d1-03 systems engineering.ppt

SOFIE PDR – October 22, 2003 - 1SOFIE CDR October 7-8, 2004

Systems Engineering, Chad Fish1

GATS

Systems Engineering

Chad [email protected]

435-797-0469



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Presentation Overview

• Key System Requirements• System Design• System Operation• Technical Resources and Error Budgets• Post-PDR System Changes• Technical Risks• Technical Coordination• Summary• Supplementary Material

– Error Budget Models– Level 3 Requirements Compendium



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Key System Requirements



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Science Objectives• SOFIE will support AIM mission in study of PMCs and the environment in which they

form. SOFIE will use differential solar occultation to measure:– Five gaseous species (H2O, CO2, O3, CH4, NO)– Temperature– Particle extinction at 10 wavelengths

• Each SOFIE channel uses two detectors to make three measurements:– Strong band absorption– Weak band absorption– Difference signal (weak band – strong band = ΔV)

Remove interference and reduce noise!

SOFIE Channel OverviewChannel 1 2 3 4 5 6 7 8

Target Absorber O3 particles H2O CO2 particles CH4 CO2 NO

Center (m)Strong bandWeak band

0.2900.328

0.8621.031

2.602.45

2.772.94

3.063.19

3.373.51

4.254.63

5.324.98



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System Requirements

IDENTIFIER SHORT DESCRIPTION REQUIREMENT(General Operational)

SOF 289 Mission Lifetime Function 25 months following a 1 month on-orbit commissioning.

SOF 288 Nominal Operability Operate 95% of the time over any 5 consecutive days during the primary science observation season.

SOF 279 Autonomous Operations

SOFIE shall be capable of autonomous operations for at least 96 hours.

SOF 172 Mission Ops SOFIE shall make 2 solar occultation measurements per orbit, one at sunrise and one at sunset.

SOF 175 Time Stamp The SOFIE science data time stamp shall be accurate to within 2.5 msec relative to successive data samples during occultation measurements.

SOF 179 Spatial Resolution The SOFIE science data products shall have 3.0 km or less spatial resolution in elevation.

SOF 308 Sampling Rate The SOFIE science data channel sample rates shall be ≥ 20 Hz during an occultation measurement.



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System Requirements (cont)

IDENTIFIER SHORT DESCRIPTION REQUIREMENT(Observational Views)

SOF 180 Instantaneous Science FOV

The SOFIE instantaneous science FOV shall be 6 arc minutes horizontal and 1.8 arc minutes vertical (defined as along the axis between Nadir and Zenith).

SOF 295 Glint FOV The SOFIE glint FOV shall be 24 deg horizontal and 32 deg vertical.

SOF 178 FOR The SOFIE steering mirror shall provide a field of regard of ± 2 º elevation and ± 2 º azimuth.

(Pointing)

SOF 300 Pointing Ability SOFIE shall point the center of its FOV to ±1 arcminute at a fixed distance relative to the solar top edge centerpoint and maintain this position during occultation measurement. The pointing position will be considered "maintained" if a 10 Hz filtering (0.1 sec running mean) of the true pointing position varies <15 arc seconds (1 sigma) in elevation and <1.0 arcmin (1 sigma) in azimuth.



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System Requirements (Cont)Table 2. SOFIE spectral band specifications and channel S/N requirements.

Band Center (m)

Band Limits, m Band Limits, cm-1 S/N*

O3 strong 0.290 0.2857 - 0.2941 34000 - 35000 1.0104

O3 weak 0.328 0.3226 – 0.3333 30000 - 31000 1.0104

particle strong

0.862 0.8475 – 0.8772 11400 - 11800 1.0106

particle weak 1.03 1.0101 – 1.0526 9500 - 9900 1.0106

H2O weak 2.45 2.427 – 2.475 4040 - 4120 2.5104

H2O strong 2.60 2.577 – 2.632 3800 - 3880 2.5104

CO2 strong 2.77 2.740 – 2.794 3580 - 3650 3.0105

CO2 weak 2.94 2.907 – 2.967 3370 - 3440 3.0105

particle strong

3.06 3.030 – 3.091 3235 - 3300 1.0105

particle weak 3.19 3.160 – 3.226 3100 - 3165 1.0105

CH4 strong 3.37 3.333 – 3.401 2940 - 3000 4.0105

CH4 weak 3.51 3.472 – 3.546 2820 - 2880 4.0105

CO2 strong 4.25 4.255 – 4.444 2250 - 2350 4.0105

CO2 weak 4.63 4.630 – 4.740 2110 - 2160 4.0105

NO weak 4.98 4.951 – 5.051 1980 - 2020 3.0105

NO strong 5.32 5.263 – 5.376 1860 - 1900 3.0105

*The effective noise bandwidth is 2 Hz.Band limits are given in different units (cm-1 = 10000/m) but are otherwise identical.

SOF 174 : Measurement Bands

SOF 183 : Radiometric SNR



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System Requirements (cont)

IDENTIFIER SHORT DESCRIPTION

REQUIREMENT(Solar Tracking and Maneuvering)

SOF 181 Altitude Range SOFIE shall be able to track the top edge centerpoint of the sun from an apparent altitude of 315 km down to the hard edge of the Earth during an occultation measurement.

SOF 176 Scanning SOFIE shall provide the capability to vertically scan across the disk of the sun four (4) times after the sunrise occultation measurement and four (4) times prior to the sunset occultation measurement.

SOF 304 Balancing SOFIE shall provide the capability to balance the ΔV signal (i.e. set Δ V to zero) using a gain setting (GA) to within 1000 counts.



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System Design



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Environmental Orbital Considerations

Orbit - 600-650 km geocentric- Polar sun-synchronous- 2 year operational lifetime

Thermal Predictions - Electronics Survival = -25 to +55 ºC- Electronics Operation = 0 to +50 ºC- Instrument Survival = -45 to +20 ºC- Instrument Operation = -40 to +20 ºC

Radiation TID = 10 kRADSEE = 37 MeV

Atomic Oxygen Strongly dependent on altitude (600 km significantly less than 450 km). Using MgF2 protective coating on our steering mirror and primary/secondary Cassegrain telescope mirrors.

