Remote-sensing Instruments for the Lagrange Operational Mission Jackie Davies & The Lagrange Remote-Sensing Consortium

ESA SSA Programme ESA’s SSA programme comprises four segments: NEO : Near Earth Objects, SST : Space Surveillance and Tracking, SWE : Space Weather and, since the start of 2017 (P3), LGR : Lagrange. The Lagrange segment focusses on developing a pathway to the launch of a space weather monitoring mission to L5 (L1 backup).

P2-SWE-X SSA/SWE Period 2 included an ITT for a pre-phase A study of an “enhanced space weather monitoring system”, comprising missions both on and away from the Sun-Earth line (P2-SWE-X). Parallel studies were awarded, led by ADS Ge and OHB, each considering missions to L1 and L5. These P2-SWE-X studies included defining preliminary mission objectives and assessing the required in-situ and remote-sensing payload to achieve these objectives.

LGR ITTs ESA ITT: AO/1-9006/17/DE/MRP : Lagrange Missions Phase A/B1 System Studies (funded through GSP and LGR) ESA ITT: AO/1-9015/17/DE/MRP : Lagrange Missions In-situ Instruments Phase A/B1 Study & Pre-Developments ESA ITT: AO/1-9014/17/DE/MR : Lagrange Missions Remote Sensing Instruments Phase A/B1 Study & Pre-Developments (completing negotiations): PMI : Photospheric Magnetic Field Imager EUVI : EUV Imager [note different funding model] COR : Coronagraph HI : Heliospheric Imager

Consortium Activities Phase Task A Support of system study analysis Instrument requirements analysis Pre-development activity proposal Instrument package definition Detailed sub-systems analysis & design tasks Ground & flight operation segment definition [DOCS] Product assurance Detailed development & verification approach Schedule, cost estimate & risk assessment Programme implementation approach B1 Definition of management & product assurance Consolidation of instrument package design & development Request for information (RFI) campaign Pre-dev Pre-dev activities shall aim to reach TRL6 by end of Phase B. Includes design/manufacture/testing of critical instrument models or components needed for the demonstration of functional/performance requirements where necessary in representative environment and at the highest possible level of representativeness. Consortium Activities

Consortium Roles Role Consortium partner Consortium lead RAL (Jackie Davies) PMI MPS [lead] OHB EUVI CSL/ROB [lead] PMOD COR RAL [lead] UGOE HI IPU (Instrument Processing Unit) ADS-Ge [lead] Ground & flight operations Deimos-UK [lead] Deimos-Ro Customer requirements UK Met Office

System Block Diagram

PMI : Photospheric Mag. Field Imager Monitoring of magnetic activity on the Sun, includes modelling of background solar wind as input to CME arrival predictions at Earth. L5 view enables such monitoring of that part of the solar disk yet to rotate towards Earth (improved background) Monitoring in visible-light (sunspot activity/complexity/development) Requirements: Magnetic field map and continuum Inst type : L-O-S (vector) FoV : full disk with margin Spatial resolution : 5 (2) arcsec Cadence : 30 (10) min Mass/power : 25 kg/30 W Telemetry : 15 (40) kbps

PMI : Photospheric Mag. Field Imager STRAWMAN INSTRUMENT : modified Solar Orbiter PHI PMI team led by PHI lead institute, MPS (PHI flight model delivered April 2017) PHI obtains the photospheric vector magnetic field of the full disk, with high resolution PMI is an optically-modified version of PHI HRT: PMI twice PHI HRT FoV Reduce aperture size to 75mm Rescale filtergraph accordingly Remove FDT Image stabilizer required? (TBD)

EUVI : EUV Imager Monitor structure and complexity of the solar atmosphere, and its evolution, including prominences, active regions and coronal holes L5 view enables such monitoring of the solar atmosphere on that part of the solar disk yet to rotate towards Earth Requirements: Low coronal images FoV : full disk with margin Wavelength : Fe 193 (Fe 193, He 304, Fe 171, Fe 211) Å Spatial resolution : 5 (2) arcsec Cadence : 20 (10) min Mass/power : 8 kg/10 W Telemetry : 10 (40) kbps

EUVI : EUV Imager STRAWMAN INSTRUMENT : Combines elements of PROBA2 SWAP and ESIO EUVI team (CSL, ROB and PMOD) work successfully together on Solar Orbiter EUI ESIO studied to Phase A/B1 via GSTP; SWAP operated successfully on PROBA2 since 2009 Baseline EUVI concept: Adapted SWAP optical layout ESIO thermo-mechanical concept [SWAP invar bench too heavy; ESIO titanium base provides lightweight and stiff structure] Low ESIO mass: duplicate instruments should multiple wavelengths be required (or solution from EUI sought).

