Instrument Design Fluxgate Magnetometer FGM Werner Magnes Institut

Instrument Design Fluxgate Magnetometer (FGM) Werner Magnes Institut fuer Weltraumforschung (IWF) Austrian Academy of Sciences Hans-Ulrich Auster Institut fuer Geophysik und Meteorologie Technical University Braunschweig (TU-BS) THEMIS Mission PDR/CAR 1 UCB, November 12 -14, 2003

FGM Team TU Braunschweig IWF Graz Karl-Heinz Glassmeier (Head) Wolfgang Baumjohann (Head) Ulrich Auster (FGM TM) Ingo Richter Karl-Heinz Fornacon Bernd Stoll Ernst Jelting Werner Magnes (FGM Co. TM) Konrad Schwingenschuh Aris Valavanoglou Özer Aydogar Rumi Nakamura Tielong Zhang Martin Volwerk Andrei Runov Zoltan Vörös Yoshihiro Asano Dragos Constantinescu Yasuhito Narita Jan Grosser Sebastian Schäfer Gero Kleindienst Carsten Schmidt Main Subcontractor: Magson Gmb. H Olaf Hillenmaier Ronald Kroth THEMIS Mission PDR/CAR 2 UCB, November 12 -14, 2003

FGM Work Distribution § TU-BS § UCB • FGS fabrication • FGE / sensor electronics • • § IWF Parts procurement PCB fabrication Boom / FGS-MLI FGE qualification • FGE / interface electronics § TU-BS & IWF • FGS qualification • FGM calibration • FGM integration THEMIS Mission PDR/CAR 3 UCB, November 12 -14, 2003

Block Diagram Instrumentation THEMIS Mission PDR/CAR 4 UCB, November 12 -14, 2003

FGS - FGE 6 U Board with the FGE Layout FGS THEMIS Mission PDR/CAR 5 UCB, November 12 -14, 2003

FGM Requirements (1) IN. FGM-1. The FGM shall measure DC and low frequency perturbations of the magnetic field IN. FGM-2. The absolute stability of the FGM shall be less than 1 n. T - Determination of 3 offsets and 9 elements of the calibration matrix (scale values, non-orthogonality, sensor orientation) through in-flight calibration once per orbit - Spinning S/C provides 8 of 12 calibration numbers - Scale values are known accurately enough from pre-flight calibration - The determination of the spin axis offset can be done to 1 n. T accuracy by known physics during a standard orbit and to +/-0. 1 n. T accuracy when being in solar wind THEMIS Mission PDR/CAR 6 UCB, November 12 -14, 2003

FGM Requirements (2) IN. FGM-3 a. The relative stability of the FGM shall be less than 0. 2 n. T/12 hrs IN. FGM-3 b. The relative stability of the FGM shall be less than 0. 1 n. T/hr - Offset / Time: < 0. 1 n. T/h; < 0. 2 n. T/12 hrs; < 1 n. T/year; - Offset / Temperature: < 0. 1 n. T/°C - Scale value / Temp. : < 24 ppm (0. 8 n. T/°C @ 32000 n. T) - Orthogonality / Temp. : can be neglected IN. FGM-5. The FGM noise level @ 1 Hz shall be less than 0. 03 n. T/sqrt(Hz) - Sensor noise: THEMIS Mission PDR/CAR < 10 p. T/sqrt(Hz) @ 1 Hz 7 UCB, November 12 -14, 2003

FGM Requirements (3) IN. FGM-4. The FGM digital resolution shall be less than 0. 1 n. T IN. FGM-6. The FGM science range shall exceed 0 -1000 n. T - FGM provides 0. 01 n. T digital resolution independent of the external field due to digital magnetometer principle - The maximum feedback field (range) is about 32000 n. T - 24 bits per field component will be sent to the IDPU - 16 bits will be selected for transmission 10 p. T digital resolution if B < 320 n. T 160 p. T digital resolution if B > 2500 n. T 1. 2 n. T digital resolution if B > 20000 n. T THEMIS Mission PDR/CAR 8 UCB, November 12 -14, 2003

