SuperNova Acceleration Probe SNAP

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SuperNova / Acceleration Probe (SNAP)

• Saul Perlmutter
• LBNL Physics Division Directors Review
• November 5, 2003

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The Expansion History of the Universe
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The Expansion History of the Universe
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The Expansion History of the Universe
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The Expansion History of the Universe
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Whats wrong with a non-zero L
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Whats wrong with a non-zero L
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Requirements Development
Science

• Measure ?M and ?
• Measure w and w (z)

Systematics Requirements
Statistical Requirements

• Identified and proposed systematics
• Measurements to eliminate / bound each one to
  /0.02 mag

• Sufficient (2000) numbers of SNe Ia
• distributed in redshift
• out to z lt 1.7

Data Set Requirements

• Discoveries 3.8 mag before max
• Spectroscopy with l/dl100
• Near-IR spectroscopy to 1.7 ?m

Satellite / Instrumentation Requirements

• 2-meter mirror Derived requirements
• 1-degree imager High Earth orbit
• Low resolution spectrograph 300 Mb/sec
  bandwidth (0.35 ?m to 1.7 ?m)

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SPACECRAFT CONFIGURATION
Secondary Mirror Hexapod and Lampshade Light
Baffle
Door Assembly
Main Baffle Assembly
Secondary Metering Structure
Primary Solar Array
Primary Mirror
Optical Bench
Solar Array, Dark-Side
Instrument Metering Structure
Instrument Radiator
Tertiary Mirror
Fold-Flat Mirror
Instrument Bay
Spacecraft
Shutter
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Pre-conceptual Design Period

• SNAP currently in pre-conceptual design period
• Development of collaboration
• Performing critical RD of new technologies, cost
  mitigation
• Requirements development
• Feasibility and early trade studies
• Transition to conceptual design development
  December 2004
• Complete ZDR and Mission concept study
• Funding rate needs to double in FY05 to complete
  technology studies
• During Conceptual Design period through December
  2005
• Complete RD
• Engineered Cost Schedule development
• Development of conceptual design report and
  associated documentation

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RD Top Schedule
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SNAP Reviews/Studies/Milestones
Nov 1999 Preproposal ad hoc committee review Mar
2000 SAGENAP-1 (recommends RD) Sep 2000 NASA
Structure and Evolution of the Universe (SEU) Dec
2000 NAS/NRC Committee on Astronomy and
Astrophysics Jan 2001 DOE-HEP Review RD (SNAP is
uniquely able) Mar 2001 DOE High-Energy Physics
Advisory Panel (HEPAP) Jun 2001 NASA Integrated
Mission Design Center (determines
feasibility) July 2001 Snowmass Workshop
(Community analysis) July 2001 NAS/NRC Committee
on Physics of the Universe Nov 2001 CNES (France
Space Agency) Dec 2001 NASA/SEU Strategic
Planning Panel Dec 2001 NASA Instrument Synthesis
Analysis Lab Jan 2002 Two Special Sessions at
AAS Meeting Jan 2002 HEPAP subpanel report HEP
Long Range Planning Mar 2002 SAGENAP-2 Apr
2002 NRC/Committee on Physics of the Universe
releases report July 2002 DOE/SC-CMSD RD
(Lehman) Oct 2002 CNES Review Dec 2002 JPL Team-X
Study (studies potential NASA cost) Jan 2003 Two
Special Sessions at AAS Meeting Jan 2003 NASA
releases SEU roadmap Beyond Einstein Feb
2003 DOE HEP Facilities Prioritization Panel Feb
2003 SNAP in the Presidents DOE budget Mar
2003 DOE HEP releases Facilities 20 Year
Roadmap
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Lehman Review Key Recommendations (July 2002)

• The need for a space-based, large field of view
  mission like SNAP to elucidate the nature of the
  Dark Energy via the study of Type Ia supernovae
  has been convincingly established.
• The proposed instruments and observing strategy
  are appropriate and sufficient to complete the
  scientific objectives of the mission.
• The detailed simulations, optimizations, and
  comparisons with ground-based facilities that
  were completed by SNAP and on which the above two
  conclusions are based should be published as soon
  as practical so they may be viewed by the wider
  community.
• The RD effort necessary to move this project
  forward should be pursued with all possible
  speed.
• The studies of weak lensing and other topics
  relevant to cosmological parameters with SNAP
  should be pursued further during the RD period.

