Next Generation Extremely Large Telescopes

1. Next Generation Extremely Large Telescopes

2. 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

3. 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

4. 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

5. 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

6. 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

7. Resolution Low resolution High resolution

8. Telescope Styles • Refracting • Lenses • Reflecting • Mirrors • Multiple Mirror • Aberration Correction

9. Refracting telescope: Objective lens

10. Cassegrain Reflecting telescope Hyperbolic Parabolic Hyperbolic Objective Mirror Hyperbolic Secondary Mirror Ritchey-Cretien

11. 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

12. Spherical Aberration How a spherical mirror creates spherical aberration A parabolic mirror focus all light to a single point

13. Coma Aberration Stars in the center of the field are not affected by coma, but the effect grows stronger toward the edge of the field.  Stars affected by pure coma are shaped like little comets (hence the name) pointed toward the center of the field.  Spot diagram of a star at the edge of the field affected by coma

14. Astigmatism Spot diagram of a star at the edge of the field affected by astigmatism • Two distinct focal surfaces exist in the presence of astigmatism • a Tangential focal surface • Sagittal focal surface

15. Gregorian Telescope • Two-mirror3-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. Final Focus hyperbolical secondary ellipsoidal primary

16. Multiple Mirror Telescopes • parabolic mirrors • eliminates spherical aberrationfrom spherical mirror • Two curved mirrors - • Ritchey–Chrétien telescope eliminates coma • Gregorian Eliminates spherical, coma, astigmatism • 3 curved mirrors • Anastigmat telescopealsocancels astigmatism. • Korsch Correctsastigmatism and field curvature • Larger field of view than one or two mirrors

17. 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

18. 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.

19. Existing Large Telescopes Ground Based

20. 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

21. New Ground Based Telescopes Existing Ground Based Telescopes Basketball court tennis court

22. 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)

23. Electromagnetic Spectrum Interstellar Communication 10 GHz 1 GHz FAST telescope microwave 300 300 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

24. Electromagnetic Spectrum wavelength Larger diameter Telescope diameter for same resolving power smallerdiameter

25. Five Hundred Meter Aperture Spherical Telescope FAST China – Sept 25, 2016

26. 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

27. Ground Based Telescopes Key Characteristics See below • Objectives • quasars • pulsars • gravitational waves • extra-terrestrial life

28. 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

29. Galaxy motion vs Electromagnetic Spectrum Stationary galaxy No shift Receding galaxy Red shift Approaching galaxy Blue shift

30. Planet rotation around star effect on Electromagnetic Spectrum Blue Shift Red Shift • Locates exoplanets that cannot be seen visually

31. Thirty Meter TelescopeTMT International Observatory Hawaii ?? - 2022 Consortium: United States, Canada, Japan, China, and India. Alternate Locations: Baja California in Mexico, Canary Islands, Chile, India and China

32. Thirty Meter TelescopeHawaii -?? - 2022

33. 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

34. Ground Based Telescopes Key Characteristics See below • Objectives • More distant and fainter objects • exoplanets • black holes • clues left from early universe

35. Giant Magellan TelescopeGMT ConsortiumChile 2021 1st light US-led in partnership with Australia, Brazil, and Korea, with Chile as the host country

36. 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

37. Ground Based Telescopes Key Characteristics See below • 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

38. European Extremely Large Telescope (EELT)European Southern Observatory (ESO)Chile – first light 2024

39. 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

40. Ground Based Telescopes Key Characteristics See below • 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

41. Large Synoptic Survey Telescope (LSST)LSST CorporationChile – first light 2019

42. Large Synoptic Survey Telescope (LSST) • Features • Telescope type • three-mirror anastigmat • Advance in speed – not size • Photograph entire sky every 3 nights • movies

43. Ground Based Telescopes Key Characteristics See below • Objectives • Measuring weak gravitational lensing in the deep sky to detect signatures of dark energy and dark matter • Mapping small objects in the Solar System, particularly near-Earth asteroids and Kuiper belt objects • Detecting transient optical events such as novae and supernovae • Mapping the Milky Way

44. FAST China 30 Meter Telescope Hawaii ?? EELT GIANT MAGELLAN LSST Chile

45. Existing Space Based Telescopes New Space Based Telescopes Hubble basketball court tennis court

46. Space Telescope Orbit Location Earth • Lagrange points, L-points, or libration points) • positions in an orbital configuration of two large bodies where a small object affected only by gravitycan maintain a stable position relative to the two large bodies.

47. New Large Space Telescopes • James Webb Space Telescope • Advanced Technology Larger Aperture Space Telescope (ATLAST) 3. Wide Field Infrared Survey Telescope (WFIRST)

48. James Webb Space Telescope (JWST)NASALaunch – Oct 2018

49. James Webb Space Telescope • Features • Type Korsch - Correctsastigmatism and field curvature • Unprecedented resolution and sensitivity from : • long-wavelength (orange – red) visible light through near-infrared to the mid-infrared • 3 X Hubble IR spectrum • Aperture 6.5 m vs Hubble 2.4 m • Can View • high-redshift objectshave their visible emissions shifted into the infrared, • cold objects such as debris disks andplanetsemit most strongly in the infrared • this band is difficult to study from the ground or by existing space telescopes such as Hubble.

50. Space Based Telescopes Key Characteristics See below • Objectives • Observing some of the most distant objects in the universe • Very first stars • Epoch of reionization, formation of the first galaxies • Understanding the formation of stars and planets • Imaging molecular clouds and star-forming clusters • Studying the debris disks around stars • Direct imaging of exoplanets • Spectroscopic examination of planetary transits