goetzfields ipdr - se spp/fields system engineering preliminary design review keith goetz university...

Goetz 1FIELDS iPDR - SE

SPP/FIELDSSystem Engineering

Preliminary Design Review

Keith Goetz

University of Minnesota

[email protected]


SPP Level-1 Requirements

SPP Level-1 Requirements

1 Trace the flow of energy that heats and accelerates the solar corona and solar wind.

1a How is energy from the lower solar atmosphere transferred to, and dissipated in, the corona and solar wind?

1b What processes shape the non-equilibrium velocity distribution observed throughout the heliosphere?

1c How do the processes in the corona affect the properties of the solar wind in the heliosphere?

2 Determine the structure and dynamics of the plasma and magnetic fields at the sources of the solar wind.

2a How does the magnetic field in the solar wind source regions connect to the photosphere and the heliosphere?

2b Are the sources of the solar wind steady or intermittent?

2c How do the observed structures in the corona evolve into the solar wind?

3 Explore mechanisms that accelerate and transport energetic particles.

3a What are the roles of shocks, reconnection, waves, and turbulence in the acceleration of energetic particles?

3b What are the source populations and physical conditions necessary for energetic particle acceleration?

3c How are energetic particles transported in the corona and heliosphere?


FIELDS Level-1

Table 4.1 Baseline Fields and Waves MeasurementsReq. Measurement Dynamic Range Cadence Bandwidth4.1.1.1 Magnetic Field 140dB 100k vectors/s DC - 50kHz4.1.1.2 Electric Field 140dB 2M vectors/s DC - 1MHz4.1.1.3 Plasma Waves 140dB 1 spectrum/s ~5Hz - 1MHz

4.1.1.4 QTN/Radio 100dB for QTN80dB for radio

1 spectrum/4s QTN1 spectrum/16s radio

10-2,500kHz QTN1-16MHz radio

Table 4.5 Threshold Fields and Waves MeasurementsReq. Measurement Dynamic Range Cadence Bandwidth4.1.2.3 Magnetic Field 125dB 256 vectors/s DC - 128Hz4.1.2.4 Electric Field 125dB 256 vectors/s DC - 128Hz4.1.2.5 Plasma Waves 90dB 1 spectrum/10s ~5Hz - 50kHz

4.1.2.6 QTN/Radio 70dB for QTN70dB for radio

1 spectrum/32s QTN1 spectrum/32s radio

10-2,500kHz QTN1-16MHz radio

• Level-1 Flow to FIELDS


FIELDS Level-3 Driving Requirements

FIELDS Driving RequirementsPAY-37 Measurement: Magnetic Field MAGPAY-38 Measurement: Magnetic Field SCM & Plasma WavesPAY-170 Measurement: Electric Field & Plasma WavesPAY-172 Measurement: Plasma Waves (AC Magnetic Field)PAY-174 Measurement: Plasma Waves (Magnetic Field Power Spectra)PAY-272 Measurement: Plasma Waves (Electric Field Power Spectra)PAY-175 Measurement: Electric Field QTN SpectroscopyPAY-176 Measurement: Electric Field Radio EmissionsPAY-105 Payload: FIELDS Burst ModePAY-113 Timekeeping: FIELDS Time Knowledge AccuracyPAY-100 Payload: Minimum Perihelion HoursPAY-101 Payload: Mission LengthPAY-104 Payload: Risk Category (single fault tolerant)PAY-109 Payload: Burst Mode ManagementPAY-112 Payload: Flight Software ModificationPAY-277 Compliance: FIELDS to SWEAP ICD (FIELDS)PAY-279 Compliance: FIELDS to Spacecraft ICDPAY-276 Compliance: General Instrument SpecificationPAY-283 Compliance: MOC to SOC ICDPAY-140 Compliance: EMECPPAY-141 Compliance: EDTRDPAY-148 Compliance: CCP


FIELDS Level-4 Flowdown – IRD

• Requirements are flowed from SPP L3 document to FIELDS subsystems with IRD– APL: 7434-9051_Rev_Dash– SPF_SYS_010_Instrument_Requirements - IRD - SE-001-01B

• L3 includes references to the FIELDS QA Matrix, Environmental Spec, EME Spec, Contamination Control, GI ICD, FIELDS ICD, etc.