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What Constitutes a Simulation?

• Simulate the Universe being observed
• Supernova behavior and intrinsic variations of
  SNe
• Redshift distributions of SNe
• Redshift/size/magnitude distributions of galaxies
  and stars
• Host-galaxy dust
• Intergalactic dust
• Gravitational lensing
• Dark Energy equation of state
• Simulate the Instrumentation and Detection
  Process
• Telescope collecting area and losses
• Distortions and Point Spread Function (PSF)
• Filter selection and spectrograph resolution
• Atmospheric effects (from ground)and zodiacal
  background
• Detector efficiency, noise, and spatial response
• Dithering, undersampling, and cosmic rays.
• Simulate the Extraction of Cosmological
  Parameters from Mission Data
• Simulate mission duration and target selection
  observing schedule.
• Model of calibration procedure and uncertainties
• Standardization process for SNe Ia (K
  corrections, dust, stretch, etc.)

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Supernova Mission Simulator

• With our Monte Carlo
• Have simulated SNAP with detector characteristics
  and observing program
• Have simulated other potential experiments
  including ground-based instruments
• Use state-of-the-art SNe models that simulate SNe
  population drift with redshift
• Included systematic effects and calibration
  errors
• Can generate error ellipses for cosmological
  parameters
• Can optimize SNAP

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Publications of Simulation Work

• Advanced Exposure-Time Calculations
  Undersampling, Dithering, Cosmic Rays. PASP 114
  98 (2001)
• Correcting for lensing bias in the Hubble
  diagram, AA (2003) 397, 819
• Effects of Systematic Uncertainties on the
  Supernova Determination of Cosmological
  Parameters, MNRAS, accepted
• Signal-to-Noise Estimates and Optimization for
  Type Ia Spectroscopy, PASP, submitted
• Supernova / Acceleration Probe A Satellite
  Experiment to Study the Nature of the Dark
  Energy, PASP, submitted
• Requirements on the Redshift Accuracy for Future
  Supernova and Number Count Surveys, (maybe
  submitted by November)
• Several papers in Proc. SPIE V. 4836 (2002),
  including Deep Wide-Field Images foom the SNAP
  Mission
• Also from the Weak-lensing group
• Weak Lensing from Space I Instrumentation and
  Survey Strategy, Astroparticle Physics, accepted
• Weak Lensing from Space II Dark Matter
  Mapping, AJ, submitted
• Weak Lensing from Space III Cosmological
  Parameters, AJ, submitted
• Dark Energy Constraints from Weak Lensing
  Cross-Correlation Cosmology, ApJ (accepted)
• Cosmological Parameters from Lensing Power
  Spectrum Tomography and Bispectrum Tomography,
  MNRAS (submitted)

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Simulated Hubble Diagrams

• Type Ia events with light curves and spectra
  obtained in 1 year of SNAP mission

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SNAPfast Results
(w?wa/2 at z1)
Uncertainties from baseline SNAP mission,
including systematic errors (Akerlof et al 2003).
Planck ellipses include expected cosmic
microwave information c. 2011.
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Present Work Simulation Architecture

• Past year design a software architecture for
  SNAP simulations, SNAPsim, to replace and extend
  the SNAPfast code. Why write a new simulation?
• A detailed simulation with a large number of
  developers requires a common environment with
  well-defined interfaces. The initial simulation
  software consists of independent code written by
  multiple developers.
• IDL, Java, C, Fortran, Perl
• Ad hoc interfaces
• Stringent requirements on traceability,
  reproducibility, and history are not supported in
  the original simulation.
• Not easily adapted to more complex simulation
  tasks, such as parameter looping and inclusion of
  many phenomena simultaneously.
• Need for detailed pixel-level simulations.
• Desire to use a system that can naturally evolve
  into the official analysis pipeline.
• Supernova simulation effort has been primarily
  redirected to SNAPsim framework.
• Weak lensing simulation effort proceeds on ad
  hoc interface mode to expedite basic parameteric
  studies.

