PDS_VERSION_ID = PDS3 LABEL_REVISION_NOTE = "2009-10-27 IR: 2.0 Changes due to RIDs of Archive Review 2012-01-03 IR: 3.0 Lutetia Reference added 2012-04-02 IR: 4.0 Update due to RIDs of LUTETIA-Review 2015-05-19 IR: 5.0 Update after PRL" RECORD_TYPE = STREAM OBJECT = INSTRUMENT INSTRUMENT_HOST_ID = RO INSTRUMENT_ID = RPCMAG OBJECT = INSTRUMENT_INFORMATION INSTRUMENT_NAME = "ROSETTA PLASMA CONSORTIUM - FLUXGATE MAGNETOMETER" INSTRUMENT_TYPE = MAGNETOMETER INSTRUMENT_DESC = " Instrument Overview =================== The ROSETTA orbiter magnetometer (RPCMAG)is part of the ROSETTA Plasma Consortium (RPC) set of Scientific instruments. The purpose of the magnetometer is the measurement of the interplanetary magnetic field close to different targets visited by the ROSETTA spacecraft. Science Objectives of the Investigation ======================================= + Measurements of the interplanetary magnetic field during the flybys at planet Mars & Earth, the asteroids and in the environment of comet 67p/Churyumov-Gerasimenko. + Study of the structure and dynamics of the cometary-solar wind interaction region. + Study of the generation and evolution of the cometary magnetic Cavity. + Study of cometary tail evolution and structure. The Cometary Magnetic Field - A historical perspective ====================================================== In 1951 the German Astronomer Ludwig Biermann used the fact that cometary tails are always pointing away from the Sun to postulate the solar wind. It was Hannes Alfven who suggested in 1957 that cometary tails are due to the draping of the interplanetary magnetic field around the cometary nucleus. To explain this draping effect C.S. Wu and R.C. Davidson in 1972 studied the pick-up of cometary ions and the associated mass loading of the solar wind. Associated strong plasma wave turbulence due to this mass loading was first detected by B.T. Tsurutani and E.J. Smith in 1986. The magnetic field draping itself was first measured by F. M. Neubauer and co-workers using magnetic field measurements made onboard the GIOTTO s/c. The ROSETTA Orbiter Magnetic Field Instrument ============================================= + Fluxgate-Magnetometer with a resolution of at least 40 pT + 2 Sensors; an Inboard sensor (IB) and an Outboard sensor (OB) which are located on a 1.55m boom outside the s/c. The separation distance is 15cm. Two sensors are used to be able to distinguish between external fields and s/c generated noise. + 20 Bit ADC + Measuring B-Field in 3 components with a max. vector rate of 20 Hz + The Fluxgate Magnetometer RPC-MAG performance parameters are in full accordance with the EID-B design goals. + The Outboard/ Inboard sampling rate can be inverted by command either for higher Inboard time resolution or in case of outboard failure. + The sensors are fully calibrated also versus a wide temperature range. The temperature at Outboard and Inboard sensor is monitored in MAG housekeeping data. FGM Classification =================== + Saturated-Core-Magnetometer + Vector measurements possible + No absolute measurements + Lightweight, compact construction + Low power consumption + Qualified for space applications RPC-MAG FGM Characteristics ============================ Mass (sensor): 45 g Volume (sensor): 23 cm^3 Mass (electronics): 336 g Mass (harness H10): 109 g Mass (harness H11): 55 g Power: 840 mW @ 28V Operation interval: 15 years Sampling: 20 vectors/s Bandwidth: 0 - 10 Hz Resolution: +-0.031 nT Dynamics range: +-16384 nT Conversion: 7 * 20Bit ADC Temperature Range: operating: -160 ... +120deg C non-operating: -180 ... +150deg C Flight Unit Components ====================== DPU: FS IB-Sensor: FM OB-Sensor: FM Major Operational Constraints ============================= + RPC-MAG has to be operational as long as power is available + RPC-MAG has a joint operational requirement with ROMAP, especially during the lander descent. + RPC-MAG has a requirement on Spacecraft Magnetic Cleanliness of 25nT at the OB sensor. According to the performed continuous magnetic mappings of all units and s/c magnetic system modelling the expected magnetic field at the OB sensor is about 45nT (without boom motor field). + MAG will see some stray fields from other units like: Reaction Wheels, Solar Panel Motor and Thruster firing. This needs to be monitored during flight, especially during switch on procedures, for purposes of inflight calibration. History of the Instrument - Design Changes ========================================== The magnetometer experiment came on board of ROSETTA in a very late phase of the project. For this reason the mechanical (mass) and electrical requirements (power) were extremely stringent: