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  • richardmitnick 10:39 am on October 23, 2020 Permalink | Reply
    Tags: "Lights out!", , , , , , , The Nancy Grace Roman Space Telescope   

    From The Kavli Foundation: “Lights out!” 


    From The Kavli Foundation

    Adam Hadhazy

    Katie McKissick
    The Kavli Foundation
    (424) 353-8800

    A coronagraph instrument being tested out on a future space telescope will help pave the way for scrutinizing Earthlike worlds for life. Pictured, the Nancy Grace Roman Space Telescope, named after NASA’s first Chief of Astronomy. Credit: NASA​.

    The Nancy Grace Roman Space Telescope won’t fly until 2025 at the soonest, but when it does, astrophysicists will be licking their chops. As its primary science objective, the telescope will scour the depths of time and space to tell us more about dark energy. Roman will additionally perform a kind of census for small-ish exoplanets like Earth, helping us to better gauge if we’re alone in the universe.

    Another key way that Roman will significantly move the science ball forward is by testing out an advanced coronagraph in space for the first time. Such a space telescope-cum-coronagraph—along with other image-boosting current technologies like deformable mirrors—would enable us to directly image Earthlike exoplanets and parse their atmospheres for signs of extraterrestrial life.

    Coronagraphs have long been used to suppress the overwhelming brightness of sunlight and starlight, the better to study otherwise-hard-to-discern, circumstellar phenomena. The goal now is to deploy powerful coronagraphs onboard space telescopes, above the blurring effects of Earth’s atmosphere that ultimately place limits on ground-based astronomy.

    But first, Roman must show us how to get the delicate coronagraph tech to perform admirably in the unforgiving environment of the final frontier. Although the astronomical community’s hope was to originally have the Roman coronagraph be a full-fledged, science-ready system, budgetary and schedule constraints have scaled back its ambition to what is known as a technology demonstration—more of a prototype to work out the kinks than to swing for the fences.

    “It’s still exciting to see a high-performance coronagraph get fielded in space,” says Bruce Macintosh, a Professor of Physics at the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) at Stanford University, who is co-leading a science investigation team for the Roman coronagraph.

    Macintosh knows a thing or two about coronagraphs. He is the Principal Investigator for the Gemini Planet Imager (GPI), an instrument mounted on the Gemini South Telescope in Chile.

    NOIRLab NOAO CTIO Gemini Planet Imager on Gemini South

    NOIRLab NOAO Gemini/South telescope, Cerro Tololo Inter-American Observatory (CTIO) campus near La Serena, Chile, at an altitude of 7200 feet on the summit of Cerro Pachon.

    GPI relies in part on a coronagraph to image young, Jupiter-like exoplanets at Jupiter-like distances from their host stars.

    The Roman coronagraph will build on what’s come before it, including the rudimentary coronagraph on the Hubble Space Telescope. There remains a good deal to prove out yet.

    “The gap between what’s been done on Hubble, or on the ground, and what we need to see Earthlike planets with a future mission is huge, and involves a lot of new tech that’s never been flown,” says Macintosh. “Getting a chance to try that out is important.”

    Coronagraphs essentially work by placing an opaque disk over a star, suppressing glare and letting the light produced by or reflected off of nearby features (such as smaller companion stars or planets) register in a telescope’s optics. The name “coronagraph” stems from the initial (and still a very common use) of the devices: for blocking out the Sun’s brightness in order to study its corona, a superhot realm of surrounding plasma.

    In the case of the Roman coronagraph—technically called CGI, for Coronagraph Instrument—researchers want to test out how vibrations, for instance, in the telescope cause the light from stars to wobble around. That wobbling makes it hard to block starlight out effectively. Researchers also want to learn how to better discern where a blocked star is in relation to any dim planets that its blocking-out reveals. That’s a necessary step for measuring the distance to the planets, which is in turn critical for gauging whether the planets reside in the star’s “habitable zone,” the temperature band where liquid water can persist on a planetary surface and thus where life as we know it is likeliest to appear.

    Cumulatively, CGI will improve our understanding across a number of planet measurement sensitivities and uncertainties. “It’ll be the first chance to play with ‘real’ coronagraph space data,” says Macintosh.

    In terms of the science returns for the tech demo mission, Macintosh says CGI might be able to see “mature” Jupiter-esque worlds, like those in our several-billion-year-old solar system. CGI will also be able to study asteroid and comet belts in other solar systems. Superficially, CGI will pick up the glow of exo-zodiacal light—the exo-version of light produced in our solar system by the dust particles released by asteroids and comets. If that exo-zodiacal light does indeed exist in mature systems like ours, if it will bear out that settled collections of asteroids and comets are common elsewhere.

    The ultimate goal for spaceborne coronagraphy remains an Earthlike planet. With Macintosh’s state-of-the-art ground-based project, GPI, it’s possible to see planets that are about a million times fainter than their star. To see to see an Earthlike planet, however, that threshold balloons to ten billion times fainter—”basically impossible for a telescope on the ground,” Macintosh says.

    But because space telescopes are very stable and still, that threshold looks achievable down the road. “Roman CGI won’t get all the way to ten billion,” says Macintosh, “but maybe ten million, which is a pretty big step forward.”

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    The Kavli Foundation, based in Oxnard, California, is dedicated to the goals of advancing science for the benefit of humanity and promoting increased public understanding and support for scientists and their work.

    The Foundation’s mission is implemented through an international program of research institutes, professorships, and symposia in the fields of astrophysics, nanoscience, neuroscience, and theoretical physics as well as prizes in the fields of astrophysics, nanoscience, and neuroscience.