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RD Phase Activities Weak Lensing

• Great progress in past year on theoretical
  understanding of the ability of weak lensing to
  constrain time-varying dark energy.
• Power spectrum and bispectrum information
  (Huterer, Takada, Jain)
• Pure geometric methods to use SNAPs
  small-scale, high-quality data (Bernstein, Jain)
• Three concurrent and complementary programs to
  calculate accuracy of dark energy constraints
  from a chosen SNAP instrument/mission choice
• Analytic S/N calculations, a.k.a. Exposure time
  calculator (G. Bernstein, H. Lin)
• Image level simulations (R. Massey)
• Catalog level simulations (A. Stebbins FNAL)
• Advanced WL data reduction algorithms to test
  systematic limits of SNAP WL data (Rusin, Massey)

bispectrum is the product of three Fourier
components, which averages zero for Gaussian
fields.
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Dark Energy Constraints from SNAP
Dark Energy Constraints from Cross-Correlation
Cosmography Bernstein Jain 2004 Constraints
from Power Spectrum and Bispectrum Takada Jain
2003 NOTE Lensing constraints do not contain
systematic error estimates.
(w?wa/2 at z1)
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Limits on WL Systematics

• SNAP WL constraints on dark energy may be limited
  by systematic errors.
• SNAP advantage over ground is primarily in
  freedom from systematic errors.
• Weak lensing is purely geometric effect, so in
  principle the measurements should be limited by
  our ability to measure the shapes of galaxies and
  the PSF. Absence of time-varying atmosphere,
  gravity loads, or thermal loads makes SNAP ideal.
• Current pixel-level lensing measurement
  algorithms do not reach available precision.
• New algorithms have been proposed (Refregier
  Bernstein) but not yet fully implemented or
  tested.
• Work before ZDR to apply new algorithms to space
  ground data, determine respective
  systematic-error floors (Rusin Massey).

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Simulation Questions Tasks
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Issues from Lehman/Responses
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Major Accomplishments in Last Year
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Institutional Responsibilities (Pre-JDEM)
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NIR Progress
Over the last year the SNAP infrared program has
crystallized with several important developments

• Two competing vendors for HgCdTe FPAs (Rockwell
  Science Center (RSC) and Raytheon Vision Systems
  (RVS)
• Alternative sensor technology (InGaAs) under
  investigation
• NIR team assembled (Caltech, IU, JPL, UCLA, UM)
• Detector procurement and development program in
  place
• Active program of device characterization under
  way
• Laboratory facilities in place

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NIR Detector Plan

• Establish large format 1.7 µm cutoff detectors
• Explore detector technology options
• Establish competitive vendor environment
• We have sought to broaden both our technology and
  vendor pool.
• Rockwell MBE HgCdTe
• Raytheon LPE HgCdTe
• Sensors Unlimited/Rockwell InGaAs
• First MCT engineering parts in January / InGaAs lt
  May
• Iteration decision in 2004
• CDR technology and vendor(s) decision in 2005

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Device Delivery Schedule 2004
Devices will be exchanged between labs for
concurrence testing
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Facilities
Michigan IU
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Infrared Detector Development
FY04
FY05
2k x 2k Science Grade
2k x 2k Engineering Grade
2k x 2k Science Grade
Dual Source (HgCdTe) Rockwell Science Center
Source Selection
2k x 2k Science Grade
1k x 1k Engineering Grade
2k x 2k Science Grade
Dual Source (HgCdTe) Raytheon Vision Systems
2k x 2k Science Grade
1k x 1k Engineering Grade
2k x 2k Science Grade
Technology Study (InGaAs) Sensors
Unlimited/Rockwell
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SNAP Visible Sensors

• Major advances in Visible Light Sensors
• CCD electronics
• CCD radiation hardness
• But,
• Dual source dual technology strategy
• Risk mitigation of new technologies
• Achievement of adequate PSF, read noise, yield
• Expanding effort in
• Commercialization effort dual vendor
• Second technology Silicon Hybrid
  (Rockwell/Raytheon)

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Visible Detector Development

• Technology development
• LBNL/DALSA CCDs
• LBNL CCD technology at a traditional CCD vendor
  in negotiation
• Silicon PIN diode hybrids Rockwell (Raytheon)