mass below 1kg, power below 1W! In addition the project mass budget went negative after few months so that the project had to run general descoping actions to reduce mass. The first mass reduction action did not safe enough mass, so a second run had to be made. This led to severe descopings on the magnetometer sensors and electronics whose mass was already in the margin of the other experiments: Actions: + reduce size and mass of sensor, + integrate small micro-D connector into sensor: as a result the MAG sensors are extremely small and have low mass of 36g ! But due to this no access to tune the inner ring-cores for low offset was possible anymore. + The electronics board was reduced by 30% in size (from 1.5 boards to 1 board only) and down to 1.5mm thickness of the big multilayer board by higher integration. Connectors had to be changed from cannon-D to micro-D. The higher integration and size reduction was reached by new very dense layout and deletion of offset temperature compensation circuit for all 6 sensor-axes ! This mass saving action later on during qualification (vibration of RPC-0) resulted in a dramatic failure of the MAG board where both ASICS (128 pins)lost several pins due to very high resonance peaks of the multilayer board. The rework and redesign took several weeks and could only be solved by increasing the stiffness of the board by adding (gluing) additional stiffeners on top and bottom side of the board thus adding several 100g of mass. Comment: at this stage of the project the launcher has changed from ARIANE 4 to 5 giving more mass for ROSETTA. FGM Location ============= Sensors : the sensors are located outside the s/c on the 1.55m Lower Boom to minimize s/c generated noise/disturbances. Distance between Sensors : 15 cm OB position on the boom at 1.48m distance from the s/c. IB position on the boom at 1.33m distance from the s/c. 2 sensors for redundancy and to eliminate residual noise from s/c. Electronics: inside s/c in RPC-0 Box, common box for ALL RPC electronics. MAG Sensor - History ==================== The prototype of the ROSETTA FGM-sensors have been successfully flown onboard the DS-1 s/c. Design Changes: Due to the extreme boom temperature it became necessary to change the MAG sensors baseplate from isolating Glassfibre to Carbonfibre which has a much better thermal conductivity in order to get rid of the internal 25mW drive power for each sensor. Without this change, each sensor would heat up much higher then expected. MAG Sensor: Characteristics =========================== Excitation Coil: 1 layer CuL, completely wounded on ring core Core material: Permalloy (Fe19Ni81) Pickup Coil: 2*129 windings in 6 layers, 0.112 mm - High Temp. CuL Bobbin: Macor + glass ceramic + Ease of machining + maximum use temperature 800 deg C. + low thermal conductivity (1.46W/mK) + high temperature insulator (0.79kJ/kgK) + excellent electrical insulator (>10^16 Ohm/cm) + zero porosity (0%) + no outgassing in ultra high vacuum + strong and rigid + Coefficient of expansion: 7.4 x 10^-6/K Housing: Lexan + Polycarbonate + Excellent impact strength + Good weatherability + Ease of machining + Thermoformability + UV resisting + flame retardancy + light transmittance 86 % + high thermal insulation MAG Sensor: Features ==================== Sensor body consists of MACOR which has a smaller thermal Coefficient of expansion (7.4 x 10^-6/K) in comparison to the Copperwire (17 x 10^-6/K) of the windings. As the copperwires are wound so tight on the MACOR body, the thermal Expansion of the copper does not play a role any more. Both sensors are equipped with a temperature sensor PT1000 inside the housing to measure the sensor temperature. A/D Converter CS5508 and Radiation Hardness =========================================== The ADC Crystal CS5508 was chosen by the Space Research Institute in Graz because of its good performance characteristics: + 20-Bits + very low power 3.72 mW + on chip self-calibration circuitry + extended temperature range. The radiation behavior of the ADC was unknown. IWF Graz bought a special lot of this component and performed tests by using the facilities at ESTEC to determine the amount of radiation the converter could withstand and still remain within specification. The CS 5508 total dose tolerance was found to be 27 krad. The devices showed high susceptibility to the Single Event Upset (SEU) as well as to the Single Event Latch-up (SEL). Additional Tantalum Metal Sheet (0.5mm) was used to shield the ADCs against irradiation during the mission period! (comment: Tantalum is used because only mass saves from total dose radiation, Tantalum has a specific density of 16.6g/cm^3!. It must be