  • richardmitnick 10:31 am on October 1, 2020 Permalink | Reply
    Tags: "How NASA’s New Telescope Will Help Astronomers Discover Free-Floating Worlds", , , , , , The Nancy Grace Roman Space Telescope   

    From smithsonian.com: “How NASA’s New Telescope Will Help Astronomers Discover Free-Floating Worlds” 

    From smithsonian.com

    September 30, 2020
    Nola Taylor Redd

    NASA Nancy Grace Roman Space Telescope.

    The Nancy Grace Roman Space Telescope will be able to detect small, distant planets without stars.

    As astronomers discover more and more planets in galaxies far, far away, they are increasingly confronted with a curious subset of orbs that are free-floating and not connected to or orbiting a particular star. Further complicating matters is that within that group, most of what they have found are gassy, Jupiter-sized (read: large), planets; few resemble rockier planets like our own Earth.

    First discovered in 2003, these potential free-floating planets are elusive and difficult to detect from the existing ground-based observatories.

    Soon, however, a revolutionary new telescope launching in 2025 may be able unlock the secrets of the darkness of space, where sunless worlds may even outnumber the stars. NASA’s Nancy Grace Roman Space Telescope will be able to see even more rocky free-floating planets, potentially hundreds as small as Mars, according to research published this August in The Astronomical Journal. These lightless worlds can shine light on how planets formed and what happens to them after their star finally dies.

    “The galaxy could be teeming with these free-floating planets, or maybe none,” says Scott Gaudi, an astronomer at Ohio State University and an author on the new research. “There could be more Earth-mass planets than stars in the galaxy…Now we’ll have the possibility with Roman to figure that out.”

    The Nancy Grace Roman Space Telescope, named after NASA’s first chief astronomer who tirelessly advocated for new tools like Hubble and made several important contributions to the field of astronomy, will engage in a trio of core surveys. Roman will study dark energy, survey a special type of supernovae and discover numerous exoplanets through a technology known as gravitational microlensing.

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

    This technique can reveal objects too dark to discover through other means, objects such as black holes or planets. When an object, like a planet, passes in front of a star, its gravity causes a very slight brightening to the stellar light. The faint magnification, predicted by the theory of general relativity, can provide insights into the passing magnifier. Unlike most other planetary discovery techniques, microlensing can find worlds cast off from their star, drifting through the darkness of space.

    “Microlensing can find planets from a little past Earth to the center of the galaxy,” says Samson Johnson, a graduate student at Ohio State University and first author on the new research. “It can find planets all throughout the galaxy.”

    The technique has its own limitations. Once a planet completes the lensing process, it continues to drift through the darkness of space, never to be seen again from Earth. But Johnson says that’s not a huge problem—after all, astronomy is full of transient, one-time events. “You don’t ask a supernova to explode again, you don’t ask black holes to re-merge,” he says.

    While free-floating planets may saturate space, finding them is something of a crapshoot. The process requires three objects—Earth, the background star, and the undiscovered mystery object—line up precisely. Rather than looking at a single star and waiting for the odds to be in their favor, astronomers instead perform massive surveys watching hundreds of millions of stars at the same time for the subtle brightening caused by microlensing. These enormous surveys allow astronomers to discover as many as 2,000 to 3,000 potential microlensing events each year, only a handful of which are wandering planets, according to microlensing observer Przemek Mroz, an astronomer at CalTech who was not part of the new research.

    NASA’s Nancy Grace Roman Space Telescope: Broadening Our Cosmic Horizons

    Earth’s atmosphere creates interference than can make these small events difficult to observe. What sets Roman apart is that it will be orbiting in space, allowing it watch for even briefer microlensing events that represent smaller planets. Additionally, since most such telescope surveys are performed using optical light, the part of the spectrum that humans see with their eyes, they cannot peer through the dust in the center of the galaxy. Roman will rely on infrared light rather than optical, allowing it to peer into the heart of the galaxy, dramatically increasing its ability to discover free-floating worlds.

    New Earth-sized worlds discovered by Roman can help researchers understand the messy process of planet formation. Previous solar system observations led scientists to suspect that the giant planets, especially Jupiter, used their gravity to hurl some of the planetary embryos and young planets out of the solar system, a process likely repeated in other systems. Roman can help to spot some of those lost worlds and determine roughly how many were ejected.

    But planets aren’t only lost during the first moments of their lives. Passing stars can wrangle away worlds that are only loosely connected to their star. A parent star can also drive away its planetary children as it evolves. In a few billion years, our own sun will swell up to a red giant, shedding enough stellar material that its gravitational hold on its planets will weaken, allowing some to wander away.

    Some planets may even form without the help of a star. Recent studies suggest that a small enough pocket of gas and dust could collapse to form not a star but a gas giant.

    While scientists can’t verify the source of a single free-floating planet because none of the ejection processes leave their fingerprint on the world, a statistical look at the population should provide its own insights. Enter Roman, which will discover a wealth of new starless worlds. “If we find a bunch of Earth-mass planets, they almost certainly formed around a star,” Gaudi says, because self-forming planets require more mass.

    Roman’s observations should provide insights about the free-floating worlds and how they became wanderers in space. “We’re starting to run into the limit of what we can do from the ground with ground-based microlensing surveys,” Gaudi says. “That’s why we need to go to space and use Roman.”

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    Smithsonian magazine and Smithsonian.com place a Smithsonian lens on the world, looking at the topics and subject matters researched, studied and exhibited by the Smithsonian Institution — science, history, art, popular culture and innovation — and chronicling them every day for our diverse readership.

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