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Diffusion Measurement Technique
LBNL pinhole projector Beam spot size 1.3 mm
rms Step size 0.4 mm with 0.1 mm resolution
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Dial in PSF with bias voltage
x-y axis pixel number z axis arbitrary
units 1100 x 800 back-illuminated CCD, 15 mm
pixels
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PSF Measurement
6.6 um
Measurement of Lateral Charge Diffusion in
Thick, Fully Depleted, Back-illulminated
CCDs, by C.J. Bebek, A. Karcher,
W.F.Kolbe,D.Maurath,V.Prasad,M.Uslenghi,M.Wager Pr
esented by A. Karcher at 2003 IEEE meeting
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Components for SNAP visible sensors are in
process

• New kind of CCD developed at LBNL
• Better red response than more costly thinned
  devices in use
• High-purity radiation detector silicon has
  better radiation tolerance
• Better PSF enabling small pixels and smaller
  focal plane

Four channel Correlated Double Sampling chip 16
bit dynamic range Noise 3.5e- rms _at_100kpix/s
including CCD noise Cyro-tested, Power 6.5
mW/channel
9 Million 10.5mm pixel CCDs specifically
developed for SNAP Radiation tolerance
demonstrated Readout chip in fabrication
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Visible Detector Development
FY04
FY05
Primary Source (CCD)
2.8k x 2.8k 10mm pixels
3.5k x 3.5k 10mm pixels
3.5k x 3.5k 10 mm pixels
DALSA Frontside LBNL Finish
3.5k x 3.5k 10mm pixels
LBNL Technology
2k x 4k 15mm pixels
3.5k x 3.5k 10 mm pixels
Secondary Source (CCD) LBNL 4 Line
Source Selection
Photodiode Qualification
3.5k x 3.5k 10 mm pixels
Secondary Source (CCD) Industrial Vendor 4
Line
Technology Study (SiPIN)
2k x 2k 18mm pixels
2k x 2k 9 mm pixels
3.5k x 3.5k 9 mm pixels
Silicon Hybrid
Rockwell Science Center
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Instrument electronics
Spectrograph
OCU Mem
Imager
Thermal Ctrl
Star Guider
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Detector front-end electronics

• Goal to mount electronics, cold at the focal
  plane
• Photons to bits on serial cable per detector.

• Required development
• Rockwell SIDECAR for NIR
• SNAP CDSADC for CCD
• CCD clocking-bias system
• DC-DC power supplies

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Linearity measurement (100kHz)
Gain 32
Gain 1
Gain 2
1 DAC count 14mV 2e
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OBSERVATORY Cross Section
Secondary Mirror, Hexapod and Lampshade Light
Baffle
Primary Mirror
Spectrograph
Instrument Dewar
Focal Plane
Instrument Thermal Radiator
Spacecraft
Door Assembly
Fold-Flat Mirror
Primary Solar Array
Main Baffle Assembly
Tertiary Mirror
Optical Bench
Secondary Metering Structure
Stovepipe Baffle
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TELESCOPE MIRROR OPTIONS

• Corning ULE Ultra-Low Expansion Glass
• Face Sheets Bonded to Water-Jetted Honeycomb Core
• 180 mm thick Core with 2.5mm Ribs Typical
• Achieves 85-90 Light weighting
• Extensive Manufacturing History
• Schott Zerodur Glass/Ceramic Material
• Solid Blank, Mass Reduced by Machining Backside
• 190 mm Pockets with 5mm Ribs Typical
• Open Back is Lowest Fabrication Risk
• Semi-Closed Back for Greater Rigidity
• Achieves 70-85 Light weighting
• Extensive Manufacturing History
• All Approaches are Viable for SNAP

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STRAY LIGHT BAFFLE DESIGN

• FUNDAMENTAL BAFFLE DESIGN CONSIDERATIONS
• Top Cut Angle Chosen to Block Sunlight in All
  Science Attitudes
• Earth-Light Region must be Well Baffled
• BaffleLamp ShadeStove Pipe diffraction line
  dictates the Hat Size
• Trades Indicate an Ordinary Aluminum Shell
  Construction is Adequate !
• Detailed ASAP Stray Light analysis are now
  underway !

