1. MAXAT-II Woods Hole 17-18 September 1999

2. Overview Science Drivers Lessons of the past Focusing on Science and Innovation

3. Global context Mauna Kea, Hawaii 10 m 8 m 4 x 8m Chile 8 m 10 m

4. Global context 2000 2010 NGST NGST ALMA ALMA VLA-upgrade VLA-upgrade Keck-Inter. ESO-VLTI Keck I&II UT1,UT2,UT3,UT4 Gemini N&S HET LBT Phase A OWL 2015 2008 20002010 MAXATCELT

5. Hubble Space Telescope moved the goal posts SpaceGround Detected  Telescope Diameter.   Signal Image Width   Signal Image Width  

6. Detected  Telescope Diameter.   Signal Image Width   Signal Image Width   Sensitivity gains for a 21 st Century telescope For background or sky noise limited observations: S  (Effective Collecting Area) 1/2.   N Delivered Image Diameter   S/N x (10 6 ) 1/2 OH line

7. V-band 0.6 arcsec Adaptive Optics on 8m -10m Telescopes Globular Cluster NGC6934 V (0.55um) band FWHM of 0.6” K (2.2um) band ~120 exposures totaling 23min FWHM of 0.09” Gemini Optical Image 2.2um (K) Hokupa’a ON

8. Challenging 8m - 10m telescopes OH line

9. 1 R 1 AU 100 AU 0.1 pc 10 pc Accretion Disks Protoplanetary Disks Planets Molecular Cloud Cores Jets/HH GMC Mol. Outflows Stellar Clusters 1 - 10 milli- arcseconds Observations at z = 2 - 5 AGN Galactic observations out to 1kpc at 10 mas resolution 10 AU Spectroscopy Imaging  100 pc Velocity dispersion R= 10 5 10 4 10 3 10 2 10 1 Flux Going beyond 0.1 arcsecond astronomy requires resolution and sensitivity

10. Scientific Drivers for the “Next Generation Groundbased Telescope ”  Telescope Diameter.   Image Diameter  Maximize  Telescope Diameter.   Image Diameter   For diffraction limited pixels S/N  D 2 /  In the detector limited regime S/N  D 2 Detector technology (t)

11. Gemini 8-M 8 2 x 50 HET 9 60 CHARA 354 5.5 LBT100 100 Keck 1 & 2 + 165 157 + 11 VLTI + 200 201 + 20 Facility Baseline (m) Collecting Area (m 2 ) What is the future of O/IR Groundbased Astronomy?

12. Gemini 8-M 8 2 x 50 HET 9 60 CHARA 354 5.5 LBT100 100 Keck 1 & 2 + 165 157 + 11 VLTI + 200 201 + 20 20 m 20 316 50-M Telescope 50 1950 OWL100 7147 Facility Baseline (m) Collecting Area (m 2 ) - technology enables innovation and, scientific discovery

13. The Scientific Impact - Modeled characteristics of 20m and 50m telescope Assumed detector characteristics  m <  m 5.5  m <  m I d N r q e I d N r q e 0.02 e/s 4e 80% 10 e/s 30e 40% Assumed point source size (mas) 20M 1.2  m 1.6  m 2.2  m 3.8  m 4.9  m 12  m 20  m (mas) 20 20 26 41 58 142 240 50M 1.2  m 1.6  m 2.2  m 3.8  m 4.9  m 12  m 20  m (mas) 10 10 10 17 23 57 94  (Gillett & Mountain, 1998)

14. The Scientific Impact - Relative Gain of groundbased 20m and 50m telescopes compared to NGST Groundbased advantage NGST advantage Imaging Velocities ~30km/s

15. The impact of technology Kitt Peak 4m c.1970 Gemini 8m c.1998 Mass = 340 tonnes Cost (1998) ~ $64M scaled to 8m ~ $415M x 10 -100 Mass = 315 tonnes Cost (1998) ~ $88M

16. Quantifying Innovation - bypassing extrapolation 4m (KPNO) 8m (Gemini) Cost(1998) $61M Scaled cost $415M Actual cost $88M Cost “gain” x ~5 Image quality 1”Image quality 0.1” Performance “gain” (rel. to diff.) x 5 “innovation factor” ~ 5 x 5 = 25

17. Changing the “paradigm” - “extrapolation is innovations worst enemy” Why ? –Because the science drives us to this scale – and because modern analytical and control systems techniques allows us to reduce risk NASA HSTNGST

18. Telescope error budget, 50% e-e diameter (arcsecs) at 2.2  m System at 45 degrees, wind at 11 m/s, 200Hz tip/tilt sampling Error budget allocation is 0.100 at Zenith, 0.0123 at 45 degrees End-to-End modeling works Gemini Systems Review #2, March 1995 GEMINI IMAGE - 8 weeks into commissioning Feb ‘99 Tip/tilt sampling = 100Hz Open loop Arcseconds jitter Pointing accuracy with active control of structure

19. Innovation Factors Innovation factor 27 - 70 80 12 20 50m $600M HST NGST’ ($2.4B) ($1B) Gemini + MCAO 50m ($100M) ($1B) VLT OWL ($100M) ($1B) Keck + LGS AO CELT ($100M) ($400M) 5

20. Baseline Approach - ambitious at the outset Diffraction limited telescope D ~ 50m - 100m Operating wavelengths 0.9  m - 3.8  m Tech. challengeScience challenge Operate over 90% of sky (airmass < 2.0) at full image quality over 75% Operate under 90% of site conditions at full performance under 75% of conditions Minimize risk -- if at all possible Focus on technologies that have the potential to produce the most innovative results Multi-conjugate AO Smart structures Optical materials and support approaches Analytical analysis of wind-buffeting “Cheap” enclosures