THEMIS MRRSystems - 1 GSFC, Jan 5, 2007 Systems Engineering.

THEMIS MRR Systems - 1 GSFC, Jan 5, 2007

Systems Engineering


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

Systems Agenda


LaunchVehicle: Delta II, Eastern RangeApogee: 91845.2 km ± 9567 kmPerigee: 435 km ± 10 km (500 km ± 7 km on or after 3/1/2007)Inclination: 16.0 deg ± 0.5 degDate: February 15, 2007

Space SegmentSpacecraft: 5 Spinning Probes with Fuel for Orbit & Attitude

AdjustInstruments: 3-Axis Electric Field, Magnetic Field

3-D Ion & Electron Particle DetectorsSpin Rate: 20 RPMOrbit Period(s): 1, 2 and 4 daysOrientation: Ecliptic Normal

Ground SegmentObservatories: 20 Northern with All Sky Imagers and MagnetometersControl Facilities: Mission and Science Operations Centers

OperationsPhases: L&EO, Cruise, Ascent, Campaigns, De-orbitLifetime: 2.3 years

Mission Summary


Instrument Configuration

IDPU: Instrument Data Processor UnitSPB : Spin Plane Booms (4x)AXB : Axial Booms (2x)SST : Solid State Telescope (2x)ESA : Electrostatic Analyzer FGM : Fluxgate MagnetometerSCM : Search Coil Magnetometer


Fuel Tank

ESA

EFI SPB

Thruster T1

EFI Axial Booms (2, Stowed)

BatteryBAU

Repress Tank

Miniature Sun Sensor

Transponder

Thruster T2

IDPU

Fuel Tank

Antenna

EFI SPB

EFI SPB

Thruster A1

Thruster A2

AEB

Gyros

Probe Configuration


Standard Delta 10 ft. Fairing Static Envelope

3712 PAF

Probe Carrier Assembly (PCA = 5 Probes + Probe Carrier) on L/V

THEMIS Launch Configuration

Probe Carrier Assembly (PCA) on Delta 3rd Stage

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 of remaining probes

Star 48 3rd Stage


Mission Profile


Mission Requirements Documentation (MRD)• THM_SYS_001K_MRD.xls

Mission Requirements Verification• 476 Requirements total• 467 Requirements verified• 5 Requirements pending• 4 Requirements waived

Requirements Status


Implementation Change• IN.ESA-08: ESA Dayside Energy Flux Attenuator

Waived: Electronic Counting Was Fast Enough

• IN.DPU-09: Stored Housekeeping Telemetry StorageWaived: BAU saves all IDPU Engineering Data

As Measured• IN.EFI-11: EFI Noise Level < 1 x 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 inchesWaived: Current static clearance is 3.75 inches.

Requirements Waived


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)

Requirements Pending


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

New Mission Profile


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)

Resources

Mass(Kg) F1 F2 F3 F4 F5Measured 78.04 77.62 76.72 76.72 78.08NTE 81.80 81.80 81.80 81.80 81.80Margin 3.76 4.18 5.08 5.08 3.72% 4.6% 5.1% 6.2% 6.2% 4.5%


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.

Operating Hours

050

100150200250300350400450500

Hours Failure Free

F1F2F3F4F5


PFR Statistics (All Spacecraft)

• Total : 237• Closed : 237• Open : 0• Unverifiable Failures : 13• Operational Work-Arounds : 10

Problem/Failure Reports


Unverifiable Failures

PFR # Problem Description Highest Probability AssessmentPFR 039 FGM Telem Errors Memory Configuration LOW: Temporary Data LossPFR 062 EFI V1 Signal Loss Sphere Grounded in Chassis LOW: Non-Flight ConfigurationPFR 070 IDPU Command Loss DMA Channel Issue LOW: Hardware ModifiedPFR 074 SST Chan 2 Data Loss FPGA Low Voltage. LOW: Hardware ModifiedPFR 108 EEPROM Load Error Writing too fast. LOW: Procedure ModifiedPFR 121 IDPU ETU Current over

specMis-measurement LOW: Minimal Current

PFR 130 BAU corrupting IDPU cmds IDPU DMA Channel Issue LOW: Hardware ModifiedPFR 131 BAU corrupting IDPU cmds IDPU DMA Channel Issue LOW: Hardware ModifiedPFR 147 BAU reset Break-out configuration MED: Operational complexityPFR 161 Receiver lock prior to vib JPL Local transmitter LOW: No commands receivedPFR 172 K1 Battery Relay flipped GSE initial turn-on LOW: Only affected monitorSAI 0215 BAU reset and cmd loss GSE Power supply too low LOW: Non-Flight ConfigurationSAI 0340 Thruster stops out of range. ITOS timing error LOW: Non-Flight Configuration


Operational WorkArounds

PFR Probe System Problem Description Operational Work-around030 A-E IDPU PCB FPGA command lockout SAFE Before Actuation Retry075 A-E ESA ESA Surge Current Disable Current Trip in Turn On164 A-E ESA ESA Supply Noise when Off Turn On ESA 183 A EFI EFI V6 Selt-test Signal Loss Ignore EFI V6 Self Test205 A-E Thermal RCS Cold Spot w/ only secondary Turn On RCS Primary Heaters210 A-E BAU RCS Missing First Pulse Start Maneuvers w/ "Stop" cmd226 A Thermal Swapped Temperature Monitors Reverse mnemonics230 A-E BAU Inaccurate 20Hz thruster counter Use VC4 data for verification231 A-E BAU Inaccurate Command Timer Do not use command timer.0339 A-E BAU IRU Noisy Measurements Ignore first samples of ACS

THEMIS MRRSystems - 1 GSFC, Jan 5, 2007 Systems Engineering.

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