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1006 angel[1]

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Clifford Stone
Clifford Stone

This document discusses plans for the NIAC Atlanta, a proposed deep field infrared observatory near the lunar pole. It would utilize a large liquid mirror telescope design to allow for very large apertures at low cost. Key points discussed include the scientific goals of an ultradeep field survey, advantages of the lunar location, challenges like dust, and plans for a potential precursor site survey mission using commercial lunar landers to assess suitable locations and environmental conditions.

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NIAC Atlanta A deep field infrared observatory near the lunar polar Roger Angel and Pete Worden March 15 2005
personnel and areas of expertise Roger Angel U. Arizona PI Design of space and ground telescopes ErmannoBorra U. Laval Unpaid Co-I Liquid mirror telescopes Paul Hickson UBC Unpaid CoI Science, liquid mirror telescopes K. Ma U Houston Co-I Superconducting bearings Pete Worden U Arizona Co-I Lunar logistics, site survey mission Gil Moretto National Solar Obs consultant Optical design Suresh Sivanandam U Arizona grad student Liquid mirrors, lunar pole sites, choice of pole
Why an observatory on the Moon? •Advantages common to free space: –No atmospheric aberration or distortion –Strong radiativecooling possible for infrared spectrum (at poles) •Unique lunar advantages –Large stable platform for many telescopes –Exploration initiative may result in infrastructure for large telescope assembly and maintainance –Gravity •Lunar disadvantage vsL2 –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)
Background light in space •Lunar sky is ~ 106times fainter than Earth’s at 10 um •-> 1000 times fainter detection limitSpace Telescope Science Institute
Ultradeepfield observatory can take best advantage of moon •deep extragalactic fields are a goldmine for understanding origins of universe and cosmology –Hubble, ground optical and radio, Spitzer, Chandra •Any direction clear of absorption by our galaxy is good •A suite of telescopes co-pointed along moon’s spin axis –Simple telescopes long exposure with no tracking –could provide ultimate deep field, across the electromagnetic spectrum •Infrared especially important to see first, highly redshiftedstars, galaxies and forming quasars –Far ultraviolet Lyman limit shifted from 912 A to 2 microns at z=20 •Interferometers to look out on spin axis also require no moving parts, greatly simplified –High resolution at longer IR and sub-millimeter wavelengths
1006 angel[1]
High-redshift galaxiesJWST10σ105sLLMT
Galaxy evolution (Spitzer 0.85 m cold telescope) •Assembly of galaxies•Formation of the Hubble sequence•Role of interactions and starbursts•Development of AGN•Evolution of disks•Role of the environmentAdvantages of LLMT: Better sensitivityBetter resolution 3.5 x 3.5 arcmin Spitzer/IRAC images (Barmbyet al 2004)
Need for very large aperture •Lunar telescope would go to the next level of sensitivity, beyond HST and JWST •JWST will be 6.5 m diameter D, cooled infrared telescope at L2, with longest integrations of t~ 1 month •Lunar telescope should have D > 20 m and integrate for many years •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
Liquid mirror telescope •way to get very large aperture at low cost –Proven on ground to 6 m –Borraand Hicksonin Canada •Current ground status •Lunar location at poles –Superconducting bearing –Reflective coating a cryogenic liquid –Optical design for long integration
The 6 m diameter mercury liquid mirror of the LZT (courtesy P. Hickson)
6 m performance (near Vancouver!) •Seeing-limited (FWHM ~ 1.4”) •RAB~ 22.5 in 100 sec •30 sq degrees every clear night •Testbedfor future projects
1006 angel[1]
Location at lunar pole •Zenith view fixed on sky along spin axis •Deep integration with no steering •Strong radiativecooling for high infrared sensitivity possible –Use cylindrical radiation shield –Shields from sun always on horizon
Artist’s impression of the 20 m telescope. The secondary mirroris erected by extending the six telescoping legs, and the sunshieldby inflation. The scientific instruments are below the bearing pier, shielded by lunar soil. ( Tom Connors)
