Solar Probe Plus · Solar Probe Plus A NASA Mission to Touch the Sun Solar Probe Plus: Humanity’s...

Solar Probe PlusA NASA Mission to Touch the Sun

Solar Probe Plus: Humanity’s First Visit

to Our StarNicola J. Fox, N.E. Raouafi, R. Decker, S. Bale, R. Howard, J.C. Kasper, D. McComas, M. Velli.

Solar Probe Plus Project [email protected]

Solar Probe PlusIUGG

A Brief History of the Solar Wind

1859: Richard C. Carrington first discovered Hα flare, which was followed by the strongest geomagnetic storm in recorded history. He suggested a connection between solar flares & geomagnetic activity.

1910: British astrophysicist Arthur Eddington suggested the existence of a solar wind, without naming it, in a footnote to an article on Comet Morehouse.

1916: Norwegian physicist Kristian Birkeland suggested that the solar wind was composed of both ions and electrons.

1930s: scientists inferred from eclipse observations that the the solar corona must be > a million degree hot through observations of emissions from highly ionized ions.

Mid-1950s: British mathematician Sydney Chapman calculated the properties of a gas at such a temperature and determined it was such a superb conductor of heat that it must extend way out into space, beyond the orbit of Earth.

Also in the 1950s: German scientist Ludwig Biermann postulated that the anti-solar orientation of comet tails results from a steady stream of particles emitted by the Sun.

1958: Eugene Parker developed the theory of hot coronal plasma evolving into what he termed the "solar wind”.

1962: Marsha Neugebauer and Conway Snyder confirmed the existence of the solar wind through in-situ measurements.


How is the Corona Heated?

Electrons and different ion species are heated differently; theoretical work has shown that single‐fluid theories are clearly not sufficient to explain this.SPP will provide measurements in the region of space where observations are most needed

SPP will bridge the measurement gap between the low corona (i.e., spectroscopic observations (SOHO/SUMER & UVCS) and heliospheric in‐situ measurements from Helios.

SPP

Reference: Cranmer & van Ballegooijen, ApJ, 2005


How is the Solar Wind Accelerated?

‘Alfvén point’: Within this point, the magnetic energy density dominates, and the gas is forced to flow along the field lines. Beyond this point, kinetic energy acquired by the flowing gas prevails and the field is forced to follow the flow.

In a magnetized plasma, the Alfvén point (colored circles in the figure below) determines radial extent of the lower (sub‐Alfvénic) corona

Reference: Kasper et al. 2010, SWEAP Proposal

It is important to measure the solar wind as close to the solar surface (below the Alfven critical point) as possible while it is still undergoing most of its acceleration.


50 years into the space age and we still don’t understand the corona and solar wind

The concept for a “Solar Probe” dates back to “Simpson’s Committee” of the Space Science Board (National Academy of Sciences, 24 October 1958)‒ The need for extraordinary knowledge of Sun from

remote observations, theory, and modeling to answer the questions:

– Why is the solar corona so much hotter than the photosphere?

– How is the solar wind accelerated? The answers to these questions can be obtained

only through in-situ measurements of the solar wind down in the corona and been of top priority in multiple Roadmaps and Decadal Surveys.


SPP Over-arching 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.


Spacecraft Overview

NASA selected instrument suites 685 kg max launch wet mass Reference Dimensions:

S/C height: 3 m TPS max diameter: 2.3 m S/C bus diameter: 1 m

C-C Thermal protection system Hexagonal prism s/c bus configuration Actively cooled solar arrays

388 W electrical power at encounter Solar array total area: 1.55 m2

Radiator area under TPS: 4 m2

0.6 m HGA, 34 W TWTA Ka-band science DL Science downlink rate: 167 kb/s at 1AU Blowdown monoprop hydrazine propulsion Wheels for attitude control


Reference Mission: Launch and Mission Design Overview

Launch Dates: Jul 31 – Aug 19, 2018 (20

days) Max. Launch C3: 154 km2/s2

Delta IV-Heavy with Upper StageTrajectory Design 24 Orbits 7 Venus gravity assist flybys

