STARDUST Project CRITICAL EVENTS READINESS REVIEW COMET P/WILD 2 ENCOUNTER NAVIGATION

1. STARDUST Project CRITICAL EVENTS READINESS REVIEW COMET P/WILD 2 ENCOUNTER NAVIGATION Kenneth E. Williams JPL: 303-411 AM / 301-427 PM LMA: MSA +1 818 354-1275 08:00 AM - 05:00 PM PST 20 Nov 2003 K. E. Williams - CERR

2. Navigation Requirements • None specified, expected Navigation performance and capability adopted as requirement • Must deliver S/C to 300 km flyby within 16 km (1-sigma) in B.T and B.R after last TCM (nominally at E-18h) • Must know (but not control) Time of Encounter to 1,100 km or 180 sec (1-sigma) at E-8h • This level of accuracy provides for: • Collecting 500 particles 15 mm or larger • Gives a probability of serious impact to the spacecraft shielding 60 times less than Giotto at Halley Encounter or less than 2 % • Enables the spacecraft to maintain carrier signal during Wild 2 Flyby K. E. Williams - CERR

3. Robust Wild 2 Encounter Navigation Design • Maneuver startegy flexible to accommodate uncertainty in time of comet detection • Success of Wild 2 Encounter and ease of operations dependent on two major factors: • Optical Nav must detect Wild 2 before E-8d (DONE!) • Expected to be seen by E-20d (already detected as of E-45d) • At least two TCM’s must be performed during Approach • One at E-10d (nominal), E-6d or E-2d (contingencies) • Another at E-2d (nominal) or as late as E-18h or E-12h • Option to do early TCM at E-30d if comet already detected • Opportunity to correct Wild 2 ephemeris error early • Not critical - ~80 m/s margin available to ensure 100 psia for ACS response during Encounter (another ~100 m/s in reserve thru EOM) • Nav had implemented all timelines and interfaces during the Annefrank Encounter real-time operations and has retested for recent ORT K. E. Williams - CERR

4. Maneuver Design • Maneuvers prior to E-2d to target to 150 km • First TCM opportunity at E-30d (preliminary Delta-V ~1.5 m/s) • Next TCM at E-10d (< 7 m/s in worst case, 275 km 1-sigma delivery error) • Time-of-flight does not need to be controlled • ~180 sec (1-sigma) worst case if uncorrected (Delta-V <3 m/s) • Can slip as late as E-6d (<5.4 m/s with no TOF correction) • Maneuver at E-2d to shift to final target at 300 km • 70% probability within 90° roll about approach velocity vector • Project desire to avoid > 90° turn away from Sun/Earth if possible • Requires < 4 m/s to improve to <65 km, 1-sigma, delivery error) • Time-of-flight not controlled (8-hr development timeline) K. E. Williams - CERR

5. Maneuver Design - Continued • Maneuver may be performed at E-18h to clean up execution errors from E-2d TCM to improve targeting precision • Will be performed only if statistically meaningful • 28% probability not needed at all • 22% probability beyond 90° roll about approach velocity vector • Time-of-flight not controlled (8-hr development timeline) • Can be slipped to as late as E-12h (< 2.3 m/s Delta-V and <24 km, 1-sigma, delivery error --> 13.5° bank angle at CA --> still supports MGA carrier only) • GO/No-GO criteria in place for all Wild 2 approach maneuvers (tested at Annefrank and to be retested in upcoming ORT) • Near-continuous DSN coverage in place with dual coverage within E±2h K. E. Williams - CERR

6. Maneuver Design - Contingencies • TCM at E-30d can be cancelled • TCM at E-10d can be slipped to E-6d or E-2d • TCM at E-2d can be slipped to as late as E-12h • As final option, up to 5 TCM’s pre-designed and tested to move away from comet in Earth-Wild 2 plane at E-6h • Will be uplinked and stored on S/C before E-2d • No attitude turns needed • Designed to cover range of 100-1000 km of movement in B-plane at E-6h • If desired, can be executed anytime after E-2d if desired to further augment movement away from Wild 2 • In the event of camera failure, flyby will be targeted to safe distance (>1,000 km) based on latest Wild 2 ephemeris knowledge • Implemented by 1 of 5 stored TCM’s if desired as late as E-6h • Nav stands down for the remainder of the Encounter period K. E. Williams - CERR

