1. XXM Status, Priorities, Plans, and Activities Icy Satellite Science
C. J. Hansen, A. Hendrix
June 2014

2. XXM Status Icy satellite observations executed since last team meeting
Tethys and Enceladus phase angle / longitude coverage
We have no PIEs in 2014

3. Satellite Flyby Hiatus

4. 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

5. 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)

6. Locations probed previously
Circles are ~250 km radius

7. 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

8. Locations - previous plus possible
Circles are ~250 km radius

9. 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

10. Locations - previous plus planned plus proximal
Circles are ~250 km radius

11. Backup

12. 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

13. System Scans - Summary of Request
June 2012
OR August hr
August hr
August hr
January resume 4 per year 64 hr cadence

14. 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

15. 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

16. Case 7a

17. Occultations in F Ring and Proximal Orbits
24 Dione occultation opportunities
12 Rhea occultation opportunities
When will we start scheduling PIEs?