Issue/Revision: 1.0 Reference: Status: For information Only ESA UNCLASSIFIED - For Official Use Solar Orbiter: Launch Options Favouring Data Return J.M. Sánchez Pérez, ESA-ESOC, HSO-GFA ESTEC

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 2 ESA UNCLASSIFIED - For Official Use Introduction 1.Period from September 2018 to December 2020 has been analysed in order to identify launch options for Solar Orbiter considering the maximisation of the data return as a major figure of merit 2.Task is now complete A number of possible candidates were analysed A set of trajectories has been identified from October 2018 until June 2020 offering better data return than the current CReMA baseline Potential downlink improvement from 15% to about 100% possible Some launch options provide as well an earlier start of science

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 3 ESA UNCLASSIFIED - For Official Use On the data return – Downlink index

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 4 ESA UNCLASSIFIED - For Official Use On the data return – Downlink index 2018 October CReMA “Bad” 4:3 Science orbit DL index = /AU October A1 “Good” 4:3 Science orbit DL index = /AU 2 Downlink driven by phasing of the Earth-Sun-Venus GAM geometry ESV angle = 69° ESV angle = -21°

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 5 ESA UNCLASSIFIED - For Official Use Comprehensive launch options search (1) 1.Assumptions and constraints: Trajectory problem tackled from launch to final 3:2 science orbit E(E)VEV, E(E)VVEV and E(E)VEEV transfer options Launch from Oct 2018 to Dec 2020 with Earth escape V ∞ <= 5.6 km/s Up to 3 full revolutions in each transfer leg, 5 during Venus resonances 0.27 AU <= Distance to Sun <= 1.57 AU Final science orbit in 3:2 resonance with solar inclination deg Total mission duration <= 10.7 years Average data return during science phase >= 2.0 Tbit/year Avoid critical superior conjunctions at GAMs (14 out of the last 20 days before a GAM with SES < 3 deg) Safe mode blackout periods <= 85 days 2.Over 400 solutions have been found and were further analysed Many solutions still non compliant with spacecraft constraints (eclipse duration, Max Sun distance, Safe mode blackout) and/or operational constraints (solar conjunction at GAM)

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 6 ESA UNCLASSIFIED - For Official Use Comprehensive launch options search (2) Cruise duration: from launch until last GAM before perihelion < 0.35 AU

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 7 ESA UNCLASSIFIED - For Official Use Comprehensive launch options search (3) Solutions cluster around same arrival dates Venus can be reached only at given solar longitudes No good solutions from Jul 2020 to Dec 2020! Empty

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 8 ESA UNCLASSIFIED - For Official Use Comprehensive launch options search (4) More strict Sun distance constraint and cruise duration 2 solution clusters: Oct 2018 and Jan-Jun 2020 Only 2 not promising solutions left in 2019

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 9 ESA UNCLASSIFIED - For Official Use Comprehensive launch options search (5) Longer mission not necessarily higher data return Earth-Venus phasing is critical Short cruise achieved with low or high max. Sun range only Empty

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 10 ESA UNCLASSIFIED - For Official Use Trajectories identified 1.Late October CReMA: issue with poor downlink 2018 October A1* & D: similar cruise as CReMA and different science phase improving downlink. D has the best downlink 2018 October E: different cruise (EVVEV) & early science start, good DL 2018 November*: fast EVEV cruise, average downlink / 2020 February Options A* and C: short EVEV cruise, average downlink Option B: very short EVVEV cruise, excellent downlink, marginal LW April: longer cruise, average downlink / 2020 June Option A*: short EVEV cruise, average DL, maximum Sun range ~1.5 AU Option B: similar to A, but compliant with Rsun <= 1.48 AU * Trajetories proposed by Dr. Langevin

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 11 ESA UNCLASSIFIED - For Official Use Downlink Classification DL index (AU -2 ) Core 4:3 or 5:4 orbit NMPEMP Total science 2018 Oct D Feb B Oct E Jul Oct A Jan Feb C April Nov Jun A Jun B Feb A Oct CReMA

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 12 ESA UNCLASSIFIED - For Official Use Downlink – “Best case” DL index (AU -2 ) Core 4:3 or 5:4 orbit NMPEMP Total science 2018 Oct D Feb B Oct E Jul Oct A Jan Feb C April Nov Jun A Jun B Feb A Oct CReMA st 5:4 core science orbit DL index = 2.43 AU -2 2 nd 4:3 science orbit DL index = 1.89 AU -2