7. Navigation Readiness Status • All operations, timelines and interfaces tested successfully at previous Annefrank Flyby • Annefrank too dim on Approach - Opt Nav performed with Flyby Annefrank/star images • New ORTs have/will retest for last 2.5 days prior to Wild 2 Encounter • Participants to be certified for operations by Project/MMO • Doppler and Ranging Only, no-Delta DOR implemented • No new observations, facilities, first-time events for Radio Nav and Maneuver • Workforce, Backups and Contingencies in place • Navigation Advisory Group (NAG) Readiness Review successfully completed • 9 RFA’s considered • Reduced number and complexity of approach maneuvers where feasible and adjusted staffing plans to reduce fatigue, meet CAN rqmts • Possible Opt Nav staffing at LMA still an open issue • All will be reconciled before Dec 15 • Agreed that Nav ready and qualified, pending final ORT, for Wild Encounter Operations K. E. Williams - CERR

8. Backup Charts BU-1 K. E. Williams - CERR

9. Navigation Staffing Plan BU-2 K. E. Williams - CERR

10. Some Feedback from Navigation Peer Review • Simplify Maneuver Plan √ • TOF control not required (adjust encounter seq start time; allow schedule for final two days to float ±1 hour, provided known by Dec 30) • Test of compressed (2.5 day) full TCM design entails schedule risk - not needed (rely on existing 8-hour and 10-day TCM design templates) • Clarify requirements/rationale for avoiding off-sun rolls for later TCMs • Adjust Staffing Plan √ • Additional OD support recommended to avoid fatigue while still meeting CAN requirements • Reduced MMNAV support (critical activities only) • Wider participation in meetings involving key decisions (include in ORT) • Recommend backup OPNAV support at LMA in case JPL goes down (as additional measure to support selection of 1 of 5 “canned” maneuvers) • Dual DSN coverage desirable for TCMs (probably not feasible given contention for DSN resources) BU-3 K. E. Williams - CERR

11. Nav Personnel Training and Certification • Thread Tests • Starting condition prior to first TCM (TCM-10 on 12/3/03) • Exercise interfaces among Nav subteams (OPNAV, Radio/OD, Maneuver; include Solar System Dynamics for second test) • Repeat interactions through subsequent TCMs up to Wild 2 Encounter • ORTs • Annefrank Encounter ORT (10/31/02) • TCM-12 and Preliminary Nucleus Tracking Update (Completed 11/5/03) • TCM-13, TCM-14 Contingency and Final Nucleus Tracking Update (Planned for 12/9-10) • Participation by all Nav personnel in recent activities provides for operational certification (endorsed by Stardust Project Mgr and MMO GNC Team Chief) BU-4 K. E. Williams - CERR

12. Navigation External Interfaces BU-5 K. E. Williams - CERR

13. Navigation Internal Interfaces BU-6 K. E. Williams - CERR

14. Communications for 300 km Flyby BU-7 K. E. Williams - CERR

15. Selected Maneuver Analysis Results BU-8 K. E. Williams - CERR

16. Final TCM GO/No-GO and Selection Criteria E-2d (150 --> 300 km) and E-18h TCM E-6h TCM (Contingency) E-18h Target Selection BU-9 K. E. Williams - CERR

17. Contingency Maneuver (E-6 Hours) for Operational Backup • Can be used at E-6 hours to deal with last-minute anomaly or earlier (e.g., E-2d) if • JPL disabled (e.g., earthquake) • Maneuver identified according to aimpoint shift expected at E-6 hours    • (effect would be 8 times greater at E-2d) • Select according to last JPL contact by default • If Op Nav support available at LMA, select according to estimate of OD uncert. • 100 and 1000 km shifts also recommended to round out set of 5 “canned” TCMs BU-10 K. E. Williams - CERR