Supernova data shows an acceleration of the expansion, implying that the universe is dominated by a new Dark Energy! Remarkable agreement between Supernovae & recent CMB. SNAP Introduction Credit STScI

“Maybe the most fundamentally mysterious thing in basic science” - Frank Wilczek “This is the biggest embarrassment in theoretical physics” - Michael Turner “Would be number one on my list of things to figure out” - Edward Witten “Right now, not only for cosmology but for elementary particle theory this is the bone in the throat” - Steven Weinberg “Our main achievement in understanding dark energy is to give it a name” – Michael Turner “In string theory, to get  > 0 but extremely small is impossible” - Ed Witten Theoretical Questions What is the Nature of the dark energy? —Largest component of our universe —Theory proposes a number of alternatives each with different properties we can measure. What is the evolution and fate of the universe?

SNAP a simple dedicated experiment to study the dark energy —Dedicated instrument, essentially no moving parts —Mirror: 2 meter aperture sensitive to light from distant SN —Photometry: with 1°x 1° billion pixel mosaic camera, high-resistivity, rad- tolerant p-type CCDs and, HgCdTe arrays. (  m) —Integral field optical and IR spectroscopy:  m, 2”x2” FOV Mission Design

Simulated SNAP data

Ground-based measurements will reach systematic limits

The Time Series of Spectra is a “CAT Scan” of the Supernova

Images Spectra Redshift & SN Properties Lightcurve & Peak Brightness dataanalysisphysics  M and   Dark Energy Properties At every moment in the explosion event, each individual supernova is “sending” us a rich stream of information about its internal physical state. What makes the SN measurement special? Control of systematic uncertainties

From Science Goals to Project Design Science Measure  M and  Measure w and w (z) Data Set Requirements Discoveries 3.8 mag before max Spectroscopy with S/N=10 at 15 Å bins Near-IR spectroscopy to 1.7  m Statistical Requirements Sufficient (~2000) numbers of SNe Ia …distributed in redshift …out to z < 1.7 Systematics Requirements Identified and proposed systematics: Measurements to eliminate / bound each one to +/–0.02 mag Satellite / Instrumentation Requirements ~2-meter mirrorDerived requirements: 1-square degree imager High Earth orbit Spectrograph High bandwidth (0.4  m to 1.7  m)

SAGENAP (2000) Science review by SAGENAP of 260-page proposal, March DOE support commenced after SAGENAP Study phase (effort to develop CDR, cost, schedule, key technologies).

R&D Review Recent DOE/Science & R&D Review (Jan 2001): —“SNAP is a science-driven project with compelling scientific goals.” —“SNAP will have a unique ability to measure the variation in the equation of state of the universe.” —“We believe that it is not an overstatement to say that the Type Ia supernova measurements will uniquely address issues at the very heart of the field…” [Implications for string theory] Issues Raised at R&D Review: —Look at greatly increasing the near-infrared capabilities —Is the proposed IR spectrograph throughput adequate? —Look at a descoped instrument complement: Can the spectroscopy be done by ground-based facilities? —Develop a calibration strategy and plan. —Address NASA relationship

Today’s Talk: Status of R&D Science Requirements Definition —Monte Carlo Event Generator —Lightcurve generator and fitter —Cosmology fitter —SNe Modeling Optical Telescope —Optical Design/Layout —Optical Quality —Technology —Stray Light —Thermal Design NASA IMDC/ISAL Studies —Spacecraft Packaging —Mass & Power —Attitude Control/Pointing —Launch Vehicle —Orbit Instrumentation —Camera —Survey Strategy —CCD Detectors —Radiation Damage —NIR Detectors —Spectrograph

Tools for Requirements Definition Monte Carlo implements detailed list of systematics Event generator - Create an object list with fluxes. Ingredients: Supernova types, Type Ia subclasses Galactic, host, and gray dust Gravitational lensing Host galaxy properties Image simulator and SN extraction - Measure photometry, spectra from images Data simulator - Generated calibrated light curves and spectra S/N calculated based on observatory parameters Calibration errors Detection efficiency - Measure contamination of non SNe Ia and Malmquist bias Light curve and spectrum fitter - Simultaneously fit key parameters of SN and dust Cosmology fitter - Determine best fit cosmological and dark energy parameters

Simulation Studies Suite Modeling + Theory  To probe dark energy, follow SN to z  optimal redshift range, SN distribution, priors Refinement of observational requirements space from -- SN observations/templates: rise time, line widths/shifts, UV -- SN explosion modeling: progenitor, C/O, kinetic energy, metallicity Study of deep, wide field surveys -- advanced exposure time calculations -- dithering, sampling, pixel strategies Gravitational lensing corrections in data analysis -- cross correlate SNAP weak lensing map with SN amplification -- direct fit of microlensing amplification distribution peak and tail

