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posted by Fnord666 on Wednesday January 10 2018, @02:37AM   Printer-friendly
from the I-can-see-clearly-now dept.

To improve the ability of telescopes to directly image exoplanets, rather than blocking light using a coronagraph, deformable mirrors could be used to bounce photons from different light sources into different sensors. The "multi-star wavefront control" method could help account for multiple light sources, which is useful for binary stars and other multiple star systems which are common in our galaxy:

Technology in development could capture images from an Earth-size planet in the nearby Alpha Centauri system in the 2020s, new research suggests. The new technique, presented Dec. 15 at the American Geophysical Union's annual meeting in New Orleans, could also help researchers see exoplanets in other systems with more than one star.

[...] Although scientists could conceivably use more than one coronagraph to block out the light from all the stars in a multiple system, tiny imperfections within the components of a telescope would inevitably cause light to leak through a coronagraph, Belikov said. "This light is only a small fraction of the original star's light but can still overwhelm planets, which are much fainter still," he told Space.com.Belikov and his colleagues have developed a way to get around that issue and image exoplanets in multiple-star systems.

[...] The new method the researchers have devised, known as the multi-star wavefront control, relies on deformable mirrors within telescopes that are used to bounce light from stars and planets onto sensors. These mirrors can alter the shape of their surfaces to correct for imperfections within the optical components of telescopes.

[...] A major advantage of this new system "is that it is compatible with many already-designed instruments," Belikov said. "A deformable mirror is all that's needed, which is almost always present with modern coronagraphs." Ideally, "we hope to infuse our technology into future space telescopes to enable them to target Alpha Centauri and other binaries," Belikov said. "These range from small telescopes like ACESat or Project Blue that can be launched in the early 2020s, WFIRST in the mid-2020s, and LUVOIR or HabEx in the 2030s. There are also telescopes on the ground that can use this technology."

Also at ExtremeTech.


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  • (Score: 4, Interesting) by JoeMerchant on Wednesday January 10 2018, @03:01AM (9 children)

    by JoeMerchant (3937) on Wednesday January 10 2018, @03:01AM (#620321)

    This deformable mirror thing is great, amazing tech.

    I think one of the first, best endeavors of a nascent space manufacturing industry would be to build a big-ass reflector mirror telescope in orbit. Get it up in a wide polar orbit - somewhere out past concerns of atmospheric drag, and just keep adding mirror elements to an expandable frame... forever. If the builders can add just 1 square meter per week to the reflector array, within 2 years they'll have a bigger reflector than Gran Canarias Observatory, after 10 years they should be out-performing the best ground based optical telescopes by a wide margin, and there's not much theoretical reason to stop... diminishing returns at some point, switch to building multiple reflectors so they can cover more sky at one time, I suppose at some point the slew-tracking mechanism would get unwieldy with too big a mirror, but there's no low friction bearing anywhere on the planet that can compete with floating in orbit.

    • (Score: 2) by Grishnakh on Wednesday January 10 2018, @05:05AM (8 children)

      by Grishnakh (2831) on Wednesday January 10 2018, @05:05AM (#620343)

      Better to put it in orbit around a Lagrangian point, so it isn't in Earth's shadow part of the day. That's what they're doing with the upcoming James Webb telescope.

      • (Score: 4, Informative) by takyon on Wednesday January 10 2018, @05:22AM (7 children)

        by takyon (881) Subscriber Badge <{takyon} {at} {soylentnews.org}> on Wednesday January 10 2018, @05:22AM (#620346) Journal

        The bigger problem for JWST is Earth's reflected heat:

        https://www.nasa.gov/topics/universe/features/webb-l2.html [nasa.gov]

        To begin with, the Webb telescope will view the universe entirely in infrared light, what we commonly think of as heat radiation. To give the telescope the best chance of detecting distant, dim objects in space, the coldest temperatures possible are needed.

