Earth-Affecting Solar Causes Observatory (EASCO): A Heliophysics Mission at Sun-Earth L5

1. Earth-Affecting Solar Causes Observatory (EASCO):A Heliophysics Mission at Sun-Earth L5 Nat Gopalswamy1 and the EASCO Team 1NASA Goddard Space Flight Center nat.gopalswamy@nasa.gov http://adsabs.harvard.edu/abs/2011SPIE.8148E..30G http://adsabs.harvard.edu/abs/2011JASTP..73..658G

2. EASCO Team • GSFC (Gopalswamy, Davila, St.Cyr, Dennis, Shih, MacDowall, Szabo, Sittler, …) • NRL (Vourlidas, Korendyke, …) • AFRL (Johnston, …) • Stanford (Schou, Duvall, Rajaguru…) • Berkeley (Bale, …) • SWPC (de Koning, …) • Institut d’Astrophysique Spatiale, Orsay, France (F. Auchere) • Université de Paris Meudon, France (Maksimovic, …) • National Space Institute, Technical University of Denmark (Vennerstrom, …) • Christian Albrecht University, Kiel, Germany (Heber,…) • Sace Research Institute, Czech Republic (Nemecek, Safrankova, …)

3. Earth-Affecting Solar Causes Earth-impacting part of the CME not imaged from Sun-Earth line • CMEs (from active regions, filament regions) and CIRs (due to coronal holes) are the large-scale structures from the Sun affecting Earth via • Geomagnetic Storms (CMEs, CIRs) • Large Solar Energetic Particles (CMEs) • Sun-Earth line is not well-suited to observe earth-affecting CMEs and CIRs • Need a different vantage point: Sun-Earth L5 May 2005

4. SEP CMEs Cornish Geoeffective CMEs (GEO) and SEP-producing CMEs are limb CMEs from L5 view From L4 view, SEP-producing CMEs are halo CMEs ”LIMB” ”GEO” L5 – stable position, suitable for detecting energetic CMEs, measuring space speeds, and detecting frontside CMEs. Heliospheric Imaging Workshop, Sunspot, NM April 8-10, 2008

5. Observing from Off the Sun-Earth Line CME/Shock Nose Observed CME/Shock Nose not Observed STEREO-B View (~90o Behind Earth) Earth View (SOHO/LASCO)

6. From Sun-Earth Line Earth-affecting parts of the CME blocked by the occulting disk

7. Away from the Sun-Earth Line Earth-affecting parts of the CME imaged by STEREO-B COR2 Preceding small CMEs affect the propagation time of Earth-affecting CMEs Measure the true speed, remove the front-back ambiguity

8. SUN EASCO to be Located here CIRs can be observed ~4 days ahead of earth arrival Earthward CMEs can be measured without projection effects SUN CIR Earth View Halo CME L5 View Limb CME 2009 October

9. Additional Science Issues White-light shock CME SHOCK UVOS, LRT, WCOR, EPD provide shock info Combined helioseismic measurements from L5 and Earth views can be used to study physical conditions in the bottom of the convection zone where solar magnetism originates

10. Type II bursts are indicators of shock-driving CMEs throughout the Sun-Earth space 18.82 Ro Type IV 7 MHz Shock Type II CME (2050 km/s) N16E04 Type III When the shock is at a distance of 18.82 Ro, the Type II burst occurs at 450 kHz as observed by the WAVES experiment on board Wind

11. Arrival of Solar Sources (Active Regions & Coronal holes) to Earth View Knowable Days Ahead

12. Synoptic Charts for modelers From L5 magnetograms, this chart can be made more accurate The magnetic information in L5 view is the oldest in Earth view

13. Science From L5 • For shock- driving CMEs directed toward Earth, the radial structure can be discerned: shock, sheath, flux rope, prominence  Measure coronal magnetic field 5 – 30 Rs; farther with HI • Solar sources of CMEs from EUV imager, magnetogram • Simultaneous radio observations at f < 15 MHz can provide radio signatures of this shock • EUV/white-light detection of shocks: Shock Physics • Flare CME relationship -- Hard X-ray imager • Plasmag analyzer for solar wind measurements • Energetic particle detector at L5 to study flare and CME contributions to SEP events