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TELESCOPE THERMAL

• OPTICS Build,Test, Fly Warm like Hubble !

• High Earth orbit (HEO) to minimize Earth-glow
  Loading
• GaAs - OSR Striping of the (warm) Solar Array
  Panels
• Front surface heat rejection Only
• Optical Solar Reflectors are back silvered
  Quartz tiles (a 8, e 80)
• Low emissivity Silvered Mirrors
• Thermal Isolation mounting and Extensive MLI
  blanketing
• Cool Light Baffle and
• Actively Heated Telescope

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SNAP OBSERVATORY STRUCTURES

• PRIMARY STRUCTURES
• Total, or Integrated Observatory Design Finite
  Element Model (FEM) is done
• Baffle, Door, Telescope, Optics Design Studies
  Posted - Stout Bus defined
• 17 Hz -1st Mode exceeds 10 Hz Delta IV reqmt,
  with 20 Launch Mass Margin

GFRP Composite Telescope Structure
Telescope Light Baffle Structure
17 Hz First Mode
Coffee Table Spacecraft Bus
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SNAP Reviews/Studies/Milestones
Nov 1999 Preproposal ad hoc committee review Mar
2000 SAGENAP-1 (recommends RD) Sep 2000 NASA
Structure and Evolution of the Universe (SEU) Dec
2000 NAS/NRC Committee on Astronomy and
Astrophysics Jan 2001 DOE-HEP Review RD (SNAP is
uniquely able) Mar 2001 DOE High-Energy Physics
Advisory Panel (HEPAP) Jun 2001 NASA Integrated
Mission Design Center (determines
feasibility) July 2001 Snowmass Workshop
(Community analysis) July 2001 NAS/NRC Committee
on Physics of the Universe Nov 2001 CNES (France
Space Agency) Dec 2001 NASA/SEU Strategic
Planning Panel Dec 2001 NASA Instrument Synthesis
Analysis Lab Jan 2002 Two Special Sessions at
AAS Meeting Jan 2002 HEPAP subpanel report HEP
Long Range Planning Mar 2002 SAGENAP-2 Apr
2002 NRC/Committee on Physics of the Universe
releases report July 2002 DOE/SC-CMSD RD
(Lehman) Oct 2002 CNES Review Dec 2002 JPL Team-X
Study (studies potential NASA cost) Jan 2003 Two
Special Sessions at AAS Meeting Jan 2003 NASA
releases SEU roadmap Beyond Einstein Feb
2003 DOE HEP Facilities Prioritization Panel Feb
2003 SNAP in the Presidents DOE budget Mar
2003 DOE HEP releases Facilities 20 Year
Roadmap
48
Report from the NRC Committee on the Physics of
the Universe
Connecting Quarks with the Cosmos

• To fully characterize the expansion history and
  probe the dark energy will require a wide-field
  telescope in space (such as the
  Supernova/Acceleration Probe).
• The Committee further recommends that NASA and
  DOE work together to construct a wide-field
  telescope in space to determine the expansion
  history of the universe and fully probe the
  nature of the dark energy.

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NASA/SEU Roadmap Beyond Einstein
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(No Transcript)
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HEPAP/Facilities Prioritization

• Resolving the mystery of what is the dark energy
  that constitutes more than two-thirds of the
  energy of the present universe is one of the
  leading scientific questions in physics and
  astronomy. .. By observing thousands of Type Ia
  supernovae with better precision than any single
  supernova has ever been measured so far, SNAP
  will measure the history of the growth of the
  universe over the past 10 billion years. The
  science addressed by SNAP in exploring the nature
  of dark energy is absolutely central. It would be
  carried out by an international collaboration and
  would be supported by both the DOE and NASA in
  the U.S. The project is now in the RD phase,
  with plans calling for project engineering and
  design starting in two years, and launch in 2009.