mentioned that the glue of heavy Tantalum shields on top of each ADC chip causes additional stress on the chip pins during vibration, therefore the Tantalum spot shield is also glued to the board on each small side.) For detailed information refer to the document: RADIATIONHARDNESS TEST OF 20-bit CS5508 ADC CONVERTER, for RPC MAG/ROSETTA, Diploma Thesis, Amira Omerbegovic, F755 9530008 TU Graz, November 1999. RPCMAG Frequency Plan ===================== RPCMAG needs 3 different frequencies which can all be derived from a single 4.194304 MHz oscillator by appropriate division within the FPGA: FGM: excitation signal 50 kHz & 12.5 kHz 4.194304 MHz / 84 = 49.93219 kHz => 12.63345 kHz The division is achieved by 84 = 26 +24 + 22 ADC: drive frequency 32.768 kHz 4.194304 MHz / 128 = 33.768 kHz Device clock for 1355 transceiver PIU I/f: 400 kHz +- 10% 4.194304 MHz / 10 = 419.439 kHz Assumptions: Environmental ========================== + Power supply: Supply Voltage provided by PIU has to be stabilized within a 1% range + Temperature: Temperature changes are taken into account by the calibration + Radiation : The ADCs are shielded by Tantalum plates (thickness: 0.5 mm) Single Event Upsets (SEU) These effects cause bitflips in memories, it can be protected by failure correction algorithms (Hamming code) or redundancy. For MAG an SEU event is uncritical because of full redundancy and because a bitflip will cause the loss of one or few vectors which can be tolerated. Single Event Latch Up protection (SEL). It was decided by the RPC team to have the latch up protection (due to shortage and therefore overcurrent in some circuitry). The circuitry is built from SEL immune parts in the central RPC power unit, which in case of an SEL measures the overcurrent (LCL) and turns off RPC within msec. Restart has to be commanded. Assumptions: Contingencies ========================== Critical parts: + Every component has to be alive for a successful operation of the FGM + The ADCs are shielded by Tantalum plates + PCB located in RPC-0 for shielding + LCL protects electronics against short-circuits (located in PIU) Possible MAG problems during flight are covered by the RPC-0 FMECA (Failure Mode Effectiveness and Criticality Analysis) Assumptions: Redundancies ========================= + 2 sensors + No redundancy for electronics Design Margins ============== The electronics design margins are standard workmanship questions for space application. Applicable to each part, especially capacitors.The design, therefore has been made according to ESA Standards as described in their documentation. Critical parts are the: + ADC CS5508 wrt. Radiation (see above) + MAX 400 Op Amp which is not on the preferred parts list of ESA or NASA, because it is not qualified yet. However, this part is used in commercial industry since years in great numbers and thus showing and demonstrating the quality level and reliability. Operations =========== The RPCMAG instrument has only two intrinsic modes: + ON + OFF After power on reset, the MAG instrument calibrates itself and starts to send continuously 20 Hz Magnetic field (B) and Housekeeping (HK) Data. Filtering is done in the PIU. MAG Instrument Software ======================= MAG software runs in a radiation hard 1280 FPGA! Detailed description of the ACTEL FPGA software can be found in the following document: The building and operation of the MAG_FPGA in the Fluxgate Magnetometer Electronics. RPCMAG has no individual s/w. It has only the capability to be switched on/off and later it runs in continuous 20 Hz sampling mode. Calibration of the ADCs once in every 24 hour. It only samples and sends 20 Hz data (6 vectors + 1 HK). All other operation is done in PIU-S/W. A RPCMAG Data Acquisition Cycle : Using a crystal oscillator the MAG FPGA sends a 'StartConvert' signal (CONV)to the ADCs at a certain time. After all ADCs have been finished the conversion (RDY Signal) the data will be read and transmitted to the Link FPGA. As the 20 Hz of the MAG unit is slightly different from the 20 Hz at the s/c there will be not an integral number of vectors in an RPC AQP. Therefore, the CONV signal is passed to the Link chip (CONV1) to send a signal to the PIU. PIU will then generate a high res time stamp for the first vector of the packet. The accuracy is better then 1ms +- 100 us. MAG Software in PIU ==================== PIU is just an observer. It has no control of what MAG is doing. The MAG S/W in the PIU has the task to + synchronize itself with the MAGs internal conversion signal + sample all 20 Hz Mag data without any loose and store on board time for the first value of the packet + prepare science and HK packets for transmission + filter the 20 Hz data to an appropriate mean value and set MAG to the right SID + handle FCPs for MAG + provide HK values, measured by the MAG ADC, for PIU, MAG, MIP + switch the desired sensor to be primary If the OB is the primary sensor (which is the default case) the IB is the secondary sensor. Via TC the order can be switched. The Primary (PRI) sensor is the one which is sampled with the higher sample rate, the secondary (SEC) the one with the lower sample rate. Details are listed in the next table. Mode description: ================= MODE SAMPLE PACKET PACKET VECTOR RATE PERIOD LENGTH RATE Minimum Mode SID1 1/32 Hz 1024 s 32 Pri Vec 0.03125 vec/s 1 Sec Vec 0.000976 vec/s Normal Mode SID2 1 Hz 32 s 32 Pri Vec 1 vec/s 1 Sec Vec 0.03125 vec/s Burst Mode SID3 20 Hz 16 s 320 Pri Vec 20 vec/s 16 Sec Vec 1 vec/s Medium Mode SID4 5 Hz 32 s 160 Pri Vec 5 vec/s 1 Sec Vec 0.03125 vec/s Low Mode SID5 0.25 Hz 128 s 32 Pri Vec 0.25 vec/s 1 Sec Vec 0.007812 vec/s Test Mode SID6 20 Hz 16 s 320 Pri Vec 20 vec/s 1 Sec Vec 0.0625 vec/s HK Mode 32 s 8 words 0.03125 vec/s Filter S/W =========== Burst data (SID3) pass the s/w unfiltered. Data of all other modes will be filtered in a multi stage process. Each stage filters and decimates the data in time. The data fields in the HK packet filtercfg stageAId stageBId control the filter mode. MODE SAMPLE FILTER IDs SAMPLES PER PACKET RATE STAGE 1 STAGE 2 STAGE 3 PRIMARY SECONDARY Minimum SID1 1/32 Hz 4 3 3 32 1 Normal SID2 1 Hz 1 2 off 32 1 Burst SID3 20 Hz off off off 320 16 Medium SID4 5 Hz 2 off off 160 1 Low SID5 0.25 Hz 4 3 off 32 1 Test SID6 20 Hz TC def. off off 320 1 Time Stamps of Data Packets ============================ Due to this complex filtering process the time stamps of the measured data are different for each mode. Each vector coming out of the PIU gets a specific time stamp according to the actual mode. These time stamps are shifted towards the real time of the physical event. The time stamps of the data lie BEFORE the real measurement time. This time displacement for the PRIMARY vectors in different modes is listed in the following table: MODE SAMPLE RATE TIME SHIFT (PRIMARY VECTORS) Minimum SID1 1/32 Hz 223.7 s Normal SID2 1 Hz 8.2 s Burst SID3 20 Hz 0 s Medium SID4 5 Hz 1.35 s Low SID5 0.25 Hz 27.7 s Thus, the true time of the physical event is achieved by adding the listed time shift to the time stamp of the vector. For the SECONDARY vectors a different time stamping applies. As the SECONDARY vectors are not filtered but just picked out of the data stream. Thus, the first SECONDARY vector of a packet is stamped with the time of the end of the data packet. Therefore, the following shifts have to be taken into account: MODE SAMPLE RATE TIME SHIFT (SECONDARY VECTORS) Minimum SID1 1/1024 Hz 1023.95 s Normal SID2 1/32 Hz 31.95 s Burst SID3 1 Hz 15.95 s Medium SID4 1/32 Hz 31.95 s Low SID5 1/128 Hz 127.95 s The archive data in the datasets labeled with V1.0 use the original time stamps. For later datasets labeled V2.0 and above the time stamps of the PRIMARY vectors have been corrected by the archive generation software. The SECONDARY vector time stamps, however, stay always as they were originally transmitted in the telemetry. Sensors extreme Temperature Tests ================================= The MAG sensors on the boom will see extreme Temperatures from -200 deg C to +150 deg C. This Temperature range for the sensors could only be tested in the Cryo-Mumetal chamber of Garchy (France), where the Magnetic field is completely shielded by Mumetal. A non Magnetic Test Table inside can be cooled by liquid Nitrogen to -191 deg C. This test was performed successfully with all sensors in January 2001. The extreme temperature range was predicted for comet Wirtanen orbit, a new prediction for the CG target does will probably be similar. In Magnetsrode the positive temperature range was tested & calibrated up to +75 deg C. However, it is impossible to test the sensors in non magnetic environment and thermal Vacuum, no facility for this exists worldwide. EMC Test ======== The magnetic field is more or less distorted by the following s/c units: Reaction wheels Solar Arrays (<0.5 nT) SADM (23 nT) Lander Thrusters (compensated) Calibration =========== The magnetometer has been calibrated on ground in the magnetic coil facility MAGNETSRODE at Braunschweig, Germany. This facility is operated by the Institute of Geophysics and extraterrestrial Physics. The complete calibration is documented in the following documents: Report: RO-IGM-TR-0002 DC-Analysis: RO-IGM-TR-0003 AC-Analysis: RO-IWF-TR-0001 Step by Step Calibration Procedure: RO-IGEP-TR-00028 Nominal (uncalibrated) Conversion of