Electric Fields and Waves (EFW)

1. Electric Fields and Waves(EFW) John Wygant EFW PI University of Minnesota RBSP RMDR 2-4 October 2007

2. Agenda • Investigation team • Overview • Driving requirements • Science compliance • Primary measurement requirements • Design description • Interface definition • Heritage • Changes since MCR • Technology development plan • Resource summary • Operations concept • Verification & validation • Risks & mitigation • Phase B plans Hope RP-Spice Magnetometer Boom Star Tracker RF Antenna (aft) Shunts (4x) Louvers MagEIS (4x) - [Low, Medium (2x), High] Axial Boom (aft) 1 of 2 SP Wire Boom (4x) RPS Battery Radiator DSAD (2x) REPT RBSP RMDR 2-4 October 2007

3. Investigation Team RBSP EFW PI J. Wygant, UM PM/SE P. Harvey, UCB Science Co-I’s QA R. Jackson, UCB Financial Mgr K. Harps, UCB Subcontracts J. Keenan, UCB Lead Mechanical P. Turin Lead Electrical M. Ludlam Sensors J. Bonnell Signal Processor R Ergun, LASP Ground Systems M. Hashii AXB: R. Duck SPB: G. Dalton Dynamics: D. Pankow Lead : J. Westfall Analog: H. Richard Digital: M. Ludlam FSW: P. Harvey LVPS: P. Berg RBSP RMDR 2-4 October 2007

4. 1 4 5 6 3 2 2 Overview • RBSP Electric Field Waves Features • Four spin plane booms (2 x 40 m and 2x 50 m) • Two spin axis stacer booms (2x6 m) • Spherical sensors and preamplifiers near outboard tip of boom (400 kHz response) • Flexible boom cable to power sensor electronics & return signals back to SC • Sensors are current biased by instrument command to be within ~ 1 volt of ambient plasma potential. • Main electronic box (filtering, A-D conversion, sensor bias control, burst memory, diagnostics, mode commanding, tm formatting • EFW science quantities include: • • E-fields: Difference between opposing sensors • (V1-V2, V3-V4, V5-V6) • Interferometric timing: SC-sensor potential (V1s, V2s, V3s, V4s, V5s, V6s) • Interface to EMFISIS instrument • Electrostatic cleanliness spec designed to keep variations of potential across spacecraft surfaces smaller than 1 Volt. RBSP RMDR 2-4 October 2007

5. Overview • Science Objective: Measure electric fields associated with a variety of mechanisms causing particle energization, scattering and transport in the inner magnetosphere. • These mechanisms include: • Energization by the large-scale convection E-field . • Energization by substorm injection fronts propagating in from the tail. • Radial diffusion of energetic particles mediated by ULF MHD waves. • Transport and energization by intense magnetosonic waves generated by interplanetary shock impacts upon the magnetosphere. • Coherent and Stochastic acceleration and scattering of particles by small-scale, large-amplitude plasma structures, turbulence and waves (EM and ES ion cyclotron waves, kinetic Alfven waves, lower hybrid, small scale magnetosonic waves,solitary waves, other non-linear structures) • EFW measurements address all 8 of the Science goals RBSP RMDR 2-4 October 2007

6. Driving Requirements RBSP RMDR 2-4 October 2007

7. Primary Measurement Requirements • Spin plane component of E-field at DC-15 Hz (>0.3 mV/m or 10% accuracy) over a range from 0 to 300 mV/m at R>2.5 Re • Spin axis component of E at DC-15 Hz (>2 mV/m or 10% accuracy) over a range from 0-300 mV/m at R>2.5Re. • Spacecraft potential measurements providing estimates of cold plasma densities of 0.1 to ~100 cm-3 at 1-s cadence (n/n<50%). • Burst recordings of large amplitude (Req.: 0-300 mV/m Capability:0-700 mV/m) E-fields ; B-fields and cold electron density variations 0-100 cm-3 with accuracy of 50% (derived from SC potential over frequency range from dc to 300 Hz). • Interferometric timing of intense (>300mV/m) small scale electric field structures and non-linear waves: timing accuracy of .06 ms for velocities of structures over 0-500 km/s. • Low noise 3-D E-field waveforms to EMFISIS: 10 Hz to 400 kHz with maximum signal 50 mV/m. For spin plane sensors: a dynamic range of 100 dB & sensitiviites of 3 x 10-14 V2/m2Hz (TBR) at 1 kHz and3 x 10-17 V2/m2Hz (TBR) at 100 kHz. For spin axis sensor pairs the dynamic range and sensitivity is an order of magnitude less. RBSP RMDR 2-4 October 2007

8. SPB Description • Mass: 2.20 kg/unit (4 total). • Envelope: 9.9”H x 4.6”W x 8.6”D. • Deployed Length: 80/100 m tip-to-tip. (47 m cable + 3 m fine wire in each SPB.) • Deploy Rate: 0.5-1.0 cm/s. • Cable Mass Rate: ~3 g/m. • Fine Wire Mass Rate: < 1 g/m. • Preamp Mass: 48 g (up to 150 g w/up-shield and cable driver). • Sphere/Keyreel Mass: 100 g. • Deployed spin MOI: 1920 kg-m2 total • Power: 2.6 W/unit (typ., deploy motor only). • Actuators: Doors are spring-loaded, SMA-released; Cable deploy is motor-driven; no pyros required for actuation. RBSP RMDR 2-4 October 2007

9. AXB Description • Mass: 6.21 kg total (2 booms + tube). • Footprint: 26” H x 6.400” OD inches. • Deployed Length: 13m tip-to-tip. • 0.5-m whip sensor stacer. • Power: 35 W max per boom for release • Actuators: Frangibolt sphere release, main boom release. • Deployment is motor-driven Flight Axial Tube & one AXB from THEMIS RBSP RMDR 2-4 October 2007