Cleanliness Internal mirrors allowed to degrade (EOL, 26 months) to Level 500. This includes effects of micro-meteroids.



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Design Description • Instrument Unit

– Purpose: • Perform science signal detection & FOV pointing and stabilization control

– Contains: • Opto-mechanics

– Mirrors, filters, beam splitters, field-stop, chopper • [1.8’ x 6’ Inst FOV; 32º x 24º Glint FOV]

• Detector assemblies (includes TECs and PreAmps)• Steering mirror [4º x 4º FOR]• Sun sensor electronics and software [2º x 2º FOV]

• Electronics Unit– Purpose:

• Perform system command and control, communication, signal conditioning, and power conditioning

– Contains:• Command and data handling electronics and system software• Position and stabilization control electronics and software• Communication, signal conditioning, and mechanisms control electronics

and software• Thermal sensor, TEC thermal control, and housekeeping electronics• Power conditioning electronics



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System Block Diagram

Sun Sensor Processor

Neutral Density FilterSpectral (700 nm) Filter

Focal Plane Array

Steering Mirror Assembly

Steering Mirror Positioning Sensor

Electronics

Aperture Cover

Pinpuller Mechanism

Secondary Mirror

Cassegrain Telescope

Primary Mirror

Sun Sensor Pickoff Mirrors

Sun Sensor Baffle

Field StopChopper

Beamsplitters

4 LWIR Bands(4.25 - 5.32 um)

4 SWIR Bands(3.03 - 3.55 um)

4 UV,NIR Bands(0.29 - 1.03 um)

Channel Separation Module Assembly

Individual Band Filters

Detector Assembly(TEC, PreAmp)

Instrument Unit

Radiator

C&DH Processor

Servo I/O

Mirror Amplifier

Power Conditioning and Distrubution

Signal Conditioning & TEC Control

Chopper Control

Electronics Unit

Data Acquisition

Spacecraft BusSurvival Heater Power and

Thermal SensorsSensor Power,

Mechanisms Power, and Thermal Sensors

Temp Sensors

Temp Sensors / Housekeeping

1553 Interface

1553 Comm Bus

4 SWIR Bands(2.43 - 2.97 um)

Pinpuller Mechanism

Mechanisms Release

Solar Input

Sun SensorHousing Assembly

Steering Mirror

Isolator Feet (14 ° Eff Wedge)

Spacecraft Deck



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Spacecraft Configuration



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Instrument UnitRadiator

SC Isolator Feet (eff 14° wedge)

Alignment cubes

Pin pullers

Aperture coverSteering mirror

N2 Purge

Circular connector interfaces

Witness Mirrors (x4)

Dynamic Envelope: 16.2 x 26.3 x 29.5 inches



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SOFIE Instrument Unit (cont)

POINTING AND STABILIZATION CONTROL

Sun Sensor

SIGNAL DETECTIONChannel Separation Module



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SOFIE Electronics Unit

Power Conditioning

Top Connectors and Cabling

SC Radiator Panel

Electronics PCBs

Dynamic Envelope: 16.2 x 26.3 x 29.5 inches



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System Operation



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Modes of Operation

Survival



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Modes of Operation (cont)

Mode Measurements Commands Code Updates

Survival Heaters

Comments

Science - Occultation- Housekeeping- System status

1. Real time processed1. Timed not processed

Processed ON Peak data rate and power mode

Standby - Housekeeping- System status

Real and timed processed

Processed ON

Safe - Housekeeping- System status

Real and timed processed

Processed ON SOFIE software can transition into this mode without a ground command but cannot transition out without a ground command

Survival NA NA NA ON System power OFF



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Science Mode

EARTH

SOFIE IFOV (1.8' x 6')

650 Km

X

Z

315 km

158 km

17.77 DEG

21.57 DEG

24.85 DEG

SUN

473 km

SUN POINTING

LAYER HEIGHT RESOLUTION = 25.75 m @ 0 km

= 22.52 m @ 157 km= 18.63 m @ 315 km

Orbital Characteristics 1. 600-650 km altitude 2. Polar sun-synchronous3. SOFIE instrument pointed by SC to within ± 1º (3 sigma) of the solar vector during an occultation



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Science Mode (cont)315 km

EARTH

535046003850310023501600850250

NOCO2CH4ParticleCO2H2OParticleO3

nm

Spectrum of the 16 bands(UV) (NIR) (SWIR) (MWIR)

Sun Sensor FOV (2o x 2o)

SOFIE IFOV (6' x 1.8')

Sun disk (0.53o)

SOFIE Max FOR(4o x 4o)



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Science Mode (cont)States General Operations

INIT Prepare system for occultation measurements•Synchronize electronics and software•Initialize timing and balance commands •Initialize tracking profiles

AQR(15 seconds)

Search and acquire sun on FPA•Find sun within FOR (if not found abort and return system error)•Position sun center at center of FPA•Begin fine tracking (arcsecond resolution) of sun•Position IFOV at desired offset from sun center Can overlap with DATA state

DATA(~ 150 seconds)

•Perform science channel measurements!•Maintain IFOV locked at desired offsets from sun center while following table driven profile (solar tracking) Fixed position Solar scanning (including azimuthal offsets)•Perform balance (set ΔV offsets) function•Save CO2 and balance data for post occultation analysis Can overlap with AQR state

Maximum science measurement duration (AQR, DATA) = 155 seconds



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Science Mode (cont)



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Conceptual Science Mode Operational Profile

………….

+2 Degrees

INIT State

AQR State

Time = 0(Channel Measurements Begin)

DATA State

BalanceTime = T0.5Nominal EL Scans

Time = TA Time = TFIN

Time = TL

Timeline Duration = 155 Seconds

Nominal Sunrise Science Occultation Measurement Profile

Time = TB = 170 kmEL and AZ Searching

………….

