-- Large optical telescopes on the Moon – Paul Hickson, Professor, Department of Physics and Astronomy, The University of British Columbia. The Moon offers some unique advantages for future very-large optical telescopes. The airless environment, slow lunar rotation and precession would enable a zenith-pointing telescope, located near one of the lunar poles, to survey a large region of sky and study the epoch of galaxy formation. I will present results from a recent NASA/CSA study that considered the feasibility of lunar liquid-mirror telescopes having apertures in the 20 to 100 metre range.

1. Large optical telescopes on the Moon
U Arizona, U British Columbia, U Houston, U Laval, NASA, ESA, CSA, ComDev
R. Angel
E. Borra
J. Burge
D. Eisenstein
B. Foing
C. Gosselin
P. Hickson
J-L. Josset
P. Klimas
K. Ma
N. Rowlands
E. Seddiki
K. Seddon
S. Sivanadam
P. van Sussante
S. Thibault
S. Worden

2. No absorption of light by the atmosphere
No blurring of images by the atmosphere
Night sky is about 1,000,000 times fainter from space, in the infrared
Why space?
Space Telescope
Science Institute

3. Liquid-mirror telescopes on the Moon Paul Hickson RASC 2006-03-14 Page 8
Hubble Space Telescope (2.4-meter)
NASA

4. Liquid-mirror telescopes on the Moon Paul Hickson RASC 2006-03-14 Page 9
James Webb Space Telescope (6-metre)
NASA

5. Why large telescopes?
HST 2.4m JWST 6m Lunar 30m
NASA

6. Liquid mirror
telescopes on the
Moon?
NASA study, 2003-2006
CSA study, 2008
The surface of a
rotating liquid is a
paraboloid
Exactly what is needed
to focus light
Lightweight
Accurate
Low cost
The Economist

7. Liquid-mirror telescopes on Earth
NASA Orbital Debris Observatory (3-m) UBC Large Zenith Telescope (6-m)
P. K. ChenChip Simons

8. Galaxies imaged
with the LZT

9. Image moves continuously across CCD due to
Earth’s rotation
Charge being generated by photons is shifted
electronically along the CCD columns at the same
rate
This prevents image smearing
Data are read continuously all night long
Time-delay integration (drift scan)
LZT

10. Initial lunar telescope concept
Telescoping structure
Deployable secondary mirror
Inflatable sunshield
Superconducting magnetic
levitation bearing
Low-temperature ionic liquid
coated with metal film
Polar location (track by
rotating the camera)
Tom Connors

11. Optical design
Three-mirror
anastigmat
F/1.5 20m liquid
primary
2.4 m convex
secondary
26 m above
primary
4 m concave
tertiary
20-arcmin field
of view
Diffraction-
limited
resolution

13. Telescope structure technologies
Inflatable Truss
Umbrella + tower system
Assembly from modular
units (truss+membrane)

14. Telescope structural analysis
Lightweight structura elements
Deployable panels assembled by robot arm
Membrane seals surface

15. Superconducting magnetic levitation bearings
Low power
Passively cooled
Active stabilization

16. Low-temperature liquids
Base liquid
Liquid eutectic (Na-K or other)
Ionic liquid
Lithium Ammonia
Coated for higher reflectivity
Interface layers (Cr, PEN)
Vacuum deposition on large
rotating mirrors

17. Polar location
Allows “tracking” by
rotating the camera
South pole has
permanently-shadowed
craters
This allows the telescope
to cool to 80K passively
Some peaks are
permanently sunlit
Place solar collectors
here and send power to
the telescope Permanently shadowed craters at Lunar
South Pole (Shevchenko et al.)

18. The North Pole in winter
15 km transmission
line needed to bring
power from sunlit
areas to telescope

19. Which pole?
The south pole field contains the Large Magellanic Cloud
The north pole field is less crowded

20. Observing strategy
18-year precession of Lunar axis
sweeps out a 3.1-degree diameter
circle
Total area accessible to the
telescope is ~3 square degrees
Available exposure time is ~6000
hours
Study galaxies, black holes at any
distance (>30 million galaxies)
Detect Earth-like planets to a
distance of ~150 parsec (~1000
planetary systems)

21. Conclusions
20-metre liquid-mirror
telescope is feasible
100-meter might be possible
Can make use of lunar base /
outpost infrastructure for
assembly
Assembly primarily by robotic
means with on-site human
supervision
Total Mass: 9400 kg
Single Altair cargo lander
Smaller wide-field precursor
telescope as first step?

22. Thank you!
More information:
Borra, E. F., Seddiki, O., Angel, R., Eisenstein, D., Hickson, P., Seddon, K. R. and
Worden, S. P., Deposition of metal films on an ionic liquid as a basis for a lunar
telescope, Nature, 447, 979-981 (2007).
Angel, R., Worden, S. P., Borra, E. F., Eisenstein, D., J., Foing, B., Hickson, P.,
Josset, J.-L., Ma, K. B., Seddiki, O., Sivanandam, S., Thibault, S., van Sussante, P.,
A cryogenic liquid-mirror telescope on the moon to study the early Universe,
Astrophys. J., 680, 1582-1594 (2008).
Klimas, P., Rowlands, N., Hickson, P., Borra, E. and Thibault, S., Lunar liquid mirror
telescope: structural concepts, Proc SPIE, 7732, 77322U-77322U-12 (2010).