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Systems Engineering

Systems Engineering. Systems Agenda. Design Mission Description Instrument and Probe Configuration Launch and Mission Description Requirements Verification Summary, Waived and Pending Requirements New Mission Profile Review Resources Operating Hours Problem Failure Reports

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Systems Engineering

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  1. Systems Engineering

  2. Systems Agenda • Design • Mission Description • Instrument and Probe Configuration • Launch and Mission Description • Requirements Verification • Summary, Waived and Pending Requirements • New Mission Profile Review • Resources • Operating Hours • Problem Failure Reports • Statistics and Status • Unverifiable Failures • Operational WorkArounds

  3. Mission Summary Launch Vehicle: Delta II, Eastern Range Apogee: 91845.2 km ± 9567 km Perigee: 435 km ± 10 km (500 km ± 7 km on or after 3/1/2007) Inclination: 16.0 deg ± 0.5 deg Date: February 15, 2007 Space Segment Spacecraft: 5 Spinning Probes with Fuel for Orbit & Attitude Adjust Instruments: 3-Axis Electric Field, Magnetic Field 3-D Ion & Electron Particle Detectors Spin Rate: 20 RPM Orbit Period(s): 1, 2 and 4 days Orientation: Ecliptic Normal Ground Segment Observatories: 20 Northern with All Sky Imagers and Magnetometers Control Facilities: Mission and Science Operations Centers Operations Phases: L&EO, Cruise, Ascent, Campaigns, De-orbit Lifetime: 2.3 years

  4. Instrument Configuration IDPU: Instrument Data Processor Unit SPB : Spin Plane Booms (4x) AXB : Axial Booms (2x) SST : Solid State Telescope (2x) ESA : Electrostatic Analyzer FGM : Fluxgate Magnetometer SCM : Search Coil Magnetometer

  5. Probe Configuration Antenna EFI Axial Booms (2, Stowed) ESA Miniature Sun Sensor Fuel Tank IDPU EFI SPB Repress Tank Transponder Fuel Tank Thruster A2 Thruster T1 EFI SPB Thruster A1 BAU Battery Gyros EFI SPB Thruster T2 AEB

  6. Launch Configuration • Dedicated launch accommodated within standard Delta 7925-10 vehicle configuration and services • 10’ Composite Fairing required to accommodate five Probes on the Probe Carrier in the “Wedding Cake” configuration • PC stays attached to Delta 3rd stage after probe dispense • Each probe dispense from the PCA is coordinated with but independent of the other probes • No single probe anomaly precludes dispense ofremaining probes Standard Delta 10 ft. Fairing Static Envelope Probe Carrier Assembly (PCA = 5 Probes + Probe Carrier) on L/V 3712 PAF Star 48 3rd Stage Probe Carrier Assembly (PCA) on Delta 3rd Stage THEMIS Launch Configuration

  7. Mission Profile

  8. Requirements Status • Mission Requirements Documentation (MRD) • THM_SYS_001K_MRD.xls • Mission Requirements Verification • 476 Requirements total • 467 Requirements verified • 5 Requirements pending • 4 Requirements waived

  9. Requirements Waived • Implementation Change • IN.ESA-08: ESA Dayside Energy Flux Attenuator • Waived: Electronic Counting Was Fast Enough • IN.DPU-09: Stored Housekeeping Telemetry Storage • Waived: BAU saves all IDPU Engineering Data • As Measured • IN.EFI-11: EFI Noise Level < 1x 10^-4 mV/m/sqrt(Hz). • Waived:EFI measured noise level is 2 to 3 x 10^-4 mVm/sqrt(Hz). • PC.Mech-1: Probe-to-Probe Static Clearance of 4 inches • Waived: Current static clearance is 3.75 inches.

  10. Requirements Pending • Launch Site Verification • M-33 Electrostatic Cleanliness requirement verification pending ESC survey after all flight close-outs (Jan 9) • M-45, M-47, PC-8 PCA Mass Properties (Mass, CG, and Principle Misalignment) requirement verification pending PCA Spin Balance Test and final weighing of PCA with fueled Probes. (Jan 12 and 13) • Post-Launch Verification • IN.ESA-13 ESA On-Orbit Calibration requires raw data to be collected prior to final coefficients to be delivered to the Science Operations Center. (March 2007)

  11. New Mission Profile • Mission Profile Review for Feb 15, 2007 Launch • EFI Boom Deploy delayed ~ 9 months on Probes 1 & 5 • THEMIS Deployment Motors Life Test (21 mo @ 50 C) • CLUSTER lifetime tests also relevant and showed no issues • RCS Re-pressurization delayed about 6 months • No Issues with RCS Components • Cassini waited several years to do the recharge. • Ascent Maneuvers Delayed appx 6 months • Increased IRU radiation qualification to 63 Krad (RDM of 2) • Power considerations • Improved launch orientation, side solar arrays in sun. • No change in number or duration of eclipses • Thermal environment • No change

  12. Resources • Mass Status • < 2% mass deviation between Probes (requirement) • Dry Mass Margin: 4.5% (Worst case) • Power Status • Probe CBE: 38.7 W • Probe Capability: 40.60 W • Probe Margin: 8.8% (First 3-hour Eclipse Season) 4.9% (Second 3- hour Eclipse Season)

  13. Operating Hours • Integrated Probe Hours: • Components : Averaged 780 hours run time prior to integration. • Failure Free Hours: Hours accumulated on core system after return of transponder and BAU during mission integration. • Late Instrument Swaps (>100 hours gained on integrated system after all swaps): • Spare SST on F1 swapped in prior to TVac in August • Spare SCM on F1 swapped in early October • EFI re-work on F1-F5 completed in November • Thermal Vacuum Hours: 120-150 failure free hours were accumulated on all components during Probe Level TVac. Components accumulated and average of 250 hours during Component Level TVac.

  14. Problem/Failure Reports • PFR Statistics (All Spacecraft) • Total : 237 • Closed : 237 • Open : 0 • Unverifiable Failures : 13 • Operational Work-Arounds : 10

  15. Unverifiable Failures

  16. Operational WorkArounds

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