First concept for superconducting levitation bearing
Suspension alternate(Ma)
HTS PM dish drive & control
“toy” system and scaling •Bearing –Superconductor diameter, 1 in., height, 0.5 in. 55g –Permanent magnet, 0.875 in., height 0.5 in. 30 g –Gap of a few mm, different each time •Suspended mirror assembly –Suspension length 12.75 in. –Weight 180g –The speed of rotation 40 RPM to 60 RPM –Liquid surface 6” diameter, f/1 •Scaling –increasing all dimensions increases bearing mass as cube, load as square –simple 30” scale up model would weigh 2.5 tons and lift 1 ton mass on the moon –Optimization could improve high mass ratio by 10 x
First success in metallizingliquid Polypropelyneglycol with vacuum deposited tin (Borra)
Location and optical design •Wide field imaging best close to zenith •Only at pole is zenith view constant –Location very close to pole strongly favored •Moon’s spin axis precession –18 year period –1.55 degree tilt angle •Axis point moves at 1/2º/year in 3ºdiacircle •½degree field will allow for 1 year integrations •Another possibility is to make optics to track ecliptic pole at 1.55 field angle –Small field correctable, but always in view
3-mirror design for 1.55ºannular field Field angle 1.43 –1.67° Encircled energy at 2.5 μm (1.7 m)
1.7 m precursor details •Diffraction limited resolution –0.3 arcsec at 2.5 μm –0.6 arcsec at 5 μm •3 degree annular field, 14 minute wide –2 square degrees –4096 x 0.2 arcsec pixels wide –30 square degrees covered during 18 yr precession •18 year mission –average 2 years integration on typical field point –~2 weeks on each of 40 differently filtered detectors in ring –Limiting sensitivity as D2√t, 25x Spitzer in same broad bands (4 of the 40 slots) i.e. 20 nJyat 3.5 μm.
Possible sequence •Micro site survey •1.7 m robotic wide field survey –Complements Spitzer and JWST •20 m –Follow up spectroscopy of JWST candidates •100 m –Completely unique
Lunar Liquid Mirror Telescope Operational Considerations S. Pete Worden Steward Observatory The University of Arizona The Ides of March, 2005
Site Selection: North or South Pole Sky Considerations: •Dust contamination/atmosphere [Both?] –Circumstantial evidence supports dust levitation and dust atmosphere. –Dust may contaminate optics, introduce stray light, and increase sky background. •Stellar field contamination [South?] –Large MagellanicCloud (LMC) contaminates South pole sky view. Note: [?] indicates we need to investigate that location further.
Operational Considerations •Power -Site illumination [North?] –North pole winter illumination not known. –South pole illumination mapped by Clementine –Desire “Peak of Eternal Light” –series of points in permanent sunlight •Communications –Either need earth line of sight or orbiting relay •Positioning –Precise map of surroundings needed •Maintenance •Site Survey
DUSTSketch by Apollo 17 astronaut, Capt. Cernan. •Streamers observed in lunar orbit at a 100 km altitude while approaching the terminator from the dark side. •Streamers interpreted to be similar to those observed terrestrially as sun sets over irregular horizon. •Possible evidence for lunar dust atmosphere extending beyond orbital module’s altitude or local scattering layer since streamers are generated by forward-scattered light. •No mechanism that generates a high-altitude lunar dust atmosphere is known. 5 seconds before sunrise
More on DUST •Observed horizon glow from Surveyor 7 images. –Modeled to be low-level levitation (10-30 cm) of micron-sized dust particles powered by photoelectric charging of lunar surface by solar UV/X-ray photons. •Anomalous Lunokhod-II sky brightness measurements. –Observed over-brightness correlated with solar zenith angle. •Anomalous brightness in solar corona observed by astronauts just after sunset. –Hypothesized to be forward-scattered light. But conditions may be fine for proposed work: •Solar flux in polar regions much smaller. •Lunar retro-reflectors have shown little degradation. Require in-situ observations for confirmation.
The circle shows the 6°diameter field accessible to the lunar zenith pointing telescope. Ultraviolet image from the Moon, John Young & Charles Duke
Stellar Contamination at ecliptic polesPOSS2 Red Images (12’by 12’FOV, 2”resolution, Rlimit= 21): South pole viewNorth pole viewMay be confusion-limited by LMC stars at the South pole.
