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Solar Probe Plus: Mission to the Solar Corona

Solar Probe Plus: Mission to the Solar Corona. J. C. Kasper Harvard-Smithsonian Center for Astrophysics S. D. Bale (UCB/SSL), N. Fox (JHU/APL), R. Howard (NRL), D. McComas (SwRI), A. Szabo (GSFC), M. Velli (JPL). Outline. Introduction to Solar Probe Plus Mission objectives and description

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Solar Probe Plus: Mission to the Solar Corona

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  1. Solar Probe Plus: Mission to the Solar Corona J. C. Kasper Harvard-Smithsonian Center for Astrophysics S. D. Bale (UCB/SSL), N. Fox (JHU/APL), R. Howard (NRL), D. McComas (SwRI), A. Szabo (GSFC), M. Velli (JPL) Solar Probe Plus - IAFA 2011 - Alpbach

  2. Outline • Introduction to Solar Probe Plus • Mission objectives and description • Scientific instrument payload • Examples of SPP Science Solar Probe Plus - IAFA 2011 - Alpbach

  3. Solar Probe Plus Objectives Send a spacecraft within 8.5 Rs of the surface of the Sun, entering the solar corona, in order to: (1) Trace the flow of energy that heats and accelerates the solar corona and solar wind (2) Determine the structure and dynamics of the plasma and magnetic fields at the sources of the solar wind (3) Explore mechanisms that accelerate and transport energetic particles. Solar Probe Plus - IAFA 2011 - Alpbach

  4. Why close to Sun? • Coronal magnetic structure still channels the flow • Maxima • Waves, turbulence are strongest • Temperature maximum • Strongest energetic particle production • Transitions • <1 to >1 • Sub-Alfvénic to Super-Alfvénic flow (enter the magnetic field of the Sun) • Collisional – Collisionless transition Solar Probe Plus - IAFA 2011 - Alpbach

  5. Key Dates and Current Project Status • Project formally started in FY 2008 • JHU/APL selected to design spacecraft and run mission in 2009 • Science investigations selected in Fall 2010 • One year Phase A initial design phase • All instruments accommodated on the spacecraft • Mission level 1 requirements written • Preparation for Mission Design Review in October 2011 • Instrument delivery 2017 • Launch 2018 Solar Probe Plus - IAFA 2011 - Alpbach

  6. Organizational Structure • NASA • Solar Probe Plus is part of the NASA Living With a Star line of missions • Adam Szabo (GSFC) is the Mission Scientist • JHU/APL • Building and operated the spacecraft and integrates the instruments • Nicky Fox is the Project Scientist • SWEAP • PI Justin Kasper (SAO) • Solar wind plasma suite • FIELDS • PI Stuart Bale (UCB/SSL) • Electromagnetic field instrument suite • WISPR • PI Russ Howard (NRL) • White light imager • ISIS • PI David McComas (SwRI) • Energetic particle instrument suite • Observatory Scientist • Marco Velli (JPL) Solar Probe Plus - IAFA 2011 - Alpbach

  7. Mission Profile • Launch – July 30, 2018 • First Encounter – October, 2018 (0.16 AU or 35 Rs) • Seven Venus flyby and gravitational assists • SEPTEMBER 27, 2018 • DECEMBER 21, 2019 • JULY 5, 2020 • FEBRUARY 15, 2021 • OCTOBER 10, 2021 • AUGUST 15, 2023 • OCTOBER 31, 2024 • First encounter at closest approach – December 19, 2024 Solar Probe Plus - IAFA 2011 - Alpbach

  8. The Solar Probe Plus Spacecraft Sun Limb Sensor Retractable solar panel Magnetometer boom Water-filled radiator Atlas V 551 Launch Vehicle Carbon heat shield Solar Probe Plus - IAFA 2011 - Alpbach

  9. The Investigations Solar Probe Plus - IAFA 2011 - Alpbach

  10. Solar Wind Electrons Alphas and Protons (SWEAP) Investigation Solar Probe ANalyzers (SPAN) – Electrostatic Analyzers behind the heat shield, detailed measurements of 3D ion and electron velocity distribution functions SWEAP Electronics Module (SWEM) – interface to s/c, operates SPC and SPAN, 32GB internal storage SPAN-A: Looks “ahead”, ions and electrons SPAN-B: Looks “behind”, electrons Solar Probe Cup (SPC) – Faraday Cup faces the Sun, high cadence (up to 128 Hz) bulk ion and electron measurements Themis Solar Probe Plus - IAFA 2011 - Alpbach

  11. Reproducing a solar encounter Solar Probe Plus - IAFA 2011 - Alpbach

  12. SWEAP Observations Solar Probe Cup (SPC) Solar Probe ANalyzers (SPAN) Fine Resolution (FR) 3D VDF at maximum energy and angular resolution at 0.5 Hz Alternating Sweep (AS) Coarse 3D VDF over full energy range and fine resolution 3D VDF at 4 Hz Rapid 2D VDF (RD) High frequency 2D VDF using B from FIELDS • Proton Tracking (PT): 1.5D proton VDF at 8 Hz, solved for Vp, Tp, np • Full Scan (FS) at 1 Hz, e- 1.5D VDF from 50 eV – 2 keV at 0.1 Hz, i+ 1.5D VDF from 50 eV – 8 keV at 0.1 Hz • Flux-Angle (FA): Total flux and flow angles at 128 Hz SPP Mission Kickoff - SWEAP Science Overview

  13. FIELDS Investigation Four electric field antennas for DC-AC electric fields 1 vector search-coil magnetometer for AC vector magnetic fluctuations 2 flux gate magnetometers for “DC” vector magnetic field Solar Probe Plus - IAFA 2011 - Alpbach

