The James Webb Telescope (NGST) to replace HST

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Carmel Foster
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1 PROLOGUE The James Webb Telescope (NGST) to replace HST Source: Key elements: 6.5m primary mirror (18 sections), lightweight, deployable (launch date 2013?) 1

$Large sunshield enables passive cooling of telescope and instruments Second Lagrange point (L2) orbit, with deployment during orbit insertion Diffraction-limited imaging quality (Strehl = 0.$

2 Large sunshield enables passive cooling of telescope and instruments Second Lagrange point (L2) orbit, with deployment during orbit insertion Diffraction-limited imaging quality (Strehl = 0.8) for lambda = 2 micron micron wavelength range with zodiacal-light-limited imaging performance below 10 micron Imaging and spectroscopic instrumentation over this wavelength range 5 years required lifetime, 10 years goal Risk mitigation by extensive testing 2

$Predicted encircled energy fraction as function of radius at 1 micron - encircled energy within 0.$

3 Predicted encircled energy fraction as function of radius at 1 micron - encircled energy within 0.15 arcsec radius, determined by sub-segment errors, is 84% at 1 micron - diffraction limited at 2 microns (Strehl ratio of 0.84, dominated by large scale errors) The log-scale image of the Point Spread Function (PSF) shows the effects of the hexagon shaped mirror at the low level fluxes of the diffraction rings Highly effective sunshield and semi-rigid mirror segments on a thermally robust backplane provides a very stable PSF. Variations in the encircled energy at 1 micron are expected to be less than 0.5% even after a worst case (hot-to-cold) thermal slew There will be no need for thermal settling and wave front corrections after large slews, significantly increasing the observatory efficiency 3

4 Second Lagrange point (L2), approximately 1.5 million km from Earth, outside the orbit of the Moon. The region about L2 is a gravitational saddle point, where spacecraft may remain at roughly constant distance from the Earth throughout the year by small station-keeping maneuvers Large halo orbit in a plane slightly out of the ecliptic plane. This orbit avoids Earth and Moon eclipses of the Sun. The halo orbit period is about 6 months. Nominal station keeping maneuvers will be performed every half orbit (3 months) Benign and essentially unchanging environment - no significant gravitational torques and thermal influence from the Earth and Moon are greatly reduced. The main operational influence to consider is the torque created by the Solar wind on the sunshield 4

5 Instruments: NIRCam Near-IR and visible camera; Sensitive over the micron wavelength range; Two broad- and intermediate-band imaging modules, each with a 2.2 x 2.2 arcmin field of view; Each imaging module has two channels, with light split by a dichroic at ~2.35 micron; Short wavelength channel " pixels, long wavelength channel " pixels Each module has coronagraphic capabilities NIRSpec Multi-object dispersive spectrograph (MOS); Capable of observing more than 100 objects simultaneously Sensitive over the 1-5 micron wavelength range; 3.4' x 3.4' field of view ~0.1" pixels o R=1000 MOS Mode, 3 gratings cover micron; o R=3000 Integral Field Unit or Long-slit Mode; o R=100 Prism, mm in one exposure; MIRI Mid-IR camera and Integral Field Unit (IFU) and long-slit spectrograph; Sensitive over the 5-28 micron wavelength range; 1.88' x 1.27' field of view imaging; 12 filters; 3" x 3" IFU R=3000 spectrograph, in 5-10 and micron channels; R=100 long-slit 5-10 micron spectrograph Coronagraphic capabilities FGS Fine Guidance System; Enable stable pointing at the milli-arcsecond level Sensitivity and field of view to allow guiding with 95% probability at any point on the sky (i.e. 95% at the galactic poles, better at most other places); 3 fields-of-view, one of which has R~100 tunable filter capability 5

6 Scientific goals The End of the Dark Ages First Light and Reionization seeks to identify the first bright objects that formed in the early Universe, and follow the ionization history 6

Assembly of Galaxies To determine how galaxies including

and active nuclei evolved to the present day These images

The first image is the original HST/WFPC2 F300W image of

The middle image is the simulated NGST 1.