Digital Values =================================================== RPCMAG contains seven 20bit ADCs. 3 are used for the digitalization of magnetic field data measured by the OB sensor, 3 are used for the magnetic field data of the IB sensor, and the seventh, which is operated with a multiplexer, converts various Housekeeping (HK) data. The reference voltage of the ADCs is 2.5 V. The converters are operated in a bipolar mode, thus input voltages in the range of +-2.5V can be converted. The relation of input voltage and counts is: 00000h <-> -2.5V 80000h <-> 0V FFFFFh <-> +2.5V Due to the small input range some voltage adaption has to be done in the MAG instrument for certain HK values: * the 2.5V reference voltage is monitored behind a voltage divider 100016 Ohm/(100000 Ohm+100016 Ohm)=0.499 as 1.2497V nom. voltage. * the +5V supply voltage is monitored behind a voltage divider 90956 Ohm /(99972 Ohm+90956 Ohm)= 0.476 as 2.38V nominal voltage. * the -5V supply voltage is monitored behind a voltage divider 27400 Ohm /(100024 Ohm+27400 Ohm)=0.215 as -0.997 V nom. voltage. * the temperatures are measured as the voltage drop of PT1000 thermistors connected to the 2.5V reference voltage via a 1kOhm serial resistor: U(T) = U_ref*(1/(R_ser/R(T)+1)). Therefore, the nominal voltages at 273K are 1.25V. Conversion to temperatures are obtained by application of 3rd order polynomials. RPCMAG sends always 20bit data to the PIU. The PIU reduces the amount of data in the following way: Science data: Data PIU-Input PIU-Output PIU-Operation Magnetic field IB 20 bit 20 bit subtract 2^19 Magnetic field OB 20 bit 20 bit subtract 2^19 Housekeeping data: Data PIU-Input PIU-Output PIU-Operation Magnetic field OB 20bit 16bit subtract 2^19 right shift by 4 digits 2.5V Ref. Voltage 20bit 20bit subtract 2^19 +5V Supply Voltage 20bit 8bit subtract 2^19 skip highest 4bits subtract offset 79F7h right shift by 4 digits -5V Supply Voltage 20bit 8bit subtract 2^19 skip highest 4bits subtract offset -370Eh right shift by 3 digits Temperature OB 20bit 16bit subtract 2^19 right shift by 4 digits Temperature IB 20bit 16bit subtract 2^19 right shift by 4 digits Detailed description of the conversion --------------------------------------- 1)Science Data: Magnetic field (range = +-15000nT , 20 Bit): Definitions: B_max = +15000 nT B_min = -15000 nT counts20 = 2^20 = 1048576 Nominal_Factor = (B_max - B_min) / (counts20-1) The TLM data contain signed 20bit data. The data range of these values in decimal representation is -(counts20/2)... +counts20/2-1. These signed integers are the EDITED RAW DATA. Unit is [counts]. In the first step of conversion to physical values an offset of counts20/2 is added, which yields to data in the range of 00000h:FFFFFh. The nominal relation between these converted TLM data and magnetic field is now as follows: 00000h <-> B_min 80000h <-> 0 FFFFFh <-> B_max To convert these data into uncalibrated [engineering, enT] nanotesla values, the following algorithm has to be applied: B= [TLMdata + counts20/2] * Nominal_Factor + B_min [enT] 2)Housekeeping Data: Magnetic field (range = +-16384nT,16 Bit): Definitions: B_max = +16384 nT B_min = -16384 nT counts16 = 2^16 = 65536 Nominal_Factor = (B_max - B_min) / (counts16-1) The TLM data contain 16bit data. The relation between the ADCvalues and the PIU output (TLM) is: TLM = (ADCvalue -2^19) shr 4 The data range of these TLM data is 0...+counts16-1. The decimal representation of these unsigned integers are the EDITED RAW HK DATA. Unit is [counts]. In the first step of the conversion to physical values an offset of counts16/2 is added if the value is smaller than counts16/2 and subtracted in the other case. The nominal relation between these converted data and magnetic field is now as follows: 0000h <-> B_min 8000h <-> 0 FFFFh <-> B_max To convert these values into uncalibrated [engineering, enT] nanotesla values, the following algorithm has to be applied: B= converted data * Nominal_Factor + B_min [enT] 3)Housekeeping Data: 2.5V Reference Voltage (Typical divided input voltage: 1.2497V, 20 Bit) Definitions: U_max = +2.5 V U_min = -2.5 V counts20 = 2^20 = 1048576 volt_divider = 100016/200016 = 0.49996 Nominal_Factor = (U_max - U_min) / (counts20-1) The TLM data contain 20bit data. The relation between the ADCvalues and the PIU output (TLM) is: TLM = (ADCvalue - 2^19) The data range of these TLM data is 0...