Final Solar Orbits Closest approach: 9.86 Rsun (3.83

million miles) Speed ~450,000 miles per hour

(~125 miles per second) Orbit period: 88 days

Mission duration: 6 yrs, 11 months

Sun

Venus

Mercury

Earth

Launch7/31/2018

1st Min Perihelionat 9.86 RS

12/19/2024

1st Perihelionat 35.7 RS11/1/2018


SPP Rapidly Explores the Inner Heliosphere

Max solar distance is 1.018 AU, and min solar distance is 0.04587 AU (9.86 RS) 1st perihelion (0.16 AU) 3 months after launch; 19 passes below 20 Rs Perihelia gradually decreases. Science measurements will commence at the first Perihelion

Venus Flyby

A1

A4A2 A3

A19A8 A9

A15 A16A14A13A12A11

A5

A18

A6

A17 A20

A7A10

A21 A22 A23 A24 A25

P20P7 P8

P4P2 P3P1

P5P6 P9 P10 P11 P12 P14 P15 P16 P18 P19 P21 P22P13 P17 P24P23

Orbit # 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24Period (d) 168 150 150 140 121 112 107 102 102 100 96 96 96 96 96 96 96 92 92 92 87 88 88 88


Reference Vehicle:Concept of Operations


Reference Vehicle: Anti-Ram Facing View

SWEAP PIJustin KasperUniversity of Michigan

At closest approach, the front the heat shield will be at 1,400°C (2500 oF), but the payload will be near room temperature


Reference Vehicle: Ram Facing View

FIELDS PIStuart Bale (UC, Berkeley)ISIS PIDavid McComas(Southwest Research Inst.)WISPR PIRuss Howard(Naval Research Lab)


Solar Probe Plus Science Investigations (1/5)

Solar Wind Electrons Alphas and Protons (SWEAP) Investigation: This investigation will count the most abundant particles in the solar wind ‐‐electrons, protons and helium ions ‐‐ and measure their properties such as velocity, density, and temperature.

SWEAP Investigation

SPC

SPAN-A+SPAN-B

SWEAP PIProf. Justin KasperUniversity of Michigan/ Smithsonian Astrophysics Observatory

Solar Probe Cup (SPC)2 Solar Probe ANalyzers (SPAN)


V1‐V4 electric antennas

MAGi, MAGo

V5 electric antenna

SCM

V1‐V4 electric antennas

‐ Five voltage sensors ‐ Two Fluxgate magnetometers ‐ One search‐coil magnetometer ‐ Main Electronics Package

Solar Probe Plus Science Investigations (2/5)

Fields Experiment (FIELDS): This investigation will make direct measurements of electric and magnetic fields and waves, Poynting flux, absolute plasma density and electron temperature, spacecraft floating potential and density fluctuations, and radio emissions.

FIELDS Investigation

FIELDS PIProf. Stuart BaleUniversity of California, Berkeley

olar Probe Plus Science vestigations (3/5) grated Science Investigation of the (ISIS): This investigation makes rvations of energetic electrons, ons and heavy ions that are lerated to high energies (10s of keV00 MeV) in the Sun's atmosphere nner heliosphere, and correlates

m with solar wind and coronal tures.

HET LET1

LET2 EPI-Hi

EPI-Lo 8 Sensor Wedges

ISIS Bracket

ISIS InvestigationISIS PIDr David McComas

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

Inner Telescope Outer Telescope

olar Probe Plus Science vestigations (4/5) e‐field Imager for Solar PRobePR): These telescopes will take images e solar corona and inner heliosphere. experiment will also provide images of olar wind, shocks and other structures ey approach and pass the spacecraft. nvestigation complements the other uments on the spacecraft providing t measurements by imaging the ma the other instruments sample.