• L3 includes Instrument Functional and Performance Requirements

• FIELDS IRD– Requirements linked up to the L3 PAY requirements– Requirements linked down the subsystem L5 or specifications– Subsystem specifications refer to their requirements from the IRD and

how the design meets those requirements– Flight and SOC Software Requirements documents flow their

requirements from the IRD down to the software modules– IRD specifies how each requirement is to be verified (Test, Analysis,

etc)– System Engineer has validated that the subsystem specifications

describe an instrument that meets requirements


Requirement Flow-down to Subsystems

• FIELDS Subsystems


Requirement Flow-down to Subsystems

ID Title L4 Requirements TBDParent ID (Level 3)

Parent Title Full TextVerification Method

(What test and when)

RFS - Radio Frequency Spectromenter and Thermal Noise Receiver

RFS-01 Mission Length RFS Components must be selected to withstand the environment of SPP for the duration of the mission

PAY-101 Payload: Mission Length All instruments shall be capable of providing an operational lifetime of at least 7 years after launch. D

RFS-02 Measure Quasi Thermal Noise RFS shall be capable of measuring QTN Spectroscopy, as follows: -- frequency range: 10 kHz - 2500 kHz; -- dynamic range: 100 dB; -- maximum field intensity: ±200mV/m at 100kHz -- sensitivity (excluding power converter frequencies): 1 x 10^(-7) V/m/sqrt(Hz) at 100 kHz; 2 x 10^(-8) V/m/sqrt(Hz) at 2 MHz; -- in one direction.

PAY-175 Measurement: Electric Field QTN Spectroscopy

EFI shall be capable of measuring QTN Spectroscopy (TNR/HFR Survey Mode) from SPP, as follows: -- frequency range: 10 kHz - 2500 kHz; -- dynamic range: 100 dB; -- maximum field intensity: ±200mV/m at 100kHz -- cadence: up to 1 spectrum / 4 seconds; -- sensitivity (excluding power converter frequencies): 1 x 10^(-7) V/m/sqrt(Hz) at 100 kHz; 2 x 10^(-8) V/m/sqrt(Hz) at 2 MHz; -- in one direction.

T

RFS-03 Measure Radio Emissions RFS electronics shall be capable of handling signals from V1-V4 with -- frequency range: 1 MHz - 16 MHz; -- dynamic range: 80 dB; -- maximum field intensity: ±100mV/m at 2 MHz -- sensitivity (excluding power converter frequences): 2 x 10^(-8) V/m/sqrt(Hz) at 2 MHz and above; -- in two orthogonal components.

PAY-176 Measurement: Electric Field Radio Emissions

EFI shall be capable of measuring Radio Emissions from SPP, as follows: -- frequency range: 1 MHz - 16 MHz; -- dynamic range: 80 dB; -- maximum field intensity: ±100mV/m at 2 MHz -- cadence: up to 1 spectrum/16 sec; -- sensitivity (excluding power converter frequences): 2 x 10^(-8) V/m/sqrt(Hz) at 2 MHz and above; -- in two orthogonal components.

T

RFS-04 Instrument Calibration RFS shall provide calibration parameters and algorithms so as to allow conversion from telemetry units to physical units (gain and offset per channel) prior to S/C Integration.

PAY-102 Payload: Launch Readiness Calibration All instruments shall be calibrated prior to launch.

I

• Example - An IRD snippet – RFS


Verification

• IRD identifies briefly how each requirement is verified

• Verification, Validation, Test, and Calibration Plan describes a plan for how requirements are verified– Discussed in I&T section

• Requirements are verified as early as possible at a low level– Verifies subsystems, retires risk

• Requirements are verified at the highest level of assembly possible– Often involves verifying a requirement at several levels

• System Engineer tracks Verification against IRD– Reports on status at PER, PSR


SPP Spacecraft


FIELDS MAG Boom


FIELDS Block Diagram


Interface Control Documents

• Spacecraft to FIELDS– General Instrument ICD is at rev - (7434-9066)– FIELDS Specific ICD (7434-9055)

• Minor open issues don’t preclude ETU development

• MOC-SOC ICD– Well developed and familiar from RBSP and STEREO

• FIELDS to SWEAP ICD (SPF_MEP_105_SWEAP_ICD)– Preliminary release signed on both sides

• Subsystem ICDs are well along– MEP, CDI, RFS, TDS, DFB, MAG, AEB, LNPS, PA, SCM

• Connectors and pin-outs (SPF_MEP_110_Connectors) well defined


Software

• DCB– Software Development Plan (SPF_MGMT_008_SDP)– Software Requirements (SPF_FSW_002_SRS)

• TDS– Software Development Plan (SPF_TDS_002_SDP)– Software Requirements (SPF_TDS_004_SRS)

• SOC– Software Development Plan (SPF_MGMT_016_SOC_SDP)

• More later


Environmental

• FIELDS to survive all environments to be encountered during ground operations, launch, and on orbit

• FIELDS to operate in spec over all environments to be encountered during ground functional tests, on-orbit commissioning and science phases– Full science performance achieved after MAG boom and FIELDS

antennas are deployed (during commissioning)

