Solar Corona Observations from space

Marta Casti

PhD Candidate - XXXI

Osservatorio Astrofisico di Torino (OATo) – ALTEC SpA

Tutor: Silvano Fineschi

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PhD Activities

Metis Coronagraph polarimeter: characterization and calibration

Proba-3 Formation Flying: development of the metrology algorithm

Space Weather:definition of the solar data processing pipeline for solar storm prediction

Outline

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Solar Orbiter Mission

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• Solar Orbiter is a ESA medium-class mission dedicated to solar and heliospheric physics.

• Top-level science questions:

o What drives the solar wind and where does the coronal magnetic field originate from?

o How do solar transients drive heliospheric variability?

o How do solar eruptions produce energetic particle radiation that fills the heliosphere?

o How does the solar dynamo work and drive connections between the Sun and the heliosphere?

Metis is an inverted-occulter coronagraph and is part of the remote sensing instruments on board Solar Orbiter The Metis experiment is an international collaboration led by the Astrophysical Observatory of Turin of the National Institute of Astrophysics. Principal Investigator: Marco Romoli(INAF)

Courtesy of Thales Alenia Space Italia

Metis Polarimeter

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• Metis will be capable of obtaining simultaneous imaging of the full corona in:

o Linearly polarized visible-light (580 – 640 nm)

o Narrow-band ultraviolet HI Lyman-α (121.6 nm)

• Image the linearly polarized K-corona on the VL detector is useful to measure the K-corona electron density (Ne) in order to characterize the physical properties of the hot coronal plasma.

• The Metis polarimeter includes a Polarization Modulation Package (PMP) composed of:

o A quarter-wave retarder;

o Two Liquid Crystal Variable Retarder cells (LCVRs) first use in space optical payload;

o A linear polarizer.

Metis Polarimeter Characterization

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• Cell#1 characterization

• Cell#2 characterization

• Cell#1+Cell#2 characterization

• Double vs Single cell comparison

• Considering different:

• Cell temperatures

• Wavelength

• Applied voltages

• Angle of Incidence

PMP Bread Board

• PMP characterization

• Polarimeter characterization

• Considering different:

• Cell temperatures

• Applied voltages

PMP and polarimeter PFM Stand-Alone • Polarimeter characterization

• Instrument demodulation matrix computation

• Flat field correction

Integrated PFM Polarimeter

PMP Bread Board

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• Set up Based on the Dual Rotating RetarderPolarimeter (DRRP) technique, originally proposed byAzzam (1978).

• Encoding of the polarimetric properties of a sample ina signal modulated by two retarders placed before andafter the sample, and rotating at 1:5 ratio.

•Cell #1 characterization

• AoI = 0; T = 30/40/50 °C

•Cell #2 characterization

•AoI = 0; T = 30/40/50 °C

•PMP characterization

•AoI = 0/±7; T = 30/40/50 °C

Retardance vs. voltages curves

at 617.2 nm

•Cell #1 characterization

• AoI = 0/±7; T = 30/40/50 °C

•Cell #2 characterization

•AoI = 0/±7; T = 30/40/50 °C

•PMP characterization

•AoI = 0/±7; T = 30/40/50 °C

Retardance vs. voltages curves

at Metis Bandpass

𝑴𝐿𝐶𝑉𝑅(𝜃,𝛿) =

1 0 0 00 𝑐𝑜𝑠2 2𝜃 + 𝑐𝑜𝑠 𝛿 𝑠𝑖𝑛2 2𝜃 (1 − 𝑐𝑜𝑠 𝛿) 𝑠𝑖𝑛2𝜃 ∙ 𝑐𝑜𝑠 2𝜃 sin𝛿 𝑠𝑖𝑛2𝜃

0 (1 − 𝑐𝑜𝑠 𝛿) 𝑐𝑜𝑠 2𝜃 ∙ 𝑠𝑖𝑛 2𝜃 𝑠𝑖𝑛2 2𝜃 + cos 𝛿 cos2 2𝜃 − sin𝛿 𝑐𝑜𝑠 2𝜃0 −𝑠𝑖𝑛 𝛿 𝑠𝑖𝑛2𝜃 sin𝛿 𝑐𝑜𝑠 2𝜃 0

PMP MuellerMatrix

PMP Bread Board

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PMP-PFM stand-alone

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POLARIMETER METIS PMP LINEAR POLARIZER

LASER SOURCE

• The PMP-FM was driven at voltages toderive the Retardance vs Voltage curve.

• The Voltage Vs Retardance curve hasbeen obtained with the PMP operating atthree different temperatures (30/ 40 /50°C on nominal channel)

• The resulting curve has been comparedwith the sum of the curves of Retardancevs Voltage for each LCVR cell, measuredby INTA.

