The Solar Orbiter Science Activity Plan: translating solar and heliospheric physics questions into action

Solar Orbiter is the first space mission observing the solar plasma both in situ and remotely, from a close distance, in and out of the ecliptic. The ultimate goal is to understand how the Sun produces and controls the heliosphere, filling the Solar System and driving the planetary environments. With six remote-sensing and four in-situ instrument suites, the coordination and planning of the operations are essential to address the following four top-level science questions: (1) What drives the solar wind and where does the coronal magnetic field originate?; (2) How do solar transients drive heliospheric variability?; (3) How do solar eruptions produce energetic particle radiation that fills the heliosphere?; (4) How does the solar dynamo work and drive connections between the Sun and the heliosphere? Maximising the mission"s science return requires considering the characteristics of each orbit, including the relative position of the spacecraft to Earth (a ecting downlink rates), trajectory events (such as gravitational assist manoeuvres), and the phase of the solar activity cycle. Furthermore, since each orbit"s science telemetry will be downloaded over the course of the following orbit, science operations must be planned at mission level, rather than at the level of individual orbits. It is important to explore the way in which those science questions are translated into an actual plan of observations that fits into the mission, thus ensuring that no opportunities are missed. First, the overarching goals are broken down into specific, answerable questions along with the required observations and the so-called Science Activity Plan (SAP) is developed to achieve this. The SAP groups objectives that require similar observations into Solar Orbiter Observing Plans (SOOPs), resulting in a strategic, top-level view of the optimal opportunities for science observations during the mission lifetime. This allows for all four mission goals to be addressed. In this paper, we introduce Solar Orbiter"s SAP through a series of examples and the strategy being followed.Agencia Estatal de Investigació

Statistical analysis of solar events associated with SSC over year of solar maximum during cycle 23: 2. Characterisation on the Sun-Earth path - Geoeffectiveness

International audienceTaking the 32 sudden storm commencements (SSC) listed by the observatory de l'Ebre / ISGI over the year 2002 (maximal solar activity) as a starting point, we performed a statistical analysis of the related solar sources, solar wind signatures, and terrestrial responses. For each event, we characterized and identified, as far as possible, (i) the sources on the Sun (Coronal Mass Ejections -CME-), with the help of a series of criteria (velocities, drag coefficient, radio waves, magnetic field polarity), as well as (ii) the structure and properties in the interplanetary medium, at L1, of the event associated to the SSC: magnetic clouds -MC-, non-MC interplanetary coronal mass ejections -ICME-, co-rotating/stream interaction regions -SIR/CIR-, shocks only and unclear events that we call "miscellaneous" events. The geoeffectiveness of the events, classified by category at L1, is analysed by their signatures in the Earth ionized (magnetosphere and ionosphere) and neutral (thermosphere) environments, using a broad set of in situ, remote and ground based instrumentation. The role of the presence of a unique or of a multiple source at the Sun, of its nature, halo or non halo CME, is also discussed. The set of observations is statistically analyzed so as to evaluate and compare the geoeffectiveness of the events. The results obtained for this set of geomagnetic storms started by SSCs is compared to the overall statistics of year 2002, relying on already published catalogues of events, allowing assessing the relevance of our approach ; for instance all the 12 well identified Magnetic Clouds of 2002 give rise to SSCs

Statistical Analysis of Solar Events Associated with SSC over Year of Solar Maximum during Cycle 23: 1. Identification of Related Sun-Earth Events

International audienceTaking the 32 sudden storm commencements (SSC) listed by the observatory de l'Ebre / ISGI over the year 2002 (maximal solar activity) as a starting point, we performed a statistical analysis of the related solar sources, solar wind signatures, and terrestrial responses. For each event, we characterized and identified, as far as possible, (i) the sources on the Sun (Coronal Mass Ejections -CME-), with the help of a series of herafter detailed criteria (velocities, drag coefficient, radio waves, polarity), as well as (ii) the structure and properties in the interplanetary medium, at L1, of the event associated to the SSC: magnetic clouds -MC-, non-MC interplanetary coronal mass ejections -ICME-, co-rotating/stream interaction regions -SIR/CIR-, shocks only and unclear events that we call "miscellaneous" events. The categorization of the events at L1 is made on published catalogues. For each potential CME/L1 event association we compare the velocity observed at L1 with the one observed at the Sun and the estimated balistic velocity. Observations of radio emissions (Type II, Type IV detected from the ground and /or by WIND) associated to the CMEs make the solar source more probable. We also compare the polarity of the magnetic clouds with the hemisphere of the solar source. The drag coefficient (estimated with the drag-based model) is calculated for each potential association and it is compared to the expected range values. We identified a solar source for 26 SSC related events. 12 of these 26 associations match all criteria. We finally discuss the difficulty to perform such associations