+2 Degrees

INIT State

AQR State

Time = 0(Channel Measurements Begin)

DATA State

Time = T0.5

Time = TA

Time = TFIN

Time = TL

Timeline Duration = 155 Seconds

Nominal Sunset Science Occultation Measurement Profile

EL and AZ Searching

Nominal EL ScansBalance

Time = TB = 170 km

= 60 Seconds

= 60 Seconds

= 15 Seconds

= 15 Seconds

FOV M

aneuversFO

V Maneuvers



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Solar Acquisition and Tracking



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FOV

Vertical Scanning

Azimuthal Offsetting(bore sighting)

1 degree (3 sigma)

10 arcminutes

12 arcminutes

1 degree (3 sigma)

Science RangeSC Pointing Accuracy Capability

1 degree (3 sigma)

10 arcminutes

12 arcminutes

1 degree (3 sigma)Scanning

Boresighting

Solar Scanning and Maneuvering



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Science Data Products

1. Occultation(20 Hz)

-Solar edge locations (X,Y)-Solar vertical edge and center images-Steering mirror command and position (X,Y)-All channel sets (Strong, Weak, ΔV)-Time stamps (SC and relative)

2. Diagnostic (Limited)

-Solar images -FPA frame images

12

1

1

El

Az



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Commissioning Phase

WEEK 1

1. APPLY SURVIVAL HEATER POWER 2. APPLY SYSTEM POWER3. EXERCISE BASIC COMM

*APERTURE COVER NOT RELEASED

WEEKS 2-3

1. EXERCISE FULL COMM AND SYSTEM FUNCTIONALITY

*APERTURE COVER NOT RELEASED

WEEKS 4-5

1. RELEASE APERTURE COVER 2. PERFORM INITIAL SCIENCE AND CALIBRATION CHECKOUTS 3. VERIFY POINTING AND STABILIZATION CONTROL

1 MONTH COMMISSIONING

PHASE



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System Technical Resources &

Error Budgets



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Technical Resources

RESOURCE CURRENT BEST ESTIMATE REQ ID

Mass 36.4 kg SOF 194

Envelope Controlled by MICD SOF 195

Average Power 74.1 W [56 W Electronics Unit, 18 W Instrument Unit] SOF 205

Peak Power 107.6 W SOF 206

Pinpuller Peak Power 32.2 W for < 0.5 sec, (130 mW Pre and Post Fire) SC ICD

Survival Heater Average Power 15.2 W SOF 272

Survival Heater Peak Power 62.8 W SOF 272

Daily Data Volume 168 Mbits/day SOF 243

Resource margin and reserve managed by mission



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Mass Budget

Part / Sub-Assembly Producer Mass (kg) Part / Sub-Assembly Producer Mass (kg)Steering Mirror Assembly Vendor 0.76 Structure SDL 4.25 Feedback Sensor Module Vendor 0.35 PCB Vendor 5.20 External Cables and Connectors Vendor 0.15 DC-DC Converters Vendor 0.40

Motherboard Vendor 0.90Fore Optics Assembly Wedge-loks Vendor 0.40 Primary Mirror SDL 0.70 Spider Structure SDL 0.25 Secondary Mirror SDL 0.05 External Cables

48-0167 Signal 1 Vendor 1.00Sun Sensor (Baffle & Optics) Assembly SDL 1.15 48-0168 Signal 2 Vendor 1.10

48-0169 Data Acquisition Vendor 0.50Optics Module Assembly 48-0170 Chopper Vendor 0.15 Far Optics Module Assembly SDL 1.60 48-0171 Sun Sensor Vendor 0.40 Near Optics Module Assembly SDL 1.60 48-0172 Release Vendor 0.15 Mid Optics Module Assembly SDL 0.20 48-0173 Position Vendor 0.30

48-0174 Motors Vendor 0.35Structure Assembly 48-0175 Heaters Vendor 0.25 Titanium Isolators SDL 0.75 Internal Cables Baseplate SDL 2.05 48-0176 Signal 1 Vendor 0.40 Lower Housing SDL 0.95 48-0177 Signal 2 Vendor 0.40 Aft Optics Bench SDL 1.40 48-0194 Data Acquisition Vendor 0.15 Upper Housing SDL 0.65 48-0195 Chopper Vendor 0.05 Fore Optics Bench SDL 1.45 48-0198 Sun Sensor Vendor 0.10 Aperture Housing SDL 1.60 48-XXXX Motors Vendor 0.05 Radiator Panel SDL 1.75 48-0212 Heaters Vendor 0.05 Witness Mirrors SDL 0.10 Survival Heaters Vendor 0.10 MLI Vendor 0.60 Fasteners Vendor 1.20

18.56Mechanisms 11.15 Pinpuller SDL 0.05 6.70 Hinge SDL 0.40 36.41

Vendor SpecificationModel PredictionMeasured

Connectors, Fasteners, Cabling

SOFIE MASS BUDGETInstrument Unit Electronics Unit

SOFIE Insrument Unit MassSOFIE Electronics Unit MassSOFIE Conn, Fast, Cabling MassCBE Total Mass



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Power Budget

Sub-Assembly 12VSM -12VSM 12V -12V 5V 3.3V 2.5V

TE Coolers (3 stage) -65 C (Aver) 7.00TE Coolers (3 stage) -65 C (Peak) 8.00TE Coolers (3 stage) -40 C (Aver) 6.30TE Coolers (3 stage) -40 C (Peak) 6.80

Signal Cond. & Thermal Cont. (Aver) 5.00 3.00 0.03 3.00 5.90Signal Cond. & Thermal Cont. (Peak) 6.00 4.00 0.04 4.00 6.60Data Acquisition (Aver) 1.90 1.30 0.40Data Acquisition (Peak) 2.50 1.80 0.50Chopper Drive (Aver) 0.65 0.50Chopper Drive (Peak) 0.90 0.60Command & Data Handling (Aver) 4.30Command & Data Handling (Peak) 5.50Sun Sensor (Aver) 2.60Sun Sensor (Peak) 5.00Steering Mirror System (Aver) 0.62 0.62 2.28 2.17 1.75Steering Mirror System (Peak) 5.75 5.75 3.15 2.80 2.67

Average Powers 0.62 0.62 9.83 6.97 9.08 10.00 12.20Peak Powers 5.75 5.75 12.55 9.20 11.21 12.00 13.40

Power Conditioning Efficiency 0.70

Average Powers 0.89 0.89 14.04 9.96 12.97 14.29 17.43Peak Powers 8.21 8.21 17.92 13.14 19.59 17.14 19.14

