CERES – Atelier Vol en formation pour l’astrophysique et la physique solaire 17 Octobre ASPICS 2 - Formation Flying for Solar Physics 100 m +/- 0.5m Study Leader : P. Duchon, CIC Team Leader : E. Hinglais, System : R. Clédassou, Schedule : September 5th 2005 to October 4th 2005 Main conclusion : The satellites are different and specialized. The Coronagraph mass is around 265 kg (including 30 kg payload). The Occulter mass is roughly 125 kg (with 20% system margin). Feasible in less than 5 years. Low level redundancy philosophy (ie. Myriade). Currently developed FF Flying techniques & technologies are well fitted. Numerous equipments from CNES Micro & Mini Sat. Science mission : 6 months mini Study context and objectives ASPICS 2 is part of a joint activity between CNES/DCT & ESA/ESTEC in the frame of PROBA-3 programme. The study objective was the operational validation of CNES concurrent Engineering Facility (named CIC). ASPICS 2 : A Solar Physics Mission to observe the solar corona between 1.02 and 3.2 solar radius, both continuum & emission lines thanks to an interferometer. Formation Flying allows to observe the corona down to the solar limb and at a very low level of scattered light thanks to the distance between the 2 S/C of the formation ( around 100m). CORONAGRAPH SPACECRAFT Attitude : +/-30 arc sec OCCULTING SPACECRAFT Attitude : +/- 1 deg RELATIVE LATERAL POSITION : +/-7 mm

CERES – Atelier Vol en formation pour l’astrophysique et la physique solaire 17 Octobre ASPICS 2 – (With CIC) Spacecrafts & Launch : Final configuration Satellites Launch capability : Dnepr ST-2, Soyuz 2.1.a or 2.1.b in lower place together with a co-passenger The 2 S/C on the launcher 440 Kg Spacecraft parameters High Elliptic Orbit ~ 400 Km / / 65 or 93 deg RF Metrology for localization and collision avoidance. Optical Metrology for accurate lateral relative position measurement: 0.15mm (transversal) Coronagraph S/C : Cold gas (FF) & Hydrazine (orbit) Occulter S/C: hydrazine & Wheels

CERES – Atelier Vol en formation pour l’astrophysique et la physique solaire 17 Octobre ë Strong points: Small satellites class mission (125 Kg kg) leading to a cheap launch Feasible in less than 5 years, Simple operations, No technological gap with respect to currently developed FF techniques & technologies, Numerous of-the-shelf equipment. … AND therefore a minimized mission cost ë Weak points study results need consolidation, Attitude stability study & payload design, risk due to low redundancy philosophy with regard to costs. ë Dedicated to the payload Coronagraph Interferometer optimization Attitude stability study and test (< 1 arc sec during 1 s) ë Formation Flying: ë in line with current work : RF metrology development. Lateral sensor Detail study 6 d.o.f. by cold gas… ë gyro stellar filter performances Conclusion R & D Links - ASPICS 2 – Synthesis

CERES – Atelier Vol en formation pour l’astrophysique et la physique solaire 17 Octobre ASPICS II - Parameters & Scenarios Satellites : 100 – 250kg Common for each scenario : Maximal heritage on other PFs off the shelf harware asymmetrical Formation Flying FF on Coronagraph Occulter on natural orbit payload on Coronagraph design to cost Open : Recurrence of the satellites “Only Cold Gas or with Hydrazine Payload uncoupled with respect to the PFs or embedded into the PFs’ Science Solar Corona : min = 1.01 to 1.03 Rs Max = 2.5 to 3.2 Rs Observation 6 h to 12 h / orbit ~6 images / 15 mn Visible : 1 Fabry-Perot interferometer ISL Distance : ~100 m Passenger LAUNCHER Ariane 5 GTO ONE DAY 300 / km ORBIT MISSION SPACECRAFTs & FF Soyuz 2.1.a 2.1.b Dnepr