+counts20-1. The decimal representation of these unsigned integers are the EDITED RAW HK DATA. Unit is [counts]. In the first step of the conversion to physical values an offset of counts20/2 is added if the value is smaller than counts20/2 and subtracted in the other case. The nominal relation between these converted data and magnetic field is now as follows: 0000h <-> U_min 8000h <-> 0 FFFFh <-> U_max To convert these values into voltages the following algorithm has to be applied: U_ref = (converted data * Nominal_Factor+U_min) / volt_divider [V] 4)Housekeeping Data: +5V Supply Voltage (Typical devided input voltage: 2.38V, 8 Bit) Definitions: U_max = +2.5 V U_min = -2.5 V U_Ref = +2.4996 V U_center = +5.0V counts8 = 2^8 = 256 volt_divider = 90956/(99972+90956) = 0.476389 cal_fak = Uref /(counts20-1) / volt_divider * 512= 0.002562 The TLM data contain 8bit data. The relation between the ADCvalues and the PIU output (TLM) is: TLM -> ((((ADCvalue -2^19) shr 4) - 79F7h) shr 4 ) The data range of these TLM data is 0...+counts8-1. The decimal representation of these unsigned integers are the EDITED RAW HK DATA. Unit is [counts]. In the first step of the conversion to physical values these unsigned integer TLM values are converted to signed integers, thus an offset of counts8 is subtracted if the value is greater than counts8/2. The nominal relation between these converted data and the original voltage is now as follows: 80h = -128d <-> 4.673V 00h = 0d <-> 5.000V 7Fh = 127d <-> 5.327V To convert these values into voltages, the following algorithm has to be applied: U_plus = cal_fak * converted data + U_center [V] 5)Housekeeping Data: -5V Supply Voltage (Typical divided input voltage: 0.997 V, 8 Bit) Definitions: U_max = +2.5 V U_min = -2.5 V U_Ref = +2.4996 V U_center = -5.0V counts8 = 2^8 = 256 volt_divider = 27400/(100024+27400) = 0.21503 cal_fak= = Uref /(counts20-1) / volt_divider * 256= 0.002838 The TLM data contain 8bit data. The relation between the ADCvalues and the PIU output (TLM) is: TLM -> ((((ADCvalue -2^19) shr 4) + 370Eh) shr 3 ) The data range of these TLM data is 0...+counts8-1. The decimal representation of these unsigned integers are the EDITED RAW HK DATA. Unit is [counts]. In the first step of the conversion to physical values these unsigned integer TLM values are converted to signed integers, thus an offset of counts8 is subtracted if the value is greater than counts8/2. The nominal relation between these converted data and the original voltages is now as follows: 80h = -128d <-> -5.36V 00h = 0d <-> -5.00V 7Fh = 127d <-> -4.64V To convert these values into voltages, the following algorithm has to be applied: U_minus = cal_fak * converted data + U_center [V] 6)Housekeeping Data: Temperatures (range = +-200 degC, 16 Bit) (Related input voltages: 0.5...1.6V, 16 Bit) Definitions: U_max = +2.5V U_min = -2.5V counts16 = 2^16 = 65536 Nominal_Factor = (U_max - U_min) /(counts16-1) The TLM data contain 16bit data. The relation between the ADCvalues and the PIU output (TLM) is: TLM= (ADCvalue -2^19) shr 4 The data range of these TLM data is 0...+counts16-1. The decimal representation of these unsigned integers are the EDITED RAW HK DATA. Unit is [counts]. In the first step of the conversion to physical values an offset of counts16/2 is added to the TLM data. To convert these values into voltages, the following algorithm has to be applied: U(T) = (TLM data + counts16/2) * Nominal_Factor + U_min [V] The calibrated temperatures can be derived from these voltages by application of a 3rd order calibration polynomial: T = T_0 + T_1*U(T)+T_2*U(T)*U(T) + T_3 *U(T)*U(T)*U(T) The coefficients T_i are: T_0 = -368.6107 T_1 = +458.4930 T_2 = -356.0289 T_3 = +180.0064 Transformation from Instrument- to s/c-coordinates. =================================================== The sensor raw data are given in the unit reference frame (URF),also called instrument coordinates. The transformation to the spacecraft- coordinates (s/c-coordinates) for the stowed boom and deployed boom orientation is done using the matrices stored in the file: ./calib/RPCMAG_SC_ALIGN.TXT Transformation to celestial coordinates ======================================== The needed transformation from s/c-coordinates to celestial coordinates (ECLIPJ2000,GSE, CSO,CSEQ,...) is done dynamically vector by vector using the SPICE system. The needed SPICE kernels are listed in each *.LBL file related to the specific Magnetic field data file. The SPICE transformation routines are imbedded in the IDL calibration software. Magnetic Cleanliness ==================== Details can be found in IABG: B-TR40-0555 RO-IGM-SR-0003 Output data =========== FGM output is: + Time series of 3 B-Field vectors from the IB-Sensor + Time series of the IB-Sensor Temperature + Time series of 3 B-Field vectors from the OB-Sensor + Time series of the OB-Sensor Temperature + Additional HK values for PIU & MIP The RPC MAG-CREW ================ PI: Glassmeier, Karl-Heinz, IGEP,TU-BS