THEMIS Mission PDR/CAR 1 UCB, November 12-14, 2003 Search Coil Magnetometer (SCM) Mission PDR/CAR Alain Roux CETP-Velizy Co-i: O.Le Contel Technical Manager: B.de la Porte Engineer: A.Bouabdellah & C.Coillot Technicians: D.Alison & S.Ruocco

THEMIS Mission PDR/CAR 2 UCB, November 12-14, 2003 Overview SCM Requirements & Specifications Block Diagrams Electrical Mechanical and Thermal Mass and Power Development Plans Peer Review Results

THEMIS Mission PDR/CAR 3 UCB, November 12-14, 2003 REQUIREMENTSCM DESIGN IN-1. The Instrument Payload shall be designed for at least a two-year lifetime Compliance. IN-2. The Instrument Payload shall be designed for a total dose environment of 33 krad/year (66 krad for 2 year mission, 5mm of Al, RDM 2) Compliance. IN-3. The Instrument Payload shall be Single Event Effect (SEE) tolerant and immune to destructive latch-up Compliance. IN-7. No component of the Instrument Payload shall exceed the allocated mass budget in THM-SYS-008 THEMIS System Mass Budget.xls Compliance. SCM Sensor: 600g Allocated. Pre-amp: 220g Allocated. (Harness and DFB Board tracked with IDPU) IN-9. No component of the Instrument Payload shall exceed the power allocated in THM-SYS-009 THEMIS System Power Budget.xls Compliance. Pre-Amp: 90mW Allocated. IN-13. The Instrument Payload shall survive the temperature ranges provided in the ICDs Compliance. IN-14. The Instrument Payload shall perform as designed within the temperature ranges provided in the ICDs Compliance. Mission Requirements

THEMIS Mission PDR/CAR 4 UCB, November 12-14, 2003 REQUIREMENTFGM 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-107 SCM Interface Control Document (Internal # THM-SCM-SYS-ICD-0.1). 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-SCM 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. Mission Requirements

THEMIS Mission PDR/CAR 5 UCB, November 12-14, 2003 REQUIREMENTSCM DESIGN IN.SCM-1. SCM shall provide a critical test for the role of waves at substorm onset, in various models (together with EFI). Compliance. IN.SCM-2. SCM shall measure the 3D AC B-field from 1 Hz to 4kHz Compliance. IN.SCM-3. The SCM sensitivity shall be better than and 0.1 kHz. Compliance. IN.SCM-4. The SCM DFT spectral range shall be in the range 16Hz to 4 kHz, transmitted as 32 steps with df/f ~ 25%. Compliance. IN.SCM-5. The transfer function of the SCM sensors (amplitude &phase) shall be known with an accuracy better than 5%. Compliance. IN.SCM-6. On each spacecraft the 3 magnetic antennas, shall be held orthogonal by a structure procured by CETP. Compliance. Sensor Requirements

THEMIS Mission PDR/CAR 6 UCB, November 12-14, 2003 REQUIREMENTSCM DESIGN IN.BOOM-1. Mag Boom deployment shall be repeatable to 1 degree Compliance. IN.BOOM-2. Mag Boom stability shall be better than 0.1 degree (includes bus and boom components) Compliance. IN.BOOM-3. Mag Boom deployed stiffness shall be greater than 0.75Hz Compliance. IN.BOOM-4. Mag Boom shall be designed to be deployed between 2 and 15 RPM about the Probe's positive Z axis. Compliance. IN.BOOM-9. The SCM boom shall be approximately 1 meters long. Compliance. IN.BOOM-12. All deployed booms shall include TBD inhibits to prevent inadvertent release. Compliance. SCM Boom Requirements

THEMIS Mission PDR/CAR 7 UCB, November 12-14, 2003 Block diagram Christophe Coillot Preamplifier Box unit Main functions: -Calibration -Regulated power supply -Low noise preamplifier, 3 channels -Same design as Cluster

THEMIS Mission PDR/CAR 8 UCB, November 12-14, 2003 Mechanical & Electrical Design V out Calibration Signal V in Feedback Amplified SignalInput Signal antenna Preamplifier Principle : 1 st level of amplification 46 dB Gain few noise Feedback 2 nd level of amplification 31 dB Gain Bandwidth 0.25mHz to 4 KHz Input from calibration network 1 layer in the Amplifier module 1 layer in the Regulator module