        "A huge advantage of deep space (like L2) when compared to Earth orbit is that we can radiate the heat away," said Jonathan P. Gardner, the Deputy Senior Project Scientist on the Webb Telescope mission and Chief of the Observational Cosmology Laboratory at NASA's Goddard Space Flight Center in Greenbelt, Md. "Webb works in the infrared, which is heat radiation. To see the infrared light from distant stars and galaxies, the telescope has to be cold. Webb's large sunshield will protect it from both Sunlight and Earthlight, allowing it to cool to 225 degrees below zero Celsius (minus 370 Fahrenheit)." For the sunshield to be effective, Webb will need to be an orbit where the sun and Earth are in about the same direction.

        With the sun and the Earth in the same part of the sky, the Webb telescope will enjoy an open, unimpeded view of the universe. In comparison, the Hubble Space Telescope is in low-Earth orbit where it goes in and out of the Earth's shadow every 90 minutes. Hubble's view is blocked by the Earth for part of each orbit, limiting where the telescope can look at any given time.

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        • (Score: 2) by JoeMerchant on Wednesday January 10 2018, @12:46PM (6 children)

          by JoeMerchant (3937) on Wednesday January 10 2018, @12:46PM (#620445)

          JWST should tell us how important IR is... which will go a long way to deciding whether the "next big thing" needs to do IR better than JWST, the same, or maybe refocus closer to visual spectrum.

          Polar orbit can be fiddled to stay out of Earth's shadow, especially if it's big enough, or go the JWST route and do solar orbit. I'm not sure that a Lagrange point is a great idea for a huge optical instrument, seems like dust and debris would collect there.

          • (Score: 2) by takyon on Wednesday January 10 2018, @05:39PM (5 children)

            by takyon (881) Subscriber Badge <{takyon} {at} {soylentnews.org}> on Wednesday January 10 2018, @05:39PM (#620536) Journal

            We already know that IR "is the next big thing". It's better for high value targets such as exoplanets (exomoons?), trans-Neptunian objects, Planet Nine if it exists, red dwarfs, brown dwarfs [wikipedia.org], rogue planets, dust belts [soylentnews.org], the most distant redshifted galaxies, etc.

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            • (Score: 2) by JoeMerchant on Wednesday January 10 2018, @06:45PM (4 children)

              by JoeMerchant (3937) on Wednesday January 10 2018, @06:45PM (#620562)

              Right, but after JWST, what's the next next big thing?

              • (Score: 2) by takyon on Wednesday January 10 2018, @09:31PM (3 children)

                by takyon (881) Subscriber Badge <{takyon} {at} {soylentnews.org}> on Wednesday January 10 2018, @09:31PM (#620638) Journal

                Probably a Hubble-like telescope but more gigantic than JWST. Similar wavelengths as Hubble, from ultraviolet to near-infrared. JWST is somewhat of a successor to Hubble, but does not cover UV or optical.

                The intent is mainly to directly image exoplanets and hopefully discover evidence of life on them (such as greenery or at the very least, "biosignatures" such as abundant oxygen).

                Here are some of the proposals:

                ATLAST [wikipedia.org]
                LUVOIR [wikipedia.org]
                HDST [wikipedia.org]

                You'll note that they all are in the 8 to 18 meter aperture range. That's a wide range, and the bigger the number, the more exoplanets that can be closely observed. Budget constraints are likely to prevent 18 meters from being realized. But they would really want it. The bigger, the better.

                The HDST proposal locks it in at 12 meters. It also has some concept art; it would have hexagonal mirror segments like JWST, but 54 of them instead of 18 and a different coating.

                LUVOIR would apparently cover far-ultraviolet to mid-infrared (wider range, longer wavelength than near-infrared).

                Each telescope would have an internal coronagraph, although those may become obsolete soon (refer to the very article we're commenting on). There's also talk of having an external starshade some distance away from the telescope. They wanted that for JWST but it never happened.

                HDST's initial cost estimate is $10 billion so you could expect the others to be similar. Or maybe more if they are over 12 meters in size.

