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Next Generation Space TelescopeStatus - Spring 2001

Bob Fosbury (ST-ECF)http://www.stecf.org/

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Science goalsSee first-light in the UniverseObserve the origin & evolution of

galaxiesStudy structure & chemical enrichment

of UniverseStudy star and planet formation

In practice, these goals are represented by the Design Reference Mission (DRM)

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The NGST

A collaboration between NASA, ESA and the Canadian Space Agency (CSA)

Observatory launched to an L2 halo orbitSun-Earth Lagrangian point, about 1.5Mkm

away

Deployable, lightweight opticsPassive cooling

=> sunshield

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The instruments

A near-infrared camera (0.6 – 5 µm)NASA + CSA

A near-infrared multi-object spectrograph (1 – 5 µm)

ESA + NASA

A mid-infrared camera/spectrograph(5 – 28 µm)

Europe + NASA

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Europe’s rôle

Provision of the NIR spectrograph by ESA(detectors and MEMS slit-selector supplied

by NASA)

European National contributions to the mid-infrared instrument (around 50%- probably optics and bench)

ESA contributions to the spacecraft(details not yet decided)

ESA support of observatory operations

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Project status

NASAPhase 1 (A/Early B) - 2 prime contractorsDownselect late 2001Technology development programmeIssue instrument AO mid-2001

ESAF2 selection: AWG, SSAC, SPC - late 2000Instrument -studiesTechnology studiesMIR studies

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Recent re-scope exercise

Increase areal density of mirror from 15 to 20+ kg m-2

Allows 1g testing

Reduce aperture from 8 to ~6.5mAllows launch (mass) and time for

polishing

Heat telescope to 45-50KAllows active thermal control

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Performance implications

Point sourceAround 0.5m in limiting sensitivityAbout a factor 2.3 in exposure time for

fixed magnitude and s/nDue to decreased aperture 8 -> 6.5m

Some thermal background added by warm telescope above 25µm - roughly another half magnitude in limiting sensitivity

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ESA pre-Phase-A studies (1998–99)

Telescope & Payload Suite Contractors: Dornier Satellitensysteme, Alcatel Space, LAS (Marseilles) & UK Astronomy Technology Centre (Edinburgh)Science Leads: Olivier Le Fevre (LAS), Gillian Wright (UK-ATC)

Multi-Object/Integral Field SpectrographContractors: Laboratoire d’Astronomie Spatiale (Marseille) & Dornier Satellitensysteme w. Durham, ESO, Cambridge, MPE & LeidenScience Lead: Olivier Le Fevre (LAS)

Visible Wavelength Camera/SpectrographContractors: Matra-Marconi Space w. Dornier Satellitensysteme, Leicester, MSSL, LAS, UCL & Obs. Paris Science Lead: Martin Ward (Leicester)

On-Board Data ManagementContractors: Laben w. Dornier Satellitensysteme, Istituto di Fisica

Cosmica (Milan), Arcetri, LAS, Leicester & Univ. College DublinScience Lead: Patrizia Caraveo (IFC)

Other Spacecraft Subsystems (In-house)

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Current NIRSpec studies

MEMS-based Near-IR Multi-Object Dispersive Spectrograph I (175 kK)Contractors: Astrium & Laboratoire d’Astronomie Spatiale (Marseille)

w. Durham, ESO, Cambridge, MPE & LeidenScience Lead: Olivier Le Fevre (LAS)

MEMS-based Near-IR Multi-Object Dispersive Spectrograph II (175 kK)Contractors: Alcatel & Laboratoire d’Astronomie Spatiale (Marseille)Science Lead: Denis Burgarella (LAS)

Alternatives to MEMS for slitmasks for a Near-IR Multi-Object Spectrograph (100 kK)ITT Issued: December 2000Closing Date: February 23

Update to Integral Field Spectrograph (75 kK)Contractors: Laboratoire d’Astronomie Spatiale (Marseille) & Astrium w. Durham,

ESO, Cambridge, MPE & Leiden Science Lead: Olivier Le Fevre (LAS)

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MEMS developments

90m

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Science operations

Simpler process than HSTDifferent orbitLonger observationsArchive volume is tiny cf. ESO

Europe will have a direct rôleInstrument science for NIRSpec and

possibly the MIRArchiving, User Support, PR etc.