying NASA’s Transiting Exoplanet Survey Satellite, or TESS. The MIT-led mission is the next step in the search for planets outside of the solar system and orbiting other nearby stars. The mission is designed to find exoplanets by blocking their light while the planets transition across. Video: NASA

    Ever since scientists discovered the first planet outside of our solar system, 51 Pegasi b, the astronomical field of exoplanets has exploded, thanks in large part to the Kepler Space Telescope.

    NASA/Kepler Telescope

    Now, with the successful launch of the Transiting Exoplanet Survey Satellite (TESS), Professor Sara Seager sees a revolution not only in the amount of new planetary data to analyze, but also in the potential for new avenues of scientific discovery.

    “TESS is going to essentially provide the catalog of all of the best planets for following up, for observing their atmospheres and learning more about them,” Seager says. “But it would be impossible to really describe all the different things that people are hoping to do with the data.”

    For Seager, the goal is to sift through the plethora of incoming TESS data to identify exoplanet candidates. Ultimately, she says she wants to find the best planets to follow up with atmosphere studies for signs that the planet might be suitable for life.

    “When I came to MIT 10 years ago, [MIT scientists] were starting to work on TESS, so that was the starting point,” said Seager, the Class of 1941 Professor Chair in MIT’s Department of Earth, Atmospheric and Planetary Sciences with appointments in the departments of Physics and Aeronautics and Astronautics.

    Seager is the deputy science director of TESS, an MIT-led NASA Explorer-class mission. Her credentials include pioneering exoplanet characterization, particularly of atmospheres, that form the foundation of the field. Seager is currently hunting for exoplanets with signs of life, and TESS is the next step on that path.

    So far, scientists have confirmed 3,717 exoplanets in 2,773 systems. As an all-sky survey, TESS will build on this, observing 85 percent of the cosmos containing more than 200,000 nearby stars, and researchers expect to identify some 20,000 exoplanets.

    “TESS is trying to take everything that people have already done and do it better and do it across the whole sky,” Seager says. While this mission relies on exoplanet hunting techniques developed years ago, the returns on this work should extend far into the future.

    Planet transit. NASA/Ames

    Radial Velocity Method-Las Cumbres Observatory

    Radial velocity Image via SuperWasp http http://www.superwasp.org-exoplanets.htm

    Direct imaging-This false-color composite image traces the motion of the planet Fomalhaut b, a world captured by direct imaging.

    “TESS is almost the culmination of a couple of decades of hard work, trying to iron out the wrinkles of how to find planets by the transiting method. So, TESS isn’t changing the way we look for planets, more like it’s riding on the wave of success of how we’ve done it already.”

    The TESS science leadership team have committed to delivering at least 50 exoplanets with radii less than four times that of Earth’s along with measured masses. As part of the TESS mission, an international effort to further characterize the planet candidates and their host stars down to the list of 50 with measured masses will be ongoing, using the best ground-based telescopes available.

    For the best exoplanets for follow up, Seager likens photons reaching the satellite’s cameras to money: the more photons you have, the better. Accordingly, the cameras are optimized for nearby, bright stars. Furthermore, the cameras are calibrated to favor small, red M dwarf stars, around which small planets with a rocky surface are more easily detected than around the larger, yellow sun-size stars. Additionally, researchers tuned the satellite to exoplanets with orbits of less than 13 days, so that two transits are used for discovery.

    See the full article here .

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  • richardmitnick 1:14 pm on December 8, 2016 Permalink | Reply
    Tags: , , , , , Sara Seager,   

    From NYT: Women in STEM – “‘The World Sees Me as the One Who Will Find Another Earth’” Sara Seager 

    New York Times

    The New York Times

    DEC. 7, 2016
    Chris Jones

    1
    Sara Seager

    Like many astrophysicists, Sara Seager sometimes has a problem with her perception of scale. Knowing that there are hundreds of billions of galaxies, and that each might contain hundreds of billions of stars, can make the lives of astrophysicists and even those closest to them seem insignificant. Their work can also, paradoxically, bolster their sense of themselves. Believing that you alone might answer the question “Are we alone?” requires considerable ego. Astrophysicists are forever toggling between feelings of bigness and smallness, of hubris and humility, depending on whether they’re looking out or within.

    One perfect blue-sky fall day, Seager boarded a train in Concord, Mass., on her way to her office at M.I.T. and realized she didn’t have her phone. She couldn’t seem to decide whether this was or wasn’t a big deal. Not having her phone would make the day tricky in some ways, because her sons, 13-year-old Max and 11-year-old Alex, had a soccer game after school, and she would need to coordinate a ride to watch them. She also wanted to be able to find and sit with her best friend, Melissa, who sometimes takes the same train to work. “She’s my best friend, but I know she has other best friends,” Seager said, wanting to make the nature of their relationship clear. She is an admirer of clarity. She also likes absolutes, wide-open spaces and time to think, but not too much time to think. She took out her laptop to see if she could email Melissa. The train’s Wi-Fi was down. She would have to occupy herself on the commute alone.