Supernova Data Sheet

Supernova Requirements

Advantages of Space

Primary Science Mission Includes…

Annular Field TMA Prolate ellipsoid concave primary mirror, 2 meter diameter Hyperbolic convex secondary mirror Flat oval 45degree folding mirror feeds transverse rear axis Prolate ellipsoid concave tertiary mirror Flat focal plane Delivers < 0.04 arcsecond FWHM geometrical blur over annular field 1.37 sqdeg Effective focal length 21.66m; f/10.8 final focus Provides side-mounted detector location for best detector cooling Current Optical Configuration

OTA geometrical ray trace TMA62 configuration Compare Airy disk 26 microns FWZ diameter at 1 micron

OTA Technologies Existing technologies are suitable for SNAP Optical Telescope Assembly New materials, processes, test & evaluation methods are unnecessary Mirror materials —Corning ULE glass: extensive flight history, but expensive —Schott Zerodur glass/ceramic composite: lower cost, widely used in ground based astronomical telescopes, higher mass optic; huge industrial base —Astrium/Boostec SiC-100: newcomer; unproven in space optics; higher CTE; adopted for Herschel/FIRST in infrared Structural materials —M55J carbon fiber + cyanate ester resin; epoxy adhesive bonds Mirror finishing technology —conventional grind/polish/figure using abrasives —ion-beam figuring available from two vendors Mirror surface metrology —same as other space telescopes, e.g. cassegrains —standard interferometer setups will do the job for SNAP —no unusual accuracy drivers have been encountered

Lightweight ULE Mirror Fab

OTA THERMAL OPTICS: Build,Test, & Fly Warm… like Hubble ! KEY DESIGN FEATURES High Earth orbit (HEO) to minimize IR Earth-glow loads GaAs cell - OSR striping of the (hot) solar array panels — Front surface heat rejection OK — Optical Solar Reflectors are back silvered Quartz tiles (  ~ 8%,  ~ 80%) Low emissivity silvered mirrors Thermal Isolation mounting and MLI blanketing

Stray Light – Baffle Design

add PASSIVE 140K CAMERA DEWAR add PASSIVE 140K CAMERA DEWAR TMA-62 Optical Prescription TMA-62 LIGHT PATH - primary - secondary - folding flat - tertiary - Giga-Cam - Spectrometer Optical Telescope Assembly (OTA)

add SECONDARY STRUCTURE low CTE - GFRP add SECONDARY STRUCTURE low CTE - GFRP add “OPTICS COFFIN” BELOW low CTE - GFRP - WITH THREE STIFF METERING TUBES add “OPTICS COFFIN” BELOW low CTE - GFRP - WITH THREE STIFF METERING TUBES add OPTICAL BENCH low CTE - GFRP add OPTICAL BENCH low CTE - GFRP Optical Telescope Assembly (OTA)

add STRAY LIGHT PRIMARY “STOVEPIPE” add STRAY LIGHT PRIMARY “STOVEPIPE” enclose OPTICS COFFIN enclose OPTICS COFFIN add PASSIVE GIGA-CAM RADIATOR add PASSIVE GIGA-CAM RADIATOR add STRAY LIGHT SECONDARY “LAMPSHADE” add STRAY LIGHT SECONDARY “LAMPSHADE” add CCD FRONT END ELECTRONICS add CCD FRONT END ELECTRONICS Optical Telescope Assembly (OTA)

add STRAY LIGHT BAFFLE(s) add STRAY LIGHT BAFFLE(s) add THERMALLY ISOLATED SOLAR ARRAY PANELS add THERMALLY ISOLATED SOLAR ARRAY PANELS Optical Telescope Assembly (OTA)

add GENERIC SPACECRAFT add GENERIC SPACECRAFT add EXTERNAL MLI THERMAL BLANKETS add EXTERNAL MLI THERMAL BLANKETS Optical Telescope Assembly (OTA)

NASA GSFC/IMDC Spacecaft Packaging Propulsion Tanks Sub-system electronics Secondary Mirror and Active Mount Optical Bench Primary Mirror Thermal Radiator Solar Array Wrap around, body mounted 50% OSR & 50% Cells Detector/Camera Assembly from GSFC - IMDC study