14. From SOHO & STEREO to L5 • SOHO & STEREO helped make enormous progress in CME research • SOHO lacked radio instrument and magnetometer • STEREO did not have a magnetograph • The L5 mission can overcome these deficits and can be enhanced with a Hard X-ray Imager (HXI) and UV Off-limb Spectrograph (UVOS)

15. L5 Payload: 10 Instruments • Remote sensing (7): • Magnetic and Doppler Imager (MADI) • Hard X-ray Imager (HXI) • Inner Coronal Imager in EUV (ICIE) • UV Off-limb Spectrograph (UVOS) • White-light Coronagraph (WCOR) • Heliospheric Imager (HI) • Low-frequency radio telescope (LRT) • In-situ (3): • Solar Wind Plasma Instrument (SWPI) • Magnetometer (MAG) • Energetic Particle Detector (EPD)

16. Spacecraft Assembly & Launch Config. Total payload mass 138 kg Electric Propulsion key. SMART-1, DAWN, Hayabusa, >100 commercial

17. Total mass 300 kg chemical propulsion

18. MDL Study Results • Propulsion: Hybrid Solar Electric (SE) and Monopropellant Hydrazine System (MHS). SE propulsion for large V maneuvers and trajectory correction. MHS for momentum unload. High -thrust chemical propulsion would require 300 kg hydrazine compared to 55 kg of Xenon for SE propulsion. SE propulsion provides greater flexibility on launch vehicles (within Taurus II capability). • Flight dynamics: 2.2 year transfer to L5 using low-thrust solar electric propulsion (Launch C3: ~2.2 km2/s2, V: ~1.5 km/s). 2 year transfer using high -thrust chemical propulsion (Launch C3: ~1.0 km2/s2, V: ~ 0.95 km/s) . Even 1 year transfer possible with SE propulsion. • Power: Solar array -13.71 m2 substrate area. Segmented for the S/C Bus 3.63m2 and for Propulsion 10.08m2 . Lithium Ion battery (24 Ah) for launch and orbit insertion. • Mission life cycle: Phase A (Preliminary analysis and mission definition)– 8 mo; Phase B (System definition and preliminary design) – 10 mo; Phase C (Final design) – 12 mo; Phase D-1 (Subsystem Development and Spacecraft Integration and Test) – 26 mo; Phase D-2 (Launch & Checkout) – 5 mo; Total ~4 years before Phase E (Operations). • Cost: ~690 M$ including 30% contingency on all elements. No contingency for the launch vehicle.

19. Operations Timeline and Ground System Year 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 Solar max Solar max Launch Spacecraft and instrument checkout Cruise Science Solar Electric Propulsion Operations L5 Science Required Goal Space Weather X-band 500 bps Mission Ops Center Mission planning & scheduling Orbit determination/control Network & contact scheduling Commanding S/C monitor/control RT health/safety processing Trending/Analysis Instrument data handling Level 0 product processing Level 0 Data Archive Space Weather Ka/X band 363 kbps Science Ops Center RT Space Weather Coordination TLM, HK DSN (Prime & Back-up) Level Zero TLM,HK Data Products CMD

20. Summary • The next logical heliophysicsmission seems to be to Sun-Earth L5 to build upon the knowledge gained on CMEs and CIRs from L1 • The Mission Design Lab (MDL) study finds that the EASCO mission is very achievable with no new technology required • A medium launch vehicle is adequate for the mission • The key to the simple yet very flexible concept is the use of existing, flight proven, electric propulsion system hardware • All other subsystems are well within standard capabilities and borrow directly from the successful STEREO mission • Full paper can be found at the following site: http://adsabs.harvard.edu/abs/2011SPIE.8148E..30G