WISPR Investigation

WISPR PIDr. Russell HowardNaval Research Laboratory

White light imager

oronal magnetic ructure still channels he flow and determines ngular momentum loss

ervations from 10‐20 Rs are required chieve the SPP Science Objectives

Solar Orbiter

Waves, turbulence rongest

emperature maximumollisional‐Collisionless ransitionMagnetic–Kinetic

P Level‐1 Science Objectives

• Trace the flow of energy that heats the corona and accelerates the solar wind

• Determine the structure and dynamics of the magnetic fields at the sources of the fast and slow solar wind

• Determine what mechanisms accelerate and transport energetic particles

There are three detailed science sub‐questions stemming from each of these objectives.

ailed Science Sub‐Questions


Example: 1st Science Objective


• SPP, with 75 hrs inside 12 Rs /400 inside 15 Rs (sub‐Alfvénic), will measure more than 20 hrs (<12 Rs) 100 hrs (< 15 Rs) of fast wind.

• SPP will provide direct measurements of Alfvén Wave Poyntingfluxes and of ion and electron thermal and kinetic energy fluxes, allowing detailed energy flow analysis.

• SPP will fly inside regions where Alfvénic turbulence is expected to peak, allowing definite confirmation/exclusion of the role played by low‐frequency fluctuations in heating and acceleration.

• SPP radial and longitudinal scans will allow us to determine the roles of reconnection and jets and instabilities in the heating and acceleration of the slow wind.

Example: 1st Science ObjectiveObservation Strategy


SPP Participation

• 31 institutions participate in SPP science teams• 23 in the US, 8 foreign• 17 educational, 5 non‐profit, 8 government labs

• 106 science team members• 69 PIs and Co‐Is• 37 additional scientists• Next generation graduate students and post‐docs


Opportunity for World‐Wide Community to Collaborate in SPP! • Full‐disk magnetograms of the photosphere and chromosphere

• Solar Orbiter, NSO Mount Wilson Observatory, GONG, Wilcox Solar Observatory, SDO, SOHO• High‐resolution spectro‐polarimetry and imaging spectroscopy of dynamic solar

atmosphere (photosphere to corona) • Solar Orbiter, ATST; GREGOR; NJIT’s Big Bear Solar Observatory New Solar Telescope (NST),

• Coronagraph observations• Solar Orbiter, MLSO White light coronagraph, STEREO, SOHO

• UV/X‐ray imaging and spectroscopy• Solar Orbiter, SDO, IRIS, SOHO

• In‐situ solar wind measurements• Solar Orbiter, SOHO, ACE, DSCVR, STEREO

• Radio observations • VLA, Green Bank Solar Radio Burst Spectrometer, Nançay radioheliograph, Nobeyama

Radioheliograph; Owens Valley Solar Array, Siberian Solar Radiotelescope; Atacama Large Millimeter Array, FASR

• Interplanetary scintillation for tomography of solar wind and ICMEs;• Differential Faraday rotation of background sources constraining magnetic field strength of outer

corona and SW. –EISCAT, LWA, MWA, ORT


Physics of the Corona: Making The Link - Summary

• Solar Probe Plus provides: – Statistical survey of outer corona

– 1st perihelion (0.16 AU 0r ~15 million miles) 3 months after launch– Closest approach below 10 Rs (0.04 AU or 4 million miles)– Excellent sampling of all types of solar wind– Measurements from within the region where all the action happens

– Particle measurements from the lowest energy plasma through the most energetic particles associated with solar flares

– Measurements of plasma waves that enable energy and momentum flow

– Coronal imaging “from the inside out” bridges local to global scales by providing the context

0 20 40 60 80 100Action Region


SPP Conclusions• Solar Probe Plus will be an extraordinary and historic mission, exploring what

is arguably the last region of the solar system to be visited by a spacecraft, the Sun’s corona.

• SPP will repeatedly sample the near‐Sun environment, revolutionizing our knowledge and understanding of coronal heating and of the origin and evolution of the solar wind and answering critical questions in heliophysics that have been ranked as top priorities for decades.