EXPERIMENTAL SET UP: - Source: laser @ 633nm- Linear PrePolarizer- Sample Metis PFM PMP- ThorLabs Polarimeter

PMP PFM stand-alone

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Calibration @ 40°C

Calibration @ 30°C

The Retardance Vs Voltage curve has been retrieved for different operative temperatures: PMP polarimatric characterization in air with respect to the cells temperature

Polarimeter – PFM (Stand-Alone)

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• EXPERIMENTAL SET UP• Source: SCHOTT EKE DCR-III;

• Metis bandpass filter (580-640) nm

• Linear pre-polarizer (fixed);

• Rotating half-wave retarder

• Polarimeter (including PMP);

• CCD camera (1024)2 24-µm pix (FLI ProLinePL1001E).

CCD DETECTOR

METIS POLARIMETER

HWRP

PRE-POLARIZER

SOURCE+METIS VL

FILTER

• The pre-polarizer was rotated intodifferent angles and in each position thePMP was driven to several voltages toderive the Intensity Vs Voltage curve atdifferent Input-polarization angles.

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Polarimeter – PFM (Stand-Alone)

• Preliminary voltage settings has beenderived for the modulation scheme of theCME-detection sequence.

Half-wave @ -(45+53) degPre-polarizer @ 100 deg

• For the first time a dual-cell, wide angle ofacceptance PMP has been successfully testedin combination with fixed-polarization opticsto operate as a linear polarization rotator(“Senarmont” configuration).

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Polarimeter - PFM (Integrated)

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Polarization performances characterization in vacuum

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Courtesy of Thales Alenia Space Italia

The mechanical integration and the alignment of the optical components of the Metis coronagraph took place at the OPSys Facility at ALTEC.

Polarimeter - PFM (Integrated)

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Linear Pre PolarizerVL Source

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Courtesy of Thales Alenia Space Italia

Polarimeter - PFM (Integrated)

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Polarimeter “rotation” = 5 Polarimeter “rotation” = 50

Polarimeter “rotation” = 95 Polarimeter “rotation” = 140

GOAL: Retrieve the experimental Modulation and Demodulation matrices

• mi: set of 4 measurements i=0, 1, 2, 3

𝑚0

𝑚1

𝑚2

𝑚3

=1

2

1 𝑐𝑜𝑠𝛿0 𝑠𝑖𝑛𝛿0 01 𝑐𝑜𝑠𝛿1 𝑠𝑖𝑛𝛿1 01 𝑐𝑜𝑠𝛿2 𝑠𝑖𝑛𝛿2 01 𝑐𝑜𝑠𝛿3 𝑠𝑖𝑛𝛿3 0

𝐼𝑄𝑈𝑉

• Theoretical LCVR retardances i = 0, 90 , 180 , 270 :

𝑚0

𝑚1

𝑚2

𝑚3

=1

2

1 1 01 0 11 −1 01 0 −1

𝐼𝑄𝑈

≡ 𝑀 = 𝑋 ∙ 𝑆

𝑆 = 𝑋+ ∙ 𝑀 → 𝑋+ =1

2

1 1 1 12 0 −2 0−0 2 0 −2

Modulation Matrix

Demodulation Matrix

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Polarimeter - PFM (Integrated)

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Flat-field Panel

Pre-polarizer

Calibrated Diode

GOAL: Retrieve the experimental Modulation and Demodulation matrices related to each pixel

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Proba-3 Mission

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• Proba-3 is ESA’s – and the world’s – first precision formation flying mission. A pair of satellites will fly together maintaining a fixed configuration and forming a so-called ‘external’ coronagraph in space.

• Expected mission results:• Validate formation flying control algorithms• Mature formation flying metrology• Demonstrate formation autonomy and robustness• Advanced assembly, integration and verification approach

and tools• Scientific return

Occulter Spacecraft

Coronagraph Spacecraft

~144 m

Proba-3 Mission

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• 8 SPS, located on the pupil plane, acquire data on the level of penumbra profile generated by the occulter spacecraft

• Requirements:• Lateral measurement accuracy 50μm

• Longitudinal measurement accuracy 1 mm

• Formation Flying technologies:• Relative GPS

• Coarse Lateral Sensor (CLS)

• Fine Lateral and Longitudinal Sensor (FLLS)

• Shadow Position Sensors (SPS)

It’s like trying to see an hair from 144m of distance !!

