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Next Generation Extremely Large Telescopes Outline

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Next Generation Extremely Large Telescopes Outline Next Generation Extremely Large Telescopes Outline • What are we looking for? • Telescope types • Telescope style • Mirror types • Size comparison – Existing vs New • New Ground Based Telescopes • Electromagnetic Spectrum • New Space Based Telescopes What are we looking for? • More distant and fainter objects: • discover new stars, galaxies, black holes, exoplanets • first objects to emit light in the Universe • Investigate dark energy and dark matter • Determine if there is life elsewhere in the galaxy • identify potentially habitable planets • Measure quasars, pulsars, gravitational waves • Mapping small objects in the solar system • near-Earth asteroids, Kuiper belt objects • Detecting transient optical events • novae and supernovae What are the objects? • Stars, starlike objects – Pulsars – Pulsing stars – Quasars – Quasi Stellar radio sources – novae and supernovae – exploding stars • Galaxies • Exoplanets – planets around other stars • Invisible items – don’t emit light – Black holes – location of intense gravity – Dark Energy – Dark Matter How do we find them? • Images of objects • Object motion • Effect on motion or image of nearby matter (other objects) – Exoplanets – transit and movement of star – Dark energy – expansion of universe – dark matter – attraction of objects Extremely Large Telescopes • Why is “bigger”/larger is better? • Greater resolving power •see more detail • More light gathering power •See dimmer objects • Space based vs Ground based • No atmospheric interference • Adaptive Optics • Removes effects of atmospheric distortion Resolution Low resolution High resolution Telescope Styles • Refracting – Lenses • Reflecting – Mirrors • Multiple Mirror – Aberration Correction Refracting telescope: Objective lens Cassegrain Reflecting telescope Hyperbolic Parabolic Hyperbolic Hyperbolic Secondary Mirror Objective Mirror Ritchey-Cretien Multiple Mirror Telescopes • Aberration – any disturbance of the rays of a pencil of light such that they can no longer be brought to a sharp focus or form a clear image. • A telescope with only 1 curved mirror will always have aberrations • Spherical aberration • Coma • Astigmatism • Aberration correction – Multiple mirrors – Mirror Shapes • Parabolic • hyperbolic Spherical Aberration How a spherical mirror creates spherical aberration A parabolic mirror focus all light to a single point Coma Aberration Stars in the center of the field are not affected by coma, but the effect Spot diagram of a star grows stronger toward the edge of at the edge of the field the field. affected by coma Stars affected by pure coma are shaped like little comets (hence the name) pointed toward the center of the field. Astigmatism Two distinct focal surfaces exist Spot diagram of a star at the edge of the field affected by in the presence of astigmatism astigmatism • a Tangential focal surface •Sagittal focal surface Gregorian Telescope Final Focus hyperbolical secondary ellipsoidal primary • Two-mirror 3-reflection system. • Concave secondary mirror (S) reflects light back to the primary (P), which then forms the final focus through an opening on the secondary. • Correction of all three aberrations, spherical, coma and astigmatism • The only remaining aberration is relatively strong field curvature. Multiple Mirror Telescopes • parabolic mirrors – eliminates spherical aberration from spherical mirror • Two curved mirrors - – Ritchey–Chrétien telescope eliminates coma – Gregorian Eliminates spherical, coma, astigmatism • 3 curved mirrors – Anastigmat telescope also cancels astigmatism. – Korsch Corrects astigmatism and field curvature – Larger field of view than one or two mirrors Telescope Styles • Gregorian – Giant Magellan Telescope • Three-mirror anastigmat – European Extremely Large Telescope (EELT) – Large Synoptic Survey Telescope (LSST) • Ritchey-Chretien – Thirty Meter Telescope • Korsch – James Webb Space Telescope (JWST) • Radio Telescope – Deformable Fixed primary - FAST Segmented Mirror Telescopes • Segmented mirror – an array of smaller mirrors designed to act as segments of a single large curved mirror. – used as objectives for large reflecting telescopes. • mirror segments – have to be polished to a precise shape – actively aligned by a computer-controlled active optics • future large optical telescopes essentially all plan to use segmented mirrors. Existing Large Telescopes Ground Based Ground Based Telescope Size Comparsion i 2.5 m 6.5 m 10 m 24.5 m 30 m Human 39.3 m EXISTING NEW New Ground Based Telescopes Existing Ground Based Telescopes tennis Basketball court court New Large Ground Based Telescopes • 500 M Aperture Spherical Telescope (FAST) • 30 Meter Telescope • Giant Magellan Telescope • European Extremely Large Telescope (EELT) • Large Synoptic Survey Telescope (LSST) Electromagnetic Spectrum Interstellar Communication 10 GHz 1 GHz microwave FAST 300 300 telescope GHz MHz . Radio astronomy Study of celestial objects at radio frequencies • FAST telescope - 70 MHz – 3 GHz • Interstellar communication (1 GHz to 10 GHz) • radiation coming from the Milky Way • stars and galaxies • radio galaxies, quasars, pulsars • Cosmic microwave background radiation Electromagnetic Spectrum wavelength smaller diameter Telescope diameter Larger diameter for same resolving power Five Hundred Meter Aperture Spherical Telescope FAST China – Sept 25, 2016 Five Hundred Meter Aperture Spherical Telescope FAST • Features • Single dish - Can shift its 4450 reflectors for pointing and focusing • Collecting area – almost 450 basketball courts – world’s largest • Type – Deformable Fixed primary • Radio telescope - 70 MHz to 3.0 GHz • Potential to search for more strange objects • to better understand the origin of the universe • boost the global hunt for extraterrestrial life • 169% larger than next largest – Arecibo • Twice as sensitive Ground Based Telescopes Key Characteristics Telescope Operational Location Aperture Signal Primary (ft/m) type objective (visible, IR, etc FAST Sept 25, China 500 radio See below 2016 meters 500 M (30 soccer Aperture fields) Spherical Telescope Objectives • quasars • pulsars • gravitational waves • extra-terrestrial life Electromagnetic Spectrum Hubble Near UV, visible, Near IR James Webb Visible (orange) – Mid IR Infrared astronomy • detect objects such as planets • view highly red-shifted objects from the early days of the universe caused by expansion of the universe • penetrates dusty regions of space such as molecular clouds Galaxy motion vs Electromagnetic Spectrum Stationary galaxy No shift Receding galaxy Red shift Approaching galaxy Blue shift Planet rotation around star effect on Electromagnetic Spectrum Blue Shift Red Shift Locates exoplanets that cannot be seen visually Thirty Meter Telescope TMT International Observatory Hawaii ?? - 2022 Consortium: United States, Canada, Japan, China, and India. Alternate Locations: Baja California in Mexico, Canary Islands, Chile, India and China Thirty Meter Telescope Hawaii -?? - 2022 Thirty Meter Telescope • Features – Telescope style: Ritchey-Chretien – 9 x light gathering power of Keck telescope – Highest altitude of all proposed Extremely Large Telescopes (ELT’s) – Adaptive optics to correct image blur due to earth’s atmosphere • Delayed due to islanders Ground Based Telescopes Key Characteristics Telescope Operational Location Aperture Signal type Primary (ft/m) (visible, IR, objective etc 30 Meter 2022? Hawaii?? 30 meters Near See Telescope UltraViolet Altitude below 492 13,287 ft Visible segmented Blue mirrors Mid Canyon Infrared 4695 ft Objectives • More distant and fainter objects • exoplanets • black holes • clues left from early universe Giant Magellan Telescope GMT Consortium Chile 2021 1st light US-led in partnership with Australia, Brazil, and Korea, with Chile as the host country Giant Magellan Telescope • Features • Telescope style - Gregorian • Resolving power 10 x Hubble Space Telescope • Advanced adaptive optics to correct atmosphere distortion • Largest optical observatory in world at first light Ground Based Telescopes Key Characteristics Telescope Operational Location Aperture Signal type Primary Notes (ft/m) (visible, IR, objective etc Giant 1st light Chile 7 8.4m Visible See Magellan 2021 Mirrors light Altitude below Telescope 8225 ft Resolving Completion Near power of 2025 Palomar Infrared 25 meter San Diego primary 5617 ft • Objectives • It should be able to probe the first objects to emit light in the Universe •To investigate dark energy and dark matter •To identify potentially habitable planets European Extremely Large Telescope (EELT) European Southern Observatory (ESO) Chile – first light 2024 European Extremely Large Telescope (EELT) • Features • Telescope type •Three mirror anastigmat with two flat folding mirrors providing the adaptive optics. • Adaptive optics • to correct image blur due to earth’s atmosphere • Images 16 times sharper than Hubble • Will be largest “light” telescope in the world Ground Based Telescopes Key Characteristics Telescope Operational Location Aperture Signal type Primary Notes (ft/m) (visible, IR, objective etc European 2024 Atacama 39.3 Visible See Extremely desert meters light below Large Chile 798 Telescope Altitude hexagonal Near IR 10,039 ft segments • Objectives •Detailed studies of: • planets around other stars, • first galaxies in the Universe, • super-massive black holes, • nature of the Universe’s dark sector, • water and organic molecules in protoplanetary disks around other stars Large Synoptic Survey Telescope (LSST) LSST Corporation Chile
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