IMDC Baseline Configuration ROM MASS: 700 kg (instrument); 500 kg (bus); 250 kg (hydrazine) ROM POWER: 250 w (instrument); 250 w (bus) MOSTLY GENERIC SUBSYSYEMS —EPS (electrical), C&DH (command & data handling), Thermal MISSION UNIQUE SUBSYSTEMS —ACS (attitude control), SMS (structure & mechanisms), Comm Evolving Bus Configuration Notes —3-axis stabilized, 4+ Reaction wheels, tactical IRUs, no torquer bars —Sun side w/ isolated body mounted solar arrays & anti-sun side radiators —Standard Hydrazine propulsion system, ~100 kg to raise perigee, ~10 kg/yr for station keeping, ~ 100 kg for Post Mission Disposal —2 Tbits SSR storage for imaging & spectroscopy data. (Avg. data rate ~52 Mbps; lossless compression plus overhead). —High speed Ka band down link near 300 Mbps to Northern Latitude ground station (Berkeley).

Pointing Accuracy »Yaw & Pitch : 1 arc-sec (1  ) »Boresight Roll:100 arc-sec (1  ) Attitude Knowledge »Yaw & Pitch :0.02 arc-sec (1  ) »Boresight Roll:2 arc-sec (1  ) Jitter/Stability -Stellar (over 200 sec) »Yaw & Pitch :0.02 arc-sec (1  ) »Boresight Roll:2 arc-sec (1  ) Sun Avoidance - VERY RELIABLE SAFE HOLD ! Earth Avoidance (mostly in orbit choice) Moon Avoidance (mostly in orbit choice) ACS Driving Requirements

Jitter —Isolate fundamental wheel frequency through detailed analysis from manufacturer —Must tune wheel isolators - type, size and interface Flexible Mode Analysis —Require extensive analysis to avoid control/structure resonance Solar Wind Tipping, given the Large Baffle Cp-Cg offset —Smaller offset will minimize thruster firing frequency and propellant required for daily momentum unloading (est. 30 Nms wheels) 3  Pointing jitter values —Use current Star tracker with a very accurate Kalman Filter —Augment Star Tracker data with instrument data (on focal plane guider) for fine pointing —May need to replace gyro with SKIRU-DII Use of Instrument guide data —Possible mitigation by use of more sophisticated focal plane-sensors ACS Issues and Concerns from IMDC

Atlas-EPF Delta-III Sea Launch Launch Vehicle Study

Orbit Optimization  High Earth Orbit  Good Overall Optimization of Mission Trade-offs  Low Earth Albedo Provides Multiple Advantages:  Minimum Thermal Change on Structure Reduces Demand on Attitude Control  Excellent Coverage from Berkeley Groundstation  Outside Outer Radiation Belt (elliptical 3 day - 84% of orbit)  Passive Cooling of Detectors  Minimizes Stray Light Chandra type highly elliptical orbit Lunar Assist orbit

Ground Station Coverage Orbit perigee remains over Berkeley for 3 years without adjustment. 6 hour ground pass over Berkeley

Camera Assembly Heat radiator Shield GigaCam

GigaCAM, a one billion pixel array l Approximately 1 billion pixels l ~140 Large format CCD detectors required, ~30 HgCdTe Detectors l Smaller than H.E.P. Vertex Detector (1 m 2 )GigaCAM

Imaging Strategy

Focal Plane Layout with Fixed Filters

Survey Strategy

Filter Wheel Concept

LBNL CCD R&D Status Goals already met Quantum efficiency from 350 nm to 1000 nm. Dark current Read noise CTE for variety of pixel sizes Proton radiation tolerance 60 Co radiation tolerance Commercialization of fabrication process Active projects Intrapixel response Device thinning at commercial foundry Packaging for ground based observatories Multistage outputs Readout electronics specification and technology assessment Future work Backup plans for device thinning Further rad hardening by defect engineering SNAP design optimization —Number of pixels —Pixel size —Thickness —Output MOSFET structure —SNAP specific packaging Design of integrated electronics running cold adjacent to CCDs

High-Resistivity CCD’s New kind of CCD developed at LBNL Better overall response than more costly “thinned” devices in use High-purity silicon has better radiation tolerance for space applications The CCD’s can be abutted on all four sides enabling very large mosaic arrays Measured Quantum Efficiency at Lick Observatory (R. Stover):

LBNL SCP Group: Supernova Spectrum at NOAO

LBNL CCD’s at NOAO See September 2001 newsletter at 1)Near-earth asteroids 2)Seyfert galaxy black holes 3)LNBL Supernova cosmology Cover picture taken at WIYN 3.5m with LBNL 2048 x 2048 CCD (Dumbbell Nebula, NGC 6853) New instrument at NOAO available in shared risk mode using LBNL CCD’s – Multi-Aperture Red Spectrometer (MARS) LBNL CCD’s scheduled for 37 nights during 2002A (Jan – July 2002) Science studies to date at NOAO using LBNL CCD’s:

Radiation Damage: Comparison to Conventional CCDs [1]L.Cawley, C.Hanley, “WFC3 Detector Characterization Report #1: CCD44 Radiation Test Results,” Space Telescope Science Institute Instrument Science Report WFC , Oct.2000 [2] T. Hardy, R. Murowinski, M.J. Deen, “Charge transfer efficiency in proton damaged CCDs,” IEEE Trans. Nucl. Sci., 45(2), pp , April 1998 CTE is measured using the 55 Fe X-ray method at 128 K. 13 MeV proton irradiation at LBNL 88” Cyclotron Degradation is about 1  g/MeV. SNAP will be exposed to about 1.8  10 7 MeV/g (solar max).

Dark Current Degradation 208K 158K Fit gives expected Si bandgap, so no new dark current sources are developing. The plateau at right is not identified yet, but could be surface leakage currents. Dark current is measured with one thousand or more second exposures. The gaussian charge distribution in the active region of the CCD is compared with the gaussian change distribution in the overscan region.

Packaging prototypes First back-illuminated image with new mount. CCD is engineering grade used for assembly practice. 2k x 2k back-illuminated mount. 2k x 4k mount similar, extending along wire-bond edge.

NIR sensors HgCdTe Working with Rockwell Tracking developments within WFC3 —Dark current ok —Read noise larger than expected —QE being addressed in a new growth of crystals Future activities Acquiring our own RSC mux in May Acquiring our own RSC sensor in Summer 2002 Explore alternative technologies – there may be none.

Shortwave HdCdTe Development Hubble Space Telescope Wide Field Camera 3 WFC-3 replaces WFPC-2 CCDs & IR HgCdTe array Ready for flight July  m cut off 18  m pixel 1024 x 1024 format Hawaii-1R MUX Dark current consistent with thermoelectric cooling < 0.5 e/s at 150 K ~0.02 e-/s at 140 K Expected QE ~60%  m Individual diodes show good QE WFC-3 IR NIC-2

Slit Plane Detector Camera Prism Collimator Integral Field Unit Spectrograph Design SNAP Design:

Mirror Slicer Stack R&D

PSF sampling with a slice At slit mirror At pupil mirror Detector sampling Diffraction Analysis Throughput: better than 90.6% (reflectance + diffraction+edge)

Technology readiness and issues NIR sensors  HgCdTe devices are begin developed for WFC3 and ESO with appropriate wavelength cutoff.  Read noise and QE not yet demonstrated. CCDs  We have demonstrated radiation hardiness that is sufficient for the SNAP mission  Extrapolation of earlier measurements of diffusion's effect on PSF indicates we can get to the sub 4 micron level. Needs demonstration.  Industrialization of CCD fabrication has produced useful devices need to demonstrate volume  ASIC development is required. Filters – we are investigating three strategies for fixed filters.  Suspending filters above sensors  Direct deposition of filters onto sensors  Filter Wheel

Technology readiness and issues On-board data handling  We have opted to send all data to ground to simplify the flight hardware and to minimize the development of flight-worthy software.  Ka-band telemetry, and long ground contacts are required. Goddard has validated this approach. Calibration  There is an active group investigating all aspects of calibration. Pointing  Feedback from the focal plane plus current generation attitude control systems may have sufficient pointing accuracy so that nothing special needs be done with the sensors. Telescope  Thermal, stray light, mechanical control/alignment Software  Data analysis pipeline architecture

Status Dark Energy a subject of the recent National Academies of Science Committee on the Physics of the Universe (looking at the intersection of physics and astronomy). One of eleven compelling questions: “What is the Nature of the Dark Energy?” HEPAP subpanel strong endorsement for continued development of SNAP APS/DPF held Snowmass meeting part of 20 year planning process for field —“resource book” on SNAP science out on CDROM International collaboration is growing, currently 15 institutions. 18 talk & 7 posters at recent AAS meeting