    Seager’s office is on the 17th floor of M.I.T.’s Green Building, the tallest building in Cambridge, its roof dotted with meteorological and radar equipment. She is a tenured professor of physics and of planetary science, certified a “genius” by the MacArthur Foundation in 2013. Her area of expertise is the relatively new field of exoplanets: planets that orbit stars other than our sun. More particular, she wants to find an Earthlike exoplanet — a rocky planet of reasonable mass that orbits its star within a temperate “Goldilocks zone” that is not too hot or too cold, which would allow water to remain liquid — and determine that there is life on it. That is as simple as her math gets.

    Seager’s office is on the 17th floor of M.I.T.’s Green Building, the tallest building in Cambridge, its roof dotted with meteorological and radar equipment. She is a tenured professor of physics and of planetary science, certified a “genius” by the MacArthur Foundation in 2013. Her area of expertise is the relatively new field of exoplanets: planets that orbit stars other than our sun. More particular, she wants to find an Earthlike exoplanet — a rocky planet of reasonable mass that orbits its star within a temperate “Goldilocks zone” that is not too hot or too cold, which would allow water to remain liquid — and determine that there is life on it. That is as simple as her math gets.

    That means Seager, who is 45, has given herself a very difficult problem to solve, the problem that has always plagued astronomy, which, at its essence, is the study of light: Light wages war with itself. Light pollutes. Light blinds.

    Seager has a commanding view of downtown Boston from her office window. She can sweep her eyes, hazel and intense, all the way from the gold Capitol dome to Fenway Park. When Seager works at night and the Red Sox are in town, she sometimes has to close her curtains, because the ballpark’s white lights are so glaring. And on this morning, after the sun completed its rise, her enviable vista became unbearable. It was searing, and she had to draw her curtains. That’s how light can be the object of her passion and also her enemy. Little lights — exoplanets — are washed out by bigger lights — their stars — the way stars are washed out by our biggest light, the sun. Seager’s challenge is that she has dedicated her life to the search for the smallest lights.

    The vastness of space almost defies conventional measures of distance. Driving the speed limit to Alpha Centauri, the nearest star grouping to the sun, would take 50 million years or so; our fastest current spacecraft would make the trip in a relatively brisk 73,000 years. The next-nearest star is six light-years away. To rocket across our galaxy would take about 23,000 times as long as a trip to Alpha Centauri, or 1.7 billion years, and the Milky Way is just one of hundreds of billions of galaxies. The Hubble Space Telescope once searched a tiny fragment of the night sky, the size of a penny held at arm’s length, that was long thought by astronomers to be dark. It contained 3,000 previously unseen points of light. Not 3,000 new stars — 3,000 new galaxies. And in all those galaxies, orbiting around some large percentage of each of their virtually countless stars: planets. Planets like Neptune, planets like Mercury, planets like Earth.

    As late as the 1990s, exoplanets remained a largely theoretical construct. Logic dictated that they must be out there, but proof of their existence remained as out of reach as they were. Some scientists dismissed efforts to find exoplanets as “stamp collecting,” a derogatory term within the community for hunting new, unreachable lights just to name them. (Even among astronomers, there can be too much stargazing.) It wasn’t until 1995 that the colossal 51 Pegasi b, the first widely recognized exoplanet orbiting a sunlike star, was found by a pair of Swiss astronomers using a light-analyzing spectrograph. The Swiss didn’t see 51 Pegasi b; no one has. By using a complex mathematical method called radial velocity, they witnessed the planet’s gravitational effect on its star and deduced that it must be there.

    There has been an explosion of knowledge in the relatively short time since, in part because of Seager’s pioneering theoretical work in using light to study the composition of alien atmospheres. When starlight passes through a planet’s atmosphere, certain potentially life-betraying gases, like oxygen, will block particular wavelengths of light. It’s a way of seeing something by looking for what’s not there.

    Light or its absence is also the root of something called the transit technique, a newer, more efficient way than radial velocity of finding exoplanets by looking at their stars. It treats light almost like music, something that can be sensed more accurately than it can be seen. The Kepler space telescope, launched in 2009 and now trailing 75 million miles behind Earth, detects exoplanets when they orbit between their stars and the telescope’s mirrors, making tiny but measurable partial eclipses.

    NASA/Kepler Telescope
    NASA/Kepler Telescope

    Planet transit. NASA/Ames
    Planet transit. NASA/Ames

    A planet the size of Jupiter passing in front of its sun might result in a 1 percent dip in the amount of starlight Kepler receives, a drop that, in time, reveals itself to be as regular as rhythm, as an orbit. The transit technique has led to a bonanza of finds. In May, NASA announced the validation of 1,284 exoplanets, by far the largest single collection of new worlds yet. There are now 3,414 confirmed exoplanets and an additional 4,696 suspected ones, the count forever increasing.