• SPP Environmental Requirements called out in 7434-9039 (dash)

• SPP EMC Requirements called out in 7434-9040• FIELDS Verification Plan described in SPF_IAT_002

– Describes how FIELDS will verify compliance with requirements, including environmental requirements

– Plan discussed in more detail in I&T section


Environmental Test Matrix


Mechanical

• Instrument designed to Environmental Specification Requirements– Limit Loads, Stiffness, Venting, Shock

• Mechanical Interfaces, mass NTE called out in the FIELDS ICD

• Instrument tested per Environmental Spec– Mass Properties at component level

• Mass, CG• MOI by analysis

– Sine, Random vibration at component level• ETU to qualification levels• FM to acceptance levels

– No acoustic test planned (no acoustically sensitive parts)

• More mechanical later


Thermal

• SPP – of course – presents its thermal challenges• FIELDS interface temperatures called out in the

EDTRD and ICD– MEP Operational: -25ºC to +55ºC – FIELDS components conductively coupled to spacecraft

structures• FIELDS’ various thermal designs to be verified by

analysis and thermal vacuum testing– Analysis to include launch transients (heating)– Modeling and Analysis performed cooperatively between

FIELDS and APL– Boom verification testing (Thermal Balance) described in I&T

section– Verification testing (Thermal Vacum) described in I&T section

• More thermal later


EMC for FIELDS

• FIELDS is a driver for EMC/ESC/MAG requirements– Power supply conversion control– Limited radiated and conducted noise– Electrostatics – S/C exterior an equipotential surface

• ΔV from point to point must be small (less than ~1V)– Spacecraft must be magnetically clean– STEREO and RBSP are good models

• Spacecraft EMC testing plan needs to be worked– FIELDS antennas and radiated emissions


EMC/ESC

• EMC– MEP box design includes EMC closeout

• stair-step joints, vent shielding, connector close-out– DC-DC converter frequency is 150kHz synchronized– DC-AC MAG heater is 150kHz synchronized– RF receiver is synchronized to a multiple of 150kHz chopping

frequency– All sampling is synchronized to 150kHz chopping frequency– Supply has front end filtering, soft start– Verification by EMC tests:

• ETU (CE on bench)• FM (CE, CS, RE, RS, BI, On/Off transients)

• ESC– Exterior surfaces are conductive and connected to chassis

ground– ESC Verification at the component level

• surface resistance measurements


DDD/Radiation

• Components inside boxes are generally immune• Harnessing is not immune

– Components connecting to external harnesses have considered DDD issues

• For example – in peer reviews– Immunity will be demonstrated by analysis– Immunity will be tested with ETU

• Radiation environment inside spacecraft is fairly benign (20kRad)– Most EEE parts have no problem– Some parts require additional screening – possibly latch-up

circuitry • PMPCB in the loop

• Electronics outside the spacecraft analyzed separately– PMPCB providing guidance and assistance

• Spot shielding may be added in some locations– Planned for SCM preamplifier


Resources – Mass

• FIELDS mass tracking• Shows 11.9% CBE to NTE


Resources – Power

• FIELDS power summary• MEP Power shows ample

contingency: 27%– At room temperature

• New power estimates at 55C show much higher power needs– Contingency is negative

• Heater power has been an issue

• Operational heating– Below .25AU is reasonable– Above .25AU needs work

• But is apt to be ok

• Limited heating on MAG sensor has caused problems


Resources – Power Detail

• FIELDS power tracking• Power broken out to indicate

dissipation location

• Heating broken into– Operational and survival– Above .25AU and below


Resources – Telemetry

• Telemetry bit-rate allows us to meet our science requirements

• Survey data goes to S/C C&DH SSR – 15Gb/perihelion• Select data goes to large FIELDS internal flash

storage– Selected data comes down during cruise – 5Gb/perihelion

• More bits is always more good!• Telecommand requirements are modest


Trades and Changes

• Survival/operational heating additions• RTAX4000 selection – implemented on daughter

boards (3 places)• FIELDS MAG boom to be built at APL• Accept virtual PPS from S/C• V1-4 Antenna brackets will accommodate one TPS

shift

• FIELDS Clocks – synchronized to power supply• Split FIELDS into two halves to enhance reliability

• Open Trades• Location of FIELDS boom sensors• Length of FIELDS boom• Length of FIELDS whips


FIELDS/TDS Evolution

• FIELDS was proposed as a single string instrument• Within FIELDS, TDS was proposed as a single science

board


TDS Evolution

• In early 2013, we recognized that FIELDS was central to meeting threshold science – occupying 4 of 9 threshold blocks

• A single failure would mean a failure to meet threshold science– LNPS or DCB failure

