1 Progress on the 30m Giant Segmented Mirror Telescope AURA New Initiatives Office Leiden, 17 May...

1

Typical 'raft', 7 mirrors per raft

Special raft - 6 places, 4 mirrors per raft

1.152 m mirror across flats

Circle, 30m dia.

Progress on the 30m Giant Segmented Mirror Telescope

AURA New Initiatives Office

Leiden, 17 May 2001

Matt MountainJim Oschmann

Knut Olsen

2




Circle, 30m dia.

GSMT

• Partnership between Gemini, NOAO and our communities

• Science Enabled• Implementation Concepts• Resources• Interfaces

• Issues

3




Circle, 30m dia.

Science & Instrument workshops

Madison MAXAT science - 1998 Woods Hole MAXAT technology -1999 Tucson MAXAT instruments -2000 Tucson GSMT science – 2000 Subsystem working group meetings 1999-

2000Systems, optics, structures…

OPTICON, Edinburgh, Leiden

4




Circle, 30m dia.

GSMT System Considerations- Astronomers View

Science Mission- DRM’s

GSMTConcept

(Phase A)

Support &Fabrication

Issues

Active Optics (aO)

SiteCharacteristics

Enclosureprotection

Adaptive Optics

InstrumentsFull System

Analysis

5




Circle, 30m dia.

Derived Top Level Requirements

Narrow field AO 1 2 3 MCAO 1 2 3 Low order AO 1 2 3 Seeing limited (PF) 1 2 3Field of View 10 arcsec + - + 2 arcmin + + 2 arcmin + 20 arcminPrinciple wavelegths 1.0 - 2.5 microns 1.0 - 2.5 microns 1.0 - 20 microns 0.4 - 2.5 micronsPSF

Resolution Diffraction limited + + Diffraction limited + 0.1-0.2 arcsec + 0.4-0.7 arcsec +Stability 1% + 5% - - 2% 2%

Strehl 80% 50% <10% 0%Photom. accuracy(derived) 1% 5% - - 2% 1%

Astrometric accuracy 10 -̂4 arcsec + + 10 -̂3 arcsec - 10 -̂2 arcsec 0.05 arcsecStability timescale 3,600 s 3,600s 3,600s 10,000 sEmissivity <20% - <20% 10% 15%Maintenance/Ops <15% <15% <15% <15%Reliability 90% 90% 90% 90%Science Efficiency 90% 90% 90% 90%

1 Galaxy Evolution and LS Structure2 Stellar Populations3 Star and Planet Formation

Key:+ meets needs- does not meet needs

irrelevant or not critical

How to r ead this table:

Four telescope “Operating regimes” are defined and the specs for thetelesc ope (not the instrument) in each regime are cited. There are columns atthe right of each regime labeled 1,2,3 for the th ree science programsdiscussed in the NO AO panel W orkshop. In these columns the spe cs areassessed in term s of the adequacy for each sc ience program .

Matt:I think this mode is important, its our only "thermal IR" mode, and we may find some spectroscopy modes are so photon starved they

6




Circle, 30m dia.

30m Giant Segmented Mirror Telescope concept




Circle, 30m dia.

30m F/1 primary, 2m adaptive secondary

GEMINI

7




Circle, 30m dia.

The Enemies…..

• Wind…..

• The Atmosphere……

8




Circle, 30m dia.

Enabling techniques

• Active and Adaptive Optics

• Active Optics already integrated into Keck, VLT and Gemini

• Adaptive Optics “added” to Keck, Gemini (and soon) VLT

Active and Adaptive Optics will have to be integrated into GSMT Telescope and Instrument concepts from the start

9




Circle, 30m dia.

GSMT Control ConceptLGSs provide full sky coverage

Deformable M2 : First stage MCAO, wide field seeing improvement and M1 shape control

10-20’ field at 0.2-0.3” seeing

1-2’ field fed to the MCAO module

M2: rather slow, large stroke DM to compensate ground layer and telescope figure,

or to use as single DM at >3 m. (~8000 actuators)

Dedicated, small field (1-2’) MCAO system (~4-6DMs).