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Priorities
53
Federal Budget

• The FY 2004 SNAP program (8,256,000) will focus
  on developing a conceptual design, the beginning
  of engineering design, and fabrication and
  testing of prototypes for the principal SNAP
  instrument. The goal of this RD effort is to
  produce a complete Conceptual Design Report by
  2006, and funding is increased by 6,876,000 to
  provide the significant resources needed to
  successfully begin the detailed design and
  prototyping phase. This increase is consistent
  with the 2002 HEPAP Subpanel recommendation that
  the physics of SNAP (the dark energy
  phenomenon) is exciting and relevant to HEP, and
  that the RD effort should be supported and the
  recent National Research Council report (Quarks
  to the Cosmos) which identified this
  interdisciplinary research area as a high
  priority for an interagency initiative. DOE is
  actively engaged with NASA to develop a
  successful research effort in this new and
  exciting field.

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NASA NRA
A Multi-Agency Approach to the Dark Energy Probe
The U.S. Department of Energy (DOE) has made
the mystery of dark energy a high science
priority and, under the leadership of its
Lawrence Berkeley National Laboratory, is funding
a study of a possible space mission entitled the
Supernova Acceleration Probe (SNAP) to address
this topic. Therefore, in order to encourage
consideration of all possible approaches, as well
as the potential of interagency collaborations,
mission concept proposals for the Dark Energy
Probe in response to this NASA solicitation may
be of two types, both of which are encouraged
with equal priority Type 1 Proposals
for a full mission investigation concept that
uses any technique to meet the science goals of
the Dark Energy Probe and Type 2
Proposals involving a significant NASA
contribution (gt 25 of the total mission cost) to
the existing DOE SNAP concept mission. Note that
prior endorsement from the SNAP team or DOE is
not required, but the proposal must clearly state
how the proposal team envisions working with the
SNAP team to develop a joint concept.
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Joint Dark Energy Mission

• NASA-DOE Joint Announcement of JDEM (Staffin,
  Hertz)
• Project is joint at the agency, DOE minority
  funder.
• Launch in 2014
• NASA assigned mission management
• 3 year DE investigation defined to be 50-50
• Succeeding 3 year program NASA defined
• Science archive assigned to NASA
• Below agency, at operational level, identical to
  GLAST
• Mission scientist and project manager assigned to
  GSFC
• Cost competitive proposals for PI-led dark energy
  investigation in 2-3 years
• New way of business for DOE-HEP
• Full cost accounting of scientists
• Cost of science and operations in total project
  cost

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Internal Review of SNAP

• SNAP Internal review Nov. 11-13 to study
  technology program
• IR sensor technology development
• Restructuring program to mold around new mandate
• Visible sensor technology development
• Director forming advisory panel, to meet year-end
• Provide feedback on JDEM plan
• GLAST lessons learned
• Advice on cost-based competition facing
  collaboration
• Advice on NASA/DOE overlaps

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Mission Design
58
Mission Design
59
(No Transcript)
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(No Transcript)
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Instrument
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Mission Design

• SNAP design meets these scientific objectives

All detectors occupy same mechanical, thermal,
optical environment.
Spectrograph
Focal plane
shutter
electronics
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Mission Design

• SNAP design meets these scientific objectives
• Integral field optical and IR spectroscopy
  0.35-1.7 mm, 3x6 FOV, low resolution, high
  throughput.

64
Technology Readiness Issues

• Instrument
• NIR sensors
• HgCdTe detectors are begin developed for JWST
• Need to demonstrate performance requirements for
  SNAP (PSF, read noise)
• Visible sensors
• We have demonstrated radiation hardness that is
  sufficient for the SNAP mission
• Industrialization of CCD fabrication has produced
  useful devices. Need to complete
  industrialization. Production of sufficient PSF
  is the challenge
• Electronics
• ASIC development is required (commercial soln.
  for HgCdTe, in house for CCDs)
• Filters
• Investigating three strategies for fixed filters
• Suspending filters above sensors
• Gluing filters to sensors
• Direct deposition of filters onto sensors
• Spectrograph
• Integral Field Unit (Slicer)

65
Technology Readiness and Issues

• Systems
• 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 exists a draft plan, this needs to be
  extended to all aspects of calibration.
• Pointing
• Feedback from the focal plane, plus current
  generation attitude control systems, has
  sufficient pointing accuracy so that no fast
  steering mirror is required
• Telescope
• Primary mirror, thermal, stray light, alignment,
  contamination, IT
• Software
• Data analysis pipeline architecture

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