TM: Richter, Ingo, IGEP, TU-BS Research Assistant: Koenders, Christoph, IGEP, TU-BS Goetz, Charlotte, IGEP, TU-BS Diedrich, Andrea,IGEP, TU-BS, died in 2007 Instrument Development: Kuhnke, Falko,TU-BS (electronics & sensor) Musmann,Guenter,TU-BS (sensor) Stoll, Bernd, IGEP,TU-BS (electronics & sensor) Co. Pfeil/Trawid, Hildesheim (sensor) Aydogar,Oezer,IWF,TU-GRAZ (electronics) Conversion Software Development Hans Eichelberger, IWF, TU-Graz Co-Is: Auster, Hans-Ulrich, IGEP,TU-BS (PI of the ROMAP FGM) Balogh, Andre, IC, London Coates, Andrew J., MSSL Cowley, S.W.H., Univ. Leicester (science, retired) Flammer, K., UCSD (science, retired) Gombosi, Tamas,Univ.of Michigan (cometary science support) Horanyi, M.,Univ. of Colorado (plasma-dust interact.) Jockers, Klaus, MPS Lindau (science, retired) Kuerth, Eckehard, DLR, Berlin (comet. nucleus physics) Ip, W.-I., MPS, Lindau (Science) Mehlem, Klaus, ESTEC (magnetic cleanliness, retired) Motschmann, Uwe,ITP, TU-BS (science planning & analysis) Musmann, Guenter, IGEP, TU-BS (ex RPC-TM, retired) Neubauer, Fritz, Univ. Cologne) (overall science support,retired) Richter, Ingo, IGEP, TU-BS (MAG TM, calibration,analysis) Rustenbach, Juergen, MPE-Berlin,(Co-I of ROMAP FGM, retired) Sauer, Konrad, MPE-Berlin (theory and simulation, retired) Schwingenschuh, Konrad, IWF-Graz(magn. cleanl.,science, retired) Szegoe, K.,RMKI-KFKI,Budapest (hardware, planning) Tsurutani, Bruce, JPL, Pasadena (science & analysis) Zang, Gary,Bart.Res.Inst,Delaware(science) Acronyms ======== ADC: Analog-Digital-Converter AQP: Acquisition Period ASIC: Application Specific Integrated Circuit B-FIELD: Magnetic Field CG: 67P/Churyumov-Gerasimenko CO-I: Co-Investigator CSEQ: Body-centered Solar EQuatorial coordinate system. +X axis is the position of the Sun relative to the body; it's the prim. vector and points from the body to the Sun; +Z axis is the component of the Sun's north pole of date orthogonal to the +X axis;+Y axis completes the right- handed reference frame. The origin of this frame is the body's center of mass CSO: Cometo centered solar orbital coordinates. Orientation: X: Pointing from COMET to SUN, Y: The inertially referenced velocity of the sun relative to the comet is the secondary vector: the Y axis is the component of this velocity vector orthogonal to the X axis. Z: Perpendicular to X and Y, completing system to be right handed CuL: Kupferlackdraht, Enamelled copper wire DDS: Data Distribution System DPU: Digital Processing Unit DS-1: NASA's Deepspace 1 Mission EAICD: Experimenter to Archive Interface Control Document ECLIPJ2000:Ecliptic Coordinates related to Equinox of Epoch J2000. Orientation: X: Pointing from SUN to Vernal Equinoxe, Y: perpendicular to X in Ecliptic Plane, Z: Perpendicular to Ecliptic plane, pointing up EID-B: Experiment Interface Document , Part B EMC: Electromagnetic Compatibility ESA: European Space Agency ESTEC: European Space Research and Technology Centre FGM: Fluxgate-Magnetometer FM: Flight Model FMECA: Failure Mode Effects and Criticality Analysis FPGA: Field programmable Gate Array FCP: Flight Control Procedure FS: Flight Spare Model GSE: Geocentric Solar Equatorial coordinate system HK: Housekeeping data (Supply voltages, Ref. voltages, Temperatures) H/W: Hardware IABG: Industrieanlagenbetriebsgesellschaft IB: Inboard Sensor ID: Identifier I/F: Interface IGEP: Institut fuer Geophysik und extraterrestrische Physik, TU-Braunschweig IWF: Institut fuer Weltraumforschung,Graz LCL: Latching Current Limiter LEXAN: Polycarbonate resin thermoplastic MACOR: Machinable glas ceramic MAG: Magnetometer MIP: RPC Mutual Impedance Probe NASA: National Aeronautics and Space Administration OB: Outboard Sensor OPAMP: Operational Amplifier PCB: Printed Circuit Board PDS: Planetary Data System PERMALLOY: Nickel Iron magnetic alloy PI: Principal Investigator PIU: RPC Power Interface Unit PSA: Planetary Science Archive PT1000: Platinum Thermistor with 1000 Ohm nominal resistance RAW: Data in units of ADC counts in instrument coordinates ROKSY: ROSETTA Knowledge Management System ROMAP: ROSETTA Lander Magnetometer RPC: ROSETTA Plasma Consortium RPCMAG: ROSETTA Orbiter Magnetometer RPC-MAG: ROSETTA Orbiter Magnetometer RPC-0: RPC Main Electronics Box SADM: Solar Array Drive Mechanism S/C: Spacecraft SID: Science Mode Identifier S/W: Software SEU: Single Event Upset SEL: Single Event Latch-up TC: Telecommand TM: Telemetry TM: Technical Manager TS: Time Series UV: Ultraviolet us: microsecond Wrt.: with respect to References ========== Alfven, H., 1957. On the theory of comet tails. Tellus, 9, 92-96. Biermann,L., 1951. Kometenschweife und solare Korpuskularstrahlung. Zeitschrift fuer Astrophysik, 