IBEX%20Concept%20Study%20Site%20Visit

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Presented by Dave McComas Southwest Research
InstituteSan Antonio, Texas on Behalf of the
IBEX Science Team
PI Dave McComas Co-Is Peter Bochsler Maciej
Bzowski Hans Fahr Horst Fichtner Priscilla
Frisch Herb Funsten Steve Fuselier Mike
Gruntman Vlad Izmodenov Paul Knappenberger Marty
Lee Stefano Livi Don Mitchell Eberhard
 Möbius Tom Moore Ed Roelof Nathan
Schwadron Peter Wurz Gary Zank Collaborators F
rederic Allegrini Mike Collier George
Gloeckler David Hollenbach Dan Reisenfeld Martin
Wieser Manfred Witte
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Whats an IBEX?
Picture from San Antonio Zoo

• ibex  n. Any of several wild goats of the
  genus Capra native to the mountains of Eurasia
  and northern Africa, having long, ridged,
  backward-curving horns.

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Outline

• The Heliosphere, Astrospheres and the
  Interstellar Interaction
• Energetic Neutral Atoms ENAs, ENA Imaging and
  IBEX Science
• IBEX Flight System, Mission Design, Launch, Orbit
  and Sky Coverage
• IBEX Payload and Instrumentation
• IBEX Operations, Science, Broad Implications and
  E/PO

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The Heliosphere, Astrospheres and the
Interstellar Interaction
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The Sun and Local Interstellar Medium (LISM)
Image courtesy of L. Huff/P. Frisch
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Our Heliosphere
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Complicated Heliosphere LISM Interaction

• Indirect observations
• Anomalous Cosmic Rays (ACR)
• Radio emissions
• Inferred complications
• Inner/Outer heliosheaths
• Hydrogen wall
• Until 1 year ago, everything we thought we knew
  had been from models and indirect observations

Simulation courtesy of G. Zank.
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Voyager 1 Reaches the Termination Shock
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Voyager 1 Particle Observations

• Two precursor events (AC)
• Enhancements in particle fluxes
• Slowing of flow
• No magnetic field enhancements
• TS crossing in the end of 2004 - 94 AU
• Nearly no flow
• Enhanced mag field
• Single polarity field

Decker et al., 2005
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Energetic Particles and ACRs

• Energetic particle spectra just past TS
• Low energy particles fit power law
• High Energy ACRs
• Still modulated below 100 MeV
• ACR spectrum not unfolded into single power law
  as predicted

Decker et al., 2005
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New Results from Voyager 1

• Voyager 1 just crossed through the TS at 94 AU
• Energetic particle enhancements
• Abrupt increase in the magnetic field magnitude
• These observations are, however, puzzling
• Contradict essentially all prior model
  predictions
• No evidence of local generation of Anomalous
  Cosmic Rays (ACRs)
• Clearly show how little we really know about our
  local cosmic accelerator
• Are ACRs generated only at special, favored
  acceleration regions on the shock?
• Are they accelerated only at some times at any
  given shock location?
• Are we completely wrong and ACRs are accelerated
  at some location further out, beyond the
  termination shock?
• Many mysteries surround Voyagers detailed
  single-point observations
• Local observations beg the question of the global
  interaction

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Astrospheres
Closeup of IRS8, resolving the bow-shock of a
fast-moving star
Left image courtesy of R. Casalegno, C.
Conselice et al., WIYN, NOAO Other images from
HubbleSite.org
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If We Could See Our Heliosphere
What would it look like?
Image courtesy of L. Huff/P. Frisch box image
courtesy of R. Casalegno, C. Conselice et al.,
WIYN, NOAO
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Energetic Neutral Atoms ENAs, ENA Imaging and
IBEX Science
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ENAs Illuminate the Global Termination Shock

• Supersonic solar wind must slow down and heat
  before it reaches the interstellar medium
• Large numbers of interstellar neutrals drift into
  heliosphere
• Ly-a backscatter
• interstellar pickup ions
• Hot solar wind charge exchanges with interstellar
  neutrals to produce ENAs
• Substantial ENA signal from outside the
  termination shock guaranteed from first principles

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ENA Observations Image the 3-D Heliosphere
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Seeing our HeliosphereDiscovering and Exploring
its Interaction with the Galaxy
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IBEXs Sole, Focused Science Objective

• IBEXs sole, focused science objective is to
  discover the global interaction between the solar
  wind and the interstellar medium.
• IBEX achieves this objective by taking a set of
  global energetic neutral atom (ENA) images that
  answer four fundamental science questions

1. What is the global strength and structure of the
   termination shock?
2. How are energetic protons accelerated at the
   termination shock?
3. What are the global properties of the solar wind
   flow beyond the termination shock and in the
   heliotail?
4. How does the interstellar flow interact with the
   heliosphere beyond the heliopause?