Average Input Protect Circ Power 2.8Peak Input Protect Circ Power 4.2

CBE SC Bus Total Average Power 74.11 56.34CBE SC Bus Total Peak Power 107.57 13.30

MEASURED

SOFIE Orbital Power Budget

1. Average Power includes (Steering Mirror Peak Power)*(5.0 minutes/96 minutes)2. Power conditioning efficiency based on an ~ 36V input

Total Average SC Bus Elec Unit Power

Total Average TEC Power (W/O Converter Loss)



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Orbital Power Profile

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95

Instrument Sub-system 90 71.05 52.1 33.15 14.2 4.75 23.7 42.65 61.6 80.55 80.5 61.55 42.6 23.65 4.7 14.2 33.15 52.1 71.05 90 Orbit average

SOFIEElectronics unit 56.34 56.34 56.34 53 53 53 56.34 56.34 56.35 57 56.34 56.34 56.34 53 53 56.34 56.34 56.34 57 56.34TECs (16) + Sun Sensor electronics 17.27 17.27 17.27 17 17 17 17.27 17.27 17.27 18 17.27 17.27 17.27 17 17 17.27 17.27 17.27 18 17.27Steering mirror 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 8.1 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 8.1 0.5

Sub-total 74.11 74.11 74.11 70.5 70.5 70.5 74.11 74.11 74.12 83.1 74.11 74.11 74.11 70.5 70.5 74.11 74.11 74.11 83.1 74.11 74.11

= Removed from orbit average for 95 min orbits

Latitude (deg)

Time after passing over North pole (minutes)

In eclipse

68

70

72

74

76

78

80

82

84

0 20 40 60 80 100

SOFIE

In eclipse



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Resource Tracking

SOFIE MASS CBE TRACKING

20.0025.0030.0035.0040.0045.00

1/1/20

03

2/1/20

03

3/1/20

03

4/1/20

03

5/1/20

03

6/1/20

03

7/1/20

03

8/1/20

03

9/1/20

03

10/1/

2003

11/1/

2003

12/1/

2003

1/1/20

04

2/1/20

04

3/1/20

04

4/1/20

04

5/1/20

04

6/1/20

04

7/1/20

04

8/1/20

04

9/1/20

04

Date

kg

SOFIE AVERAGE POWER CBE TRACKING

60.0065.0070.0075.0080.0085.00

5/8/

2003

6/8/

2003

7/8/

2003

8/8/

2003

9/8/

2003

10/8

/200

3

11/8

/200

3

12/8

/200

3

1/8/

2004

2/8/

2004

3/8/

2004

4/8/

2004

5/8/

2004

6/8/

2004

7/8/

2004

8/8/

2004

9/8/

2004

Date

Wat

ts

SOFIE DAILY DATA DOWNLINK VOLUME CBE TRACKING

60

80

100

120

140

160

180

12/1

2/20

03

12/2

6/20

03

1/9/

2004

1/23

/200

4

2/6/

2004

2/20

/200

4

3/5/

2004

3/19

/200

4

4/2/

2004

4/16

/200

4

4/30

/200

4

5/14

/200

4

5/28

/200

4

6/11

/200

4

6/25

/200

4

7/9/

2004

7/23

/200

4

8/6/

2004

8/20

/200

4

9/3/

2004

9/17

/200

4

Date

MB

its/d

ay

Resource CDR/PDR Ratio

Mass 36.4 / 34.6 = 1.05

Power 74.1 / 83.5 = 0.89

Data 168 / 73.6 = 2.28



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Error Budgets

BUDGET REQUIREMENT EXPECTED PERFORMANCE

Radiometric WC Band 15 (NOWEAK) SNR = 3.0 x 105

SNR = 9.33 x 105 (Margin = 3.11)

Pointing 15 Arcseconds (1 Sigma)over 0.5 seconds <1 Arcsecond (0.5 Arcseconds)

StaticAlignment 0.5 ° to SC 3 Arcminutes CBE

Will be calibrated out on orbit!



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Post-PDR System Changes



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Changes since PDR

SMA Caging Mechanism Removed

Wedge Removed

Radiator Reshaped

Cable Ports Relocated



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Changes since PDR (cont)

Electronics Power

ConditioningRedesigned

Detector Packages

nowNon-hermetic

Repositioned in SC and Radiator Removed



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System Technical Risks



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Technical Risks

RISK ID = SOFIE_RISK_4 SOFIE depends upon an active pointing system to provide the required sun

pointing accuracy and precision. The active pointing and control system algorithm may be unable to provide the required sun pointing accuracy and precision and the science capability would be degraded.

CRITICALITY Green

MITIGATION Extensive prototype and protoflight testing will be conducted.



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System Technical Coordination



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Technical Coordination – SDL Design Processes

• Engineering Design and Development– System Design

• QP0401 – Software Design

• QP0406• Document Control and Configuration Management

– Document Control• QP0501

– Software Configuration Management• QP0403, SOFIE Software Configuration Management Plan

– SDL to maintain up-down information flow• Waivers, Problem Failure Reports (PFR)

– QP1301



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Technical Coordination – Internal Peer Review

• Review follows Breadboard/Prototype design phase– Includes SDL members both internal and external to SOFIE– System and component level

• Following review, design placed in configuration control



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Technical Coordination – SDL Design Processes (cont)

Standards SOURCEPCB Design - IPC 2221, IPC 2222PCB Fabrication- Class 3 of IPC 6011, IPC 6012, NASA GSFC S312-P-003PCB Coupon Inspection- To be performed by customer

MAP, GDRD

SMT Assembly- NASA-STD-8739.2Hand Soldered Assembly- NASA-STD-8739.3

MAP, GDRD

Cable, Crimp, and Harness- NASA-STD-8739.4 MAP, GDRD

Conformal Coating- SDL Internal Process SDL QW0915

ESD- SDL Internal Process SDL QP1503

Mechanical Torque- SDL Internal Process SDL QW0914

SOFIE GENERAL DESIGN STANDARDS



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Documentation Status

Document Status

SOFIE Level 3 Requirements Mission Approved

SOFIE Specifications Document Released

SOFIE Flight Software Development Plan Released

SOFIE Flight Software Specifications Released

SOFIE Program Management Plan Released

SOFIE Product Assurance Plan Released

SOFIE Safety Plan Released

SOFIE Contamination Control Plan Baseline Released

SOFIE EEE and Materials Parts Lists Controlled. Initial lists submitted to Mission November 2003

SOFIE Risk Management Database Controlled

SOFIE Calibration Plan Baseline Released

SOFIE Integration and Test Plan Baseline Released

SOFIE Software Design Document and Test Plan Baselines Released

SOFIE Electrical/Software ICD Baseline Released

Subcontractor SOWs and ICDs Released



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SE Summary

• Designs are mature and provide margin on system requirements• Technical resources are being managed and tracked• Error budgets are being managed



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Supplementary Material



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Radiometric System RequirementsTable 2. SOFIE spectral band specifications and channel S/N requirements.