• By making direct, in‐situ measurements of the region where some of the most hazardous solar energetic particles are energized, SPP will make a fundamental contribution to our ability to characterize and forecast the radiation environment in which future space explorers will work and live.

• Fantastic mission of discovery to the Sun• Only opportunity to understand basic plasma physics mechanisms where the

magnetic field dominates• Trace the flow of energy that heats the corona and accelerates the solar wind• Determine structure and dynamics of the B fields at sources of the fast & slow

solar wind• Determine what mechanisms accelerate and transport energetic particles

• Great collaborative opportunities

It has been 50+ years since the Solar Probe Concept was introduced. . .

We are on our way!

olar Probe PlusASA Mission to Touch the Sun

Back-up

rmine the structure and dynamics of the ma and magnetic fields at the sources of olar wind

ow does the magnetic field in the solar wind source regions onnect to the photosphere and the heliosphere?

Potential Field Source Surface models show that the magnetic field expansion up to the source‐surface plays a crucial role in determining global solar wind outflow properties, including the terminal velocity, which is inversely correlated to the expansion factor itself.

re the sources of the solar wind steady or intermittent?To date it has not been possible to determine the origin and variability of the fast solar wind as connections between solar events and high‐speed wind features have not been adequately measured.

ow do the observed structures in the corona evolve into the olar wind?

Structures emanating from active regions and coronal holes can be traced to several solar radii above the solar surface, but it is unclear how they evolve into the solar wind. Their respective contributions to the solar wind has proven to be hard to quantify from distant (e.g., 1 AU)

rmine the structure and dynamics of the netic fields at the sources of the solar

xtended measurements of equatorial extensions of high‐titude coronal holes as well as equatorial coronal holes. peeds of 110 km/s for perihelia at 20 Rs and ~190 km/s below 0 Rs— allows sampling of the structures, such as plumes, inside he equatorial extensions of the coronal holes.t a radial distance of ~31.5 Rs, there are two periods (one bound, one outbound) where Solar Probe Plus will be in quasi‐orotation and will cross a given longitudinal sector slowly. In hese intervals, the spacecraft will be able to sample the solar ind for significant radial distances along a field line before oving across the sector.olar Probe Plus, orbiting in the ecliptic, will remain inside the reamer belt for a significant fraction of the 3 encounters inside

( h ) d h b l ( h )

rmine what mechanisms accelerate transport energetic particles hat are the roles of shocks, reconnection, waves, and turbulence in the celeration of energetic particles? Identifying the specific SEP acceleration process is a fundamental goal for the SPP mission. Measurements made near SEP acceleration sites will reduce uncertainties due to modifications of angular distributions by propagation and thus provide the timing needed to differentiate specific acceleration processes.

hat are the source populations and physical conditions necessary for nergetic particle acceleration?

Continuous monitoring of the intensity and composition of suprathermal seed particles in the high corona and inner heliosphere (along with the plasma conditions) are needed to constrain the physical conditions necessary for particle acceleration, their intensity, energy spectrum, and composition.

ow are energetic particles transported in the corona and heliosphere?Good pitch‐angle coverage during the observation of these small events close to the Sun is necessary to determine whether the longitudinal spreading of SEP events is due to a direct magnetic connection to the particle source or because of other transport mechanism(s) (e.g., cross‐field diffusion).

rmine what mechanisms accelerate transport energetic particles ong observing times in the inner heliosphere enable extensive ampling of shocks and particle acceleration and transport rocesses.apid scans in longitude allow direct exploration of the spatial xtent of particle acceleration sites olar Probe Plus, orbiting in the ecliptic, will remain inside the reamer belt for a significant fraction of the 3 encounters inside 0 Rs (15 hrs) and the previous 5 below 12 Rs (50 hrs). xtensive radial exploration of the inner heliosphere will clarify he origin of the “ubiquitous” power‐law supra‐thermal tails. addition, the synergy of SEP measurements from SPP and 1 U spacecraft will help constrain the role of cross‐field transport ithin 1 AU.

