THEMIS : RESOLVING THE PHYSICS OF ONSET AND EVOLUTION OF SUBSTORMS OBJECTIVE: Study energy releases from Earth’s magnetosphere known as substorms (magnetic phenomena that intensify auroras near Earth's poles) RATIONALE: Provide scientists with important details on how the planet's magnetosphere works, specifically: better understanding of the physical instability (trigger mechanism) for magnetospheric substorms comprehensive look at the onset of substorms and how they trigger auroral eruptions Fundamental to our understanding of space weather Mission Science

Mission Architecture Constellation of 5 satellites (probes), each carrying identical instrumentation fluxgate magnetometer (FGM) electrostatic analyzer (ESA) solid state telescope (SST) search coil magnetometer (SCM) electric field instrument (EFI) Line up in magnetosphere every 4 days launched into “cruise phase” 33 hr orbit maneuver into 1, 2 and 4 day orbits for winter season 2008 Conjunction with ground based instruments 20 northern sites with all sky imagers and magnetometers

January 5, 2007THEMIS Mission Readiness Review 3 Standard Delta 10 ft. Fairing Static Envelope 3712 PAF Probe Carrier Assembly (PCA = 5 Probes + Probe Carrier) on L/V Probe Carrier Assembly (PCA = 5 Probes + Probe Carrier) on L/V THEMIS Launch Configuration Probe Carrier Assembly (PCA) on Delta 3 rd Stage Launch Configuration Dedicated launch accommodated within standard Delta 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 3 rd 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 3 rd Stage

January 5, 2007THEMIS Mission Readiness Review 4 Launch Vehicle Overview Vehicle Configuration: Delta 7925–10C Launch Site: Eastern Range (ER), SLC-17B at Cape Canaveral Air Force Station (CCAFS) Mission Specifics: –Perigee: 435 km, Apogee: km –Orbit Inclination: 16 degrees –Spacecraft (SC) Mass (will not exceed) »829 kg ( lb) kg actual –STAR 48B Motor »Nutation Control System »Yo-Yo de-spin system Spin rates: –During Third Stage operation - max  70 rpm –S/C after spin-down and separation - 16  2 rpm Mission Unique –3712 Bolted PAF –Sep System (at PAF/PC Interface) Non-Standard Services –Category 1 Analysis »(1st C ER) –Five - 24” Doors –Two 61 pin connectors –Fairing Cleaning to VC 6 Separation System provided by THEMIS Spacecraft, contracted through Launch Services Program (LSP) NASA Launch Service (NLS) Contract

January 5, 2007THEMIS Mission Readiness Review 5 Depletion Burn: Removes Stage 2 from vicinity of spacecraft, while lowering Stage 2 perigee altitude and orbit inclination Flight Profile

Simple, Robust, Fault Tolerant System: Power positive in all attitudes with instruments off (launch, safe hold modes) Passive spin stability achieved in all nominal and off-nominal conditions Passive thermal design using MLI and thermostatically controlled heaters tolerant of longest shadows (3 hours) S-Band communication system always in view of earth every orbit at nominal attitude. In view for greatest part of orbit in any attitude Monoprop blow down RCS (propulsion) system is self balancing on orbit Probe Bus Design

PAF Adapter Ring/Tube & Attach to Launch Vehicle Main Deck Center Spool (4) Lower Probe Standard Separation Fittings (1) Upper Probe Standard Separation Fitting (8) External Struts Probe Carrier (PC) Simple probe carrier utilizes –Machined aluminum structure –Standard heritage payload attach fittings utilize pyro- actuated clampband –Straight-forward umbilical interconnect harness Detailed design supported by analysis and full system test –NASTRAN model to recover material stresses and fundamental frequencies –Base drive analysis used to verify strength and recover component loads –Coupled Loads Analysis –PCA Vibration/Acoustic Test Probe layout on carrier maximizes static and dynamic clearances –Design is the best balance between deployment clearances and probe mass First Axial Mode: Hz First Lateral Mode: Hz Probe Carrier Fundamental Natural Frequencies: Displacements Not to Scale Probe Carrier Design