7 Assembly of Galaxies To determine how galaxies including gas, stars, metals, physical structures (like spiral arms) and active nuclei evolved to the present day These images show the merger UGC06471 and UGC06472 at different redshifts. The first image is the original HST/WFPC2 F300W image of this z = 0.01 galaxy pair. The middle image is the simulated NGST 1.76 micron image if this same galaxy pair was at z = 5.0. The right image is for z = 12.0 and at a wavelength of 3.81 micron 7

$e. diffraction-limited at 2 microns).$

8 A 24"x 24" simulated NGST image labeled with redshifts. The image has 0.06 arcsecond resolution in all three bands (i.e. diffraction-limited at 2 microns). This represents only 1% of the total NIRCam field of view The full 2'x2' image 8

The Birth of Stars and Protoplanetary Systems This project focuses on the birth and early development of stars and the formation of planets Planetary Systems

9 The Birth of Stars and Protoplanetary Systems This project focuses on the birth and early development of stars and the formation of planets Planetary Systems and the Origins of Life Studies the physical and chemical properties of solar systems (including our own) and where the building blocks of life may be present 9

10 LATEST NEWS - 22 August 2011 Last updated at 23:50 GMT - Jonathan Amos BBC science correspondent Nasa says it will now cost $8.7bn to launch the James Webb Space Telescope in 2018 and operate it for five years. It is the full life-cycle cost - to build, launch and operate the observatory. Delays and cost overruns have dogged the project, and now some politicians want JWST cancelled. Nasa responded to the all criticism by making management changes and ordering a "bottoms-up review" of the project. It is this review that has now established the $8.7bn figure as the new baseline price tag for JWST, a Nasa spokesman told BBC News. The agency would explain how to fund the revised baseline in the US President's 2013 budget request to Congress made at the beginning of next year, the spokesman added. The House Appropriations Committee put forward a draft 2012 budget for the US space agency last month that would terminate funding for the observatory. The equivalent Senate body has yet to have its say, however. An independent assessment last year suggested the telescope's total cost had ballooned from $3.5bn to $5bn, and that continued delays would inflate the final bill well beyond $6bn. In parallel with the price escalation, the probable launch date has slipped deeper and deeper into the decade with some commentators wondering whether JWST might not even be ready to fly this side of One complicating factor for US politicians as they move to decide the future of JWST is the international fall-out that would result from cancellation. JWST is being prepared in partnership with Europe and Canada. Europe, for example, is providing two of the telescope's four instruments and the rocket to put it in orbit. This commitment would guarantee its astronomers 15% of the observing time on the observatory. 10

11 Astronomy Today $$$$$--BIG BUSINESS--$$$$$ We can observe in all the EM spectrum New technology in optical on Earth 4 above 9m, 8 above 8m (std), 2 above 5m (largest during ~30yrs) o QEUE observing Data mining (SOAR 2.3m telescope) through internet Under construction Projects to build 30m and bigger still 40-60m James Webb telescope ALMA mm SKA radio LHC (search for WIMP) In a world where the economy is weak or failing how can we justify and get support for these projects? Is this the only way to do astronomy? Does it produce good science? What is good science anyway? What is the importance and impact of astronomy on society? Nobel prize for accelerating universe? Press Release 4 October 2011 The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Physics for 2011 "for the discovery of the accelerating expansion of the Universe through observations of distant supernovae" Saul Perlmutter, Lawrence Berkeley National Laboratory and University of California Brian P. Schmidt, Australian National University,Weston Creek, Australia Adam G. Riess, Johns Hopkins University and Space Telescope Science Institute Saturday, 27 August 2011: Results from the Large Hadron Collider (LHC) have all but killed one version of supersymmetry, an enticing new theory of sub-atomic physics: o Dr Joseph Lykken of Fermilab -- among the conference organisers, says he and others working in the field are "disappointed" by the results - or rather, the lack of them they worry that the basic idea of supersymmetry might be wrong: "It's a beautiful idea. It explains dark matter, it explains the Higgs boson, it explains some aspects of cosmology (inflation); but that doesn't mean it's right. It could be that this whole framework has some fundamental flaws and we have to start over again and figure out a new direction," 11

Scientific Capability of the James Webb Space Telescope and the Mid-InfraRed Instrument

Scientific Capability of the James Webb Space Telescope and the Mid-InfraRed Instrument Oliver Krause (Max Planck Institute for Astronomy, Heidelberg) on behalf of Gillian Wright (Royal Observatory Edinburgh)