MAXAT-II

Woods Hole17-18 September 1999

Overview

• Science Drivers • Lessons of the past• Focusing on Science and

Innovation

Global context

Mauna Kea, Hawaii

10 m

8 m

8 m

4 x 8m

Chile

8 m

10 m

Global context

2000 2010

NGST NGST ALMAALMA VLA-upgradeVLA-upgrade

Keck-Inter. ESO-VLTI

Keck I&II

UT1,UT2,UT3,UT4 Gemini N&S HET LBT

Phase A

OWL

201520082000 2010

MAXAT CELT

Hubble Space Telescope moved the goal posts

Space

Ground

Detected Detected Telescope Diameter Telescope Diameter . .

Signal Image Width Signal Image Width

Detected Detected Telescope Diameter Telescope Diameter . .

Signal Image Width Signal Image Width

Sensitivity gains for a 21st Century telescope

For background or sky noise limited observations:

S (Effective Collecting Area)1/2 .

N Delivered Image Diameter

S/N x (106)1/2

OH

lin

e

OH

lin

e

V-band0.6 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 ImageGemini Optical Image 2.2um (K)Hokupa’a ON

Challenging 8m - 10m Challenging 8m - 10m telescopestelescopes

OH

lin

e

1 R 1 AU 100 AU 0.1 pc 10 pc

Accretion Disks

Protoplanetary Disks

Planets

Molecular Cloud Cores

Jets/HH

GMC

Mo

l. O

utf

low

s

StellarClusters

1 - 10 milli-arcseconds

Observations at z = 2 - 5

AGN

Galactic observations out to1kpc at 10 mas resolution

10 AU

Spectroscopy Imaging

100 pc

Velo

city

dis

pers

ion

R=

10

5 10

4 10

3 10

2 10

1

Flux

Going beyond 0.1 arcsecond astronomy requires resolution and sensitivity

Scientific Drivers for the “Next Generation

Groundbased Telescope”

• Maximize Telescope Telescope DiameterDiameter . . Image DiameterImage Diameter

• For diffraction limitedpixels S/N D2 /

• In the detector limited regime S/N D2

Detector technology (t)

• Gemini 8-M 8 2 x 50• HET 9 60• CHARA 354 5.5• LBT 100 100• Keck 1 & 2 + 165 157 + 11• VLTI + 200 201 + 20

Facility Baseline (m) Collecting Area (m2)

What is the future of O/IR Groundbased Astronomy?

What is the future of O/IR Groundbased Astronomy?

• Gemini 8-M 8 2 x 50• HET 9 60• CHARA 354 5.5• LBT 100 100• Keck 1 & 2 + 165 157 + 11• VLTI + 200 201 + 20• 20 m 20 316• 50-M Telescope 50 1950• OWL 100 7147

Facility Baseline (m) Collecting Area (m2)

- technology enables innovation and, scientific discovery

The Scientific Impact- Modeled characteristics of 20m and 50m

telescope

Assumed detector characteristics

m <m 5.5m <m

Id Nr qe Id Nr qe

0.02 e/s 4e 80% 10 e/s 30e 40%

Assumed point source size (mas)

20M 1.2m 1.6m 2.2m 3.8m 4.9m 12m 20m (mas) 20 20 26 41 58 142 240

50M 1.2m 1.6m 2.2m 3.8m 4.9m 12m 20m (mas) 10 10 10 17 23 57 94

(Gillett & Mountain, 1998)

The Scientific Impact- Relative Gain of groundbased 20m and 50m telescopes compared to

NGST

Gro

un

db

ased

ad

van

tag

eN

GS

T a

dva

nta

ge

1 101E-3

0.01

0.1

1

10

1001 10

1E-3

0.01

0.1

1

10

100

50m R=10,000

20m R=10,000

Wavelength (m)

1 101E-3

0.01

0.1

1

10

1001 10

1E-3

0.01

0.1

1

10

100

50M R=5

20m R=5

S/N

Ga

in

Wavelength (m)

ImagingImaging Velocities ~30km/sVelocities ~30km/s

The impact of technologyThe impact of technology

Kitt Peak 4m c.1970 Gemini 8m c.1998

Mass = 340 tonnesMass = 340 tonnesCost (1998) ~ $64MCost (1998) ~ $64Mscaled to 8m ~ $415Mscaled to 8m ~ $415M

x 10 -100

Mass = 315 tonnesMass = 315 tonnesCost (1998) ~ $88MCost (1998) ~ $88M

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

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

HST NGST

Area Raw Open Autoguide Tip/tilt Focus ActiveOptical Design 0.065 0.065 0.065 0.065 0.065 0.065Surface Errors 0.201 0.187 0.187 0.148 0.105 0.046Optical Alignment 0.014 0.014 0.014 0.014 0.014 0.014Self Induced Seeing 0.027 0.027 0.027 0.027 0.027 0.027Dynamic Alignment 0.147 0.036 0.036 0.004 0.004 0.004Wind Shake 0.363 0.363 0.182 0.036 0.036 0.036Meassurement Error 0 0 0 0.025 0.025 0.025Off-Axis Error 0 0 0 0.013 0.013 0.013Non-Linear Effects 3.658 0.636 0.278 0.033 0.033 0.033

RSS Totals 3.658 0.76 0.389 0.169 0.139 0.102

• Telescope error budget, 50% e-e diameter (arcsecs) at 2.2m • 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 weeksinto commissioning

Feb ‘99Feb ‘99

Tip/tilt sampling = 100Hz Open loop

Arc

seco

nd

s jit

ter

Pointing accuracy with active control of structure

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

Baseline Approach - ambitious at the outset

• Diffraction limited telescope D ~ 50m - 100m• Operating wavelengths

0.9m - 3.8mTech. challenge Science 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