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Moon exploration beyond Apollo? Roger Angel Steward Observatory University of Arizona

Moon exploration beyond Apollo? Roger Angel Steward Observatory University of Arizona. Hazards and opportunities. Rocket technology has not advanced since Apollo. Each Apollo shot sent 50 tons toward the moon, landed ~ 20 tons Moon return now will have similar mass limit

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Moon exploration beyond Apollo? Roger Angel Steward Observatory University of Arizona

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  1. Moon exploration beyond Apollo?Roger AngelSteward ObservatoryUniversity of Arizona Hazards and opportunities

  2. Rocket technology has not advanced since Apollo • Each Apollo shot sent 50 tons toward the moon, landed ~ 20 tons • Moon return now will have similar mass limit • Probably less money available • May not survive if seen as WPA for aerospace industry and states with NASA Centers

  3. But imagination of US and world might be captured by: • goal of a sustained human outpost on Moon • Promise of accomplishing truly outstanding and exploration and science goals • Good science in 4 billion year old fossils • Light from early universe • Fossil record of bombardment and formation of life • Definitive imaging and atmospheric spectroscopy of other Earths

  4. Catch 22 (like space station) – if astronomers get enthusiastic, their budget could be used to help pay for a program and they become the tail of a very large dog that could die at any moment • But - HST uniquely showed potential of synergy of human exploration, science and public engagement • Moon exploration could do the same

  5. Look into the crystal ball Future of NASA

  6. Global warming

  7. Space program over next decades • As global warming crisis hits, likely to be increasing NASA focus on actively helping our own Earth • Research on other Earths and our moon may be deemphasized • Moon proposed as source of energy: • Source of He3 as clean nuclear fuel (Schmidt) • Base for space solar relayed via microwaves • Both are a stretch, even given moon infrastructure • Non-moon space endeavors more likely • Space solar power • L1 sunshade to cool Earth’

  8. Potential for space solar power • Current world electricity consumption ~ 1700 GW, 24 hours • 1/3 of total carbon emission • China adds 1 GW from coal every week • Next 50 yrs – additional 3000 GW • All need to be fossil free to prevent CO2 from more than doubling • new energy will sell for > $1 trillion/year • Commercial expenditure in space could be 10 to 100 times NASA budget to seize this

  9. Space solar from geostationary orbit could deliver 24 hr to the whole Earth Only these spacecraft shadowed, near equinox Geo orbit Earth Drawn to scale

  10. World grid could connect all ground sources for 24 hour power but superconducting cables my be too costly 1 is fantasy 5 is ready to go

  11. Space solar receiving stationsabout 4 required for whole US, 200 GW/station Avoids transmission line problem for Earth-based renewable energy

  12. Mankins study: single 30 km2 5 GW geosynchronous power satellite “bicycle fork” configuration Collector 6 km diameter photovoltaics, 330W/m2generate10 GW power transmitted as microwaves by 1 km phased array5 GW power received for distribution on earth

  13. NASA cost study • Six 5 GW satellites built over 30 years • 1 ground receiver per satellite • Lifetime = 40 years • Total mass 10,000 to 100,000 tons ? • Costs • Launch cost taken as $400/kg • Commercial cost-to-first-power - $30-40B • Constellation Installation Cost - $150B (-$5/W) • Average power cost – 2 cents/kW-hr

  14. Suppose half world need supplied by space solar • Fill-in for drop outs of ground based solar, wind • 1500 GW would require launch of 300 stations • Challenges • Launch cost • In-space construction

  15. R&D to seed such development could soon rise to 10% of NASA’s budget • Innovation in freight launch aimed at millions of tons • e.g. magnetic launch + ion propulsion • Or rocket costs for huge volume become closer to fuel cost, like air transportation • Space exploration to focus on large scale construction in space

  16. Transportation cost in large volume • For both automobiles and aircraft cost is few times fuel cost • For air transport • fuel mass ~ payload mass • Cost is ~$10/kg of payload • For rockets • fuel mass ~ 30x payload mass • High volume should bring cost down to ~ $300/kg

  17. A by-product of making carbon free energy could be a serious freight and space construction capability • Large free-flyer telescopes easy compared to a single 5 GW solar power station • sustained human outpost on the moon also manageable