Focal plane

Active M1 (0.1 ~ 1Hz)619 segments on 91 rafts

10




Circle, 30m dia.

AO Technology constraints (50m telescope)

r0(550 nm) = 10cm No. of Computer CCD pixel Actuator pitch S(550nm) S(1.65m) actuators power rate/sensor

(Gflops) (M pixel/s) 10cm 74% 97% 200,000 9 x 105 800

25cm 25% 86% 30,000 2 x 104 125

50cm 2% 61% 8,000 1,500 31 SOR (achieved) 789 ~ 2 4 x 4.5

Early 21st Century technology will keep AO confined to > 1.0mfor telescopes with D ~ 30m – 50m

11




Circle, 30m dia.

MCAO on a 30m: summary

• MCAO on 30m telescopes should be used m• Field of View should be < 3.0 arcminutes,

• Assumes the telescope residual errors ~ 100 nm rms• Assumes instrument residual errors ~ 70 nm rms

– Equivalent Strehl from focal plane to detector/slit/IFU > 0.8 @ 1 micron– Instruments must have:

• very high optical quality• very low internal flexure

(m) Delivered Strehl

1.25 0.2 ~ 0.4 1.65 0.4 ~ 0.6 2.20 0.6 ~ 0.8

9 Sodium laser constellation4 tip/tilt stars (1 x 17, 3 x 20 Rmag)

PSF variations < 1% across FOV

Rigaut & Ellerbroek (2000)

12




Circle, 30m dia.

AO an integral part of the GSMT Concept

• Low order correction for wind buffeting and “seeing improvement”– 3 Natural Guide stars give full sky coverage

• Narrow Field AO requires at least one LGS for m– Science requires low emissivity implementation

• MCAO requires multiple NGS and multiple DM’s

13




Circle, 30m dia.

Comparative performance of a 30m GSMT with a 6.5m NGST

1 101E-3

0.01

0.1

1

10

Comparative performance of a 30m GSTM with a 6.5m NGST

S/N

Ga

in (

GS

MT

/ N

GS

T)

Wavelength (microns)

R=5 R=1,000 R=10,000

Assuming a detected S/N of 10 for NGST on a point source, with 4x1000s integration

GS

MT

a

dv

an

tag

eN

GS

T a

dva

nta

ge

R = 10,000 R = 1,000 R = 5

14




Circle, 30m dia.

Comparative performance of a 30m GSMT with a 6.5m NGST

1 101E-3

0.01

0.1

1

10

Comparative performance of a 30m GSTM with a 6.5m NGST

S/N

Ga

in (

GS

MT

/ N

GS

T)


R=5 R=1,000 R=10,000

Assuming a detected S/N of 10 for NGST on a point source, with 4x1000s integration

OW

LO

WL

a

dv

an

tag

eN

GS

T a

dva

nta

ge

R = 10,000 R = 1,000 R = 5

R = 5

100 m100 m

15




Circle, 30m dia.

GSMT Implementation concept- wide field (1 of 2)

Barden et al (2001)

16




Circle, 30m dia.

Optical “seeing improvement” using low order AO correction

16 consecutive nights of adaptive optics the CFHT

Image profilesare Lorenzian

17




Circle, 30m dia.

GSMT Implementation concept- wide field (2 of 2)

20 arc minute MOSon a 30m GSMT

• 800 0.75” fibers• R=1,000 350nm – 650nm• R=5,000 470nm – 530nm• Detects 13% - 23% photons hitting 30m primary

1m

Barden et al (2001)

18




Circle, 30m dia.

GSMT Implementation concept- MCAO/AO foci and instruments

MCAO opticsmoves with telescope

Narrow field AO ornarrow field seeing limited port

MCAO Imagerat vertical Nasmyth

elevation axis

4m

Oschmann et al (2001)

19




Circle, 30m dia.

Spot diagrams for MCAO + Imager

Diffraction limited performance for 1.2m – 2.2 m can be achieved

20




Circle, 30m dia.