10. IDPU Description • Mass: 4.6 kg. • Dimensions: 9.75H x 4.7W x 7.95D inches • Power: 7.8 W CBE. • Elements and Function: • Chassis – provides structural and rad shielding • Backplane – signal and power distribution. • Low-Voltage Power Supply (LVPS) - conversion • Power Controller Board (PCB) – switching • Data Controller Board (DCB) – cmd & telem • Solid State Recorder - data storage • Boom Electronics Board (BEB) – sensor control. • Digital Fields Board (DFB) –signal processing. • EMFISIS Interface – buffering of E & B signals RBSP RMDR 2-4 October 2007

11. Flight Software Description • Development Plan : RBSP_EFW_SW_001 • Heritage : CRRES, Polar, Cluster, THEMIS • Language: 8085 (Harris RH) • Requirements: ~200 • Effort : ~10000 SLOC in 22 modules • Test Platform: ETU • Phases: Board, Box, Inst, Autonomy • Quality : Integrated with Flight Development • Major Functional Elements: • Command Reception & Distribution • Real-Time Data Collection and Playback • On-Board Data Evaluation for Burst Triggering • Burst Data Collection and Playback • Sine-Wave Fits of E-Field Signal • Delta Mod Compression • Boom Deployment Control RBSP RMDR 2-4 October 2007

12. Interface Definition SPB1 X-Axis IDPU SPB2 COMMANDS SPB3 TELEM Y-Axis SPB4 MAIN +28V SPB Power AXB1 Z-Axis EFW X,Y,Z MAG X,Y,Z AXB Power SCM X,Y,Z AXB2 EMFISIS RBSP RMDR 2-4 October 2007

13. Heritage Spacecraft SPB’s AXB’s Mag Booms S3-2 4 S3-3 4 2 ISEE 2 VIKING 4 FREJA 6 FIREWHEEL* 2 CRRES 2 POLAR 4 2 FAST 4 2 2 CLUSTER I* 16 CLUSTER II 16 THEMIS 20 10 10 SPARES 26 6 2 Lunar Prospector 1 Sounding Rockets ~50 ----- ----- ----- 110 26-76 15 * LV did not achieve orbit RBSP RMDR 2-4 October 2007

14. Major Changes Since MCR • AXB Booms Aligned on Center • AXB Deployed DAD Section is Below Antenna • AXB Sensor Folding Rigid Section (Whip) • AXB Motor Drive for On-Orbit Adjustable Lenth • IDPU Higher Data Allocation • IDPU Added Internal Foldback Limits (Redundant E-Fields) RBSP RMDR 2-4 October 2007

15. New Development Items • Boom Deployment Systems • Units based on ISEE, CRRES, Polar, FAST, Cluster-II, and THEMIS heritage. • Changes will include thinner cable, using SPB-type motor type for AXB instead of brake. • Sensor Electronics (Preamp and BEB) • Units are based on Polar, Cluster-II, and THEMIS heritage. • Changes will include thinner cable, possible cable driver. • IDPU Power, DSP, DPU, and Burst Memory • Units are based on Polar, FAST and THEMIS heritage. • Changes will include interfaces to other instruments and SC, adjustments to filter frequencies and ADC rates, flight software changes. RBSP RMDR 2-4 October 2007

16. Resource Summary CBE (NTE) • Mass: 21.3 (23.6) kg • Power: 7.8 (8.6) W • Telemetry rate: 16.5 (16.5) kbit/sec RBSP RMDR 2-4 October 2007

17. Operations Concept • Commissioning • Draft Deployment Sequence Delivered to APL • Sequence takes appx 2 weeks including science diagnostics • Z-axis adjustment operations are to be decided • Normal operations • Constant Real-Time Data Streaming • Playback of stored events • Bursting • Automatic detection of interesting events • Burst Flag sent to S/C • S/C directed burst events • Command and data handling • Commands determined and sent from UCB • Telemetry distribution at UCB • SOH determination at UCB • SOC Operations will be run from UC Berkeley RBSP RMDR 2-4 October 2007

18. Instrument Verification & Validation Plan EFW Verification Plan (RBSP_EFW_SYS_300) RBSP RMDR 2-4 October 2007

19. S/C Level Instrument V & V Plan EFW Will Support APL’s Verification of Spacecraft EFW Flow Will be as Simple as Possible Expect “Bolt-Hole” Alignments are Sufficient for Boom Systems EFW-EMFISIS Verification Expected to Require Boom Deployment Deployment of Spin Plane Booms and +Z Axial Sensor is Practical at I&T RBSP RMDR 2-4 October 2007

20. 5 L I K E L I H O O D 4 3 2 1 Criticality L x C Trend Approach M – Mitigate W – Watch A – Accept R - Research Decreasing (Improving) Increasing (Worsening) Unchanged New since last month  High   Med * Low Risks and Mitigation 4 1 5 3 2 1 2 3 4 5 CONSEQUENCES RBSP RMDR 2-4 October 2007

21. Risks and Mitigation RBSP RMDR 2-4 October 2007

22. Phase B Plans Activities 06/08 EFW Instrument Requirements Review 09/08 EFW Instrument Preliminary Design Review 09/08 EFW SOC Preliminary Design Review 11/08 Support MPDR 01/09 SPB ETU Design, Fab & Test 01/09 AXB ETU Design, Fab & Test 12/08 IDPU ETU Design, Fab 12/08 Harness ETU Design, Fabrication 12/08 S/C – EFW Interface Test (Emulator) RBSP RMDR 2-4 October 2007