    Before Kepler, the nature of the transit technique meant that most of those exoplanets were “Hot Jupiters,” giant balls of hydrogen and helium with short orbits, making them scalding, lifeless behemoths. But in April 2014, Kepler found its first Earth-size exoplanet in its star’s habitable zone: Kepler-186f. It’s about 10 percent larger than Earth and orbits on the outer reaches of where the temperature could allow life. No one knows the mass, composition or density of Kepler-186f, but its discovery remains a revelation. Kepler was searching, somewhat blindly, an impossibly small sliver of space, and it found a potentially habitable world more quickly than anyone might have guessed.

    In August, astronomers at the European Southern Observatory announced that they had detected a somewhat similar planet orbiting Proxima Centauri, the single star closest to us after the sun.

    Centauris Alpha Beta Proxima 27, February 2012. Skatebiker
    Centauris Alpha Beta Proxima 27, February 2012. Skatebiker

    They named it Proxima Centauri b. Studying the data, Seager supported the discovery and agreed that it might boast a life-sustaining — or at least non-life-threatening — surface temperature. There are now nearly 300 confirmed exoplanets or candidates orbiting within the habitable zones of their stars. Extrapolating the math, NASA scientists now believe that there are tens of billions of potentially life-sustaining planets in the Milky Way alone. The odds practically guarantee that a habitable planet is somewhere out there and that someone or something else is, too.

    In some ways, the search for life is now where the search for exoplanets was 20 years ago: Common sense suggests a presence that we can’t confirm. Seager understands that we won’t know they’re out there until we more truly lay eyes on their home and see something that reminds us of ours. Maybe it’s the color blue; maybe it’s clouds; maybe, however many generations from now, it’s the orange electrical grids of alien cities, the black rectangles of their lightless Central Parks. But how could we ever begin to look that far? “Everything brave has to start somewhere,” Seager says.

    The beginning of her next potential breakthrough hangs on the wall opposite the window in her office. It is a two-thirds scale model of a single petal of something called the starshade.

    6

    She has been a leading proponent of the starshade project, and outside her teaching, it is one of her principal professional concerns.

    Imagine that far-off aliens with our present technology were trying to find us. At best, they would see Jupiter. We would be lost in the sun’s glare. The same is true for our trying to see them. The starshade is a way to block the light from our theoretical twin’s sun, an idea floated in 1962 by Lyman Spitzer, who also laid the groundwork for space telescopes like Hubble. The starshade is a huge shield, about a hundred feet across. For practical reasons that have to do with the bending of light, but also lend it a certain cosmic beauty, the starshade is shaped exactly like a sunflower. By Seager’s hopeful reckoning, one day the starshade will be rocketed into space and unfurled, working in tandem with a new space telescope like the Wfirst, scheduled to launch in the mid-2020s.

    NASA/WFIRST
    NASA/WFIRST

    When the telescope is aimed at a particular planetary system, lasers will help align the starshade, floating more than 18,000 miles away, between the telescope and the distant star, closing the curtains on it. With the big light extinguished, the little lights, including a potential Earthlike planet and everything it might represent, will become clear. We will see them.

    The trouble is that sometimes the simplest ideas are the most complicated to execute. About once a decade since Spitzer’s proposal — he could work out the math but not the mechanics — someone else has taken up the cause, advancing the starshade slightly closer to reality before technological or political inertia set in. Three years ago, Seager joined a new, NASA-sponsored study to try to overcome the final practical hurdles; NASA then chose her from among her fellow committee members to lead the effort.

    After those decades of false starts, Seager and her team have already succeeded in making the starshade seem like a real possibility. NASA recognized it as a “technology project,” which is astral-bureaucracy speak for “this might actually happen.” Today the starshade is a piece of buildable, functional hardware. Seager packs that single petal into a battered black case and wheels it, along with a miniature model of the starshade, into classrooms and conferences and the halls of Congress, trying to find the momentum and hundreds of millions of dollars that allow impossible things to exist.

    “If I want the starshade to succeed, I have to help mastermind it,” Seager says. “The world sees me as the one who will find another Earth.” She has her intelligence, and her credentials, and her audience. She has her focus. But maybe more than anything else, Seager understands in ways few of us do that sometimes you need darkness to see.

    Seager grew up in Toronto, wired in a way all her own. “Ever since I was a child, there was just something about me that wasn’t quite like the others,” she says. “Kids know how to sort through who’s the same and who’s different.” After her parents divorced, her father, Dr. David Seager, achieved a certain fame by becoming one of the world’s leaders in hair transplants. The Seager Hair Transplant Center still operates and bears his name a decade after his death. David Seager was besotted with his bright daughter and wanted her to become a physician.

    Seager did her best to fit in. Sometimes she did; mostly she didn’t. Eventually, she gave up trying. She still talks breathlessly — “without enough modulation,” she has learned by listening to other people talk. She has never had the patience to invest in something like watching TV. “Things just move too slowly,” she says. “It feels like a drag.” She sleeps a lot, but that’s just a concession to her biology; she recognizes that she’s a more efficient machine when she’s rested. But if Seager’s apartness didn’t make her insecure, it also made her feel as though the expectations of others didn’t apply to her. “I loved the stars,” she says. When she was 16, she bought a telescope.