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IBEX Science Critical to NASA and NRC Plans

• The Sun to the Earth and Beyond A Decadal
  Research Strategy in Solar and Space Physics
  (2002)
• Challenge 2 Understanding heliospheric
  structure, the distribution of magnetic fields
  and matter throughout the solar system, and the
  interaction of the solar atmosphere with the
  local interstellar medium. The boundary between
  the solar wind and the local interstellar medium
  (LISM) is one of the last unexplored regions of
  the heliosphere. Very little is currently known
  about this boundary or the nature of the LISM
  that lies beyond it. certain aspects of these
  regions can be studied by a combination of remote
  sensing and in situ sampling techniques. This
  investigation could be accomplished by a mission
  to obtain energetic neutral atom images of the
  heliospheric boundary. Such a mission is gauged
  to be feasible within the resource limits of the
  Explorer program
• Sun-Earth Connection Roadmap 2003-2028
  Understand how the Sun, Heliosphere, and the
  Planetary Environments are Connected in a Single
  System (January 2003)
• An entirely new level of information on the
  interface between the heliosphere and the LISM is
  required. Imaging of the outer boundaries 100
  AU away can also be done from orbits near 1AU.
  Remote-sensing techniques such as energetic
  neutral atom (ENA) imaging of energetic
  protonsnear the termination shock and in the
  heliosheath should provide additional diagnostics
  of the interfaces with the galaxy.
• National Aeronautics and Space Administration
  2003 Strategic Plan
• Objective 5.13 Understand the changing flow of
  energy and matter throughout the Sun,
  heliosphere, and planetary environments. We
  also will show how the outer layers of the solar
  atmosphere are energized, and we will track the
  causes of terrestrial disturbancesEven the
  interstellar gas that enters the solar system can
  be analyzed using remote sensing.

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Global ENA Images Questions I III

• Global ENA images easily differentiate types of
  TS interactions
• Gross Differences
• Upstream/Downstream
• Dawn/Dusk
• North/South
• Subtle asymmetries in global images illuminate
  flow patterns beyond the termination shock

Extremes of differential ENA fluxes from 0.3-0.6
keV predicted for a strong gas-dynamical TS (top)
and a TS weakened by a large pickup ion pressure
(bottom) Gruntman et al., 2001.
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Global Energy Spectra Questions I, II III

• ENA energy spectra provide direct measures of
  ions beyond TS
• Solar wind
• Pickup Protons
• Energetic protons
• Spectra as a function of direction show 3D
  configuration of the shock and energy partition
  of the ions at the shock
• Spectra also provide information about how EP
  pressure modifies the TS and what types of
  injection processes may be at work there

Predicted ENA distributions near HSp nose for
strong (black) and weak (green) TS Gruntman et
al., 2001. ENAs gt1 keV are accelerated inner
heliosheath protons based on projecting observed
distributions beyond TS.
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Interstellar Neutral Oxygen Question IV

• Question IV-Interstellar Flow and interaction
• First direct measurements of filtered
  interstellar neutral oxygen
• Measure speed, direction and temperature of the
  interstellar oxygen inside TS
• Compare to unfiltered He
• Provide information about filtration and the
  interstellar interaction further out, beyond the
  heliopause

Neutral O flux as a function of velocity angle
measured during optimum times twice each year.
The filtered secondary population is slower,
hotter and more strongly deflected than the
primary population.
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The IBEX Approach Levels of Exploration
Broadly scoped science strategy with three levels
of exploration

• Discovery level
• Discover global, fundamental properties of the
  interstellar interaction
• Directly available from IBEX data products
  MODEL INDEPENDENT!
• Exploration Level
• Explore global fundamental properties of
  interstellar interaction
• Combining IBEX data products with simple
  physics-based calculations, theory and limited
  modeling ONLY
  SLIGHTLY MODEL DEPENDENT
• Understanding Level
• Understand in depth global properties of the
  interstellar interaction
• Iterative analysis using IBEX data to test
  refined 3D models of the heliosphere - MODEL
  DEPENDENT DRIVES MODELS

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Measurement Requirements
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IBEX Flight System, Mission Design, Launch, Orbit
and Sky Coverage
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Lead Institutional Responsibilities
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IBEX S/C Simple Sun-Pointed Spinner
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IBEX Launch June 2008

• Launch ops
• Pegasus XL
• First use of Solid Rocket Motor (SRM) on top of
  Pegasus
• Orbit raising
• STAR-27 SRM to 12 RE
• S/C hydrazine system boosts apogee to 25-50 RE
  perigee to 7000 km

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Mission Design Maximizes Heliospheric Viewing