  18. Greenhouse is basic lunar habitation element. What scale size? • Roof thickness of 20 m needed to hold 14 psi internal air pressure • Radiation protection also favors thick cover • ~100 m diameter thus appropriate unit size • sunshine reflected in through 1 m glass window at apex (O’Neill) • Several MW illumination entering • Heat removed to radiative exchanger outside • Water from lunar ice, then recycled

  19. 100 m lunar greenhouse at polewith O’Neill rotating parabolic mirror Dirt 20 m thick (20 psi). Build over temporary inflated balloon 1 m window from Earth AAAAAAAAAAAAAA

  20. Not much mass required from Earth to build greenhouses: • Bulldozer to operate at 1/6 g • Thick glass window 1 m diameter • Ultra-light 100 m solar reflector and rotator • Binder for lunar dirt of igloo • Heat exchanger • In-situ water and organic material extraction • Water recycling gear • seeds

  21. Moon with human presence ideal location for very large long-lived telescopes • HST parallel • continuing upgrading and maintenance • International science community builds over time

  22. with this infrastructure really unique astronomy would be possible • 100 m telescopes on the N and S poles • Diffraction limited • Example 1 - serious spectroscopy of other Earths • l/D = 10 mm/100 m = 20 mas • 2 l/D limit is 40 mas = 1 AU at 25 pc • Example 2 – 1st stars after dark ages and entire evolution of galaxies become observable Greenbank 100 m telescope

  23. 100 m fully steerable cold polar telescope • Similar scale of engineering to greenhouse • Adds to sense of purpose of outpost • Facesheet of 0.3m SiC segments 5 kg/m2 • 7000 m2 facesheet weighs 35 tons • Total moving mass maybe 1000 tons carbon fiber • Turn face down when dust being generated nearby. Free orbits don’t last long

  24. 100 m liquid mirror survey telescope a simpler precursor doable with far less infrastructure

  25. 20 m LMT as precursor precursor2 m as precursor3

  26. 3 years of funding from NASA NIAC Phase II now finishing A Deep Field Infrared Observatory Near the Lunar Pole

  27. Study team • Roger Angel University of Arizona • Ermanno Borra Laval University • Jim Burge University of Arizona • Daniel Eisenstein University of Arizona • Paul Hickson University of British Columbia • Ki Ma University of Houston • Ken Seddon Queen’s University Belfast • Suresh Sivanandam University of Arizona • Paul van Susante Colorado School of Mines • Pete Worden NASA Ames • Stan Dubyn Millennium Space systems • Vince Deno Millennium • Tomas Svitek Millennium

  28. NIAC organization • Roger Angel PI of Phase I • Pete Worden Phase II • Paul van Susante deputy PI • Major collaboration with separately funded Canadian team, Ermanno Borra (Laval) and Paul Hickson (UBC)

  29. advantages of the moon for astronomy • Potential for very long lived observatories • Lifetimes of ~ 100 years rather than ~ 10 • Big stable platform for many telescopes across the electromagnetic spectrum • Good for viewing along spin axis (near ecliptic poles) • Possibility of huge cryogenic liquid mirrors at poles • aperture of 20-100 meters diameter and capable of integrations of days to years with Hubble quality imaging • NASA exploration program could enable large construction

  30. Comparison with free space location • Common advantages with free space: • No atmospheric aberration or distortion • Strong radiative cooling possible for infrared observations (at poles) • Unique lunar advantages • Large permanent platform for many telescopes • Exploration initiative may result in infrastructure for large telescope assembly and maintenance • Gravity • Lunar disadvantage vs L2 • Powered descent needed for surface landing • dust might be a problem for optics or bearings • bearings and drives required for pointing and tracking (versus gyros for free space)

  31. No limit to size or resolution or cooling on the moon

  32. Scientific potential for LMT • Ultra-deep survey of early universe • formation of the first stars and their assembly into galaxies. • radiation of the first stars red shifter into infrared