    Friendless for most of her childhood, Seager eventually forged her way to her own vision of the good life. She found and married a quiet man named Mike Wevrick, whom she met on a ski trip with her canoe club. He had seen something in her that nobody other than her father fully saw; he saw her as special as well as strange. Later, she graduated from Harvard, an early expert in exoplanets. (51 Pegasi b was discovered just when she was searching for a thesis topic. “I was born at the perfect time,” she says.) She and Wevrick had Max and Alex; Seager was hired by M.I.T., and she and Wevrick and the boys moved into a pretty yellow Victorian in Concord, Mass. She took the train to work. Wevrick, a freelance editor, managed just about everything that didn’t involve the search for intelligent life in the universe. Seager never shopped for groceries or cooked or pumped gas. All she had to do was find another Earth.

    Then, in the fall of 2009, Wevrick got a stomachache that drove him to bed. They figured it was the flu. Wevrick didn’t have the flu, but a rare cancer of the small intestine. They were told that the initial prospects were good, and he fought the cancer sufferer’s systematic fight. But while laws govern astrophysics, cancer is an anarchist. About a year after Wevrick’s diagnosis, he and Seager went cross-country skiing, and he couldn’t keep up. A few more terrible months passed, and he began writing out a methodical three-page list, practical advice for Seager after his death. It wasn’t a love letter; it was an instruction manual for life on Earth. By June 2011, he was 47 and in home hospice. Seager asked him how to get the roof rack that carried his canoes off the car. “It’s too complicated to explain,” Wevrick said. That July, he died.

    The first couple of months after Wevrick’s death were weird. Seager felt a surprising sense of relief from the uncertainties of sickness, a kind of liberation. She didn’t care about conventions like money, which she had never needed to manage, and she took the boys on some epic trips. There are pictures of them smiling together in the deserts of New Mexico, on mountaintops in Hawaii. Then one day, she went into Boston for a haircut, got turned around and accidentally walked into a lawyer’s office next to the salon. Seager ended up talking to a woman inside. That woman was also a widow, and she told Seager that there would be a moment, as inevitable as death itself, when her feelings of release would be replaced by the more lasting aimlessness of the lost. Seager walked back outside, and just like that, the world came out from under her feet. She fell into an impossible blackness.

    Later that winter, she took the boys sledding at the big hill in Concord. Two other women and their children were there. Seager stared at them coldly. They were smiling and carefree with their perfect, blissful lives. Seager felt ugly and ruined next to them. Then Alex, who was 6 at the time, had a meltdown. He sprawled himself across the hill so that the other children couldn’t go down it. The two other mothers tried to get him to move. “He has a problem,” Seager told them. They continued to try to shift him.

    “HE HAS A PROBLEM,” Seager said. “MY HUSBAND DIED.”

    “Mine, too,” one of the other women said. That was Melissa. A few weeks later, on Valentine’s Day, Seager was invited to her first gathering of the widows.

    Today, Melissa says she could detect the telltale “flintiness” of the recently bereaved the moment she saw Seager on the hill. Now there were six widows united in Concord, each middle-aged, each in a different stage of grief, drawn together by the peculiar pull of the unlucky. Three had been widowed by cancer, two by accidents — bicycling and hiking — and one by suicide. Melissa’s husband was four years gone, Seager’s seven months.

    Widowhood was like a new universe for Seager to explore. She had never understood many social norms. The celebration of birthdays, for instance. “I just don’t see the point,” she says. “Why would I want to celebrate my birthday? Why on earth would I even care?” She had also drawn a hard line against Christmas and its myths. “I never wanted my kids to believe in Santa.” After Wevrick’s death, she became even more of a satellite, developing a deeper intolerance for life’s ordinary concerns.

    Making dinner seemed an insurmountable chore, the routine of school lunches a form of torture. The roof needed to be replaced, and she didn’t have the faintest idea how to get it fixed. She wasn’t sure how to swipe credit cards. If the answers to her questions weren’t somewhere on Wevrick’s three wrinkled sheets of paper, it could feel as though they were locked in a safe.

    There was a pendant light in her front hall, where the boys would fight with their toy lightsabers, and sometimes they would hit the light with their wild swings. Seager decided that either the light or one of the boys was going to end up damaged. She asked the widows how to do electrical work — “I have to parcel out things with logic and evidence,” she says — got out the ladder and took down the light, carefully wrapping black tape around the ends of the bare wires that now poked through the hole in the ceiling. She remembers thinking that her removing that light, all by herself, represented the height of her new accomplishment. She felt so reduced. She felt so gigantic.

    For all of her real and perceived strangeness, the most unusual thing about Seager is her blindness to her greatest gift. She is more than aware of her preternatural mathematical abilities, her possession of a rare mind that can see numbers and their functions as clearly as the rest of us see colors and shapes. “I’m good at that stuff,” she says with her brand of factual certainty that is sometimes confused with arrogance. She knows she is unusually capable of turning abstract concepts into things that can be packed into a case. What she doesn’t always see is her knack for connection between places if not always people, the unconventional grace she possesses when it comes to closing unfathomable distances.

