solar probe plus – a mission to touch the sun

Solar Probe PlusA NASA Mission to Touch the Sun

Solar Probe Plus – A Mission to Touch the Sun

Rob Decker and Nicky FoxJohns Hopkins Applied Physics Laboratory

Laurel, Maryland, USA

Representing SPP Project and Science Investigation Teams

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European Solar Physics Meeting 14 08 Sep 2014

Solar Probe History (1958 - present)

Solar Probe studies, reports; NAS: 1962, 1985, 1995, 2003; 2013

2 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 ….

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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?4



SPP Investigations to Answer the Science Questions

Investigation Instruments Principle InvestigatorFields Experiment (FIELDS)

4 x Electric Antennas (+ 1 probe on mag boom)2 x Fluxgate Magnetometer (MAG)1 x Search Coil Magnetometer (SCM)

Prof. Stuart D. Bale, University of California Space Sciences Laboratory, Berkeley, CA

Integrated Science Investigation of the Sun (ISIS)

High energy Energetic Particle Instrument (EPI-Hi)Low energy Energetic Particle Instrument (EPI-Lo)

Dr. David J. McComas, Southwest Research Institute, San Antonio, TX

Solar Wind Electrons Alphas and Protons (SWEAP)

Solar Probe Faraday Cup (SPC)2 Solar Probe ANalyzers (SPAN; ESAs)

Dr. Justin Kasper, University of Michigan, Ann Arbor, MI & Smithsonian Astrophysical Observatory, Cambridge, MA

Wide-field Imager for Solar PRobe (WISPR)

White light imager Dr. Russ Howard, Naval Research Laboratory, Washington, DC

Heliospheric Origins with Solar Probe Plus (HeliOSPP)

Observatory Scientist:Addresses SPP science objectives via multi-instrument data analysis to optimize the scientific productivity of the mission

Dr. Marco Velli, Jet Propulsion Laboratory, Pasadena, CA

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Level 1 Objectives & Processes Require High-quality, Integrated MeasurementsL1 Science Objectives

Sample Processes

Needed Measurements

Instruments

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.

- heating mechanisms of the corona and the solar wind;

- environmental control of plasma and fields;

- connection of the solar corona to the inner heliosphere.

- particle energization and transport across the corona

- electric & magnetic fields and waves, Poynting flux, absolute plasma density & electron temperature, spacecraft floating potential, & density fluctuations, & radio emissions

- energetic electrons, protons and heavy ions

- velocity, density, and temperature of solar wind e-, H+, He++

- solar wind structures and shocks

FIELDS- Magnetic Field- Electric Field- Electric/Mag Wave

ISIS- Energetic electrons- Energetic protons and

heavy ions- (10s of keV to ~100 MeV)

SWEAP- Plasma e-, H+, He++- SW velocity &

temperature

WISPR- White light measurements of solar wind structures (add context)

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Reference Vehicle: Anti-Ram Facing View

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Reference Vehicle: Ram Facing View

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Particle Instrument capabilities meet Level 1 requirements with margin

electrons

protons

ions

helium

1eV 1keV 1MeV 1GeVEnergy (log)

L1 RequirementSWEAP-SPC

ISIS-EPI-Lo

SWEAP-SPAN

SWEAP-SPC

SWEAP-SPCSWEAP-SPAN

SWEAP-SPAN

ISIS-EPI-Lo

ISIS-EPI-Lo

ISIS-EPI-Lo

ISIS-EPI-Hi

ISIS-EPI-Hi

ISIS-EPI-Hi

ISIS-EPI-Hi

Particle SensorsSWEAP/SPANSWEAP/SPCISIS/EPI-LoISIS/EPI-Hi

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Fields & Waves Instrument capabilities meet Level 1 requirements with margin

Frequency (log)

Fields & WavesSensors

FIELDS/FGMFIELDS/SCMFIELDS/EFIFIELDS/PWI

~DC 10Hz 1kHz 1MHz

DC Magnetic

DC Electric

AC Magnetic

PlasmaWaves

Radio

Quasi-thermalNoise

FIELDS FGM

FIELDS EFI

FIELDS PWI

FIELDS SCM

FIELDS PWI

FIELDS PWI

L1 Requirement

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Reference Mission: Launch and Mission Design Overview

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 daysMission duration: 7 years

Sun

Venus

Mercury

Earth

Launch7/31/2018

1st Min Perihelionat 9.86 RS

12/19/2024

1st Perihelionat 35.7 RS

11/1/2018

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SPP Rapidly Explores the Inner Heliosphere

0

5

10

15

20

0 300 600 900 1200 1500 1800 2100 2400 2700

Time (days from launch)

Pe

rih

eli

on

(R

s)

0

0.2

0.4

0.6

0.8

1

1.2

0 300 600 900 1200 1500 1800 2100 2400 2700

Time (days from launch)

So

lar

Dis

tan

ce (

AU

)

1st perihelion (0.16 AU) 3 months after launch

24 passes below 43 Rs 19 passes below 20 Rs

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0.25 A.U.

Cruise/Downlink Period

24 Solar Encounter Orbits

Orbital Periods Vary

(168 days to 88 days)

Encounter Operations Primary science data collection phase – All

instruments will be powered on Fanbeam antenna periodically available for

communications & Nav No SSR Playbacks

Orbital Operations Concept

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

Cruise/Downlink Period

Solar Encounter

Period

(10-11 days)

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0.25 A.U.



Reference Vehicle:Concept of Operations

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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!

solar probe plus – a mission to touch the sun

Documents

solar corona

solar probe history

solar wind steady

solar wind source regions

lower solar atmosphere

transport energetic

science objectivesthere

presentsolar probe studies