Band Center (m)

Band Limits, m Band Limits, cm-1 S/N*

O3 strong 0.290 0.2857 - 0.2941 34000 - 35000 1.0104

O3 weak 0.328 0.3226 – 0.3333 30000 - 31000 1.0104

particle strong

0.862 0.8475 – 0.8772 11400 - 11800 1.0106

particle weak 1.03 1.0101 – 1.0526 9500 - 9900 1.0106

H2O weak 2.45 2.427 – 2.475 4040 - 4120 2.5104

H2O strong 2.60 2.577 – 2.632 3800 - 3880 2.5104

CO2 strong 2.77 2.740 – 2.794 3580 - 3650 3.0105

CO2 weak 2.94 2.907 – 2.967 3370 - 3440 3.0105

particle strong

3.06 3.030 – 3.091 3235 - 3300 1.0105

particle weak 3.19 3.160 – 3.226 3100 - 3165 1.0105

CH4 strong 3.37 3.333 – 3.401 2940 - 3000 4.0105

CH4 weak 3.51 3.472 – 3.546 2820 - 2880 4.0105

CO2 strong 4.25 4.255 – 4.444 2250 - 2350 4.0105

CO2 weak 4.63 4.630 – 4.740 2110 - 2160 4.0105

NO weak 4.98 4.951 – 5.051 1980 - 2020 3.0105

NO strong 5.32 5.263 – 5.376 1860 - 1900 3.0105

*The effective noise bandwidth is 2 Hz.Band limits are given in different units (cm-1 = 10000/m) but are otherwise identical.

SOF 174 : Measurement Bands

SOF 183 : Radiometric SNR



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Radiometric Model Error Budget

Aperture Cover

Secondary Mirror


Primary Mirror

Field Stop

Beamsplitters

4 LWIR Bands(4.25 - 5.32 um)

4 SWIR Bands(3.03 - 3.55 um)





4 SWIR Bands(2.43 - 2.97 um)

Solar Input

Steering Mirror

Entrance Pupil Area

Obscuration Diameter

Telescope Aperture Diameter

NEP and SNR

Telescope Aperture Diameter = 10.2 cmObscuration Diameter = 3.0 cmEntrance Pupil Area = 74.0 cm2

Entrance Pupil FOV = 9.14-7 SR

Chopping Factor (Modulation Form Factor) = 0.4Radiometric Electrical Signal Bandwidth = 2 HzRadiometric Electrical Noise Bandwidth = 3.14 HzDetector Area = 0.01 cm2

Optical Input Path



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Radiometric Model Error Budget (cont)

System Transmittances includes a linear multiplication of appropriate mirror and filter transmittance, reflection, and absorption (due to end of life contamination) coefficients.

Optical Math Model Transfer Function

Band Wavelengths = System Transmittances = Incident Detector Power =

Band 1

Band 16

NEP = SNR = SN Margin =

Y is the table of wavelengths corresponding to the wavenumbers of table B

Y

1 2

12

3

4

5

6

7

8

9

10

11

12

13

14

15

16

0.294 0.2860.333 0.323

0.877 0.847

1.053 1.01

2.475 2.427

2.632 2.577

2.793 2.74

2.967 2.907

3.091 3.03

3.226 3.16

3.401 3.333

3.546 3.472

4.444 4.255

4.739 4.63

5.051 4.95

5.376 5.263

m

1

12

3

4

5

6

7

8

9

10

11

12

13

14

15

16

0.0110.017

0.305

0.409

0.614

0.596

0.617

0.614

0.639

0.594

0.581

0.588

0.63

0.607

0.445

0.47

A

1

12

3

4

5

6

7

8

9

10

11

12

13

14

15

16

3.8879·10 -6

1.0399·10 -5

4.1062·10 -4

5.2872·10 -4

6.5677·10 -5

5.8379·10 -5

4.8409·10 -5

4.3974·10 -5

3.9877·10 -5

3.469·10 -5

3.196·10 -5

2.566·10 -5

3.4048·10 -5

1.718·10 -5

6.9515·10 -6

1.0554·10 -5

W

NEP

1

12

3

4

5

6

7

8

9

10

11

12

13

14

15

16

9.844·10 -14

9.844·10 -14

2.953·10 -13

1.772·10 -13

1.79·10 -11

1.611·10 -11

6.329·10 -12

5.538·10 -12

1.477·10 -11

1.266·10 -11

1.042·10 -11

4.663·10 -12

5.212·10 -12

4.43·10 -12

6.815·10 -12

6.563·10 -12

W SR

1

12

3

4

5

6

7

8

9

10

11

12

13

14

15

16

3.949·10 7

1.056·10 8

1.39·10 9

2.984·10 9

3.669·10 6

3.624·10 6

7.649·10 6

7.941·10 6

2.7·10 6

2.741·10 6

3.066·10 6

5.503·10 6

6.533·10 6

3.878·10 6

1.02·10 6

1.608·10 6

Margin

1

12

3

4

5

6

7

8

9

10

11

12

13

14

15

16

3.949·10 3

1.056·10 4

1.39·10 3

2.984·10 3

146.771

144.958

25.497

26.471

27.005

27.407

7.665

13.757

16.332

9.695

3.4

5.36



GATS

Radiometric Model Error Budget (cont)

Detector Band A

Detector Band B

Detector Channel Pair

Front End

PreAmp BPF (1 kHz)

G

Phase Sensitive Detector(Synchronous Recitification)