• Routine Operations
• Nominal orbit 25-50 Re x 7000 km altitude, 3-8
  days per orbit
• Sun-pointing spinning S/C (4 rpm)
• Science Observations gt 10 Re
• Engineering lt 10 Re
• Data download and command upload
• Adjust spin axis 5 (Earths orbital motion)
• Nearly full sky viewing each 6 months

Earths Magnetosphere
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High Sensitivity Observations Provide Good
Statistics
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IBEX Payload and Instrumentation
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How ENA Sensors Work
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IBEX Payload

• IBEX-Hi
• Energy range 0.3-6 keV
• Team LANL (Lead), UNH, SwRI

• IBEX-Lo
• Energy range 0.01-2 keV
• Team LMATC (Lead), UNH, GSFC, APL

• CEU
• Provides electronic support and control for
  payload
• Developed by SwRI

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IBEX-Lo Subsystems
TOF (Cluster/CODIF)
Collimator (Phase A Prototype)
ENA? Ion Conversion (IMAGE/LENA)
Ion ESA (Polar/TIMAS)
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IBEX-Lo Full-Scale Prototype

• IBEX prototype
• Flight quality CVD DLC conversion surface
• Verified ion optics
• Verified background suppression
• Separate collimator tests
• Separate mass (TOF) subsystem tests using
  Stereo/PLASTIC

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IBEX-Hi Subsystems
Collimator (Phase A Prototype)
ENA ? Ion Conversion (IMAGE/MENA)
Coincidence Subsystem
Standard ESA
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IBEX-Hi Full-Scale Prototype

• IBEX-Hi prototype verified all major sensor
  characteristics
• Ionization of hydrogen ENAs
• Verification of ion optics
• Double and triple coincidence
• Good agreement with electro-optic simulations
• Detector backgrounds
• Separate collimator tests

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Payload Cross-Calibration
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Potential Noise and Background Sources
Noise Source Background Source
Diffuse UV, UV from stars ENAs from planetary magnetospheres
X-rays from photoelectron acceleration toward, and impact with, biased collimator grids Ions from magnetosheath and foreshock
Photoelectrons and secondary electrons generated at conversion surface Charge exchange of plasma ions with outgassing spacecraft species
Penetrating radiation radionuclide decay in detectors Secondary ions generated in entrance subsystem
Penetrating radiation cosmic rays ENAs from CMEs, CIRs, and pickup ion charge exchange in the heliosphere
Penetrating radiation Solar Energetic Particle events
Penetrating radiation Magnetospheric energetic particles

• Noise the result of particles that generate
  uncorrelated (non-coincident) counts in the
  sensor detectors
• UV
• X-rays
• Photo and secondary electrons
• Penetrating radiation
• Background the result of an ion or atom that
  masquerades as a signal ENA in the IBEX sensors
• ENAs
• Ions

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Large Signal/Noise at all Energies
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Integration of IBEX Payload
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IBEX Operations, Science, Broad Implications and
E/PO
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IBEX Ground Segment
IBEX ScienceOperations Center(ISOC) (SwRI)
Antenna Sites (USN)
Mission Control Center (MCC) (Orbital)
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End-to-End Data Flow
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Broad Science Opportunities

• Critical new heliospheric observations
• 2M IBEX-funded GI program
• NASA peer-reviewed and selected
• Supports researchers outside of IBEX science team
• Astrophysical connections
• Composition of LISM
• Heliosphere Astrosphere comparisons ? ground
  truth
• Team astrophysicists help ensure broad
  astrophysics connections
• High sensitivity magnetospheric ENA observations

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Relevant to Exploration GCR Shielding
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Education and Public Outreach E/PO

• Led by Adler Planetarium Astronomy Museum with
  12 national partners
• Active engagement of PI science team
• Full 2 funding ( 1.8M) guaranteed as Level 1
  programmatic requirement
• Additional Adler contribution of 650k

Single aspect of IBEX that will most engage the
general public Visualization of our home in the
galaxy and how it may have evolved over time and
affected the formation and development of life in
the solar system
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Upcoming Planetarium Show
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Audience Member Unveiled
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Summary

• ENA imaging is the only way to globally observe
  the interaction between the solar wind and the
  interstellar medium (structures, dynamics,
  energetic particle acceleration and charged
  particle propagation) in the complex region that
  separates our solar system from the galactic
  environment
• IBEX launches in June 2008 to make the first
  global observations of the outer heliosphere,
  discovering the global interaction between the
  solar wind and the interstellar medium on a
  low-cost (SMEX) budget
• IBEXs first global observations of the
  interstellar interaction will disclose its
  fundamental nature and provide the observations
  needed for detailed modeling and in-depth
  understanding

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Interstellar Boundary Explorer
Interstellar Boundary Explorer IBEX It is time
for IBEXs breakthrough mission of exploration
and discovery beyond the planets!
Imaging the Edge of Our Solar System and Beyond
Any Questions?