Solar Probe Plus – A Mission to Touch the Sun Rob Decker and Nicky Fox Johns Hopkins Applied Physics Laboratory Laurel, Maryland, USA Representing SPP Project and Science Investigation Teams 1
Solar Probe History (1958 - present) Solar Probe studies, reports; NAS: 1962, 1985, 1995, 2003; 2013 European Solar Physics 14
Science Questions Addressed by Solar Probe Plus OVERARCHING SCIENCE OBJECTIVE • To determine the structure and dynamics of the Sun’s coronal magnetic field, understand how the solar corona and wind are heated and accelerated, and determine what mechanisms accelerate and transport energetic particles. Detailed Science Objectives • Trace the flow of energy that heats and accelerates the solar corona and solar wind. • Determine the structure and dynamics of the plasma and magnetic fields at the sources of the solar wind. • Explore mechanisms that accelerate and transport energetic particles. • Level 1 Mission and Measurement Requirements have been derived in order to achieve these science objectives • There are three detailed science sub-questions stemming from each objectives ….
Detailed Science Sub-Questions • Trace the flow of energy that heats and accelerates the solar corona and solar wind. • How is energy from the lower solar atmosphere transferred to, and dissipated in, the corona and solar wind? • What processes shape the non-equilibrium velocity distribution observed throughout the heliosphere? • How do the processes in the corona affect the properties of the solar wind in the heliosphere? • Determine the structure and dynamics of the plasma and magnetic fields at the sources of the solar wind. • How does the magnetic field in the solar wind source regions connect to the photosphere and the heliosphere? • Are the sources of the solar wind steady or intermittent? • How do the observed structures in the corona evolve into the solar wind? • Explore mechanisms that accelerate and transport energetic particles. • What are the roles of shocks, reconnection, waves, and turbulence in the acceleration of energetic particles? • What are the source populations and physical conditions necessary for energetic particle acceleration? • How are energetic particles transported in the corona and heliosphere?
Level 1 Objectives & Processes Require High-quality, Integrated Measurements
Particle Instrument capabilities meet Level 1 requirements with margin Particle Sensors SWEAP/SPAN SWEAP/SPC ISIS/EPI-Lo ISIS/EPI-Hi SWEAP-SPAN electrons SWEAP-SPC ISIS-EPI-Lo L1 Requirement ISIS-EPI-Hi SWEAP-SPAN protons SWEAP-SPC ISIS-EPI-Lo ISIS-EPI-Hi SWEAP-SPAN helium SWEAP-SPC ISIS-EPI-Lo ISIS-EPI-Hi ions ISIS-EPI-Lo ISIS-EPI-Hi 1eV 1keV 1MeV 1GeV Energy (log)
Fields & Waves Instrument capabilities meet Level 1 requirements with margin DC Magnetic L1 Requirement FIELDS FGM AC Magnetic FIELDS SCM DC Electric FIELDS EFI Plasma Waves Fields & Waves Sensors FIELDS/FGM FIELDS/SCM FIELDS/EFI FIELDS/PWI FIELDS PWI Radio FIELDS PWI Quasi-thermal Noise FIELDS PWI ~DC 10Hz 1kHz 1MHz Frequency (log)
Reference Mission: Launch and Mission Design Overview 1st Min Perihelion at 9.86 RS 12/19/2024 Launch 7/31/2018 Launch • Dates: Jul 31 – Aug 19, 2018 (20 days) • Max. Launch C3: 154 km2/s2 • LV will be a Delta 4 Heavy or Falcon Heavy (Space News, 25 Jul 2014) Trajectory Design • 7 Venus gravity assist flybys Final Solar Orbits • Perihelion: 9.86 RS • Aphelion: 0.73 AU • Inclination: 3.4° from ecliptic • Orbit period: 88 days Mission duration: 7 years Sun Mercury Venus Earth 1st Perihelion at 35.7 RS 11/1/2018
SPP Rapidly Explores the Inner Heliosphere • 1st perihelion (0.16 AU) 3 months after launch • 24 passes below 43 Rs • 19 passes below 20 Rs
Orbital Operations Concept 0.25 A.U. 24 Solar Encounter Orbits Orbital Periods Vary (168 days to 88 days) Solar Encounter Period (10-11 days) Cruise/Downlink Period Cruise/Downlink Period 0.25 A.U. Cruise Operations • Instruments Can Be Powered On • (Sun Distance < 0.82 AU) • Instruments off during some activities • Fanbeam for communications – H/K data only • Commanding as needed to support spacecraft maintenance Science Downlink Operations • All instruments powered off • HGA for communications – SSR playbacks • Commanding as needed to support spacecraft maintenance Solar Encounter Period Encounter Operations • Primary science data collection phase – All instruments will be powered on • Fanbeam antenna periodically available for communications & Nav • No SSR Playbacks
Solar Cycle: SPP will be going from minimum to ascending phase? Cycle 25 ?? 2025
It has been 50+ years since the Solar Probe Concept was introduced. . . Solar Probe Plus, currently in mid Phase C, is moving along!