Large Lunar Telescopes

1. Large Lunar Telescopes Human aided construction of large lunar telescopes Final Presentation

2. Project members • Dr. Michael Duke (P.I. , CSM) • Dr. Robert King (advisor, CSM) • Dr. Jeff van Cleve (astronomer, Ball Aerospace) • Yuki D. Takahashi (grad. student, UC Berkeley) • Paul J. van Susante (grad. student, CSM)

3. Table of Contents • Task 1 : Determine types of lunar astronomical observations / instruments • Task 2 : Environmental considerations • Task 3 : Design approach for a telescope • Task 4 : Define construction steps • Task 5 : Determine role of humans • Task 6 : Characterize cost factors • Synergies

4. Task 1 description • Identify astronomical observations that takes advantage of the moon. • Define requirements • Size • Stability • Other factors in siting and construction process • Assemble references and literature on the topic (not in presentation)

5. Types of observations • Objectives in astronomy after ~2020: • Discover extrasolar life signatures. (Spectroscopic studies of extrasolar planets found by the TPF to detect any chemical dis-equilibrium.) • Discover and image the earliest galaxies in formation. (Resolving objects far beyond any deep fields taken by the JWST.) • Why Infrared ? • Light from the earliest galaxies in formation is red-shifted to infrared. • Stars and planets form in regions surrounded by obscuring dust. • Relative brightness between a planet and its host star is typically more favorable in the infrared (~1:106) than in the visible (~1:109). • Molecular signatures of almost all chemistry important to life. • Order of magnitude improvement over planned leading telescopes in 2020.

6. Why the moon ? • Stable platform: • Techniques for finding life on extrasolar planets require extraordinary stability. • May be feasible only on the Moon (difficulty in formation flying and vibration control in free space). • Thermal stability: • These techniques also require very stable thermal condition. • Permanently dark floors of lunar polar craters (probably the most thermally stable locations). • In free space, temperature on the mirror varies depending on its orientation with respect to the sun shield. • Lower risk: • Construction is much less risky on a solid platform with gravity than in free space where everything needs to be kept track of (e.g. by tethering). • Accessibility from a nearby lunar base allows service / upgrades for never-ending contribution to astronomy.

7. Leading telescopes in 2020 • SMM (E) ALMA (2010-) 64x 24 m (12 km) • FIR single-aperture (S) SAFIR (2015-) 8 m • FIR interferometer (S) SPECS (2015-) 3x 4 m (1 km) • MIR single-aperture (S) JWST (2010-2020) 6.5 m • MIR interferometer (S) TPF/Darwin (2015-) 5x 3 m (40-1000 m) • NIR-V (E) OWL (2020-) 100 m • V-UV (S) SUVO (2015-) 8 m (E)=earth based (S)=space based

8. Limitations of TPF/JWST • Unable to find life signatures on extrasolar planets (requires long stable exposures). • Extreme difficulties in long baseline interferometry (100s of meters). • No maintenance possible (or very complex) • Limited lifetime (5-10 years) • Time-consuming to reposition (~2 hours for TPF) • Long down times • Thermal gradients (degrade w/ meteoroids, propellants)

9. Requirements • Stability & Vibrations • Coronograph ~ 1 milli arc sec pointing stability • Nulling interferometer ~ 1/1000th of wavelength beam path error (10s of nanometers) • Pointing and continuous tracking during observation (Alt-Azimuth) • Low downtime (high observation efficiency) • Adaptive optics (3 actuators / m2)

10. Requirements • Wavelength : 5-25 micron (MIR) • Temperature • Goal : telescope 35 K (17 micron optimized) • Wavelength * temp (K) < 600 • Thermal gradients across telescope < 10 K for T<80K • Instruments actively cooled to 4 –10 K • Volume : about 50 m3 for instruments • Size : 25m single aperture

11. Requirements • Site selection… • Permanently shadowed crater • Close to sunlit areas for power generation (preferably lit >50% of the lunar day) • See as much of the universe as possible • Half the universe is not enough??  Earth • Targets pretty uniformly distributed • Galactic Center in view if possible

12. Lunar South Pole Margot et. al DEM of the Lunar South Pole White is +6.5 km black is – 9 km or unknown Permanent shadow

13. Task 2 description • Analyze the environmental considerations that could place limits on the operation of these telescopes. • Determine if these limits are critical to scientific investigations. • Identify countermeasures or design criteria to mitigate these limitations.

