HESSI Science Objective Impulsive Energy Release in the Corona Acceleration of Electrons, Protons,...
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Transcript of HESSI Science Objective Impulsive Energy Release in the Corona Acceleration of Electrons, Protons,...
HESSI Science ObjectiveHESSI Science Objective
Impulsive Energy Release in the Corona Acceleration of Electrons, Protons, and Ions Plasma Heating to Tens of Millions of degrees Energy and Particle Transport and Dissipation
To explore the basic physics ofparticle acceleration and
explosive energy release in Solar Flares
A1309.03
HESSI Non-Solar Science HESSI Non-Solar Science ObjectivesObjectives
The Crab Nebula
– Imaging spectroscopy with 2” resolution Gamma Ray Bursts and Cosmic Transient Sources
– Detected over a large fraction of the sky
– High resolution spectroscopy
– Search for cyclotron line features Steady X-ray and gamma-ray sources (point and diffuse)
– Detect by Earth occultation or through the rear grids
– Obtain high resolution spectra
– Search for line features
A1309.04
HESSI Primary ObservationsHESSI Primary Observations
Hard X-ray Images– Angular resolution as fine as 2 arcseconds– Temporal resolution as fine as 10 ms– Energy resolution of <1 keV from 3 keV to 400
keV High Resolution X-ray and Gamma-ray Spectra
– keV energy resolution– To energies as high as 15 MeV
A1309.05
Complementary ObservationsComplementary Observations
SOHO EUV images and spectra
Coronagraph images
Particle spectra and abundances
GOES Images from the Soft X-ray Imager
ACE Energetic particle spectra and abundances
TRACE UV & XUV high resolution images
CGRO X-ray and gamma-ray spectra and time histories
Ground-based Observatories
Radio and optical images and spectra
Magnetograms
A1309.06
HESSI FirstsHESSI Firsts
Hard X-Ray Imaging Spectroscopy
High Resolution Spectroscopy of Solar Gamma-Ray Lines
Hard X-Ray and Gamma-Ray Imaging above 100 keV
Imaging of Narrow Gamma-Ray Lines
High Resolution X-ray and Gamma-Ray Spectra of Cosmic Sources
Hard X-Ray Images of the Crab Nebula with 2-arcsecond Resolution
A1309.07
Relevance to Strategic PlanRelevance to Strategic Plan
Part of the Solar Connections Program - in the Roadmap for the next solar maximum.
Seeks to understand fundamental physics of solar flare energy release and particle acceleration.
Relevant to understanding relation between flares and coronal mass ejections and their effects on the Earth and its environs.
A1309.08
Expected Numbers of FlaresExpected Numbers of Flares
Microflares Tens of thousands
Hard X-ray flares with crude imaging and spectra >1000to >100 keV
Hard X-ray flares with >103 counts s-1 detector-1 Hundredsabove 20 keV allowing spatial scales to befollowed on timescales of 0.1 s
Flares sufficiently intense to allow the finest Tenspossible imaging spectroscopy
Flares with the detection of gamma-ray lines Up to 100
Flares with detailed gamma-ray line spectroscopy Tensand the location and extent of the sourcedetermined to ~40 arcseconds
HESSI Observational HESSI Observational CharacteristicsCharacteristics
Energy Range 3 keV to 15 MeV Energy Resolution ~1 keV from 3 keV to 1 MeV
Increasing to 5 keV at 15 MeV Angular Resolution 2 arcseconds to 100 keV
7 arcseconds to 400 keV
36 arcseconds to 15 MeV Temporal Resolution Tens of ms for basic image
2 s for detailed image Field of View Full Sun Effective Area - cm2 10-3 at 3 keV, 1 at 10 keV
100 at 100 keV, 50 at 10 MeV Numbers of flares ~1000 imaged to >100 keV.