Interplanetary journey of a coronal mass ejection to Mars and to Comet 67P/Churyumov-Gerasimenko

International audienceWe discuss observations of a large coronal mass ejection (CME) ejected on 14 October 2014, which hit Mars on 17 October 2014, 1.5 days before the Mars close encounter with the Siding Spring comet. Clear disturbances of the Mars' upper atmosphere are identified in the Mars Express and MAVEN data sets. Interestingly, comet 67P/Churyumov-Gerasimenko was perfectly aligned with the Sun and Mars at 1.7 AU behind Mars, with the Rosetta spacecraft orbiting at 10 km above the cometary surface. The Rosetta plasma package and the radiation monitor detected the event on 22 October 2014. We describe the propagation of this CME from the Sun to Rosetta and show comparison with dedicated WSA-ENLIL (large-scale, physics-based prediction model of the heliosphere) simulations. CME effects on the Mars and comet 67P environments are reported. In particular, large and similar Forbush effects - a transient decrease followed by a gradual recovery in the observed galactic cosmic ray intensity- were observed at both places, as recorded by the MSL RAD instrument aboard the Curiosity rover at the surface of Mars and by the Radiation Environment Monitor aboard Rosetta. Fortuitously, the New Horizons spacecraft was also along the propagation direction of the CME, which can take 3-5 months to reach the distance of 31.7 AU. By the time the solar wind travels that far from the Sun, the fast solar wind parcels have interacted with slower wind parcels emitted at an earlier time along the same radial line. We investigate if the CME observed at Mars and Rosetta has a unique signature at New Horizons. This presents a challenge since many solar structures can either be worn down as they propagate, or they can merge into larger ones. We present also preliminary 3D WSA-ENLIL simulations out to 40 AU showing the evolution of the CME, including other CMEs during this period

Interplanetary journey of a coronal mass ejection to Mars and to Comet 67P/Churyumov-Gerasimenko

International audienceWe discuss observations of a large coronal mass ejection (CME) ejected on 14 October 2014, which hit Mars on 17 October 2014, 1.5 days before the Mars close encounter with the Siding Spring comet. Clear disturbances of the Mars' upper atmosphere are identified in the Mars Express and MAVEN data sets. Interestingly, comet 67P/Churyumov-Gerasimenko was perfectly aligned with the Sun and Mars at 1.7 AU behind Mars, with the Rosetta spacecraft orbiting at 10 km above the cometary surface. The Rosetta plasma package and the radiation monitor detected the event on 22 October 2014. We describe the propagation of this CME from the Sun to Rosetta and show comparison with dedicated WSA-ENLIL (large-scale, physics-based prediction model of the heliosphere) simulations. CME effects on the Mars and comet 67P environments are reported. In particular, large and similar Forbush effects - a transient decrease followed by a gradual recovery in the observed galactic cosmic ray intensity- were observed at both places, as recorded by the MSL RAD instrument aboard the Curiosity rover at the surface of Mars and by the Radiation Environment Monitor aboard Rosetta. Fortuitously, the New Horizons spacecraft was also along the propagation direction of the CME, which can take 3-5 months to reach the distance of 31.7 AU. By the time the solar wind travels that far from the Sun, the fast solar wind parcels have interacted with slower wind parcels emitted at an earlier time along the same radial line. We investigate if the CME observed at Mars and Rosetta has a unique signature at New Horizons. This presents a challenge since many solar structures can either be worn down as they propagate, or they can merge into larger ones. We present also preliminary 3D WSA-ENLIL simulations out to 40 AU showing the evolution of the CME, including other CMEs during this period