    Seager has lined the hallway outside her office with a series of magical travel posters put out by the Jet Propulsion Laboratory. Each gives a glimpse of the alien worlds that, in part because of her, we now know exist. There’s a poster for Kepler-16b, an exoplanet that orbits a pair of stars, like Luke Skywalker’s home planet of Tatooine. Kepler-186f is depicted with red grass and red leaves on its trees, because its star is cooler and redder than the sun, which might influence photosynthesis in foliage-altering ways. There’s even one for PSO J318.5-22, a rogue planet that doesn’t orbit a star but instead wanders across the galaxy, cast in perpetual darkness, swept by rain of molten iron.

    After the discovery of Proxima Centauri b, Seager wrote a galactic postcard from it for the website Quartz. She closed her eyes and imagined a world 25 trillion miles away. “For the average earthling,” she wrote, “visiting this planet might not be much fun.” She saw a planet perhaps a third larger than Earth, with an orbit of only 11 days. Given its proximity to its small, red star, she suggested that the ultraviolet radiation on Proxima Centauri b is probably intense but the light Martian-dim. She also deduced that Proxima Centauri b is “tidally locked.” Like the moon’s relationship to Earth, one side of the planet always faces its star, which is always in the same place in its sky. Parts of Proxima Centauri b are cast in perpetual sunrise or sunset. One side is always in darkness.

    At first, after Wevrick’s death, Seager thought about abandoning her work, because she was having such a hard time with her responsibilities at home. Her dean talked her out of quitting, giving her financial support to hire caregivers for the boys and urging her to redouble her efforts. “I had worked so hard,” she says. “I had all the years I called the lost years with Mike when I ignored him. We had little tiny kids. I was working all the time, exhausted all the time. But I was like: We’ll have money some day. We’ll have time some day.”

    She paused. Her face was blank, emotionless. “Now I’ll cry.” Seconds later, tears spilled out of her eyes, and her voice modulated. “I wanted to make it up to him, and I never did.”

    Seager has always found comfort and perhaps even solace in her work, in her search for another and maybe better version of our world. In her mourning, each discovery represented one more avenue of escape. In the spring of 2013, she was given responsibility for the starshade. That July, she met a tall, fast-walking man named Charles Darrow.

    Darrow, who is now 53, was an amateur astronomer and the president of the Toronto branch of the Royal Astronomical Society of Canada, and at the last minute he decided to go to the society’s annual meeting in Thunder Bay, Ontario. Darrow was on his way out of a profoundly unhappy marriage; he worked for his family business, an engine-parts wholesaler. He needed a break, and he pointed his car north. “I wanted to be alone,” he says. At a reception on the Friday evening, Darrow noticed a hazel-eyed woman staring at him from across the room. “I thought she was looking at someone behind me,” he says. Then he went into the lecture hall, and the same woman was that night’s keynote speaker. She talked about exoplanets. The next day, lunch was in a university cafeteria. The woman was in the salad line ahead of him, and she turned around. Darrow mustered up his courage and invited Sara Seager to join him. “I knew about five minutes into the conversation that my life was going to change,” he says.

    Seager was taken with Darrow the night she saw him in Thunder Bay. She had been struck by the contrast between the whiteness of his shirt and his tanned summer skin. But she didn’t have the same certainty that possessed him at their lunch the next day. She wasn’t sure how to develop a relationship across the 549 miles between her home in Concord and his home outside Toronto. She thought they might never cross paths again.

    They might not have, except Darrow resolved during his drive back home that he had to call her. He picked up the phone five times but always hung up before she answered. On the sixth, he spoke to her, beginning a long correspondence, emails and conversations over Skype. Darrow and Seager talked every way but face to face. They fell in love remotely. “I had to follow my heart,” Darrow says. “I decided that I wasn’t going to die unhappy.”

    Melissa, meanwhile, told Seager that if she could close the gap between here and a planet like Kepler-186f — a journey that would take us 500 light-years to complete — then the 549 miles between Concord and Toronto shouldn’t seem like such an insurmountable gulf. By her usual measures, he was right next door.

    Seager and Darrow married in April 2015. In different ways, each had rescued the other. Seager was the cataclysm that allowed Darrow to make every correction. He divorced, left his family business and moved into a pretty yellow Victorian in Concord. The two boys started calling him dad. For Seager, Darrow was a second chance to know love, even deeper than the one she had known, because it seemed so improbable in her sadness. “I feel so lucky to have found him,” Seager says. “What are the chances?”

    Adapting to his new life hasn’t always been easy for Darrow. He is determined, as he puts it, “to make Sara the happiest woman in the multiverse.” He cooks dinner; he helps take care of the boys; he maintains the house; he walks with Seager to the train station every morning, and he picks her up every night. He has chosen to take care of the mundane so that she can devote herself to the extraordinary. But he banged his head more than once on Wevrick’s canoe, which still hung from the back of the garage.