Formation Flight Algorithm

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Formation Flight based on the SPSs:

• Data related to penumbra value read by each SPS are collected by the electronics on board;

• A dedicated algorithm receives in input these values and gives as output the computed actual relative position of the two spacecraft;

• Data related to the spacecraft relative position are provided to Guidance and Navigation Control system

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Formation Flight Algorithm

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Mean = 0,45 mmStd = 2,55 mm

Mean = -0,03 mmStd = 0,03 mm

Space Weather Heliospheric Data Centre

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The Heliospheric Data Centre is a joint effort between ALTEC and INAF-OATo. The project hastwo main objectives.

1. Consolidate and evolve the Heliospheric Data Centre, initially set up with the SOHO datacoming from the ESA approved SOLAR (SOho Long-term ARchive) archive, in order tomanage additional solar archives storing solar coronal and heliospheric data comingfrom ESA and NASA space programs.

2. Develop a Heliospheric Space Weather Centre for forecast of impacts of solardisturbances on the heliosphere and the Earth’s magnetosphere.

Space Weather Heliospheric Data Centre

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LASCO STEREO DSCOVR K-Cor ACE AIA

Conclusions

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PhD Activities

Metis Coronagraph polarimeter:Results : Polarimeter calibration at system levelFuture works: - Pixels optical characterization

- Upgrade the polarimeter mathematical model

Proba-3 Formation Flying:Results : Algorithm definition and encodingFuture works: - Algorithm experimental validation

- Algorithm integration in the Guidance and Navigation System close loop simulation

Space Weather:Results : Pipeline architecture definitionFuture works: - Pipeline verification with near real-time

data

• "The shadow position sensors (SPS) formation flying metrology subsystem for the ESA PROBA-3 mission: present status and future developments", M.Focardi, V.Noce, S.Buckley, K.O'Neill, A.Bemporad, S.Fineschi, M.Pancrazzi, F.Landini, C.Baccani, G.Capobianco, D.Loreggia, M.Casti, M.Romoli, G.Massone, G.Nicolini, L.Accatino, C.Thizy, J.S.Servaye, I.Mechmech, E.Renotte, Proc. SPIE 9904, Space Telescopes and Instrumentation 2016 (July 29, 2016); doi:10.1117/12.2231699.

• "Characterization of the ASPIICS/OPSE metrology sub-system and PSF centroiding procedure", D.Loreggia, S.Fineschi, G.Capobianco, A.Bemporad, M.Focardi, F.Landini, G.Massone, M.Casti, G.Nicolini, M.Pancrazi, M.Romoli, V.Noce, C.Baccani, I.Cernica, M.Purica, M.Nisulescu, C.Thizy, J.S.Servay, E.Renotte, Proc. SPIE 9904, Space Telescopes and Instrumentation 2016 (July 29, 2016); doi:10.1117/12.2232378

• "The satellite formation flying in lab: PROBA-3/ASPIICS metrology subsystems test-bed", G.Capobianco, D.Loreggia, S.Fineschi, M.Focardi, A.Bemporad, M.Casti, V.Noce, F.Landini, C.Baccani, M.Pancrazzi, M.Romoli, G.Massone, G.Nicolini, S.Buckley, K.O'Neill, I.Cernica, M.Purica, E.Budianu, C.Thizy, J.S.Servaye, I.Mechmech, E.Renotte, Proc. SPIE 9904, Space Telescopes and Instrumentation 2016 (July 29, 2016); doi:10.1117/12.2233207

• "An improved version of the Shadow Position Sensor readout electronics on board the ESA PROBA-3 Mission", V. Noce, M. Focardi, S. Buckley, A. Bemporad, S. Fineschi, M. Pancrazzi, F. Landini, C. Baccani, G. Capobianco, D. Loreggia, M. Casti, M. Romoli, L. Accatino, C. Thizy, F. Denis, P. Ledent, SPIE 10397, UV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XX, 103971B (29 August 2017); doi: 10.1117/12.2273694.

• "Test plan for the PROBA3/ASPIICS scaled model measurement campaign", F. Landini, C. Baccani, S. Vives, S. Fineschi, M. Romoli, G. Capobianco, G. Massone, M. Casti, A. Bemporad, M. Focardi, M. Pancrazzi, D. Loreggia, V. Noce, A. J. Corso, C. Thizy, E. Renotte, B. Marquet; Proc. SPIE 10397, UV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XX, 103971C (29 August 2017); doi: 10.1117/12.2273921

• Sent to 2017 Conference on Big Data from Space (BiDS'17) - 28/29 November (Accepted as poster with proceeding):“Data Integration of remote sensing and in situ data from several solar space missions for space weather service”, M.Casti, S.Fineschi, R.Messineo, E. Antonucci, A.F. Mulone, A. Bemporad, A. Fonti, R. Susino, F. Filippi, D. Telloni, F. Solitro, G.Nicolini, M. Martino.

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