  14. FIELDS Observatons Solar Probe Plus - IAFA 2011 - Alpbach

  15. ISIS-EPI (Energetic Particle Instruments) EPI-Lo single wedge prototype EPI-Lo – Electrons (25-500 keV) and ions (0.02-7 MeV protons and 0.02-2 MeV/nuc heavier ions). Resolves all major species and 3He and 4He in multiple directions EPI-Hi – Two Low Energy Telescopes (LET) and a High Energy Telescope (HET) they cover 1 to >100 MeV/ nuc for protons and heavy elements and 0.5 to 6 MeV for electrons Solar Probe Plus - IAFA 2011 - Alpbach

  16. ISIS Observations SWEAP Solar Probe Plus - IAFA 2011 - Alpbach

  17. Wide Field Imager for Solar Probe (WISPR) WISPR – white light images of Thompson scattered sunlight Solar Probe Plus - IAFA 2011 - Alpbach

  18. Polar Wind WISPR Observations • Images over an encounter used to determine large scale structure, inverted to produce electron density profile • High time resolution images used to study variable structures near the spacecraft: shocks, streams, reconnection exhausts, turbulence Solar Probe Plus - IAFA 2011 - Alpbach

  19. Observatory Scientist ?  As the mission's observatory scientist, Marco is responsible for serving as a senior scientist on the science working group. He provides an independent assessment of scientific performance and acts as a community advocate for the mission.  Solar Probe Plus - IAFA 2011 - Alpbach

  20. SP+ Science Solar Probe Plus - IAFA 2011 - Alpbach

  21. Evolution of the energy budget Solar Probe Plus - IAFA 2011 - Alpbach

  22. Identification of dominant heating mechanisms SPP Mission Kickoff - SWEAP Science Overview

  23. Collisional/Collisionless transition SPP Mission Kickoff - SWEAP Science Overview

  24. Role of instabilities in the inner heliosphere SPP Mission Kickoff - SWEAP Science Overview

  25. Evolution of solar wind solar sources • Interfaces between streams of wind more distinct closer to Sun • In situ measurements of solar wind state: temperature, density, velocity, He/H, magnetic field strength, turbulence • Remote imaging of local structures with WISPR • Connect to solar surface and corona observations, and to models SPP Mission Kickoff - SWEAP Science Overview

  26. Connection between coronal sources, streamer belt, and heliospheric current sheet (Antiochos et al. 2011) • In situ measurements of solar wind state: temperature, density, velocity, He/H, magnetic field strength, turbulence • Remote imaging of local and global structures with WISPR • Connect to solar observations and models Solar Probe Plus - IAFA 2011 - Alpbach

  27. Small coronal structures in the solar wind • Width of streamer belt, flux tubes, discontinuities, reconnection exhausts, shocks, current sheets, fast/slow transitions, flux ropes, filaments • Fine-scale structures extending from coronal base. Fast 50-150 km/s Type-II Spicules 200 km thick and occur at great frequency • Bulk plasma properties, e- strahl, and e- PAD from SWEAP. Link to Type III radio bursts seen by FIELDS, energetic particles from ISIS, density column from WISPR SPP Mission Kickoff - SWEAP Science Overview

  28. Variable magnetic connection • Determine the fraction of the corona magnetically open to interplanetary space, change in total open flux over solar cycle, variability of connectivity on short timescales. • Combine SWEAP solar wind conditions, electron pitch angle distributions, FIELDS magnetic field direction, WISPR images of local structure SPP Mission Kickoff - SWEAP Science Overview

  29. Crossing the Alfvén surface • Where is the Alfvén surface located? • Does the corona really co-rotate at this surface? • How do coronal waves pass through this transition? • Signatures: Alfvénic Mach number, ratio of ingoing/outgoing wave power, rotational speed of plasma (Ofer Cohen) (Velli) Solar Probe Plus - IAFA 2011 - Alpbach

  30. Energetic particle propagation • Understanding solar energetic particle (SEP) acceleration at 1 AU is difficult • distance from sources • mixing during transport • Helios showed advantages of near-Sun observations of SEP processes near origin • SP+ will observe 50-100 ISEP and ≳50 large SEP events inside 0.25 AU • Enabling detailed studies of • flare and CME-shock acceleration • seed particle identities • the effects of particle transport in the interplanetary medium. (Wibberenzand Cane 2006) Solar Probe Plus - IAFA 2011 - Alpbach

  31. Shocks in the inner heliosphere • Acceleration of particles • Structure of CMEs • Heating of corona? • Observations • Derive local shock properties using SWEAP and FIELDS • Large scale shock structure from WISPR • Energetic particle production with ISIS Solar Probe Plus - IAFA 2011 - Alpbach

  32. Suprathermal tails • What mechanisms produce the widely observed suprathermal tails and how do they feed into SEP acceleration? • Are they produced in the corona by flares or are they produced in the heliosphere by stochastic acceleration? • Investigate by combining • Variation of the suprathermal tail itself – EPI-Lo • Electromagnetic fluctuations – FIELDS • Plasma fluctuations and type of solar wind – SWEAP Solar Probe Plus - IAFA 2011 - Alpbach

  33. Conclusions • Exciting science • First direct sampling of the atmosphere of a star • General interest to plasma astrophysics • Heating • Acceleration • Shocks • Co-rotation • Suggestions for related work • Numerical simulations to guide planning for observations • Solar wind structures on global and kinetic scales • Predictions of wave power • Magnetic reconnection exhausts • Theoretical work and observational techniques • How do you study turbulence when the Taylor hypothesis breaks down? Solar Probe Plus - IAFA 2011 - Alpbach

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