    Not long ago, Darrow was looking for the right ways to assert his presence, to make a claim to a house that didn’t always feel like his. The wires dangling from the front hall ceiling bothered him. They looked bad and seemed dangerous. A few months after his arrival in Concord, he took his opening. He carved out some of the plaster, installed a plastic box, ran the wires through it and hooked up a new fixture, flush mounted, so that the boys wouldn’t hit it during their duels.

    Darrow climbed down from the ladder and flicked the switch.

    The morning after she forgot her phone, Seager woke up and decided, just like that, to skip the commute. With the house to herself, she tried to make coffee. She left out part of the machine, and after some terrible noises, the pot was bone dry. She sat down at her kitchen table with her empty mug and began talking about hundreds of billions of galaxies and their hundreds of billions of stars. Tens of billions of habitable planets, far more of them than there are people on Earth. There has to be other life somewhere out there. We can’t be that special.

    “It would be arrogant to think so,” Seager said. But in her lifetime, after the Wfirst telescope rockets into orbit, and maybe her starshade follows it — she puts the chances of success at 85 percent — she will have time to explore only the nearest hundred stars or so. A hundred stars out of all those lights in the sky, a fraction of a fraction of a fraction.

    Will one of them have a small, rocky planet like Earth? Probably. Will one of those small, rocky planets have liquid water on it? Possibly. Will the planet sustain life? Now the odds tilt. Now they are working against her, and she knows it. Now they’re maybe one in a million that she’ll find what she’s looking for.

    She did some private math. “I believe,” she said.

    Seager’s discovery will be fate-altering if it comes, but it will also be quiet, a few pixels on a screen. It will obey the laws of physics. It will be a probability equation: What are the chances? We won’t discover that there is life on other planets the way we’ve been taught that we’ll learn. There won’t be some great mother ship descending from the sky over Johannesburg or a bizarre lightning storm that monsters will ride to New Jersey. What Seager will have is a photograph from a space telescope of a distant solar system, with its star eclipsed by her starshade, and with a familiar blue dot some safe and survivable distance away from it. That’s all the evidence she will have that we’re not alone, and that will be all the evidence she will need. Her proof of life will be a small light where there wasn’t one before.

    See the full article here .

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  • richardmitnick 5:40 pm on April 17, 2016 Permalink | Reply
    Tags: , , , Sara Seager   

    From CNN: “The planet hunter searching for another Earth” Sara Seager 

    1
    CNN

    April 15, 2016
    Jacopo Prisco

    “I want to find another Earth. That’s what I’m living for.”
    MIT astrophysicist Sara Seager has been looking at planets beyond our solar system, known as exoplanets, for almost 20 years.
    When the first ones were discovered in the 1990s, many questioned the finding and didn’t think it was real. But since then, with better technology, we have observed more than 6,000 of them, most of which are giant balls of gas.

    Today, the list grows every week.

    With so many planets now coming out of hiding, the race is on to identify one that resembles Earth: a rocky world with liquid water just like ours, and suitable to host life.
    Seager believes she knows how to make that discovery.

    ‘These aren’t planets!’

    It’s not easy to see exoplanets as you can’t just look at them through a telescope. This is due to the blinding light coming from their host stars, which can be very different in size and features compared to our sun. The process is often described as trying to spot a firefly circling a lighthouse, from thousands of miles away.

    The first ones were discovered indirectly, in 1995, by just looking at stars to see if they would wobble slightly, responding to the pull of another object’s gravity.

    At this time, Seager was a graduate student at Harvard searching for a topic for her Ph.D. and she was intrigued by the newborn field of faraway planets.
    “Since the planets were discovered indirectly, most people didn’t believe that the discoveries were real. They’d say to me ‘Why are you doing this? These aren’t planets!’,” says Seager.
    The contrarians weren’t entirely wrong: the wobble can be caused by other factors such as another star and several planet discoveries have been retracted over time for this reason.
    But then a different technique was found to make their hunt easier, called transit.

    Planet transit. NASA
    Planet transit. NASA

    This is when a planet moves in front of its host star and causes the star’s light to dim slightly.

    “One of the planets from the wobble technique showed transit: it went in front of the star at exactly the time it was predicted to and that was basically incontrovertible,” says Seager.
    Exoplanets were real.

    1
    Dwarfing even Jupiter – HD-106906b is a gaseous planet 11 times more massive than Jupiter. The planet is believed to have formed in the center of its solar system, before being sent flying out to the edges of the region by a violent gravitational event. No image credit.

    Alien atmospheres

    Seager did not want to simply look for distant planets. She set her sights on something more specific — their atmosphere. She was the first person to do so.
    “Atmospheres are important because they’re a way to look for signs of life: we look at gases that don’t belong and may have been produced by some life form,” she explains.
    But if seeing an exoplanet is already difficult, how do you observe an atmosphere? For this purpose the light from the star can come in handy. “When a planet transits in front of its star, we can very carefully analyze the atmosphere’s composition, thanks to the light of the star shining through it,” says Seager.