FGM Requirements (4) IN. FGM-7. The FGM frequency range shall exceed DC-1 Hz - FGM primary data rate is 128 Hz (7. 5 ms measurement, 0. 3 ms feedback setting) - Further averaging will be done in the FGE FPGA and/or by the IDPU THEMIS Mission PDR/CAR 9 UCB, November 12 -14, 2003

Mission Requirements (1) REQUIREMENT FGM DESIGN IN-1. The Instrument Payload shall be designed for at least a two-year lifetime Compliance. Lifetime has been considered in all aspects of FGM design (parts, performance degradation, etc). IN-2. The Instrument Payload shall be designed for a total dose environment of 33 krad/year (66 krad for 2 year mission, 5 mm of Al, RDM 2) Compliance. Common Parts Buy for Instrument Payload. All parts screened for total dose. Radiation testing planned if TID is unknown (AD 648) or has already been performed by TUBS (AD 625, MIC 4425). All FGE components under UCB control. IN-3. The Instrument Payload shall be Single Event Effect (SEE) tolerant and immune to destructive latch-up Compliance. Common Parts Buy for Instrument Payload. Most parts screened for SEE. Radiation testing planned if LET is unknown (AD 625, MIC 4425). All FGE components under UCB control. IN-7. No component of the Instrument Payload shall exceed the allocated mass budget in THM-SYS-008 THEMIS System Mass Budget. xls Compliance. FGM Sensor: 80 g Allocated. FGS mass is 76 g. (Harness and FGE Board tracked with IDPU) THEMIS Mission PDR/CAR 10 UCB, November 12 -14, 2003

Mission Requirements (2) REQUIREMENT FGM DESIGN IN-9. No component of the Instrument Payload shall exceed the power allocated in THM-SYS-009 THEMIS System Power Budget. xls Compliance. 900 m. W Allocated. - - Needed supply voltages and bread board: currents based on VEX-MAG and • +5 Vd & +2. 5 Vd (FPGA & DAC) 10 m. A • +8 Va (excitation & amplifiers) 50 m. A (30 m. A+20 m. A) • -8 Va (amplifiers) 20 m. A • +/-5 Va (ADC) 15 m. A 760 m. W if all voltages will be provided (+80/-0 m. W) No EEE part with > 100 m. W power dissipation! THEMIS Mission PDR/CAR 11 UCB, November 12 -14, 2003

Mission Requirements (3) REQUIREMENT FGM DESIGN IN-13. The Instrument Payload shall survive the temperature ranges provided in the ICDs Compliance. See further down IN-14. The Instrument Payload shall perform as designed within the temperature ranges provided in the ICDs Compliance. Calibration and verification facilities exist in Graz (IWF) and Braunschweig (TUBS). Detailed calibration procedure planned • operating temperature range (sensor/electronics): – 100°C / -20°C to +65°C / +45°C • cold start (sensor/electronics): -100 °C / -50°C • survival temperature range (sensor/electronics): – 100°C / -50 °C to +65°C - FGM sensor qualified for +/-100°C (Rosetta, Venus. Express) THEMIS Mission PDR/CAR 12 UCB, November 12 -14, 2003

Mission Requirements (4) REQUIREMENT FGM DESIGN IN-16 The Instrument Payload shall comply with the Magnetics Cleanliness standard described in the THEMIS Magnetics Control Plan Compliance. THM-SYS-002 Magnetics Control Plan. IN-17 The Instrument Payload shall comply with the THEMIS Electrostatic Cleanliness Plan Compliance. THM-SYS-003 Electrostatic Cleanliness Plan IN-18 The Instrument Payload shall comply with the THEMIS Contamination Control Plan Compliance. THM-SYS-004 Contamination Control Plan IN-19. All Instruments shall comply with all electrical specifications Compliance. THM-IDPU-001 Backplane Specification IN-20. The Instrument Payload shall be compatible per IDPU-Instrument ICDs Compliance. THM-SYS-106 FGM Interface Requirements Document (Internal # THM-FGM-DS 0001 V 1. 3). Verification Matrices to be completed. IN-21. The Instrument Payload shall be compatible per the IDPU-Probe Bus ICD Compliance. THM-SYS-112 Probe-to-FGM Mag Boom ICD. Verification Matrices to be completed. IN-23 The Instrument Payload shall verify performance requirements are met per the THEMIS Verification Plan and Environmental Test Spec. Compliance. THM-SYS-005 Verification Plan and Environmental Test Specification preliminary draft. Verification matrix to be completed. IN-24 The Instrument Payload shall survive and function prior, during and after exposure to the environments described in the THEMIS Verification Plan and Environmental Test Specification Compliance. THM-SYS-005 Verification Plan and Environmental Test Specification preliminary draft. Verification matrix to be completed. THEMIS Mission PDR/CAR 13 UCB, November 12 -14, 2003