Probe Bus Systems Probe Structure Carbon Composite, Total Mass 126 kg Payload Interface Single, simple RS-422 Interface between UCB Instrument Data Processor (IDPU) and Swales Bus Avionics Unit (BAU) RF Communications S-band Transponder, 5 W Hexagonal Microstrip Patch Antenna Toroidal Antenna Pattern, LHCP 10 Telemetry Rates: kbps Command Data Rate: 1.0 kbps Thermal Subsystem Passive Hot Biased System with Local Radiators Thermostatically Controlled Heaters Power System Total Power: 40 W Solar Panels: 6 Sets, Body Mounted Solar Cells: GaAs Triple-junction Battery: Lithium Ion, 28 V, 11.8 Ah Charge Control: Direct Energy Transfer Propulsion System Hydrazine Blow-down System 4 Thrusters 2 Axial, 2 Tangential, 4.4 N 2 Propellant Tanks Total Fuel Load: 49.0 kg MEOP: 2750 kPa at 40 C Repressurizing Tank, He Latch and Solenoid Valves Attitude Control System Spin-stabilized Platform Open Loop Spin Control, 20 rpm Miniature Spinning Sun Sensor Flux Gate Magnetometer Inertial Reference Units (2) Attitude Control Via Propulsion System Command and Data Handling ColdFire Processor, MHz RTEMS Operating System Bulk Memory, SDRAM, 64 MBytes CCSDS V1 TLM and CMD Formats

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

Probe Block Diagram

Attitude Control System

Reaction Control System Four 4.4-N Thrusters for maneuvers -2 Axial, 2 Tangential Latch valves opened right after launch, prior to first maneuver Redundant Cat-beds used prior to all firings to avoid cold starts Isolation valve opened right before pyro valve is fired at specific pressure for system repress:

Two axial thrusters (A1, A2) for major orbit changes and attitude control Two tangential thrusters (T1, T2) for spin control and minor orbit changes Thruster Placement

RCS Operational Modes Maneuver Type Thrusters Involved Depiction of Operational Mode Purpose of Maneuver Axial Thrust A1 and A2 Continuous Firing Perigee or Apogee Change or Combined In-plane and Out-of-plane Orbit Change with Stowed EFI Booms Side Thrust T1 and T2 Pulsed Firing Perigee or Apogee Change with Deployed EFI Booms Beta Thrust A1 and A2 Continuous Firing Alternating With T1 and T2 Pulsed Firing In-plane and Out-of-plane Orbit Change with Deployed EFI Booms Attitude Precession A1 or A2 Pulsed FiringAttitude Change Spin-up / Spin-down T1 or T2 Continuous or Pulsed Firing Spin Rate Adjustment

Instrument Systems Electric Field Instrument (EFI) Three dimensional experiment Measures electric field 4 spin-plane spherical sensors mounted on 20m deployable cable 2 axial tubular sensors mounted on 4m deployable stacer element Experiment and booms built at UCB Fluxgate Magnetometer (FGM) Single triaxial fluxgate magnetometer Mounted on 2 meter deployable boom Measures low frequency magnetic field Sensors built by TUBS (Germany) Electronics built by IWF (Austria) Boom built by UCB Magnetic cleanliness led by UCLA Search Coil Magnetometer (SCM) Single unit, three orthogonal u-metal rods Mounted on 1 meter deployable boom Measures high frequency magnetic field Sensor, Electronics built by CETP (France) Boom built by UCB Electrostatic analyzer (ESA) Single unit, mounted to IDPU Measures thermal plasma; electrons and ions in the range 5-40 KeV Built by UCB, nearly identical to the ESA Instruments on the FAST Spacecraft Solid State Telescope (SST) Two double-ended telescope units Measures super-thermal plasma; electrons and ions in the range KeV Built by UCB, similar to WIND Instrument Data Processing Unit (IDPU) Provides the electronic interface between the Probe and the Instrument sensors Collects and formats all instrument data, and controls instrument operations Multi-slot 6U VME chassis Consists of 6 boards (LVPS, PCB, DCB, FGE, DFB, BEB, DAP) 8085 Processor 256MB SDRAM Storage ~2x loss-less compression

Instrument Configuration Deployed Configuration Instrument Suite − Stowed Configuration

