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XXM Status, Priorities, Plans, and Activities Icy Satellite Science
C. J. Hansen, A. Hendrix June 2014
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XXM Status Icy satellite observations executed since last team meeting
Tethys and Enceladus phase angle / longitude coverage We have no PIEs in 2014
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Satellite Flyby Hiatus
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Solstice Mission Enceladus Flybys
All Enceladus flyby’s in XXM have executed except E21 E20 and E22 are relatively distant flybys on Rev 223 and Rev 228, resp., in 2015
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Proximal Mission Phase Priorities
Two more potential Enceladus stellar occs in the future One is equatorial 22 June :19 Rev 280 Mean anomaly = 116 The other requires a trajectory tweak – occ rayheight is currently 3000 km) 11 March :57 Rev Mean anomaly = 220 Approved The other main priority for UVIS are the Dione stellar occ opportunities MAG sees mass-loading in the magnetosphere at ~7 kg/sec (Enceladus supplies ~200 kg/sec) Dione plume won’t go as high or lose as much gas (escape velocity is higher because Dione is larger, gravity higher)
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Locations probed previously
Circles are ~250 km radius
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Future Occultations – PIEs lost, New requested Prime
Rev Star Lat Lon 217 Alpha Vir ingress -50.9 53.5 Lost due to heating issues egress 72.3 177.1 220 Alpha Eri 37.6 224.2 In conflict with RSS -27.5 338.5 232 Alp Vir -22.4 166.6 Request in CIMS, in XD 24.4 346 233 17.8 53.3 -8.5 230.4 Gam Ori -40 135 Already integrated (RWG) -34 298 242 Sig Sgr 55.8 199 Lost with new trajectory 31.5 304.6 252 Zeta Ori -53.6 35.6 -9.7 211.7
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Locations - previous plus possible
Circles are ~250 km radius
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Future Occultations – no PIEs Yet – in Proximal and F ring orbits
Rev Star Lat Lon 263 Beta Cru ingress -21.7 128.8 egress 19.3 319 268 Alp Eri 30.8 212 -36.7 329
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Locations - previous plus planned plus proximal
Circles are ~250 km radius
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Backup
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Reference Trajectory Schedule
April 2013 Discuss Enceladus occultation with scientists May 2013 Gather initial feedback from science teams June 2013 Release of Enceladus occultation study for Summer PSG June/July 2013 Release of proximal orbits trade space October 2013 PSG decides on proximal orbit and approves Enceladus occultation trajectory January 2014 Preliminary release of reference trajectory March 2014 Final release of reference trajectory; covers remainder of tour
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System Scans - Summary of Request
June 2012 OR August hr August hr August hr January resume 4 per year 64 hr cadence
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Hello Helene! Helene is Dione’s leading co-orbital; one of 4 of Saturn’s moons in the Lagrangian L4 point Phoebe-size: 36 x 32 x 30 km Sub-Saturnian side 36x32x30 km (like Phoebe), imaged June 18 from 7000 km
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XXM Planning Status Requested PIEs for all occultations by:
Dione and Tethys Look for volatiles being released, supplying E ring Rhea Look for rings or other evidence of volatile release 15 occs requested 8 in as occ PIEs 2 “in” SOST but in conflict 4 out 1 not scheduled yet Iapetus in apoapsis Rev 196 Now looking at occs in proximal orbit
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Case 7a
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Occultations in F Ring and Proximal Orbits
24 Dione occultation opportunities 12 Rhea occultation opportunities When will we start scheduling PIEs?
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