    The process becomes similar to looking at a rainbow.
    “If you look at a rainbow very closely, you see tiny little dark lines between the colors, pieces that are missing. Those lines are there because Earth’s atmosphere is taking away some of the light.”
    The dark lines are like fingerprints for specific gases and special tools can decode which ones are there. In 1999, Seager suggested that one particular element, sodium, should leave a detectable fingerprint.
    “It’s like skunk spray: a tiny bit of sodium can make a very big signature,” she says.

    Seager was right — her prediction was independently confirmed two years later using the Hubble telescope.

    NASA/ESA Hubble Telescope
    NASA/ESA Hubble Telescope

    Sodium was found in the atmosphere of a “Hot Jupiter,” the name given to the first exoplanets ever discovered. These are huge spheres of gas many times larger than Earth — like our Jupiter — orbiting dangerously close to their stars, making them very hot.
    Because of their size, Hot Jupiters are the easiest exoplanets to spot, and hundreds have been found to date. But as they don’t have a solid surface, they are nothing like Earth.
    To find life, we need small, rocky planets — like ours.

    The Goldilocks Zone

    Compared to finding “Hot Jupiters”, searching for rocky planets is far more difficult, mainly because of their smaller size. And when spotting gases, it’s not sodium we’re after.

    “The number one thing we want to see in a planet’s atmosphere is water vapor,” says Seager.
    We see water vapour in some of the giant planets, like Jupiter, as they have it naturally within their atmosphere. “We have not seen that yet in a rocky planet.”
    Detecting water vapor on a rocky planet would be the tell-tale sign of a liquid ocean, and therefore the potential for life. “All life on Earth needs water, and we believe that all life needs a liquid,” says Seager.
    The need for liquid to create life is theorized due to the chemistry of molecules, as they require liquids to react and reform into other things — such as lifeforms. “Water is simply the most abundant liquid out there,” says Seager.
    For a planet to have liquid water, some basic conditions must be met. The planet must be such that its surface temperature is not too hot — or water will boil away — and not too cold — or it will freeze into ice. This all depends on its distance from the parent star: either too close, or too far.
    Astronomers call this sweet spot the “Goldilocks zone,” from the children’s tale “The Three Bears,” in which young Goldilocks likes her porridge “Not too cold, not too hot, but just right.”

    Habitable planets Current Potential Planetary Habitability Laboratory U Puerto Rico Arecibo
    Habitable planets Current Potential Planetary Habitability Laboratory U Puerto Rico Arecibo.

    These planets are not rare, but the challenge in spotting them can make it seem that way.
    “As many as one in five stars like the sun could have a planet with liquid water. And even though this number could be wrong, as things change quickly, we know for sure that small rocky planets are not rare,” says Seager.
    There may be billions of Earth-like planets in our galaxy alone.

    The galaxy’s finest

    Out of the 6,000 planets discovered so far, approximately 2,000 have been confirmed to be actual planets — work is underway on the rest — but only about 30 are considered potentially habitable.

    In 2014, NASA found the first Earth-sized planet orbiting a star in the habitable zone. This was named Kepler-186f — after the Kepler space telescope, used to spot it — and is about 500 light-years away in the constellation Cygnus, the galactic equivalent of our neighbourhood since the Milky Way is about 100,000 light years across.

    NASA/Kepler Telescope
    NASA/Kepler Telescope

    This planet is 10% larger than Earth.
    Described by NASA as “a significant step toward finding worlds like our planet Earth,” Kepler-186f orbits around a type of common star known as a red dwarf, which is about half the size of our sun.
    Then, in 2015, astronomers found the first Earth-like planet orbiting a star just like our sun, called Kepler-452b. This was dubbed Earth’s “bigger, older cousin,” as the planet is 60% larger than Earth and completes one orbit in 385 days, making its years remarkably close to our own
    With our current technology, however, it’s hard to know much more than the size of an exoplanet and how far it is from its star.
    But that’s about to change.

    New eyes in the sky

    The majority of exoplanet discoveries have been made by the Kepler space telescope, after which most of them have been named. Launched in 2009, the telescope has now entered emergency mode 75 million miles away from Earth, due to a malfunction.
    To study the atmospheres of potential Earth twins, scientists need new eyes in the sky.
    To date, Seager has only been able to study the atmospheres of a handful of exoplanets — all gas giants — but she’s involved in a new NASA program launching in 2017 to just scout the brightest nearby stars for small rocky planets in the habitable zone.


    Access mp4 video here .

    Called TESS (Transiting Exoplanet Survey Satellite), the two-year mission will accumulate data that will then be fed into the James Webb Space Telescope, the next Hubble, which is due to launch in 2018: “It’s going to be amazing,” says Seager.

    NASA/TESS
    NASA/TESS

    NASA/ESA/CSA Webb Telescope annotated
    NASA/ESA/CSA Webb Telescope annotated

    The James Webb telescope — named after the head of NASA during the pioneering era of the 1960s — will look at the cosmos with unprecedented clarity thanks to its use of a primary mirror about five times larger than Hubble’s. It will also offer direct imaging of exoplanets by blocking the blinding light of their host stars with special instruments that make them more visible. This will allow Seager and other astronomers to study exoplanets like never before.
    Seager believes many of the planets in their search will be the rocky, watery worlds she’s been looking for.
    “I’m absolutely confident they’re out there.”