rticipating Organizations

lifornia Institute of Technologyntre Spatiale de Liege, BELSPO rvard University perial College t Propulsion Laboratory hns Hopkins University / APL boratoire d'Astrophysique de

arseille - CNRS s Alamos National Laboratory

assachusetts Institute of chnology ax Planck Institute for Solar System udies - DLR

ASA Goddard Space Flight Center ASA Marshall Space Flight Center val Research Laboratory ris Observatory LESIA-CNRS

• Royal Observatory of Belgium • Smithsonian Astrophysical

Observatory• Southwest Research Institute • Swedish Institute of Space Physics • University of Alabama, Huntsville • University of Arizona • University of California, Berkeley • University of Chicago • University of Colorado, Boulder • University of Delaware • University of Gottingen - DLR • University of Maryland, College Park • University of Michigan• University of Minnesota • University of New Hampshire

U i it f O l CNRS

ar Probe Plus Timeline

ssion Confirmation: March 14tical Design Review (CDR): rch 2015unch: July 2018 on Delta IV‐avy with Upper Stagest perihelion (r = 34 Rs): tober 2018st perihelion with r < 10 Rs: cember 2024

icle Instrument capabilities meet el 1 requirements with margin

ons

ons

s

m

1eV 1keV 1MeV 1GeV

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

ds & Waves Instrument capabilities t Level 1 requirements with margin

Fields & WavesSensors

FIELDS/FGMFIELDS/SCMFIELDS/EFIFIELDS/PWI

~DC 10Hz 1kHz 1MHz

gnetic

ectric

gnetic

asmaaves

adio

ermale

FIELDS FGM

FIELDS EFI

FIELDS PWI

FIELDS SCM

FIELDS PWI

FIELDS PWI

L1 Requirement

ds and Waves Measurement Tables

Measurement Dynamic Range Cadence BandwidthMagnetic Field 140 dB 100k vectors/s DC - 50 kHz

Electric Field 140 dB 2M vectors/s DC - 1 MHz

Plasma Waves 140 dB 1 spectrum/s ~ 5 Hz - 1 MHz

Quasi-Thermal Noise/Radio

100 dB for QTN80 dB for radio

1 spectrum/4 s QTN1 spectrum/16 s radio

10-2500 kHz QTN1-16 MHz radio

Meas. Energy range(1)

Energy Res.

FOV Ang. Res.(2)

VDF cadence

Mass Res.(3)

Thermal Ions

10 eV –20 keV

< 20% nadir and ram directions

10ox25o 1 Hz d(m/q)/(m/q) < 25%

Thermal Electrons

5 eV –20 keV

< 20% > 75% of the sky

10ox10o 1 Hz n/a

rmal Particle Measurement uirements Tables


Energy Res.

FOV Ang. Res.(2)

VDF cadence

Mass Res.(3)

Thermal Ions

10 eV –20 keV


10ox25o 1 Hz d(m/q)/(m/q) < 25%

Thermal Electrons

5 eV –20 keV

< 20% > 75% of the sky

10ox10o 1 Hz n/a


Energy Res.

FOV Ang. Res.(2)

VDF cadence

Mass Res.(3)

Thermal Ions

100 eV –10 keV


20ox25o 1 Hz None

Thermal Electrons

5 eV – 2 keV

< 30% > 65% of the sky

20ox20o 1 Hz n/a

seline

reshold

rgy range not required in all directions

ite Light Baseline Measurement quirements Tables

Meas. Cadence FOV Inner FOV

bound.

Spatial res.