Electrical Instrumentation • Interfaces defined and documented: – – • • Four-wire serial digital I/F with CLK, CMD, TMH and TML Supply voltages as presented before THEMIS/FGM I/F Requirements I 1 R 3 (TH-FGM-DS-0001) THEMIS/IDPU Backplane Specification 001 H Proposed design will meet functional requirements Sufficient maturity in design to proceed to detailed design – Digital magnetometer design based on existing space H/W (MIR-MAG, Rosetta Lander, Venus Express) – Separate BBM for testing design changes is currently under test • Risks have been identified – Sophisticated fabrication, calibration and integration process (Europe, Berkeley and Swales) THEMIS Mission PDR/CAR 14 UCB, November 12 -14, 2003

GSE Concept MGSE for FGS • Mu-metal can EGSE for FGE commanding and testing • • Digital interface simulator (bread board EGSE) with limited features for bread board testing (supplied by IWF) Full functional EGSE for ETU and FM (supplied by UCB) Themis Calibration Unit (TCU) • • Three layer mu-metal can including calibration coils and mechanics for sensor rotation Three systems located in Braunschweig, Graz and Berkeley THEMIS Mission PDR/CAR 15 UCB, November 12 -14, 2003

Mechanical & Thermal Mechanical • • Same sensor design used for Rosetta Lander and Venus Express For Venus Express it was just qualified to – Sinusoidal vibration: 5. . 100 Hz; 25 g – Random vibration: 20. . 2000 Hz; 18 Grms – Quasistatic acceleration: 25 g Thermal • One internal / collectively controlled unit: FGE – Part of the common electronics box • One external / individually controlled unit: FGS – Extended operating and non-operating temperature range – Standard Kapton-VDA MLI is sufficient – Thermal model will be supplied THEMIS Mission PDR/CAR 16 UCB, November 12 -14, 2003

Development Plans (1) Sub-units • FGS: Flux. Gate Sensor • FGE: Flux. Gate Electronics Models • • BBM: Bread Board Model (FGE-BBM) STM: Structural and Thermal Model (FGS-STM) ETU: Engineering and Testing Unit (FGE-ETU 1/2) FM: Flight Model (FGS-F 1/F 6 and FGE-F 1/F 5) Locations • • US-Berkeley (UCB) US-Swales E-Braunschweig (TU-BS) E-Graz (IWF) THEMIS Mission PDR/CAR 17 UCB, November 12 -14, 2003

Development Plans (2) FGE BBM / FGE ETU THEMIS Mission PDR/CAR 18 UCB, November 12 -14, 2003

Development Plans (3) FGS FM / FGE FM THEMIS Mission PDR/CAR 19 UCB, November 12 -14, 2003

Development Plans (4) FGS F 6 / FGE ETU-1 THEMIS Mission PDR/CAR 20 UCB, November 12 -14, 2003

Peer Review Results 21 Findings: • • From No. 1 - Jitter spec. of CLK 8 MHz should meet the FGM requirements (i. e. 10%) To No. 21 – Magnetic control plan and S/C test in GSFC coil facility (under UCB control) FGM team fully understands the findings and will take it into account during the upcoming instrument development process! 2 RFAs: RFA FGM-1: Magnetic Cleanliness Status: UCB is working on it RFA FGM-2: Anti-Aliasing Filter Status: FGM working on it – It was always planned to implement such a filter – Final filter spec is dependant on a trade-off between anti-aliasing, data decimation and impact on the quality of the de-spinning process. THEMIS Mission PDR/CAR 21 UCB, November 12 -14, 2003