MCAO Optimized Spectrometer

• Baseline design stems from current GIRMOS d-IFU tech study occurring at ATC and AAO– ~2 arcmin deployment field

– 1 - 2.5 µm coverage using 6 detectors

• IFUs– 12 IFUs total ~1.5”x1.5” field

– ~0.05” spatial sampling R ~ 6000 (spectroscopic OH suppression)

21




Circle, 30m dia.





elevation axis

4m


22




Circle, 30m dia.





elevation axis

4m


23




Circle, 30m dia.

High resolution, high Signal/Noise observations

1 10

0.01

0.1

1

10

17.0

12.3

4.6

Molecular line spectroscopy S/N = 100

S/N

Gai

n (

GS

MT

/ N

GS

T)


R=10,000 R=30,000 R=100,000

Detecting the molecular gas from gaps sweptout by a Jupiter mass protoplanet, 1 AU from a 1 MO young star in Orion (500pc) (Carr & Najita 1998)

GSMT observation ~ 40 mins (30 mas beam)

24




Circle, 30m dia.

8,960 actuators, 30cm spacing on Primary3,225 actuators, 50cm spacing

50cm actuator pitchGood conditions (0.5" seeing): lambda diameter["] %energy 1.25000 0.0226732 0.251838 1.60000 0.0290217 0.395080 2.25000 0.0408118 0.559923 3.8 0.66 5.00000 0.0906928 0.744220 10.0000 0.181386 0.785671 20.0000 0.362771 0.796393

30cm actuator pitch Good conditions (0.5" seeing): lambda diameter["] %energy 1.25000 0.0226732 0.338447 1.60000 0.0290217 0.473207 2.25000 0.0408118 0.613434 3.8 0.71 5.00000 0.0906928 0.758112 10.0000 0.181386 0.789314 20.0000 0.362771 0.797315

GSMT will need an Adaptive Secondary

25




Circle, 30m dia.

Sky coverage andStrehl for narrow field, thermal infrared observations using an adaptive secondary(wind buffeting on M1)

(Rigaut, 2001) for m single laser beacon required

26




Circle, 30m dia.

End-to-End Approach

• Science Requirements (including instruments)• Error Budget• Enclosure concept

– Interaction with site, telescope and budget

• Telescope structure– Interaction with wind, optics and instruments

• Optics– Interaction with telescope, aO/AO systems and instruments

• AO/MCAO – Interaction with telescope, optics, and instruments

• Instruments– Interaction with AO and Observing Model

• Observing Model

27




Circle, 30m dia.

Wind Loading

• Driving characteristic may be wind– Lower wind sites with good seeing

– How to protect telescope• Enclosure needs

• May be more limiting than local seeing to performance

• Cost drivers

• Advance methods for correcting

More critical than for existing telescopes

28




Circle, 30m dia.

0 50 100 150 200 250 300-2

-1.5

-1

-0.5

0

0.5

1

1.5

Time History: time (second)

pres

sure

(N

/m2)

AVERAGE Pressure (C00030oo)

10-3

10-2

10-1

100

101

100

101

102

103

104

105

106

107

Frequency Response Function: frequency (Hz)

mag

nitu

de

AVERAGE Pressure (C00030oo)

SUM = -226

29




Circle, 30m dia.

Average pressure PSD DATA- effect of enclosure shutters

30




Circle, 30m dia.

average pressure PSD by EL

Note: No elevation dependence on average pressure on primary

31




Circle, 30m dia.

How to scale to 30 meters:Average pressure SF (C00030oo)

D(d) = 0.096 d 0.41

0 1000 2000 3000 4000 5000 6000 7000 80000

0.5

1

1.5

2

2.5

3

3.5

4

sensor spacing, d (mm)

RM

S p

ress

ure,

Prm

s (N

/m2)

Average Structural Function for C00030oo

Prms = 0.076124 d ** 0.4389

30M

RMS pressure differences

Spatial scale

32




Circle, 30m dia.

An enclosure is essential: scaled up and taller variation of JCMT Enclosure

33




Circle, 30m dia.

30m Giant Segmented Mirror Telescope concept

X Y

Z

Output Set: Mode 1, 2.156537 Hz, Deformed(0.0673): Total Translation

Horizon Pointing - Mode 1 = 2.16 Hz

34




Circle, 30m dia.