SWITCHING DEMODULATION

LPF (12.8 Hz)G =1

Phase Reference

Optical Chopper (1 kHz)

Chopper Drive Control

Chopper Reference Signal Phase Control

G = -1

Balance Attenuation

Chopped (1 kHz) Optical Input

Signal Conditioning

A

Data Acquisition

Front End

PreAmp BPF (1 kHz)

G

Phase Sensitive Detector(Synchronous Recitification)

SWITCHING DEMODULATION

G =1

G = -1

Balance Attenuation

Signal Conditioning

A

Differential Amp

Signal Conditioning

G

LPF (2.15 kHz)

u1x1

14-bit ADCBalance Attenuation Controlled Externally

MUX

Ground Processing(2 Hz Information Bandwidth,

3.14 Hz Effective Noise Bandwidth)

1us Resolution

DemodulatedSignal

DemodulatedSignal

LPF (12.8 Hz)

LPF (12.8 Hz)

Demodulation and Signal Conditioning System Equivalent LPF = 10Hz

20 Hz Sampling Rate32 X Oversampling

Bit Resolution = 366uVLPF Settling to 12 RC Constants

LPF (12.8 Hz) LPF (12.8 Hz)

Electronics Path

Effective Sync Rect Q = 500



GATS

Radiometric Model Error Budget (cont)Band /

Detector TypeSNR

3.14 Hz bwRequired

SNR Margin

1 / PV 5.81E+06 1.00E+04 581.402 / PV 7.19E+06 1.00E+04 719.423 / PV 8.38E+06 1.00E+06 8.384 / PV 8.38E+06 1.00E+06 8.385 / PC 3.59E+06 2.50E+04 143.536 / PC 3.54E+06 2.50E+04 141.587 / PC 6.79E+06 3.00E+05 22.648 / PC 6.94E+06 3.00E+05 23.149 / PC 2.65E+06 1.00E+05 26.4810 / PC 2.68E+06 1.00E+05 26.7711 / PC 2.98E+06 4.00E+05 7.4412 / PC 4.87E+06 4.00E+05 12.1713 / PC 5.39E+06 4.00E+05 13.4714 / PC 3.11E+06 4.00E+05 7.7715 / PC 9.33E+05 3.00E+05 3.1116 / PC 1.48E+06 3.00E+05 4.92



GATS

Pointing Model Error Budget

IDENTIFIER SHORT DESCRIPTION REQUIREMENT(Pointing)

SOF 300 Pointing Ability SOFIE shall point the center of its FOV to ±1 arcminute at a fixed distance relative to the solar top edge centerpoint and maintain this position during occultation measurement. The pointing position will be considered "maintained" if a 10 Hz filtering (0.1 sec running mean) of the true pointing position varies <15 arc seconds (1 sigma) in elevation and <1.0 arcmin (1 sigma) in azimuth.



GATS

Pointing Model Error Budget (cont)

• 2D derived by hand, includes 1 mode in mirror and 1 mode in structure (4 plant states)• Integrates OSC’s latest S/C model (from AIM Bus CDR) and SSG’s latest SMA model



GATS


Error/Disturbance Source Value DescriptionSun Sensor Noise 0.5 arcsec (1-σ) White noise up to 2 Hz SMA DIT Sensor Noise 0.2 arcsec (1-σ) White noise up to 10 kHzSMA DIT Thermal Drift 26.88 arcsec/ºC slopeSMA Bit Resolution 0.7 arcsec 14-bit A/DTiming Error 1 msec (1-σ) White noise up to 50 HzS/C Disturbance varies (see plot) supplied by Orbital

0 5 10 15 20 25 30 35 40 45 50-25

-20

-15

-10

-5

0

5

10

15

20

25

Time (sec)

S/C

Mot

ion

(arc

sec)



GATS


Description Jitter in Sun Elevation Position

(arcsec, 1σ)

Jitter in Sun Azimuth Position

(arcsec, 1σ)

S/C Reaction Torque in Elev. Plane (N-m, 1σ)

Two-D simple model with 4 states 0.499 N/A 0.0001



GATS

Alignment Knowledge Error Budget – SOFIE FOV to ROS

Sun Sensor Processor

Neutral Density FilterSpectral (700 nm) Filter

Focal Plane Array

Steering Mirror Assembly

Steering Mirror Positioning Sensor

Aperture Cover

Pinpuller Mechanism

Secondary Mirror


Primary Mirror

Sun Sensor Pickoff Mirrors

Sun Sensor Baffle

Field StopChopper

Beamsplitters

4 LWIR Bands(4.25 - 5.32 um)

4 SWIR Bands(3.03 - 3.55 um)





Instrument Unit

4 SWIR Bands(2.43 - 2.97 um)

Pinpuller Mechanism

Solar Input

Sun SensorHousing Assembly

Steering Mirror

±25 mils = ±2.5 ArcMin


±10 mils = ±1 ArcMin

Alignment Cube

Fore DeckMid DeckAft Deck


SOF231 The SOFIE optical axis shall be aligned to the spacecraft optical axis with an accuracy of 0.25 prior to launch. This alignment will be maintained to within ±0.5 on orbit.

From MRD SYS837

SOF292 The SOFIE reference axis alignment to the observatory reference axis shall be known to better than +/-10 arcsec. From MRD SYS753

SOFIE Instrument Pointing Knowledge Budget

Initial Mechanical Alignment due to Tolerancing7.5 ArcMin Worst Case

Alignment after Optical Alignment Process22 ArcSec Worst Case

Spacecraft Pointing Knowledge Requirements

Fix Steering Mirror, Telescoping, Mirrors, Filters,

Field Stop, and Chopper

Co-Align Detectors and Sun Sensor with

Pin Spot Source

Finish Instrument Assembly

Optical Alignment Process

Co-Align Detectors/Sun Sensor to Alignment Cube with

Theodolites/Columated Source

7 ArcSec Resolution

15 ArcSec Resolution



GATS

Alignment Knowledge Error Budget – Slow Thermal Dynamic

• Assumptions– Hot case thermal loads considered– Restrained temperatures:

• CSM Assembly – 37 F to 48 F• Radiator Interface – 24.5 F• Aft Optics Deck – 30 F to 37 F• Fore Optics Deck – 25 F to 32 F• Bottom Deck – 32 F to 35 F• Sun Sensor – 39 F to 43 F• Mid Optics – 39 F• M1 and Hub – 34 F• M2 and Mount – 52 F• Isolator interface at S/C – 86 F

– Only conduction heat transfer considered

– Steady-state temperature predicted– Displacements from 70 F– Displacements relative to Field Stop

Simulation of Hot Case Conditions

Node Mirror

Displacement (in) Rotation (Degrees)

X Y Z X Y Z

81101 M2/SS1 -1.5E-3 -2.7E-3 -1.2E-3 -8.1E-5 -2.8E-5 -9.7E-6

106497 Chop -3.8E-4 4.0E-5 1.7E-6 -4.0E-6 -1.2E-6 -1.5E-5

106510 M3 1.7E-5 3.8E-4 -1.4E-4 -2.4E-6 -1.2E-5 7.0E-6

106520 Field Stop 0 0 0 0 0 0

107175 SS2 -3.0E-5 -1.1E-3 -1.1E-3 -8.1E-5 -3.2E-5 8.9E-6

116912 SS4 -2.4E-4 7.5E-4 1.9E-6 -7.8E-5 -3.9E-5 1.8E-5

116922 SS3 -1.1E-3 2.1E-3 1.7E-4 -1.2E-4 -4.3E-5 3.2E-5



GATS

Simulation of Cold Case Conditions

Node Mirror

Displacement (in) Rotation (Degrees)

X Y Z X Y Z

81101 M2/SS1 -1.1E-3 -1.4E-3 -2.5E-4 -1.4E-5 -1.5E-5 1.0E-5

106497 Chop -2.7E-4 2.7E-5 -1.8E-6 7.2E-6 -2.1E-7 -1.3E-5

106510 M3 4.5E-5 2.3E-4 -7.3E-5 -1.6E-5 -8.6E-6 -1.1E-6

106520 Field Stop 0 0 0 0 0 0

107175 SS2 -2.1E-4 -9.3E-4 -2.7E-4 -1.2E-5 -1.8E-5 1.8E-6

116912 SS4 -1.6E-4 5.4E-4 1.6E-5 -1.2E-5 -4.1E-6 -2.5E-6

116922 SS3 -7.9E-4 1.4E-3 2.0E-4 -2.1E-5 -4.3E-5 5.2E-7

• Assumptions– Hot case thermal loads considered– Restrained temperatures:

• CSM Assembly – -27 F• Radiator Interface – -35 F• Aft Optics Deck – -26 F• Fore Optics Deck – -31 F• Bottom Deck – -30 F• Sun Sensor – -27 F• Mid Optics – -25 F• M1 and Hub – -28 F• M2 and Mount – -26 F• Isolator interface at S/C – -4 F

– Only conduction heat transfer considered

– Steady-state temperature predicted– Displacements from 70 F– Displacement relative to Field Stop




GATS

Simulation of SOFIE to SC Deflections

Node in center of Aperture Cover (SOFIE FEM coordinate system)

Hot Case: Tx: 3.03e-4 in Ty: -6.05e-3 in Tz: -8.46e-3 in

Rx: -2.14e-4 degrees Ry: 5.39e-5 degrees

Rz: -4.41e-5 degreesCold Case: Tx: 6.00e-4 in Ty: -1.82e-2 in Tz: -1.99e-2 in

Rx: -6.77e-4 degrees Ry: 6.92e-5 degrees

Rz: -3.87e-5 degrees




GATS

Pointing Budget – SOFIE to SC AccuracySOFIE Science FOV Boresight to Sun Center

(SYS755)

Required 60

SOFIE Science FOV Boresight to ROS Error

CBE 0.4

SOFIE ROS to S/C Deck I/F Plane Launch Shift

CBE 2

SOFIE ROS to S/C Deck I/F Plane Static Error

CBE 1

SOFIE ROS to S/C Deck I/F Plane Slow Dynamic Error

CBE 2

MRC Pointing Accuracy (SYS844)

Required 17

S/C Deck I/F Plane to MRC Error (SYS837)

Required 2

ACS Accuracy (BUS272)

Required 5

Ephemeris Error (SYS844)

Required 36

SOFIE ROS to S/C Deck I/F Plane Error

(SOF231)

Required 30

RSS = 3 Arcminutes (3 Sigma)

RSS



GATS

GFOV Clearance

0.69in.

Glint FOV

Science FOV

9.53in.



GATS

Level 3 & 4 Requirements Compendium



GATS

AIM Science Objectives Traceability to SOFIE

Science Question1. Morphology 2. GW Affects 3. Dynamics 4. H-chemistry 5. Nucleation

Geophysical Parameters Required to Answer Science QuestionSOFIE

ObservationPMC

Morphology,Particle Sizes

PMC Morphology

PMC Morphology

PMC Morphology

PMC Morphology

Cloud Extinction

TemperatureProfile

T,CO2 Profiles,

Circulation

Temperature Profile

Temperature Profile

CO2 Absorption

H2O Profile H2O Profile,Circulation

H2O Profile H2O Profile H2O Absorption

O3 Profile O3 Absorption

CH4 Profile,Circulation

CH4 Profile,Circulation

CH4 Absorption

NO Profile NO Absorption



GATS

Level 3 Requirements Management

• Requirements will be utilized as the main method for defining the functionality, performance, design constraints, and interfaces for the AIM program

• Requirements will be used throughout all phases of the program to guide design, development, integration, and test

• Requirements tracking and compliance assurance will be an integral part of peer, design, integration, and test reviews to insure that the system development is proceeding in accordance with the systems engineering and management process

• After initial completion, the requirements and interfaces will baselined and change tracking will occur:

– Access control will allow those teams and individuals with responsibility for portions of the requirements to propose changes to those requirements.

– The system engineering team will work with the necessary engineers and management personnel to access the impact of requirements changes on the remainder of the system.