Can we resolve LMC stars? HST ACS HRC F606W Image of field near the south ecliptic pole. (29”by 26”FOV, diffraction-limited 0.06”resolution) •To first order, HST can resolve LMC stars, though this image is not nearly as deep as will be obtained from moon. •The lunar pole telescope will have higher diffraction limited resolution in infrared than this visible image•Suresh is modeling the faint-end of the LMC stellar population using a LMC star catalogue. •He will determine the average separation of stars to deep field magnitude limit
1006 angel[1]
North Pole Illumination: SMART-1SMART-1 image extending close to lunar North pole. •ESA’sSMART-1 lunar probe has made observations of the North pole during January 2005, the middle of the lunar winter in the northern hemisphere. •We will analyze the data in the near future to determine if there are peaks of eternal light in the North pole as seen in the South pole.
Power: South Pole Illumination in Winter
Power: South Pole Illumination in Winter
Communications •Store and Forward via polar relay •Direct line of sight –need to determine horizon features of selected sites –Is the earth permanently in view?
Numerous Lunar Polar Orbiters Planned –Communications and Situation Awareness
Tele-robotics vsAutonomous Operation
Site Survey Proposal •Determine Sky Brightness in the IR and Visible •Determine Dust Environment –Expose Liquid Test Cell •Small Fisheye Cameras – for Visible •Cooled IR Zenith Camera Fisheye Images from the MMT, Mt Hopkins, AZ
Commercial Lunar Lander – Millennium Space Design SubsystemCBE Mass (kg) Structure22.80Communications4.66Power11.18Attitude Control1.69Avionics1.55Propulsion39.62Thermal2.10Mechanisms3.20Payload5.30Propellant533.50Launch Vehicle Adapter2.11
Horizon –Zenith Fisheye CamerasRadiativelycooled 5μ skybrightnesssensor Mirror Dust Collector- MonitorCutaway viewOf IR Sensor NOTIONAL LUNAR LANDER PAYLOAD LAYOUT 5-10 kg goal
New Launch Options –Low Cost •Space-X FALCON •Falcon I –500kg to LEO -$5.9M •Falcon V –5000kg to LEO -$15M •“BFR” --TBD
CONCLUSIONS •Lunar polar telescope sites appealing – issues to be resolved –Dust –Solar and Terrestrial access –Deepest Fields Possible? N vsS Pole •Low Cost Survey Mission Possible to resolve issues –Definition Needed •As in Real Estate –LOCATION, LOCATION, LOCATION!

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1006 angel[1]

  • 1. NIAC Atlanta A deep field infrared observatory near the lunar polar Roger Angel and Pete Worden March 15 2005
  • 2. personnel and areas of expertise Roger Angel U. Arizona PI Design of space and ground telescopes ErmannoBorra U. Laval Unpaid Co-I Liquid mirror telescopes Paul Hickson UBC Unpaid CoI Science, liquid mirror telescopes K. Ma U Houston Co-I Superconducting bearings Pete Worden U Arizona Co-I Lunar logistics, site survey mission Gil Moretto National Solar Obs consultant Optical design Suresh Sivanandam U Arizona grad student Liquid mirrors, lunar pole sites, choice of pole
  • 3. Why an observatory on the Moon? •Advantages common to free space: –No atmospheric aberration or distortion –Strong radiativecooling possible for infrared spectrum (at poles) •Unique lunar advantages –Large stable platform for many telescopes –Exploration initiative may result in infrastructure for large telescope assembly and maintainance –Gravity •Lunar disadvantage vsL2 –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)
  • 4. Background light in space •Lunar sky is ~ 106times fainter than Earth’s at 10 um •-> 1000 times fainter detection limitSpace Telescope Science Institute
  • 5. Ultradeepfield observatory can take best advantage of moon •deep extragalactic fields are a goldmine for understanding origins of universe and cosmology –Hubble, ground optical and radio, Spitzer, Chandra •Any direction clear of absorption by our galaxy is good •A suite of telescopes co-pointed along moon’s spin axis –Simple telescopes long exposure with no tracking –could provide ultimate deep field, across the electromagnetic spectrum •Infrared especially important to see first, highly redshiftedstars, galaxies and forming quasars –Far ultraviolet Lyman limit shifted from 912 A to 2 microns at z=20 •Interferometers to look out on spin axis also require no moving parts, greatly simplified –High resolution at longer IR and sub-millimeter wavelengths