                ATLAST is the oldest of these proposals with the bitter pun name. Here's an article [theatlantic.com] in which the size of the aperture is linked to imaging more planets (in enough detail to find evidence of life):

                If I assume that every single star has a planet around and that it's in exactly the right place, then I won't need to look at very many to have a good chance of finding life. With a 4-meter telescope, you can look at 10 systems, the 10 closest systems, in this way (the Hubble has a 2.4-meter mirror and the James Webb Space Telescope will have a 6-meter mirror). If I have an 8-meter mirror, I can observe hundreds of star systems in this way, and if I have a 16-meter mirror I can observe thousands. Those may sound like pretty big numbers, but remember in this scenario I'm assuming that there's an Earth in just the right place around every one of these stars. But we're not sure how many stars have a planet in just the right place, and we obviously don't know how many of those planets have an atmosphere with life in it. Kepler is giving us a handle on the first unknown, and it's looking like the answer is 0.1. It's looking like one in ten stars might have a planet in the habitable zone.

                So while 12 meters is a big deal, going to 16+ meters give us a better chance of finding life on an exoplanet.

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                • (Score: 2) by JoeMerchant on Wednesday January 10 2018, @09:54PM (2 children)

                  by JoeMerchant (3937) on Wednesday January 10 2018, @09:54PM (#620658)

                  So, an 18 meter aperture is ~250 square meters of reflecting area.

                  What if... reflectors even as small as 10cm x 10cm could be assembled accurately in-orbit - 250,000 of them would get your 18 meter aperture... I think the biggest trick would be the alignment, but if the joints could be "smart" self-calibrating/aligning joints...

                  • (Score: 2) by takyon on Thursday January 11 2018, @12:17PM (1 child)

                    by takyon (881) Subscriber Badge <{takyon} {at} {soylentnews.org}> on Thursday January 11 2018, @12:17PM (#620904) Journal

                    That would be great. Maybe in the future we can use the "swarm of dust" telescope [rit.edu].

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                    • (Score: 2) by JoeMerchant on Thursday January 11 2018, @12:59PM

                      by JoeMerchant (3937) on Thursday January 11 2018, @12:59PM (#620913)

                      Yeah, that's taking the idea to another order of magnitude extreme (ditch the frame, guide the dust with lasers...) I'm not sure they've accounted for solar wind in this, unless we're locating the telescope beyond the orbit of Jupiter those steering lasers are going to be very busy.

                      Funny thing, both of these are essentially deformable mirrors (though maybe slow moving) by default, but don't need to be because they also are too weak to exist in gravity.

  • (Score: 0, Troll) by Anonymous Coward on Wednesday January 10 2018, @03:06AM (1 child)

    by Anonymous Coward on Wednesday January 10 2018, @03:06AM (#620325)

    Stop calling math science,, if you cannot test it it is unfalsifiable it is not science

    • (Score: 0) by Anonymous Coward on Wednesday January 10 2018, @04:32PM

      by Anonymous Coward on Wednesday January 10 2018, @04:32PM (#620505)

      Stop calling math science,, if you cannot test it it is unfalsifiable it is not science

      You might be on to something. 2 + 2 = 4? Say, let me go get some bottle caps...

  • (Score: 0) by Anonymous Coward on Wednesday January 10 2018, @01:12PM (1 child)

    by Anonymous Coward on Wednesday January 10 2018, @01:12PM (#620450)

    deform-able mirror this, deform-able mirror that.

    the links just link text spaghetti and a "artists rendering".
    one would think that there would be a actual picture or at least a schematic of this so-called deform-able mirror?

    because, some people might think, that mirrors are suddenly deform-able, maybe like silver-nitrate
    in a parabolic dish that can be tilted and the liquid swirl-es inside the parabola surface ... when in reality it is
    a mirror made up of lots of tiny mirror and each tiny-mirror has an actuator ... or what or how?

    • (Score: 1, Informative) by Anonymous Coward on Wednesday January 10 2018, @03:29PM

      by Anonymous Coward on Wednesday January 10 2018, @03:29PM (#620487)

      Some mirrors are made up of actuated parts, like the Keck, but smaller deformable mirrors are made up of a semi-rigid reflective surface behind which are a number of linear actuators, or pistons, that act like little poking fingers behind the mirror. When the actuators push on the back of the mirror, it bends the mirror locally.

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