GATS

Level 3 Requirements Management (cont)

AIM Requirements Traceability & Specification Tree (from AIM SEMP)

ScienceRqmts Doc

MissionRqmts Doc

Verification& Validation

Plan

SoftwareDevelopment

Plan

GroundSystem Spec

RF ICD

LV ICD

IPISpec

BusSpec

CDESpecICD

Documents DOORSU

L

L

L

L

L

L

L O L

CIPSSpec

L

SOFIESpec

S L

I/FDefinitions A

BusRqmts

O

IPIRqmts

L

GroundSystemRqmts L

CIPSRqmts

L

CDERqmts

L

SOFIERqmts

S

Responsibility:L: LASP H : HUNS: NASA S: SDLO: Orbital U: UAFG: GATS A: All

ScienceRqmts

U

H

Mission/SystemRqmts

L

U

H

U

Level 1

Level 2

Level 3

ScienceRqmts Doc

MissionRqmts Doc

Verification& Validation

Plan

SoftwareDevelopment

Plan

GroundSystem Spec

RF ICD

LV ICD

IPISpec

BusSpec

CDESpecICD

Documents DOORSU

L

L

L

L

L

L

L O L

CIPSSpec

L

SOFIESpec

S L

I/FDefinitions A

BusRqmts

O

IPIRqmts

L

GroundSystemRqmts L

CIPSRqmts

L

CDERqmts

L

SOFIERqmts

S

Responsibility:L: LASP H : HUNS: NASA S: SDLO: Orbital U: UAFG: GATS A: All

ScienceRqmts

U

H

Mission/SystemRqmts

L

U

H

U

Level 1

Level 2

Level 3



GATS

Level 3 Requirements Management (cont)

AIM Requirements Development Approach and Guidelines (from AIM SEMP)

Input Interfaces:•Electrical•Thermal•Commands•Data•Attitude•Optical,•etc.

Output Interfaces:•Electrical•Thermal•Commands•Data•etc.

General Requirement Guidelines:-Define these types of requirements:

-Functional: “What”, “How Many”,“When”, “Where”, etc.

-Performance: “How Well”, “How Often”,“Within How Long”, etc.

-Design Constraints: Environmentalconditions/limits, Contract/missionrestrictions, standards, plans,interaction w/ existing systems, etc.

-Interfaces: Inputs & outputs (at particularrequirement level) to other parts ofthe system or external to system

-Consider allocated requirements: thoseflowed-down from higher-level requirements-Consider derived requirements: thoseinferred from higher level or same levelrequirements-Insure requirements are:

-Understandable-Unambiguous-Comprehensive-Complete-Precise-Verifiable-Consistent-Appropriate to levelFunctional Examples:

•Mandatory (minimum) and required (goal) as necessary•Measurements to be made•Criteria for when to collect measurements•Pointing required for measurements•Operational sequences•Conditions/events to which system must respond•Operator and data processing considerationsPerformance Examples:•Quality of measurements (accuracy, precision, stability)•Quantity and frequency of measurements•Input/Output data size & ratesDesign Constraint Examples:•Mass, power, volume limitations•Environmental conditions (temp, radiation, cleanliness)•Capacity & throughput limitations•Technology limitations•GFE, COTS, etc.

“Black Box” Requirements

IPIRqmts L

BusRqmts O Ground

SystemRqmts L

SOFIERqmts S

Responsibility:L: LASPNS: NASAO: OrbitalG: GATSH : HUS: SDLU: UAFA: All

ScienceRqmts H

U

CDERqmts L

MissionRqmts U

L SystemRqmts U

L

CIPSRqmts

OtherSources

L

Input Interfaces:•Electrical•Thermal•Commands•Data•Attitude•Optical,•etc.

Output Interfaces:•Electrical•Thermal•Commands•Data•etc.

General Requirement Guidelines:-Define these types of requirements:

-Functional: “What”, “How Many”,“When”, “Where”, etc.

-Performance: “How Well”, “How Often”,“Within How Long”, etc.

-Design Constraints: Environmentalconditions/limits, Contract/missionrestrictions, standards, plans,interaction w/ existing systems, etc.

-Interfaces: Inputs & outputs (at particularrequirement level) to other parts ofthe system or external to system

-Consider allocated requirements: thoseflowed-down from higher-level requirements-Consider derived requirements: thoseinferred from higher level or same levelrequirements-Insure requirements are:

-Understandable-Unambiguous-Comprehensive-Complete-Precise-Verifiable-Consistent-Appropriate to levelFunctional Examples:

•Mandatory (minimum) and required (goal) as necessary•Measurements to be made•Criteria for when to collect measurements•Pointing required for measurements•Operational sequences•Conditions/events to which system must respond•Operator and data processing considerationsPerformance Examples:•Quality of measurements (accuracy, precision, stability)•Quantity and frequency of measurements•Input/Output data size & ratesDesign Constraint Examples:•Mass, power, volume limitations•Environmental conditions (temp, radiation, cleanliness)•Capacity & throughput limitations•Technology limitations•GFE, COTS, etc.

“Black Box” Requirements

IPIRqmts L

BusRqmts O Ground

SystemRqmts L

SOFIERqmts S

Responsibility:L: LASPNS: NASAO: OrbitalG: GATSH : HUS: SDLU: UAFA: All

ScienceRqmts H

U

CDERqmts L

MissionRqmts U

L SystemRqmts U

L

CIPSRqmts

OtherSources

L



GATS

Level 3 & 4 Requirements Management (cont)

• SOFIE Level 3 requirements derived from AIM Level 1 & 2 requirements– Level 3 requirements report (DOORS) created in accordance with WBS– Approved by AIM Mission systems engineer and Deputy SE

• Level 3 requirements managed by SOFIE systems engineer – Level 3 requirements assigned to appropriate discipline leads

• Level 4 requirements derived from Level 3 requirements by systems engineer and discipline leads– Subcontractors requirements are also managed as Level 4

• Level 3 and Level 4 requirements derivation includes source traceability and verification process information– Serves as Verification Matrix

• SOFIE Instrument Specifications and SOFIE Flight Software Specifications captured in SDL/04-004 and SDL/04-003, respectively



GATS

Level 3 Verification Matrix



GATS

Level 3 Verification Matrix (cont.)



GATS




GATS

Level 3 Requirements Database

Acrobat Document

chad



GATS

Level 4 Requirements Database

Acrobat Document Acrobat Document

chad