~100 with spectroscopy to ~10 MeV
HESSI SummaryHESSI SummaryInstrument 9 germanium detectors (7-cm dia. x 8 cm)
Cooled to 75 K with Sunpower cooler
Grid pitches from 34 microns to 2.75 mm
1.55-m grid separation
Solar Aspect System to <1 arcsecond
Roll Angle System to 1 arcminute
Weight 120 kg
Power 110 watts
Telemetry <11 Gbits/day
Spacecraft Spinning at 12 - 20 rpm
Pointing to within 0.1° of Sun center
Launch Vehicle Pegasus XL from KSC
Orbit 38° inclination
600 km altitude, >3-year life
Launch Datemid-2000
Operations 3 yearsA1309.011
HESSI PI and Co-IsHESSI PI and Co-IsRobert Lin University of California, Berkeley PI
Brian Dennis GSFC/682 Mission ScientistCarol Crannell GSFC/682 Education & Outreach Gordon Holman GSFC/682 Flare TheoryReuven Ramaty GSFC/661 Flare TheoryTycho von Rosenvinge GSFC/661 ACE Collaboration
Patricia Bornmann NOAA GOES CollaborationRichard Canfield Montana State University Ground-based ObservationsGordon Emslie Huntsville Flare TheoryHugh Hudson Solar Physics Research Corp. ImagingGordon Hurford Caltech ImagingNorman Madden LBNL Germanium Detectors
Arnold Benz Inst. of Astronomy, Zurich, Switzerland Radio ObservationsJohn Brown Univ. of Glasgow, Scotland Flare TheoryShinzo Enome NAO, Japan Radio ObservationsTakeo Kosugi NAO, Japan ImagingFrank van Beek Delft Univ., The Netherlands Grids and ImagingNicole Vilmer Observatoire de Paris, Meudon, France Data AnalysisAlex Zehnder Paul Scherrer Inst. Switzerland Telescope design
and fabrication
A1309.012
HESSI Prime ResponsibilitiesHESSI Prime Responsibilities
UC Berkeley Germanium detectors & electronics
I & T
Ground station, MOC/SOC
Data Analysis
GSFC Grid characterization & testing
Cooler, cryostat design
Data analysis, distribution, and archiving
PSI (Switzerland) Telescope & aspect system
Thermo Electron Tecomet Finest grids (#1 - 4)
van Beek (The Netherlands) Coarser grids (#5 - 9) & mounts
Spectrum Astro Spacecraft
A1309.013
GSFC InvolvementGSFC InvolvementScience
Dennis (682) Mission Scientist
Hurford (Caltech) Imaging Scientist
Holman (682), Ramaty (661) Solar flare physics
von Rosenvinge (661) ACE/HESSI coordination
Crannell (682) Education & Public Outreach
Imaging
Clark (547), Amato (544) Grid environmental testing
Orwig (682), Lang (CUA),
Uribe (Raytheon ITSS) Optical & X-ray grid characterization
Schmahl (UMd) Image reconstruction
Spectrometer
Boyle (713) Cryostat design, cooler evaluation
Provide flight-qualified Sunpower cooler
Schwartz (Raytheon ITSS) Spectral deconvolution
Data Analysis
Gurman (682), Zarro (ARC) Solar Data Analysis Center
Tolbert (Raytheon ITSS) Data archiving and distribution
A1309.014
HESSI Imaging ParametersHESSI Imaging Parameters
Test Fine GridsTest Fine Grids
A1309.015
Tecomet Grid #1
Material: MolybdenumPitch: 34 micronsSlit width: 15 micronsTotal thickness: 1.2 mmLayer thickness: 15 micronsNo. of layers: 75Active area: 9 cm diameterAspect ratio: >50:1
• Second of two identical grids fabricated by Thermo Electron Tecomet in Woburn, MA.
• Finest, high-aspect-ratio X-ray collimator ever made.
• Provides modulation to X-ray energies in excess of 100 keV.
• Allows imaging on HESSI with an angular resolution of 2 arcseconds.
• Picture shows circular active area with fiducial and mounting features in the integral rim.
• Direction of slits is revealed by the white bar at 45º resulting from light transmitted from below through the ~1º opening angle of each slit.
Tecomet Grid #1
HESSI Top Grid TrayHESSI Top Grid Tray
Tecometgrid
van Beek grid
Aspect systemlens
Germanium DetectorGermanium Detector
A1309.019
Sunpower M77 Stirling-Cycle CoolerSunpower M77 Stirling-Cycle Cooler
Instrument SensitivityInstrument Sensitivity
Angular Coverage vs. Photon EnergyAngular Coverage vs. Photon Energy
Relative Modulation AmplitudeRelative Modulation Amplitudevs. Photon Energyvs. Photon Energy
Composite Flare SpectrumComposite Flare Spectrum
Energy Resolution vs. Photon Energy Resolution vs. Photon EnergyEnergy
A1309.024
Count Rates in Each Detector for Count Rates in Each Detector for One RotationOne Rotation
A1309.025
Prelaunch Twist Monitoring Prelaunch Twist Monitoring System (TMS)System (TMS)
A1309.026