29, 274. Coates, A.J., Jonstone, A.D., Wilken, B., Neubauer,F.M., 1993. Velocity Space Diffusion and Nongyrotropy of pickup Water Group Ions at Comet Grigg-Skjellerup. J. Geophys. Res. 98, A12, 20985-20994. Eichelberger, H.U., Schwingenschuh, K., Aydogar, Oe., Baumjohann, W., 2002. Calibration Report RO-IWF-TR0001, Sample Rate and Frequency Response. Analysis of ROSETTA RPC-MAG, IWF. Glassmeier, K.H., Neubauer, F.M., 1993. Low-Frequency Electromagnetic Plasma Waves, Comet P/Grigg-Skjellerup: Overview and Spectral Characteristics. J. Geophys. Res. 98, A12, 20921-20935. Glassmeier, K.H., Motschmann, U., Mazelle, C., Neubauer, F.M., Sauer, K., Fuselier, S.A., Acuna M.H., 1993. Mirror Modes and Fast Magnetoacoustic Waves Near the Magnetic Pileup Boundary of Comet P/Halley. J. Geophys. Res. 98, A12, 20955-20964. Glassmeier, K.H., Richter, I., Diedrich, A., Musmann, G., Auster, U., Motschmann, U., Balogh, A., Carr, C., Cupido, E., Coates, A., Rother, M., Schwingenschuh, K., Szegoe, K., Tsurutani, B.,2007. RPC-MAG The Fluxgate Magnetometer in the ROSETTA Plasma Consortium. Space Sci. Rev., 128, 649-670. Hedgecock, P.C., 1975. A correlation technique for magnetometer zero level determination. Space Sci. Instr., 1, 83. Huddleston, D.E., Coates, A.J., Jonstone, A.D., Neubauer, F. M.,1993. Mass Loading and Velocity Diffusion Models Heavy Pickup Ions at Comet Grigg-Skjellerup. J. Geophys. Res. 98, A12, 20995-21002. Johnstone, A.D., Coates, A.J., Huddleston, D.E., Jockers, K., Wilken,B., Borg, H., Gurglio, C., Winningham, J.D., Amata, E., 1993. Observations of the solar wind and cometary ions during the encounter between Giotto and comet P/Grigg-Skjellerup. Astron. Astrophys., 272, L1-4. Motschmann, U., Glassmeier, K.H.,1993. Nongyrotropic Distribution of Pickup Ions at Comet P/Grigg-Skjellerup: A Possible Source of Wave Activity. J. Geophys. Res. 98, A12,20977-20983. Neubauer, F.M., 1981. The Giotto Magnetometer Experiment.ESA SP-169.4. Neubauer, F.M., Musmann, G., Acuna, M.H., Burlaga, L.F., Ness,N.F., Mariani F., Wallis, M., Ungstrup, E., Schmidt, H., 1983. The Giotto magnetic field investigation. In: Cometary Exploration, Proc. Int. Conf. Comet. Explor., 15-19 November 1982, Budapest (Ed. Gombosi T.), 401-410. Neubauer, F.M., Marschall, H., Pohl, M., Glassmeier, K.H., Musmann, G., Mariani, F., Acuna, M.H., Burlaga, L.F., Ness, N.F., Wallis, M.K., Schmidt, H.U., Ungstrup, E.,1993. First Results from the Giotto magnetometer experiment during the P/Grigg-Skjellerup encounter. Astron. Astrophys., 268, L5-8. Neubauer, F.M., Glassmeier, K.H., Coates, A.J., Johnstone, A.D., 1993. Low-Frequency Electromagnetic Plasma Waves at Comet Grigg-Skjellerup: Analysis and Interpretation. J. Geophys. Res. 98, A12, 20937-20953. Neuhaus, A., 2001. RO-IGM-SR-003, Study on the DC magnetic Requirements, System Report. Inst. fuer Geophysik und Meteorologie. Omerbegovic, A., 1999. Radiationhardness test of 20-bit CS5508 ADC Converter for RPC MAG/ROSETTA. Diploma Thesis, F755 9530008, TU Graz. Othmer, C., Richter, I.,2001. RO-IGM-TR-0003, Fluxgate Magnetometer Calibration for Rosetta:Analysis of the FM Calibration, Inst. fuer Geophysik und Meteorologie, Braunschweig. Richter, I., Rahm, M.,2001. RO-IGM-TR-0002, Fluxgate Magnetometer Calibration for Rosetta: Report on the FM and FS Calibration. Inst. fuer Geophysik und Meteorologie, Braunschweig. Richter, I., Cupido, E., 2011. RO-RPC-UM, Rosetta Plasma Consortium: User's Manual,Inst. fuer Geophysik und extraterrestrische Physik, Braunschweig. .. Richter, I. et al.,2011.Magnetic field measurements during the ROSETTA flyby at asteroid (21) LUTETIA. Planet. Space. Sci., doi:10.1016/J.pss.2011.08.009 Schmidt, H.U., Wegmann, R., 1982. Plama flow and magnetic field in comets. In: Comets (Ed. Wilkening L.) Univ. of Arizona Press,538-560. Sulivan, J.,2001. The building and operation of the MAG_FPGA in the Fluxgate Magnetometer Electronics, KFKI RMKI, Budapset. Tsurutani, B.T., Smith, E., 1986. Hydromagnetic waves and instabilities associated with cometary ion pickup: ICE observations turbulence associated with comet Giacobini Zinner. Geophys. Res. Let., 13. Wallis, M.K., 1973. Weakly shocked flows of the solar wind plasma through atmospheres of comets and planets. Planet. Space Sci., 21, 1647-1660. Winske, D., Wu, C.S., Li, Y.Y., Mou, Z.Z., Guo, S.Y.,1985. Coupling of newborn ions to the solar wind by electromagnetic instabilities and their interaction with the bow shock, J. Geophys. Res.,90, 2713-2726. Wum, C.S. Davidson, R.C., 1972. Electromagnetic Instabilities produced by Neutral-Particle Ionization in Interplanetary Space, J. Geophys. Res. 77, 5399." 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