  • 8. Galaxy evolution (Spitzer 0.85 m cold telescope) •Assembly of galaxies•Formation of the Hubble sequence•Role of interactions and starbursts•Development of AGN•Evolution of disks•Role of the environmentAdvantages of LLMT: Better sensitivityBetter resolution 3.5 x 3.5 arcmin Spitzer/IRAC images (Barmbyet al 2004)
  • 9. Need for very large aperture •Lunar telescope would go to the next level of sensitivity, beyond HST and JWST •JWST will be 6.5 m diameter D, cooled infrared telescope at L2, with longest integrations of t~ 1 month •Lunar telescope should have D > 20 m and integrate for many years •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
  • 10. Liquid mirror telescope •way to get very large aperture at low cost –Proven on ground to 6 m –Borraand Hicksonin Canada •Current ground status •Lunar location at poles –Superconducting bearing –Reflective coating a cryogenic liquid –Optical design for long integration
  • 11. The 6 m diameter mercury liquid mirror of the LZT (courtesy P. Hickson)
  • 12. 6 m performance (near Vancouver!) •Seeing-limited (FWHM ~ 1.4”) •RAB~ 22.5 in 100 sec •30 sq degrees every clear night •Testbedfor future projects
  • 14. Location at lunar pole •Zenith view fixed on sky along spin axis •Deep integration with no steering •Strong radiativecooling for high infrared sensitivity possible –Use cylindrical radiation shield –Shields from sun always on horizon
  • 15. Artist’s impression of the 20 m telescope. The secondary mirroris erected by extending the six telescoping legs, and the sunshieldby inflation. The scientific instruments are below the bearing pier, shielded by lunar soil. ( Tom Connors)
  • 16. First concept for superconducting levitation bearing
  • 18. HTS PM dish drive & control
  • 19. “toy” system and scaling •Bearing –Superconductor diameter, 1 in., height, 0.5 in. 55g –Permanent magnet, 0.875 in., height 0.5 in. 30 g –Gap of a few mm, different each time •Suspended mirror assembly –Suspension length 12.75 in. –Weight 180g –The speed of rotation 40 RPM to 60 RPM –Liquid surface 6” diameter, f/1 •Scaling –increasing all dimensions increases bearing mass as cube, load as square –simple 30” scale up model would weigh 2.5 tons and lift 1 ton mass on the moon –Optimization could improve high mass ratio by 10 x
  • 20. First success in metallizingliquid Polypropelyneglycol with vacuum deposited tin (Borra)
  • 21. Location and optical design •Wide field imaging best close to zenith •Only at pole is zenith view constant –Location very close to pole strongly favored •Moon’s spin axis precession –18 year period –1.55 degree tilt angle •Axis point moves at 1/2º/year in 3ºdiacircle •½degree field will allow for 1 year integrations •Another possibility is to make optics to track ecliptic pole at 1.55 field angle –Small field correctable, but always in view
  • 22. 3-mirror design for 1.55ºannular field Field angle 1.43 –1.67° Encircled energy at 2.5 μm (1.7 m)
  • 23. 1.7 m precursor details •Diffraction limited resolution –0.3 arcsec at 2.5 μm –0.6 arcsec at 5 μm •3 degree annular field, 14 minute wide –2 square degrees –4096 x 0.2 arcsec pixels wide –30 square degrees covered during 18 yr precession •18 year mission –average 2 years integration on typical field point –~2 weeks on each of 40 differently filtered detectors in ring –Limiting sensitivity as D2√t, 25x Spitzer in same broad bands (4 of the 40 slots) i.e. 20 nJyat 3.5 μm.
  • 24. Possible sequence •Micro site survey •1.7 m robotic wide field survey –Complements Spitzer and JWST •20 m –Follow up spectroscopy of JWST candidates •100 m –Completely unique
  • 25. Lunar Liquid Mirror Telescope Operational Considerations S. Pete Worden Steward Observatory The University of Arizona The Ides of March, 2005
  • 26. Site Selection: North or South Pole Sky Considerations: •Dust contamination/atmosphere [Both?] –Circumstantial evidence supports dust levitation and dust atmosphere. –Dust may contaminate optics, introduce stray light, and increase sky background. •Stellar field contamination [South?] –Large MagellanicCloud (LMC) contaminates South pole sky view. Note: [?] indicates we need to investigate that location further.