  33. Galaxy Formation major goal • Since a liquid mirror telescope must point ~vertically, the interesting targets must be ones that have no closer examples elsewhere on the sky. • Galaxies at z>0.5: galaxies evolve and so there is no substitute for looking far away. • Special objects where the best example happens to fall in the field of view, e.g. the Large Magellenic Cloud • zodiacal sky background is lowest in the 2-5 µm spectral region, allowing for extremely deep images, to be first explored by JWST

  34. A Rough History of Galaxies • First stars (z~20) • First galaxies (z~15) • Larger galaxies & reionization (z~10) • Current frontier (z~6) • Peak epoch of formation (z~2-3) • Growth of hot halos (z~1) • Shut-off and cluster formation (z<0.7)

  35. Opportunity • A liquid mirror telescope on the moon offers the opportunity to go super-deep in the IR. • This is well matched to the study of very-high redshift galaxies and perhaps even the first stars. • Must cover down to 1.5 mm or bluer to see Ly a dropout. • Probably need to reach at least to 4 mm. • First objects are very faint: 10 picoJy or less in the continuum. • 20-meter telescope could reach earlygalaxies 100 times smaller than JWST. • Should consider spectroscopy of z>10 "JWST" galaxies (few nanoJy).

  36. Why infrared is required – universe opaque below 90 nm wavelength • We'd like to study galaxies in the rest-frame optical and UV, say 0.12–1 micron, but the light from distant galaxies has its wavelength stretched by the expansion of the Universe. • At z>7, all of the galaxy's light is in the IR. • No light passes shortward of 0.1216(1+z) mm. Labbe et al. (2006)

  37. IR limit vs mirror temperature Maximum wavelength for which observations will be limited by zodiacal sky background, as a function of mirror surface temperature. Emissivity of 1% by the spinning liquid mirror is assumed Sky background includes both thermal emission and sunlight scattered from zodiacal particles. Target temperature ≤ 150K

  38. Need for very large aperture • JWST will be 6.5 m diameter D, cooled infrared telescope at L2, with longest integrations of t~ 1 month • Sensitivity as D2√t: compared to JWST • 20 m for 1 year will be 30 times more sensitive • 100 m would be 1000 times more sensitive • Virtually impossible by rigid mirror technology

  39. Diffraction limit advantage20 m at 5 mm = 2.4 m at .6 mm

  40. Designs of increasing size

  41. Cold reflective liquid surface? • Critical issue • Mercury frozen at 150K • Need to evaporate metal on cryogenic dielectric liquid • Will this work?

  42. Early try - mirror surface of silver on polypropylene glycol deposited by Borra

  43. ionic liquids - Prof Ken Seddon • Ionic fluids preferred • Low vapor pressure • Currently low melting T ~ 170K • 150K should be easily reachable • Very active field of research • Like liquid salt, except anions and cations big and organic • Application for vapor free solvents in chemical manufacture (Change physical properties by changing anions and cations: huge number of possible liquids (Billions!)

  44. Ionic liquids take silver wellBorra results for Ag on ECOENG212 Best reflectivity in near IR for Ag, relative to Hg

  45. Interferometry (P-V = 0.04 microns)

  46. Superconducting bearing- not disturbed by dust - model with spinning liquid mirror on a superconducting bearing by Professor Ma. (a) shows the bearing, with a nitrogen-cooled YBCO superconductor in the upper cup, and a neodymium magnet in the inverted cup below. The gap is ~ 3 mm. Hanging on 3 strings below (b) is a 20 cm spinning dish of black soy sauce with ~ 8” focal length. The lettering is the reflection of a screen above

  47. Will dust be a problem? • Dust levitated ~ 1 meter by electrostatic force, well established from surface measurements • Dust to ~ 10 km? • Atmospheric horizon glow seen occasionally from Apollo command module • Not confirmed by Clementine

  48. Sketch by Apollo 17 captain Cernan

  49. Sivanandam planning ground-based adaptive optics imaging • Require guide star for wavefront measurements. Use high illuminated peaks on the dark side • Image small 30” region above the polar surface in the 1.6 micron band and of the polar region itself in 5 micron band. • 100s of meter resolution imaging

  50. Location – near lunar pole • Zenith view fixed on sky along spin axis • Deep integration with no steering • Strong radiative cooling for high infrared sensitivity possible • Use cylindrical radiation shield • Shields from sun always on horizon

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