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 13 ESA UNCLASSIFIED - For Official Use 5:4 orbit 4:3 orbit Downlink – “Best case” 1 st 5:4 core science orbit DL index = 2.43 AU -2 2 nd 4:3 science orbit DL index = 1.89 AU

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 14 ESA UNCLASSIFIED - For Official Use Downlink – Excellent science orbits DL index (AU -2 ) Core 4:3 or 5:4 orbit NMPEMP Total science 2018 Oct D Feb B Oct E Jul Oct A Jan Feb C April Nov Jun A Jun B Feb A Oct CReMA

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 15 ESA UNCLASSIFIED - For Official Use Perihelion Radius (AU)Solar inclination (deg) Evolution of parameters – Late Nov starts science almost as fast as 2018 Oct E and much higher inclination during NMP. However: < 0.3 AU only at EMP, limited final inclination and average downlink Trajectories with better downlink have delayed raise of the inclination

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 16 ESA UNCLASSIFIED - For Official Use Evolution of parameters &2020 Perihelion Radius (AU)Solar inclination (deg) Also fast mission with excellent downlink 2020 Feb B lags behind in inclination 2020 Feb A and Jun A start science later at higher inclinations always > 20 deg with average downlink, better than 2018 Oct CReMA, but worse than 2017 Jan or Jul Other options are intermediate in terms of evolution of orbit parameters

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 17 ESA UNCLASSIFIED - For Official Use Trajectories identified 1.Late October CReMA: issue with poor downlink 2018 October A1 & D: similar cruise as CReMA and different science phase improving downlink. D has the best downlink 2018 October E: different cruise (EVVEV) & early science start, good DL 2018 November: fast EVEV cruise, average downlink / 2020 February Options A and C: short EVEV cruise, average downlink Option B: very short EVVEV cruise, excellent downlink, marginal LW April: longer cruise, average downlink and science / 2020 June Option A: short EVEV cruise, average DL, maximum Sun distance ~1.5 AU Option B: similar to A, but compliant with Rsun <= 1.48 AU Most promising for late 2018

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 18 ESA UNCLASSIFIED - For Official Use 2018 Oct Option D Science phase: 5:4-4:3-3:2-3:2 (inbound) Cruise: 3.1 years 1 perihelion at 0.31 AU in E2-V2 leg 9.4 years to i s >30° Core science orbit: 5:4 reached after 3.8 years Inclination is low 12.7°, then raises fast Superb data return – DL index 2.43 AU -2 Excellent data return – DL index 1.89 AU -2 Maximum Sun range: AU Launch window 30 days both Atlas V & A5ECA

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 19 ESA UNCLASSIFIED - For Official Use 2018 Oct Option E Very fast cruise: 2.3 years – Type EVVEV 2 perihelions at AU in E1-V3 leg 7.5 years to i s >30°, max. i s after 9.3 years Core science orbit: 4:3 reached after 3.15 years Inclination is low 13.1°, then raises fast Superb data return – DL index 2.09 AU -2 Very good data return – DL index 1.55 AU -2 Max. Sun range: AU – No hibernation Launch window 30 days Atlas V, 20 d A5ECA Science phase: 4:3-3:2-3:2-5:3-3:2 (outbound)

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 20 ESA UNCLASSIFIED - For Official Use 2018 Oct E vs Oct D Perihelion Radius (AU)Solar inclination (deg) Evolution of parameters 2018 Oct. D vs. E 2018 Oct E starts science earlier, goes faster <0.3 AU 2018 Oct E has more science orbits even if last 3:2 is ommited: 20 or 17 vs. 16 Inclination steps are similar, but 2018 Oct E is earlier 2018 Oct D has better downlink and more stable perihelion radius

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 21 ESA UNCLASSIFIED - For Official Use Summary – Science Performance Case CReMA Limits 2018 Oct CReMA 2018 Oct A Oct D 2018 Oct E 2018 Nov 2019 April 2020 Feb A 2020 Feb B 2020 Feb C 2020 Jun A 2020 Jun B +1 year if launched in 2019 Total Duration (y) 8.87 – Cruise duration (y) 2.94 – st perih. < 0.3 AU (y) 3.50 – Time to is 30 deg (y) Time to max. solar i (y) 7.86 – NMP+EMP duration (y)