  • 27. Operational Considerations •Power -Site illumination [North?] –North pole winter illumination not known. –South pole illumination mapped by Clementine –Desire “Peak of Eternal Light” –series of points in permanent sunlight •Communications –Either need earth line of sight or orbiting relay •Positioning –Precise map of surroundings needed •Maintenance •Site Survey
  • 28. DUSTSketch by Apollo 17 astronaut, Capt. Cernan. •Streamers observed in lunar orbit at a 100 km altitude while approaching the terminator from the dark side. •Streamers interpreted to be similar to those observed terrestrially as sun sets over irregular horizon. •Possible evidence for lunar dust atmosphere extending beyond orbital module’s altitude or local scattering layer since streamers are generated by forward-scattered light. •No mechanism that generates a high-altitude lunar dust atmosphere is known. 5 seconds before sunrise
  • 29. More on DUST •Observed horizon glow from Surveyor 7 images. –Modeled to be low-level levitation (10-30 cm) of micron-sized dust particles powered by photoelectric charging of lunar surface by solar UV/X-ray photons. •Anomalous Lunokhod-II sky brightness measurements. –Observed over-brightness correlated with solar zenith angle. •Anomalous brightness in solar corona observed by astronauts just after sunset. –Hypothesized to be forward-scattered light. But conditions may be fine for proposed work: •Solar flux in polar regions much smaller. •Lunar retro-reflectors have shown little degradation. Require in-situ observations for confirmation.
  • 30. The circle shows the 6°diameter field accessible to the lunar zenith pointing telescope. Ultraviolet image from the Moon, John Young & Charles Duke
  • 31. Stellar Contamination at ecliptic polesPOSS2 Red Images (12’by 12’FOV, 2”resolution, Rlimit= 21): South pole viewNorth pole viewMay be confusion-limited by LMC stars at the South pole.
  • 32. Can we resolve LMC stars? HST ACS HRC F606W Image of field near the south ecliptic pole. (29”by 26”FOV, diffraction-limited 0.06”resolution) •To first order, HST can resolve LMC stars, though this image is not nearly as deep as will be obtained from moon. •The lunar pole telescope will have higher diffraction limited resolution in infrared than this visible image•Suresh is modeling the faint-end of the LMC stellar population using a LMC star catalogue. •He will determine the average separation of stars to deep field magnitude limit
  • 34. North Pole Illumination: SMART-1SMART-1 image extending close to lunar North pole. •ESA’sSMART-1 lunar probe has made observations of the North pole during January 2005, the middle of the lunar winter in the northern hemisphere. •We will analyze the data in the near future to determine if there are peaks of eternal light in the North pole as seen in the South pole.
  • 35. Power: South Pole Illumination in Winter
  • 36. Power: South Pole Illumination in Winter
  • 37. Communications •Store and Forward via polar relay •Direct line of sight –need to determine horizon features of selected sites –Is the earth permanently in view?
  • 38. Numerous Lunar Polar Orbiters Planned –Communications and Situation Awareness
  • 40. Site Survey Proposal •Determine Sky Brightness in the IR and Visible •Determine Dust Environment –Expose Liquid Test Cell •Small Fisheye Cameras – for Visible •Cooled IR Zenith Camera Fisheye Images from the MMT, Mt Hopkins, AZ
  • 41. Commercial Lunar Lander – Millennium Space Design SubsystemCBE Mass (kg) Structure22.80Communications4.66Power11.18Attitude Control1.69Avionics1.55Propulsion39.62Thermal2.10Mechanisms3.20Payload5.30Propellant533.50Launch Vehicle Adapter2.11
  • 42. Horizon –Zenith Fisheye CamerasRadiativelycooled 5μ skybrightnesssensor Mirror Dust Collector- MonitorCutaway viewOf IR Sensor NOTIONAL LUNAR LANDER PAYLOAD LAYOUT 5-10 kg goal
  • 43. New Launch Options –Low Cost •Space-X FALCON •Falcon I –500kg to LEO -$5.9M •Falcon V –5000kg to LEO -$15M •“BFR” --TBD
  • 44. CONCLUSIONS •Lunar polar telescope sites appealing – issues to be resolved –Dust –Solar and Terrestrial access –Deepest Fields Possible? N vsS Pole •Low Cost Survey Mission Possible to resolve issues –Definition Needed •As in Real Estate –LOCATION, LOCATION, LOCATION!