14. Environmental considerations • “Gravity is the enemy of large telescopes” ?? • Not necessarily : • Deformation of mirror support structure and mirrors  predictable and reproducible • Vibration damping  much easier in gravity • Pointing and tracking  much easier in gravity • Construction is much safer / more reliable in gravity • 1/6 G is much easier than 1 G

15. Environmental considerations • Temperature in permanently shadowed crater • Variations? (small (10’s of K over month), slow and mostly indirect) • Temperature effect on telescope? (not known, estimated to be small, more information, simulation and modeling is required) • Temperature of instruments/detectors (actively cooled so should be no problem)(point of attention vibrations) • Extreme cold operations (should not be a problem for operation of telescope, but could pose problem for construction temperature controlled storage) • Presence of water in cold traps (vapor, deposits, mainly during construction)

16. Environmental considerations • Temperature effect mitigations • Possible thermo electric coolers for mirror? • Build shield against scattered sun rays and Earth shine • Always look away from hot spots on crater rim • Temp variations between 30-80 K in itself not problematic for observations • Variations are slow (effects vary with T4) • Differences over mirror should be very small (<1K)

17. Environmental considerations • Dust • Very fine (avg. size 70 micron) • Very abrasive (lack of erosion processes to round particles) • Electro statically charged (but not moving due to UV) • Very important for coronagraph • Size of grains close to wavelength

18. Environmental considerations • Dust mitigation measures • During construction • No part will ever touch the ground or other contaminated surfaces • Transportation will happen on prepared ground • Slow movement and dust spread mitigation (like good fenders) • Landing and launching will happen > 10 km away • Crater rim as natural extra shield • Sequence of events (sensitive parts last) • During operations • Landing and launching >10km away • Transport using “ski”-lift cable system • Use of super-conducting magnetic bearings • During maintenance/upgrading (robots on telescope)

19. Environmental considerations • Special deep polar telescope requirements • Power (10-20KW) • Communication/data (2Mbit/s raw data plus other data, health monitoring, etc.) • Sky accessibility (1/4-1/2 of sky visible depending on location and local terrain) • Seismic stability • Single aperture  good enough • Interferometry  questionable, but lack of data (lunar-A will gather seismic data from 2004) • Magenetic bearing could damp out small seismicity. • Meteroid impact (~1/2 of free space)

20. Environmental considerations • Special lunar polar capabilities vs general lunar infrastructure • Not a 1-time visit but building/maintaining/upgrading over many years • Combining / synergy with other lunar activities such that they don’t disturb each other

21. Task 3 description • Characterize at least one design approach for a very large lunar telescope based on concepts previously discussed in the literature. • Analyze siting requirements and construction techniques from literature • Consider facilities located near south pole as well as near the equator (infrared  limited to polar areas)

22. Telescope Concept • Type alt-azimuth • Size 25 m diameter primary segmented single aperture (491 m2) secondary mirror (~3 m diameter) • Wavelength 5-25 micron • Location Shackleton crater at south pole • Special characteristics • Hexagons (r = 1.15m) • Super conducting magnetic bearings • Operating temperature about 35 K • Sky coverage ½ to ¼ depending on location and terrain

23. Dome vs. Heat shield • Functions of dome on Earth • Temperature regulation • Wind protection • Weather protection • Housing for other activities, humans, instruments, machinery etc. • Heat shield has different function • Only passive temperature regulation

24. Super Conducting Magnetic Bearing • High Temperature Super conducting magnetic bearings • Weight ~4% of mass to carry (600kg – 15 ton) • Power usage low • Complexity relatively high • Technology Readiness Level 2 (lab tested) • Reliable long duration • No friction • Precise and stable (using flux-pinning)

25. Task 4 description • Define the construction steps required in emplacement/erection of elements of the telescope • Site preparation • Emplacement/erection of elements

26. Site preparation • Site preparation • Building of infrastructure • Landing/launching area • communication and power • ski-lift • construction shack • Road preparation • Sand foundation and excavation • Stability of dry sand foundations is very good • Expansion of sand because of dense packing • (wet beach sand)

27. Construction sequence • 1 foundation • 2 first ring • 3 second ring and main struts • 4 mirror support structure & contra weight • 5 secondary mirror support structure • 6 place secondary mirror & instruments • 7 place main mirror segments • 8 commissioning phase

28. R=12.5 m Foundation • Place laser range finders • Dig holes • Place poles • Apply pre-load

29. 4 6 3 5 7 2 1 Construction sequence • Placement of foundation 2) First superconducting magnet ring • Second ring & main supports 4) Main axis, contra weight & instrument housing 7) Mirrors and Instruments Installed 8) Commissioning phase 5) Main mirror support structure 6) Secondary mirror supports

30. Task 5 description • Determine the appropriate roles of • human on-site operations • Tele-operation from the moon • Tele-operation from Earth in construction, maintenance, refurbishment and expansion of the telescope • Identify facilities required for support of on-site humans and constraints to prevent contamination or degradation of telescope.