January 5, 2007THEMIS Mission Readiness Review 17 Mass Status < 2% mass deviation between Probes (requirement) Dry Mass Margin: 4.5% (Worst case) Power Status Probe CBE: 38.7 W Probe Capability: W Probe Margin: 8.8% (First 3-hour Eclipse Season) 4.9% (Second 3- hour Eclipse Season) Resources

Mass History Mass –Probe Dry Mass was limiting mass resource –Probe Dry Mass Current Best Estimate (CBE): 77.5 kg –Probe Dry Mass Not to Exceed (NTE) due to Delta-V requirement: 81.8 kg –All Probes measured during spin balance, <1% variability between Probes –Probe Dry Mass Margin: 5.6%

Power History Power –Late increase in Probe power was from additional heater power predicted from updated thermal model. –Late increase in capability was based on measured S/A LAPSS performance data for F2 S/As, coupled with BEAST time history analysis. Probe CBE: 36.6 W Probe Capability: W Probe Margin: 10.2%

Ground Based Observatories 20 GBO (GMAG and ASI) units Automatic Data Collection and Archiving Remote Commanding and Diagnostics Expect to be Fully Functional at Winter 2008 Courtesy H.Frey, UCB Geographic Longitude 324° Geographic Longitude 195° Geomagnetic North Pole Geographic North Pole

Ground System Diagram Ground System Elements Ground Stations Ground Network Space Network Mission Operations Center Science Operations Center Flight Dynamics Center Including Mission Design Orbit & Attitude Determination Maneuver Planning Limit Detection and Notification Network Security

January 5, 2007THEMIS Mission Readiness Review 22 Ground Stations Ground Station Station Designator Figure of Merit LocationFunction Berkeley, CABGS 11-m24.0 dB/K ° N ° W Primary TLM/CMD/TRK Wallops Island, VAWGS 11-m23.0 dB/K ° N ° W Secondary TLM/CMD/TRK Merritt Island, FLMILA 9-m 1/221.6 dB/K ° N ° W Secondary TLM/CMD/TRK Santiago, ChileAGO 9-m21.6 dB/K ° S ° W Secondary TLM/CMD/TRK Hartebeesthoek, SAHBK 10-m20.4 dB/K ° S ° E Secondary TLM/CMD/TRK Mission Supported by 5 Ground Stations Ground Stations: BGS, WGS, MILA, AGO, HBK GN, SN and FDF Support Documented in PSLA All Stations Have Successfully Flowed Data with MOC

January 5, 2007THEMIS Mission Readiness Review 23 Mission Operations Center BGS Antenna, Equipment Racks and FOT Workstations at the Mission Operations Center

January 5, 2007THEMIS Mission Readiness Review 24 UCB MOC

Integration and Test Flow Instruments delivered to UCB for Instrument Suite Integration –Integration to IDPU (BAU simulator is used) –Interface tests and self-compatibility, complete functional testing before/after environments –Environmental Test Sequence on Instrument Suite Probe Buses delivered to UCB for Probe/Instrument Suite Integration –Component-wise integration of Instrument Suite with Probe Bus –Interface tests and self-compatibility –RF Performance and End-to-End Mission Operations Center testing –Comprehensive Performance Tests, Mission Simulations 1 st Integrated Probe to JPL for Environmental Tests (Pathfinder) –Magnetics, EMI/EMC –Vibration –Thermal Vacuum (Cycling and Extended Balance) Remaining 4 Probes and Probe Carrier (PC) to JPL for Environmental Tests –Probe Carrier Assembly (PCA - PC and 5 Probes) Vibration and Acoustic Test –Mass Properties and Spin Balance –Thermal Vacuum –Magnetic Survey Probes and Probe Carrier to Cape –Probes Fueled, mass properties –Final PCA build-up and spin balancing

Environmental Test Environmental Test Matrix (ETM): NOTES: A = AnalysisQ = Qualification unit only T = TestI = Inspection TS = Test on 1st unit only, rest by similarityW = Weigh TL = Limited Test