Cannot MakeThreshold

Measurements

3 9

Magnetic Field

(4.1.2.3)

Plasma Waves

(4.1.2.5)

Electric Field

(4.1.2.4)

Quasi-Thermal Noise/Radio

(4.1.2.6)

Thermal Ions

(4.1.2.7)

Thermal Electrons(4.1.2.8)

Visible Broadband

(4.1.2.9)

Energetic Electrons(4.1.2.10)

Energetic Protons & Heavy Ions

(4.1.2.11)

FLDS-B FLDS-E FLDS-E FLDS-E SPC

SPAN-A

SPAN-A

SPAN-B

WISPR EPI-HI

EPI-LO

EPI-HI

EPI-LO


System-6

• FIELDS then suggested a number of alternatives– increasing reliability

• Eventually, we settled on System-6• Split

– FIELDS1/2– LNPS

• LNPS1/2– AEB

• AEB1/2– DPU function

• DCB/TDS


FIELDS Clocks

• FIELDS instrument to use unified clocking– Receivers, sampling, power supplies, clocks

• FIELDS LF instruments to operate in sync• FIELDS HF instrument relies on picket-fence for RF

sensitivity– Power supplies chop – making lines noise as a function of

frequency– Un-avoidable but controllable chopping at controlled

frequencies• All S/C power supplies must be controlled• N * 50 kHz with N starting at 3 – e.g. 150 kHz, 200 kHz and so on• Frequencies are crystal controlled (±100PPM)

– Make RF observations as a function of frequency in between lines of noise

• In earlier analog super-heterodyne receivers, we used sharp crystal filters to create the picket fence– Observing in between lines of noise


Picket Fences


FIELDS HF Clocks

• In the past, we used sharp crystal filters to create the picket fence

• With our new all-digital receiver, we implement sharp picket-fence filtering with simple high speed time series and poly-phase filtering

• Samples must be in sync with FIELDS’ and S/C power supplies

• FIELDS/HFR high end is about 20 MHz – sampling at ~40 MSa/s– Exact frequency must fall on the picket fence with room for an

FFT

• Master RFS sampling frequency is thus of the form 150 kHz * 2^N

• Master sampling frequency is 150,000 * 256 Hz is 38,400,000 Hz– (±4 kHz)


FIELDS LF Clocks

• Other FIELDS instruments will be operated in synchronization with power supply chopping frequency (SWEAP too)– Power supply chopping frequency is 150,000 Hz

• For lower frequencies we’ll shift down by powers of two

• For lowest sample rates we’ll shift down by powers of two to ~293 Sa/s– 150,000 Hz / 512 (292.968750 Sa/s)

• However, making convenient and compressible packets still requires a packet sizes and cycle times corresponding to a power of 2 samples– A standard packet should start with 256 samples

• Giving a FIELDS internal cycle time of .87 seconds/cycle– 131,072 / 150,000 Hz– FIELDS’ New York second


FIELDS Synchronized Sampling

• MAGs produce samples at ~293 vectors per second– MAGs produce chunks/packets at 256 vectors per cycle– Out-board MAG survey data down-sampled at ~36.3

vectors/second– In-board MAG survey data down-sampled at ~2.3

vectors/second• DFB can sample from all 4 SCM axes and all 5 electric

axes– Sampled at 150,000Sa/s– Low frequency DFB packets

• DFB samples in sync with DC MAGs• 256 vectors at 293Sa/s covering .87s and 1 cycle in duration –

lowest resolution– DFB mid-frequency spectra– DFB mid-frequency select time series

• TDS time series triggered bursts – V, E, B and SWEAP– ~2MSa/s (1.92MSa/s = 38,400,000 / 20)

• RFS spectra– Sampled in sync at ~40MSa/s


Issues

• Mass margin is tight– +11.9% (16.51kg CBE vs 18.48kg NTE)

• Power margin is tight – especially when operating hot– -0.7% (22.71W CBE vs 22.56W NTE)– +27.8% (17.66W CBE vs 22.56W CBE) at 20C

• Heater power has been an complex issue– DC MAG sensors should be warmer– +53.4% (3.98W CBE vs 6.10W NTE) in the best operational

case – -29.0% (8.59W CBE vs 6.10W NTE) in the worst operational

case – +2.5% (10.05W CBE vs 10.30W NTE) in the worst survival case

• LVDS over-voltage protection solution has proved elusive– DCB and TDS

• Monitoring non-op FIELDS Boom sensor temperatures remains open– MAGi, MAGo, SCM


Conclusion

• Issues are workable• Requirements are understood• Preliminary FIELDS system design meets

requirements• Documentation is in place

• FIELDS is ready to move into ETU development