COR : Coronagraph Earliest definitive confirmation of CME launch L1 confirms Earth-directed CME, while L1/L5 resolves ambiguity between radial distance and angular width Basis of CME parameterization for most CME arrival predictions Requirements: Visible-light images of the K-corona FoV (radial) : 3 – 22 (2.5 – 30) RSun FoV (azimuthal) : 360° Wavelength : 500 – 900 nm Spatial resolution : <2 arcmin Cadence : 10 (5) min Mass/power : 20 kg/25 W Telemetry : 12 (24) kbps

COR : Coronagraph STRAWMAN INSTRUMENT : SCOPE Currently under Phase A/B1 study via GSTP Various potential orbits: LEO, GEO, L1/L5 RAL Space [lead] : requirements; flight instrument design UGOE : design/manufacture of optics bread-board (OBB) CSL : straylight testing of OBB ADS Ge : DHU H/W & S/W; environmental assessment ROB : image processing software Design : direct-imaging instrument (like STEREO/HI) Stack of 5 disk occulters (separated by 50mm) Side baffles and conical baffles Straylight rejection to 20% of F-corona Single shot door/protection shutter CCD-based detector system Status : Manufacture of OBB; recent CDR

HI : Heliospheric Imager Fills under-sampled region between corona and 1 AU to mitigate deficiencies in modelling CME arrival based on near-Sun observations L5 provides clearer side-on view of Earth-directed CMEs out to Earth Provides additional information on background solar wind Requirements: Visible-light images of the heliosphere FoV (radial) : 10 – 40° (4 – 60°) FoV (azimuthal) : Towards Earth Wavelength : 500 – 900 nm Spatial resolution : ~4 arcmin Cadence : 60 (30) min Mass/power : 20 kg/22 W Telemetry : 15 (30) kbps

HI : Heliospheric Imager STRAWMAN INSTRUMENT : STEREO HI Built by UK-led European consortium Over 10 years of successful operation Modification of FoV to reflect view from L5 Threshold FoV : single camera Goal FoV : two cameras (as STEREO HI) Improved H/W and S/W resilience (addition of a protection shutter in case of off-points) HI-1 HI-2 To Sun HI-2 HI-1

Mass/Power/Telemetry   Mass (kg) Power (W) Telemetry (kbps) Threshold Goal Sensor unit PMI 21.5 13.8 15.0 40.0 EUV 8.0 3.6 3.5 COR 12.0 7.0 28.0 HI 16.3 18.0 10.0 14.0 Processing unit PMI electronic unit 6.0 19.7 N/A IPU 10.8 27 Harness PMI harness 0.9 Harnesses (excl. PMI) 5.8 Total 81.3 97.1 37.5 122.0 Requirements <80 <100 <60 <150

IPU

IPU The purpose of the IPU is to provide: power to the FEE of each RS instrument thermal control for each instrument commands to control operational modes communication link between FEE and S/C data processing for the RS Instruments, except PMI Potential benefits of a common IPU: to facilitate data processing reduced mass /power Main trades: number of processing units redundancy concept of the IPU choice of TM/TC and data busses (aim to standardize I/Fs) inclusion of mass memory (depends on DOCs, central mass memory)

Ground & Flight Ops Analyse the impact of the RS instruments on: the operations concept; the flight operations ground segment; This feeds into the mission studies. Analyse the impact of the operations concept on instrument definition/design. For each of the instrument processing chains: identify the elements in the processing chain up to Level-1b; produce the Algorithm Theoretical Baseline Document (ATBD).

Ground & Flight Ops An End-to-end (E2E) Mission Performance Simulator Architecture simulates the E2E data flow of a mission, from observed scene to final products. Space and ground segment are modelled, with relevant noise/errors An E2E simulator will support activities such as: performance consolidation on mission level, by assessing observation capabilities vs. performance of processing algorithms; quantification of the impact of technical trade-offs, by simulating possible scenarios or by instrument sensitivity analysis; consolidation of system specification and early preparation of user community for mission exploitation. We will use a standard approach built on the Space Science E2E Mission Performance Simulator Reference Architecture.

Pre-development Activities PMI etalon development : PHI is based on a Lithium Niobate (LiNb03) etalon, enabling a lightweight and compact instrument. The producer of the PHI etalons has discontinued production, hence a pre-development activity is required to secure a replacement supply. COR optics breadboard : A proposed pre-development activity is to build a further breadboard, thermo-mechanically representative of COR, and measure the straylight rejection in vacuum and in a representative thermal environment. “Cosmic ray” scrubbing : It is critical for space weather instruments to operate effectively during period of high SEP flux. A proposed pre- development activity is development of an efficient scrubbing algorithm for COR and HI to test in a relevant environment (e.g. running on a software emulator of the baselined processor).

Design Considerations As an operational mission, consideration must be made of: The need for continuous synoptic observations; Robustness/redundancy [of hardware and software]; Operation under extreme space weather conditions [of hardware and software]; Cost savings driven by commonalities vs loss of heritage; Future-proofing to ensure that the operational system can benefit from future improvements in understanding/data analysis/modelling.

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