Environmental Test Thermal Vacuum Instruments: 2 cycles Instrument level, 6 cycles Instrument Suite level. Probe Bus: 8 cycles component level. Probe System: 4 cycles on all probes. Extended thermal balance completed on 1 st Probe. Limited Thermal Balance on subsequent probes. Vibration/Shock/Acoustics Instruments: Qualification vibe on ETUs, Acceptance vibe on all flight units Probe Bus: Qualification/Acceptance vibe on ETU/flight or Protoflight vibe on 1 st flight unit Probe System: Protoflight vibe on 1 st Probe. Sine vibration and acoustics on PCA. 2 shock tests on 1 st Probe (1 complete, 1 after PCA acoustics), 1 shock test on subsequent probes after PCA acoustics. 1 sep test on ETU sep system after PCA Mass Dummy Vibration. EMI/EMC Instruments: Conducted EMC on FM1 Instrument Suite, self-compatibility on all Suites Probe Bus: Conducted and radiated EMC on 1 st BAU and transponder Probe System: Radiated EMC completed on 1 st Probe at JPL. EMC comparison checks and self- compatibility tests during probe integration. Magnetics Instruments and Probe Bus: Measurements and deguass (if necessary) prior to Integration Probe System: For 1 st Probe, DC Magnetics in JPL coil facility (powered and un-powered probe states), AC magnetics during EMC. For all Probes, final DC magnetics check.

Thermal Vac Test Plan

January 5, 2007THEMIS Mission Readiness Review 29 Environments Thermal Vacuum Acoustics Spin Balance EMC Vibration Magnetics

January 5, 2007THEMIS Mission Readiness Review 30 Probe Carrier Assembly during Vibration Installation of Thermal Vacuum Shrouds Probe on GSFC Spin Balance Miller Table Two Probes Ready for TV Testing Environments

January 5, 2007THEMIS Mission Readiness Review 31 Probe Processing Bolt Cutter Installation Performance Tests Solar Array Illumination Delivery to ASO

January 5, 2007THEMIS Mission Readiness Review 32 Probe Fueling Preps FM2/FM3 Thermal Vacuum Vibration Thermal Vacuum Acoustics Spin Balance Storage Dry Weigh & Pressurize Ready for Fuel

January 5, 2007THEMIS Mission Readiness Review 33 Carrier Processing VibrationAcoustics Spin Balance Storage PC Unload SSS Installation Ready for Probes

January 5, 2007THEMIS Mission Readiness Review 34 THEMIS Probe Carrier Assembly (PCA) in Launch Configuration Launch Configuration

January 5, 2007THEMIS Mission Readiness Review 35 THEMIS was originally scheduled to launch on October 19 th, 2006: – delays caused by workmanship problems with Delta II second stages delayed launch to Feb 15 th, 2007 – weather conditions on Feb 13 th delayed fueling of the second stage, launch pushed back 24 hours – on February 16 th, launch was scrubbed in a hold at the T-4 minute point in the countdown due to the final weather balloon reporting a no-go condition for upper level winds – 24-hour turnaround procedure was initiated, targeting a new launch window between 23:01 and 23:17GMT on February 17 th Launch Delays…

January 5, 2007THEMIS Mission Readiness Review 36 THEMIS successfully launched at 6:01 pm EST, February 17 th, 2007: – Probes separated from the launch vehicle approximately 73 minutes after liftoff – 8:07 p.m. EST, mission operators at the University of California, Berkeley, commanded and received signals from all five spacecraft, confirming nominal separation status – (then didn’t hear from Probes for 33 hours… ) Launch!

January 5, 2007THEMIS Mission Readiness Review 37 LEO Acquisition Multiple Ground Assets Had Good View Following Launch Probe Attitude Around 1:30 MET is Poor for Telemetry Probes Contacted at 4Kbps for 5 Minutes each from 1:20 to 1:40

January 5, 2007THEMIS Mission Readiness Review 38 LEO Operations State Vector Delivered to UCB via SECO-2 (65min) Monitoring of Probe Separation via TDRSS –Top Probe was commanded to transmit at T+70 mins –Separation occurred at T+73 minutes –All Probes were recording Engineering Data –Separation was recorded by each Probe individually –Engineering Data dumped in later passes Probes Are Released at Good Sun Angle, Power Positive –43 degrees Side to Sun Probe A Released First Probes B−E Released Simultaneously 3 s Later All Probes Independent of Each Other

January 5, 2007THEMIS Mission Readiness Review 39 Mission Profile