31. Short scenario description • 1 communication relay • 2 communication relay and power generation • 3 lunar base with landing / launching pad • 4 construction shack • 5 telescope construction site 1 Sketch not to scale 2 5 3 4 ~10 km ~120 km

32. 1) Landing on Malapert Mountain (communication relay) 2) Landing on PEL (communication relay, power generation and transport of ROCADI I & II) 3a) Unmanned part : Lay cable down, prepare lift system first leg, prepare landing pad and setup landing beacon for lunar base, land base modules 3b) Manned part : inspection of base facilities, inspect lift system, expand power generation at PEL, start human exploration and research, propellant production Support infrastructure outside crater I 4) Use ROCADI II to lay cable into crater, inspect construction site and be landing beacon Support infrastructure inside crater II 5) Bring construction shack, make lift system second leg operational, prepare for first human visitors in crater. Project phases

33. 6) Land foundation elements at manned lunar base, transport them to crater, prepare construction site, prepare road surface, dig holes and place foundation poles, check by humans and lay power-data cables. Telescope construction and assembly 7) Land elements at lunar base. Put them in storage if necessary, start assembly of first ring and second ring, connect temporary power and data lines and place telescope robots on the telescope who will do the rest of the assembly III 8) Assemble main support struts and temporary axis, assemble main axis, build the primary mirror support structure and the secondary mirror support struts. Commissioning phase & operations IV 9) Place secondary mirror, the primary mirror segments and the instruments, connect permanent power and data lines 10) Test all functions and operations. Telescope robots will move to their permanent home on the telescope. Fix and inspect anomalies or diversions from specifications. Expansion, maintenance & upgrading V 11) Operational phase Project phases

34. Human presence and activities

35. Human requirements • Human suits need to have advanced sensors and display capabilities (construction oriented, but also good for exploration) • Easy control of information display and mapping functions of drawings / schematics • Humans on site do not control robots but should have power to override if necessary • Humans should be able to make decisions in construction process on site (maybe reprogramming or giving alternate commands) • High quality, high bandwidth communication

36. Advanced sensors (suit & robots); Robust communications Robotic involvement • 4 different robots needed • Rocadi (2x) • Dirty work robot • Transport robot • On-telescope robot (2x) • Interaction with humanson site required (override, data access, next steps overview) • Humans need to be equipped well

37. Human-Robot team safety • Construction and crew safety • Lower risk on moon than in free-space • Long duration stays less dangerous (less effects) • Radiation protection easier and cheaper • 0-G operation requires much more special tools etc. than 1/6 G • Human location awareness should be built into robots • Humans on-site should have emergency override • Suit may need extra protection against falling things or tools (hardhat and steel nosed shoe equivalents)

38. Task 6 description • Characterize the factors that must be included to determine the cost of constructing and operating the lunar telescope • Make a preliminary estimate of the cost of establishing the facility

39. Cost factor determination • Cost effectiveness • Previous studies : high cost of • Precision landing (here shared with human act.) • Accumulating elements (at lunar base, then ski-lift) • Do not include cost of astronauts (time sharing) • Effective operation time (low down time (10% instead of 40%)) • Vibration damping (easier and faster than free-space) • Pointing and tracking (easier and faster than free-space) • Faster and easier maintenance (no travel with whole telescope for months to e.g. E-M L1)

40. Cost factor determination • Why more massive is acceptable on lunar surface • Quality control on-site possible • Simpler technology • Simpler and safer construction • There is no space-worthy design at present • Large down-time in case repairs are necessary for free-space-based telescopes, if possible at all • Reliability is higher than free-space • Dynamic stability is greater than free-space • Faster pointing and tracking than in free-space • Resulting in much more effective observing time

41. Very rough cost factoring • NGST  $1 billion 6 m diameter • For same architecture cost = (diameter)2 • For 25 m  42=$16 billion • Factor 2 for on the moon  $32 billion • Permanent facility plus other activities • Much better performance • Safer and easier to build

42. SYNERGIES • Comet Asteroid Protection System (CAPS) • Tracking moving objects possibility (NRC decadal study of planetary exploration rec.) • Exploration of the moon • Science on and of the moon • Mining operations (volatile extraction) • Manufacturing operations (solar cell production)

43. Precursors and experiments • More topographical information with sufficient resolution (<1m) needs to be available • More information on seismic stability is needed (Lunar-A in 2004) • More information about the presence of ice and its composition etc. • Knowledge about the temperature regime in the permanently shadowed craters is necessary for modeling purposes • More knowledge about the lunar dust migration

44. Precursors and experiments • More knowledge about the extent of the influence of human presence on the lunar environment (atmosphere, dust, vibrations) • High temperature super-conducting magnetic bearings need to be further developed • Human-robot construction interaction studies need to be performed • Robots need to be developed and tested