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 22 ESA UNCLASSIFIED - For Official Use Summary – Science Performance Case CReMA Limits 2018 Oct CReMA 2018 Oct A Oct D 2018 Oct E 2018 Nov 2019 April 2020 Feb A 2020 Feb B 2020 Feb C 2020 Jun A 2020 Jun B Min Sun distance (AU) ≥ # Perih < 0.3 AU 7 – Time spent < 0.3 AU (d) 46.5 – # Below 0.4 AU 12 – Time spent < 0.4 AU (d) – Max. solar i (deg) (31.3) (30.2) Max. angular rate (deg/d) 7.76 – |Heliolatitude|>25 deg (8) (3)6(3) 8 9 Heliolatitude>+25 deg (d) (137) (90) Heliolatitude<-25 deg (d) (187) (57) |Heliolat.|>25 deg (d) (323) (147)

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 23 ESA UNCLASSIFIED - For Official Use Summary - Constraints Case CReMA Limits 2018 Oct CReMA 2018 Oct A Oct D 2018 Oct E 2018 Nov 2019 April 2020 Feb A 2020 Feb B 2020 Feb C 2020 Jun A 2020 Jun B LW Atlas V 411 (d) LW Ariane 5 ECA (d) (only 2019) ~26 (only 2019) 30 (only 2019) 30 Max Sun distance (AU) – SM Blackouts*: longest (d) ≤ Conjunctions*: longest (d) ≤ Longest eclipse - LW (min) ≤ Longest occultation (min) ≤ SES angle at Venus (deg) Feb B marginal launch window with Atlas V Nov and 2020 June A marginally above max. Sun distance constraint All other constraints are respected, including OPS constraint to avoid Solar superior conjunction at Venus GAM

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 24 ESA UNCLASSIFIED - For Official Use Conclusions 3 launch options allow fast start of science and excellent downlink improving performance of current CReMA’s best (2017 July) Generally very high downlink leads to lower inclinations at start of NMP and a delay in the inclination raise Selection process for new baseline in late 2018 – Most promising: October D favouring downlink October E favouring fast start of and more science Additional trajectories compliant with all mission constraints provide better downlink than CReMA 2018 Oct and give flexibility to launch in different periods from 2019 Feb to 2020 June Backup launch options are ensured until 2020 June allowing to accommodate different launch delays Selection not considered critical at this point

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 25 ESA UNCLASSIFIED - For Official Use SPARE SLIDES

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 26 ESA UNCLASSIFIED - For Official Use 2018 Oct CReMA Science phase: 1:1-1:1-4:3-3:2-3:2 (inbound) Cruise: 3.2 years 1 perihelion at AU in E2-V2 leg 8.2 years to i s >30° Core science orbit: 4:3 reached after 5.1 years Inclination 21.7° Poor data return – DL index 0.73 AU -2 Overall poor data return – DL index 1.09 AU -2 Maximum Sun range: AU Launch window 30 days both Atlas V & A5ECA

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 27 ESA UNCLASSIFIED - For Official Use 2018 Oct Option A1 Science phase: 1:1-4:3-4:3-3:2-5:3 (inbound) Cruise: 3.1 years 1 perihelion at 0.31 AU in E2-V2 leg 8.1 years to i s >30° Core science orbit: 4:3 reached after 4.4 years Inclination is lower 16.9° Good data return – DL index 1.60 AU -2 Good overall data return – DL index 1.42 AU -2 Poor data return during EMP Maximum Sun range: AU Launch window 30 days both Atlas V & A5ECA

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 28 ESA UNCLASSIFIED - For Official Use 2018 November Science phase: 4:3-3:2-5:3-5:3* (inbound) Very fast cruise: 2.7 years 7.7 years to i s >30° However, not possible to reach i s >31° Core science orbit: 4:3 reached after 2.7 years Inclination is 19.1° Average data return – DL index 0.90 AU -2 Average data return – DL index 1.26 AU -2 Max. Sun range: AU – Above constraint Launch window 30 days both Atlas V & A5ECA

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 29 ESA UNCLASSIFIED - For Official Use 2019 April Science phase: 4:3-3:2-3:2-5:3 (outbound) Cruise is long: 3.9 years 7.0 years to i s >30° Core science orbit: 4:3 reached after 3.9 years Inclination is 16.0° Poor data return – DL index 0.72 AU -2 Average total data return – DL index 1.28 AU -2 Max. Sun range: 1.13 AU – No hibernation Launch window 30 days Atlas V & 24 d A5ECA