Response to Wind

Current concept will now go through “second iteration” of designIn response to wind analysis

Fig. 4-7 – Central Raft Displacement Power Spectral DensityVent Gates Open, Wind Screen Open, Pointing into Wind, Zenith Angle = 30 deg.

0.001

0.01

0.1

1

10

100

0.1 1 10 100

Frequency (Hz)

PS

D (

m/s

qrt

(Hz)

)

TX

TY

TZ

35




Circle, 30m dia.

Point DesignInitial Analysis

• Finite element model of structure– Gravity sag and initial modal analysis

• Wind PSD’s calculated from Gemini tests– To be applied to current model

• Structure function approach to scaling Gemini data on wind buffeting to 30 meter– Preparing to apply wind buffeting to point design

• Aid in systems flow down of requirements

• Early trades possible soon

36




Circle, 30m dia.

Objectives: Next 2 years

• Develop point design for GSMT & instruments

– Carried out within NIO

• Attack key technical problems

– Adaptive optics

– Wind loading

– Mirror segment fabrication

• Continue community involvement in defining:

– Science & technical requirements

– Instrumentation options; technology paths

• Support design studies that complement other projects (CELT, FELT, OWL, etc.)

37




Circle, 30m dia.

Resources: Next 2 years

• Combined Gemini partnership + NOAO resources: $2.1M• Core NIO effort focused on studies to:

– Analyze point design– Attack key technical issues– Develop instrument and subsystem concepts– Explore science and instrument requirements

• Additional US National efforts: $2.0M external studies:– Enable community efforts: science; instruments

+ Study contracts+ Broad community workshops

– Enable key external engineering studies; alternate concepts+ End-to-end system model + detailed error budget+ Alternate system design concept studies+ Alternate AO system design and modeling studies+ Develop site testing equipment; apply in Chile

38




Circle, 30m dia.

AURA New Initiatives Office

E n g in eerin g O vers ig h tJ im O sch m an n

P ro jec t S c ien tis tS teve S trom

C on trac ted s tu d iesTB D

P art t im e su p p ortN O A O & G em in i

A d m in is tra tive ass is tan tJen n ife r P u rce ll

O p ticsL arry S tep p

C on tro lsG eorg e A n g e li (N O A O )

A d ap tive O p ticsB ren t E lle rb roek (G em in i)

In s tru m en tsS am B ard en (N O A O )

M ech an ica l D es ig n erR ick R ob les

S tru c tu resP au l G ille tt

S ite Tes tin gA lis ta ir W a lker (N O A O )

P rog ram M an ag erL arry S tep p

S ys tem s S c ien tis tB rooke G reg ory

M an ag em en t B oardM att M ou n ta inJerem y M ou ldW illiam S m ith

Adaptive OpticsFrancois Rigaut (Gemini)

39




Circle, 30m dia.

GSMT STEERING COMMITTEE

John Casani Jet Propulsion LaboratoryAlan Dressler Carnegie ObservatoryRichard Ellis CalTechBob Fugate Starfire Optical RangeJay Gallager University of WisconsinBob Gehrz University of Minnesota Riccardo Giovanelli Cornell UniversityBob Kirshner Harvard-Smithsonian, CfARolf Kudritzki University of HawaiiSimon Lilly HIAJoe Miller University of CaliforniaJerry Nelson University of CaliforniaLarry Ramsey Penn State UniversityChuck Steidel CalTech

Present Members

40




Circle, 30m dia.

Interfaces• Community task groups; workshops• NSF, other Gemini Agencies (PPARC, NRC,

ARC..) • Potential partners: CELT; ESO; others• Other next generation telescope projects• Private sector/government lab consultants• NIO steering committee• US System steering group

– GSMT is the apex of US system– System must support GSMT

• OPTICON

Date post:	05-Jan-2016
Category:	Documents
Upload:	loreen-richard
View:	214 times
Download:	0 times

1 Progress on the 30m Giant Segmented Mirror Telescope AURA New Initiatives Office Leiden, 17 May...

Documents