    See the full article here .

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  • richardmitnick 5:04 pm on January 1, 2016 Permalink | Reply
    Tags: , , Direc imaging of an exoplanet, , Sara Seager,   

    From space.com: “Direct Imaging: The Next Big Step in the Hunt for Exoplanets” 

    space-dot-com logo

    SPACE.com

    December 31, 2015
    Nola Taylor Redd

    Temp 1
    This false-color composite image traces the motion of the planet Fomalhaut b, a world captured by direct imaging.
    Credit: NASA, ESA, and P. Kalas (University of California, Berkeley and SETI Institute)

    The hunt for planets around other stars is gaining speed. NASA’s Kepler Space Telescope revealed more than 4,600 planetary candidates over its brief lifetime [Kepler is still active as the K2 mission].

    NASA Kepler Telescope
    NASA/Kepler

    But what does the future hold for exoplanets? When almost 350 exoplanet scientists gathered in Hawaii earlier this month, Space.com asked several of them what they were most looking forward to. Many expressed enthusiasm over the progress made in the field of direct imaging.

    2
    This image shows the light from three planets orbiting a star 120 light-years away. The planets’ star, called HR8799, is located at the spot marked with an “X.” This picture was taken using a small, 1.5-meter (4.9-foot) portion of the [Caltech] Palomar Observatory’s Hale Telescope, north of San Diego, Calif. This is the first time a picture of planets beyond our solar system has been captured using a telescope with a modest-sized mirror — previous images were taken using larger telescopes. The three planets, called HR8799b, c and d, are thought to be gas giants like Jupiter, but more massive. They orbit their host star at roughly 24, 38 and 68 times the distance between our Earth and sun, respectively (Jupiter resides at about 5 times the Earth-sun distance).

    Caltech Palomar 200 inch Hale Telescope
    Caltech Palomar Hale Telescope interior
    Caltech Palomar Hale telescope

    4
    Beta Pictoris
    This composite image represents the close environment of Beta Pictoris as seen in near infrared light. This very faint environment is revealed after a very careful subtraction of the much brighter stellar halo. The outer part of the image shows the reflected light on the dust disc, as observed in 1996 with the ADONIS instrument on ESO’s 3.6 m telescope; the inner part is the innermost part of the system, as seen at 3.6 microns with NACO on the Very Large Telescope. The newly detected source is more than 1000 times fainter than Beta Pictoris, aligned with the disc, at a projected distance of 8 times the Earth-Sun distance. Both parts of the image were obtained on ESO telescopes equipped with adaptive optics.

    ESO 3.6 Meter Telescpe
    ESO’s 3.6 m telescope at La Silla

    ESO NACO
    ESO/NACO on VLT

    ESO VLT Interferometer
    ESO/VLT at Paranal

    “The new technique now is direct imaging,” Sara Seager, a professor of planetary science and physics at the Massachusetts Institute of Technology, told Space.com.

    3
    Sara Seager

    “It’s really like the start of a brand-new era of exoplanets.”
    “Not just stamp collecting”

    At its heart, the direct-imaging method resembles photography, whether via visible or infrared light. But photographing a planet isn’t easy, especially when it is literally outshone by its parent star. Scientists must use an instrument known as a coronagraph to block the light from the star, revealing the dimmer light reflected by a planet in its shadow.

    “It’s not just that you know that [the planets] are there, it’s that you can see it with your own eyes,” Thayne Currie, a research associate at Subaru Telescope, told Space.com.

    NAOJ Subaru Telescope
    NAOJ/Subaru

    Other methods of planet detection are indirect, meaning they find evidence of the planet’s presence, but often do not see the light it emits.

    “To me, [direct detection] means something fundamentally more special.”

    Although scientists have been taking pictures of stars since the early days of photography, the first directly imaged planet wasn’t discovered until 2004. That planet was orbiting a brown dwarf, an object sometimes known as a “failed star” because it never gets massive enough to begin fusing material in its core. As a result, brown dwarfs are far dimmer than stars like the sun. In 2008, scientists announced the discovery of Fomalhault b, a planet directly imaged in visible light and orbiting a full-grown star. The same day, a separate team announced the successful image of the star HD 8799 in the infrared — but instead of one world, this star boasts four.

    Since then, direct imaging has been growing by leaps and bounds, according to the scientists we spoke to.

    According to Currie, one of biggest benefits of direct imaging is the amount of information that can be revealed with the method.

    “It’s not just stamp collecting. We’re able to study these objects in exceptional detail,” he said. “We actually know more about these planets than we knew about Jupiter a hundred years ago.”

    Direct imaging allows astronomers to understand a planet’s orbit, the composition of its atmosphere and the probability it has clouds. Water, methane and carbon dioxide can all be detected with the technique.

    “The wealth of information you have is staggering,” Currie said.

    See the full article here .

    Please help promote STEM in your local schools.

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