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 30 ESA UNCLASSIFIED - For Official Use 2019/2020 February A Science phase: 4:3-3:2-5:3-5:3* (outbound) Cruise: 3.1 years (4.1 years in 2019) 6.2 years to i s >30° (7.2 years in 2019) Core science orbit: 4:3 reached after 3.1 years (4.1 years) Inclination is high 21.9° Poor data return – DL index 0.81 AU -2 Average total data return – DL index 1.23 AU -2 Max. Sun range: 1.11 AU – No hibernation Launch window: 2019 Atlas V & A5ECA both 30 days 2020 Atlas V 29 days

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 31 ESA UNCLASSIFIED - For Official Use 2019/2020 June A Science phase: 4:3-3:2-5:3-5:3* (inbound) Cruise: 2.7 years (3. 7 years in 2019) 5.8 years to i s >30° (6.8 years in 2019) 7.6 years to i s >32° (6.8 years in 2019) Core science orbit: 4:3 reached after 2.7 years (3.7 years) Inclination is 20.3° Average data return – DL index 0.92 AU -2 Average total data return – DL index 1.26 AU -2 Max. Sun range: AU – Above constraint Launch window Atlas V & A5ECA both 30 days

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 32 ESA UNCLASSIFIED - For Official Use 2019/2020 June B Science phase: 4:3-3:2-3:2-3:2-3:2 (inbound) Cruise: 2.7 years (3. 7 years in 2019) 7.0 years to i s >30° (8.0 years in 2019) 8.2 years to i s >31.5° (9.2 years in 2019) Core science orbit: 4:3 reached after 2.7 years (3.7 years) Inclination is only 12.1° Poor data return – DL index 0.84 AU -2 Average total data return – DL index 1.24 AU -2 Max. Sun range: AU Launch window Atlas V & A5ECA both 30 days

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 33 ESA UNCLASSIFIED - For Official Use 2019/2020 February B Science phase: 5:4-4:3-3:2-5:3 (inbound) Very fast cruise: 1.8 years – Type EVVEV (2.8 years in 2019) 1 perihelion at AU in E1-V3 leg 8.1 years to i s >30° (9.1 years in 2019) 9.3 years for i s >33° (not in 2019) Core science orbit: 5:4 reached after 2.6 years (3.6 years) Inclination is very low 8.7° Superb data return – DL index 2.42 AU -2 Excellent total data return – DL index 1.72 AU -2 Max. Sun range: 1.02 AU – No hibernation Launch window marginal: only 17 days 2020 Atlas V only, 2019 Atlas V & A5ECA

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 34 ESA UNCLASSIFIED - For Official Use 2019/2020 February C Variant of Feb A with 5:4 instead 1:1-4:3 Science phase: 5:4-4:3-3:2-5:3 (outbound) Cruise: 2.5 years (3.5 years in 2019) 8.0 years to i s >30° (9.0 years in 2019) Core science orbit: 5:4 reached after 2.5 years (3.5 years) Inclination is low 13.9° Average data return – DL index 0.98 AU -2 Average total data return – DL index 1.35 AU -2 Max. Sun range: 1.11 AU – No hibernation Launch window: 2019 Atlas V & A5ECA both 30 days 2020 Atlas V 29 days

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 35 ESA UNCLASSIFIED - For Official Use Data Return – Good NMP case, but … DL index (AU -2 ) Core 4:3 or 5:4 orbit NMPEMP Total science 2018 Oct D Feb B Oct E Jul Oct A Jan Feb C April Nov Jun A Jun B Feb A Oct CReMA st 4:3 core science orbit DL index = 1.60 AU -2 2 nd 4:3 science orbit DL index = 1.91 AU -2

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 36 ESA UNCLASSIFIED - For Official Use Data Return – … bad EMP DL index (AU -2 ) Core 4:3 or 5:4 orbit NMPEMP Total science 2018 Oct D Feb B Oct E Jul Oct A Jan Feb C April Nov Jun A Jun B Feb A Oct CReMA st 3:2 science orbit DL index = 0.92 AU -2 2 nd 3:2 science orbit DL index = 1.08 AU -2

J.M. Sánchez Pérez | ESOC | 18/06/2015 | Slide 37 ESA UNCLASSIFIED - For Official Use Data Return – Good EMP DL index (AU -2 ) Core 4:3 or 5:4 orbit NMPEMP Total science 2018 Oct D Feb B Oct E Jul Oct A Jan Feb C April Nov Jun A Jun B Feb A Oct CReMA :2 science orbit DL index = 1.79 AU -2 5:3 science orbit DL index = 1.05 AU -2 Additional 3:2 science orbit DL index = 1.56 AU -2