SNAP Collaboration G. Aldering, C. Bebek, W. Carithers, S. Deustua, W. Edwards, J. Frogel, D. Groom, S. Holland, D. Huterer*, D. Kasen, R. Knop, R. Lafever, M. Levi, S. Loken, P. Nugent, S. Perlmutter, K. Robinson (Lawrence Berkeley National Laboratory) E. Commins, D. Curtis, G. Goldhaber, J. R. Graham, S. Harris, P. Harvey, H. Heetderks, A. Kim, M. Lampton, R. Lin, D. Pankow, C. Pennypacker, A. Spadafora, G. F. Smoot (UC Berkeley) C. Akerlof, D. Amidei, G. Bernstein, M. Campbell, D. Levin, T. McKay, S. McKee, M. Schubnell, G. Tarle, A. Tomasch (U. Michigan) P. Astier, J.F. Genat, D. Hardin, J.- M. Levy, R. Pain, K. Schamahneche (IN2P3) A. Baden, J. Goodman, G. Sullivan (U.Maryland) R. Ellis, A. Refregier* (CalTech) J. Musser, S. Mufson (Indiana) A. Fruchter (STScI) L. Bergstrom, A. Goobar (U. Stockholm) C. Lidman (ESO) J. Rich (CEA/DAPNIA) A. Mourao (Inst. Superior Tecnico,Lisbon)

SNAP Reviews/Studies/Milestones Mar 2000SAGENAP-1 Sep 2000NASA Structure and Evolution of the Universe (SEU) Dec 2000NAS/NRC Committee on Astronomy and Astrophysics Jan 2001DOE-HEP R&D Mar 2001DOE HEPAP Jun 2001NASA Integrated Mission Design Center July 2001NAS/NRC Committee on Physics of the Universe Nov 2001CNES (France Space Agency) Dec 2001NASA/SEU Strategic Planning Panel Dec 2001NASA Instrument Synthesis & Analysis Lab Mar 2002SAGENAP-2 NOW July 2002DOE/SC-CMSD R&D (Lehman) Sept 2002NASA/SEU Releases Roadmap Oct 2002CNES Review

Timelines for Selected Roadmap Projects.Approximate decision points are marked in black.R&D is marked in yellow,construction in green,and operation in blue. Roadmap for Particle Physics

A Resource for the Science Community

SNAP at the American Astronomical Society Meeting, Jan Oral Session 111. Science with Wide Field Imaging in Space: The Astronomical Potential of Wide-field Imaging from Space S. Beckwith (Space Telescope Science Institute) Galaxy Evolution: HST ACS Surveys and Beyond to SNAP G. Illingworth (UCO/Lick, University of California) Studying Active Galactic Nuclei with SNAP P.S. Osmer (OSU), P.B. Hall (Princeton/Catolica) Distant Galaxies with Wide-Field Imagers K. M. Lanzetta (State University of NY at Stony Brook) Angular Clustering and the Role of Photometric Redshifts A. Conti, A. Connolly (University of Pittsburgh) SNAP and Galactic Structure I. N. Reid (STScI) Star Formation and Starburst Galaxies in the Infrared D. Calzetti (STScI) Wide Field Imagers in Space and the Cluster Forbidden ZoneM. E. Donahue (STScI) An Outer Solar System Survey Using SNAPH.F. Levison, J.W. Parker (SwRI), B.G. Marsden (CfA) Oral Session 116. Cosmology with SNAP: Dark Energy or WorseS. Carroll (University of Chicago) The Primary Science Mission of SNAPS. Perlmutter (Lawrence Berkeley National Laboratory) The Supernova Acceleration Probe: mission design and core surveyT. A. McKay (University of Michigan Sensitivities for Future Space- and Ground-based SurveysG. M. Bernstein (Univ. of Michigan) Constraining the Properties of Dark Energy using SNAPD. Huterer (Case Western Reserve University) Type Ia Supernovae as Distance Indicators for CosmologyD. Branch (U. of Oklahoma) Weak Gravitational Lensing with SNAPA. Refregier (IoA, Cambridge), Richard Ellis (Caltech) Strong Gravitational Lensing with SNAPR. D. Blandford, L. V. E. Koopmans, (Caltech) Strong lensing of supernovaeD.E. Holz (ITP, UCSB) Poster Session 64. Overview of The Supernova/Acceleration Probe: Supernova / Acceleration Probe: An Overview M. Levi (LBNL) The SNAP TelescopeM. Lampton (UCB) SNAP: An Integral Field Spectrograph for Supernova IdentificationR. Malina (LAMarseille,INSU), A. Ealet (CPPM) Supernova / Acceleration Probe: GigaCAM - A Billion Pixel ImagerC. Bebek (LBNL) Supernova / Acceleration Probe: Cosmology with Type Ia SupernovaeA. Kim (LBNL) Supernova / Acceleration Probe: Education and OutreachS. Deustua (LBNL)

Conclusion SNAP will provide space observations of thousands of supernovae needed to characterize the “dark energy” accelerating the expansion of the universe and may lead to a fuller understanding of gravity & space-time.