THEMIS Mission PDR/CAR 9 UCB, November 12-14, 2003 Electrical design Christophe Coillot Preamplifier design Prototype exists -Fits requirements (sensitivity, power). -Measurement conditions close to Flight model : -Same design for sensor -Same kind/length for cable -Same design as 3D+ PA -Powered by 3D+ voltage regulator

THEMIS Mission PDR/CAR 10 UCB, November 12-14, 2003 Mechanical & Electrical Design  3 radiation shielding levels  BBM exists; no risk  3D+ has large experience; generic evaluation CNES/ESA/NASA 2002, qualification CNES/ESA 2003 Heating network * Radiation Shielding (Tantalium plates) 1 st amplification level 2 nd amplification level * Circuit not included for the THEMIS mission

THEMIS Mission PDR/CAR 11 UCB, November 12-14, 2003 Mass & Power Preliminary design meets all system requirements ItemSpecification/ allocation Status Sensor bandwith Sensitivity 0.3 Hz to 4 kHz 1 Hz Achieved (below) Antenna size Antenna mass 175x175x175mm 600 gr. 175x175x175mm 570gr (+/-7%) Pre-amp. Mass Pre-amp Power 220 gr. 90 mW 200gr (+/- 15%) 75 mW (with BBM)

THEMIS Mission PDR/CAR 12 UCB, November 12-14, 2003 Electrical SCM sensitivity curve (BBM; measured in the lab)

THEMIS Mission PDR/CAR 13 UCB, November 12-14, 2003 Electrical Instrumentation Interfaces with DFB defined and documented (see DFB presentation) Proposed design will meet functional requirements Detailed design proceeding Risks have been identified (tight schedule); under control; close interaction with UCB. Sufficient maturity in design (existing BBM) to proceed to detailed design Thermal design: a MLI is requested around SCM antennas (UCB responsibility) Cluster heritage illustrates reliability of the design Ground Support Equipment SCM antennas+PA tested at Chambon la Foret Magnetic axis knowledge +/- 0.2° Short tests at S/C level with antennas in mu-metal boxes

THEMIS Mission PDR/CAR 14 UCB, November 12-14, 2003 mechanical

THEMIS Mission PDR/CAR 15 UCB, November 12-14, 2003 Mechanical & Thermal Mechanical Structure Design proposed by GDTech has been iterated. It is now agreed upon by CETP&UCB. Numerical analyses will start to check for vibration load…Preliminary analyses shows that mass is below specs. Design modified in agreement with suggestions made by review committee: differential dilatation between Ketron Peek&aluminium. Design modified to allow the passage of the cable inside boom, as requested by UCB. Thermal A thermal blanket is needed during eclipses. This is provided by UCB.

THEMIS Mission PDR/CAR 16 UCB, November 12-14, 2003 Mechanical

THEMIS Mission PDR/CAR 17 UCB, November 12-14, 2003 Mechanical

THEMIS Mission PDR/CAR 18 UCB, November 12-14, 2003 Development Plans Breadboarding/Eng Modeling BBM of antennas and PA exist and meet specs Part list for PA is frozen; fabrication of EM is starting Tests EM beginning of january PA Flight Units  FM1+2+3: sept 24  FM4+5+FS: nov. 19 Schedule is tight for FM1/PA delivery No problem expected for antennas and structures

THEMIS Mission PDR/CAR 19 UCB, November 12-14, 2003 Peer Review Results Status of RFAs RFA1: -AC magnetic cleanliness Status - Main issue is solar cells rotation (non circular S/C). Magnetic modeling will be made to estimate spurious noise at SCM location, once the info on solar cell wiring is available. UCLA is conducting a mag-cleanliness program; they have the software to carry out this evaluation -CETP can help by providing a “sniffer”, to measure spurious noise from s/c, and from other instruments. Involves some extra cost.

THEMIS Mission PDR/CAR 20 UCB, November 12-14, 2003 Peer Review Results RFA2: -Schedule problem with FM1/PA -Part list to be agreed with UCB Status: -delivery of FM1 together with FM2&3 on september 24 th ; agreed with UCB. -Final part list sent to UCB nov 10 th. RFA3: -Alignment budget Status : -Magnetic axis determined within 0.2% during tests at Chambon, once the antenna are mounted on their structure. -Main difficulty is stability/knowledge of boom axis.