Photometric sensitivity (SNR/pixel)

Visible Broadband

≤16.5 min ≥76° radial x ≥20°transverse at 14°elongation to ≥44°transverse at 90°

elongation

≤ 14° ≤ 6.4 arcmin

≥ 20

Meas. Energy range (1)

Highest cadence (2)

FOV (3) Angular sector

Composition(4)

Energetic electrons

≥1.5 decade in the range from 0.02 - 6 MeV

≤10 sec ≥π/4 sr in sunward &anti-sunward hemispheres

sunward vs anti-sunward

n/a

Energetic protons and heavy

≥2 decades in the range from 0.02 to 100

≤10s, protons; 1 min, ion

≥π/4 sr in sunward &anti-sunward


protons, heavy ion groups (He, CNO,

ergetic Particle Measurement quirements Tables


Highest cadence

(2)


Composition(4)

Energetic electrons

≤0.05 to ≥3 MeV

≤1 sec (select rates)

≥π/2 sr in sunward & anti-sunward hemispheres

≤45°sectors

n/a

Energetic protons and heavy ions

≤0.05 to ≥50

MeV/nuc

≤5 sec (selected

rates)

≥π/2 sr in sunward & anti-sunward hemispheres

≤30°sectors

at least H, He, 3He, C, O, Ne,

Mg, Si, Fe


Highest cadence (2)


Composition(4)

Energetic electrons

≥1.5 decade in the range from 0.02 - 6 MeV

≤10 sec ≥π/4 sr in sunward &anti-sunward hemispheres


n/a

Energetic protons

≥2 decades in the range from

≤10s, protons; 1

≥π/4 sr in sunward &

sunward vs anti-

protons, heavy ion groups

seline

reshold

P High Level Organizational Chart

Mission System Engineer

MSE: J. KinnisonDMSE: M. Lockwood

EV Manager: H. HunterPlanning Manager: C. BattistaFinancial Manager: S. Diamond

NASA Science Mission Directorate

Heliophysics DivisionDirector: S. Clarke

Program Scientist: M. GuhathakurtaProgram Executive: J. Lee

GSFC LWS Program OfficeProgram Manager: N. Chrissotimos

PM for APL Projects: M. GoansMission Scientist: A. Szabo

Solar Probe Plus Project OfficeProject Manager: A. Driesman

Deputy Project Manager: P. HillDeputy PM for Instruments: K. CooperProduction Planning Mgr: C. Battista

Project ScientistN. Fox

R – NRL*HowardPlunkett

ISIS – SwRIPI: D. McComasPM: S. Weidner

FIELDS – UCBPI S B lP SAO

Project SAM: L. Becker

APL/SES Management

EPOD. Turney

HELIOSPP – JPL*PI: M. Velli, Obs Sci

ker’s ‘solar wind’ model - 1958

Sun's corona is strongly attracted by solar gravity, but it is such a good ductor of heat that it is still very hot at large distances. Since gravity kens as distance from the Sun increases, the outer coronal atmosphere pes supersonically into interstellar space.

A ‘solar wind’ is accelerated from the coronaweakening effect of the ity has the same effect on odynamic flow as a de Laval le (or jet engine): it incites nsition from subsonic to ersonic flow.uires energy input at the . kTph is not nearly enough! uires non‐thermal energypredicts a critical point

e solar wind is heated continuously

s spacecraft urements from 0.3 U

ger spacecraft urements outward

/r

batic cooling cts a much more decay

ires continuous, buted energy input

Waves/turbulence vs reconnection

otpoint shuffling of open d lines generates Alfvénves. Waves propagate ward and damp

Reconnection injects energy from closed field regions

(Cranmer cartoon)

ere are we today?

e corona requires a non-thermal source of heat A sufficiently heated corona will expand super-sonically and super-Alfvénically to form a ‘solar wind’ The expanding solar wind requires additional heating

e large coronal magnetic energy density is a sufficient energy source. s is our ‘dark energy’. But problems remain: How are the magnetic fields created and transported How is the magnetic energy converted to thermal energy: magnetic reconnection, shocks, waves and turbulence What is the role of ambipolar electric fields?

Solar Probe Plus · Solar Probe Plus A NASA Mission to Touch the Sun Solar Probe Plus: Humanity’s...

Documents

Transcript of Solar Probe Plus · Solar Probe Plus A NASA Mission to Touch the Sun Solar Probe Plus: Humanity’s...