themis fdmo cdr peer review − l&eo and normal operations 1june 1-2, 2004 l&eo and normal...

THEMIS FDMO CDR Peer Review − L&EO and Normal Operations 1 June 1-2, 2004

L&EO and Normal Operations

Manfred Bester


L&EO and Normal Operations

Overview• Launch• Early Orbit Checkout• Maneuver Operations• Instrument Commissioning• Normal Science Operations


L&EO Operations

Launch & Early Orbit Operations• Delta II Launch Sequence with Release of Probes• Probe A Radiating During Separation, Monitored Via TDRSS• Subsequent Round Robin State-of-Health Monitoring• Initial Attitude and Orbit Determination• Uplink of First Set of Command Loads to Each Probe• Change Attitude from Release to Commissioning Attitude• Systematic Instrument Power-up and Check-out• Decision of Probe Placement − Based on Functional Check-out• Orbit Placement Maneuvers• Critical Operations Performed Real-time Contact• Approval to Proceed via Command Authorization Meetings

(CAMs)


Launch Configuration

Third Stage and Probe Carrier Assembly

Delta II 7925-10


Probe Exterior and Interior View

Probe Bus – Exterior View with Magnetometer Booms Stowed

Probe Bus – Interior View


Probe Separation

Separation from PCA• Monitoring of Separation via TDRSS• One Probe Will Be Transmitting (THEMIS A, Top of PCA)• All Probes Will Be Recording Data• Round-robin Status Polling After Separation• Each Probe Will Be Contacted for 5 Minutes Initially


Dispersion Analysis

Post-launch Probe Dispersion Analysis• Use Relative Separation Velocities• Perform Inter-probe Range Analysis (Not Yet Completed)

Relative Separation Velocities

X [m/s] Y [m/s] Radial [m/s] Z [m/s]

PCA + LV 0.0000 0.0160 0.01600 -0.2700

Probe A 0.0084 -0.0349 0.03590 0.2563

Probe B 1.5726 -0.9411 1.83269 0.1549

Probe C 0.9456 1.5864 1.84684 0.1416

Probe D -1.5818 0.9589 1.84975 0.1326

Probe E -0.9545 1.5681 1.83576 0.1460


Mission Profile


Post-launch Scenario

Power Profile• Probes Are Power Positive with Minimum Loads• Need to Perform Attitude Maneuver to Orient Probe +Z Axis

Perpendicular to Probe-sun Line to Allow for Check-out Activities

Thermal Profile• Worst Case Is Top or Bottom Deck to Sun

Communications Coverage• Scenario Based on Launch Trajectory Provided by KSC• Modeled Probe Antenna Pattern• Dynamic Link Margin Calculated for Telemetry Data Rate of

4.096 kbps


Launch Scenario


Probe Antenna Pattern

Calculated Probe Antenna Pattern

Specification:-3 dB Points at 90° ± 45°

Polarization: LHCP

Pattern: Toroidal, Centered in X−Y Plane

Top Deck of Probe Body Affects Gain Pattern:Blockage at −ZRipples at +Z


Launch Scenario

Data Rate: 4.096 kbps


Launch Scenario

Polar Plot of First Two BGS View Periods


L&EO Timeline


Maneuver Planning & Execution

Maneuver Planning• Determine Pre-maneuver State Vector and Attitude with Required Accuracy• Perform Maneuver Analysis with Current and Target State Vectors• Verify Delta V Budget• Perform Contact Schedule and Shadow Analysis• Develop Detailed Thruster Firing Sequence• Validate Probe Configuration and Maneuver Sequence on Probe Simulator

Maneuver Execution• Establish Two-way Communications with Probe• Ramp Down ESA High-voltage Supply, Place SST into Attenuated Mode• Uplink Command Sequence to Perform Reorientation and Orbit Maneuvers• Download and Verify Command Buffer and Verify Firing Attitude• Monitor Maneuver Execution in Real-time• De-configure Probe Systems and Monitor Health and Safety

Maneuver Calibration• Determine Post-maneuver Orbit and Attitude• Calibrate Thrusters and Analyze Overall Maneuver Efficiency and Accuracy• Perform Accurate Bookkeeping of Fuel Usage


Pre-launch Testing & Validation

Pre-launch Testing and Validation of Maneuvers• Develop Representative Command Profile

– Required to Perform End-to-end Tests for All Operational Scenarios for Each Probe

• Post-test Analysis of Captured VirtualSat Telemetry Data– Validate ACS Flight Software for Thruster Control, On-orbit

Attitude Determination and Fault Protection– Validate Ground-based Attitude Determination Software


Probe Operations Functions

Ground Operations Functions

Perform Mission Design to Determine Target Probe Orbit

and Attitude

Perform GMAN Run with Current and Target Orbit

and Attitude

Formulate Specific Maneuver Events,

Attitudes and Durations

Generate Discrete Thruster Profile and Pulse

Firing Sequence

Generate Discrete Stored Command

Sequence Via MPS

Upload TLM Table, Firing Sequence

and Downlink Data Rate

Perform Off-line Validation of Entire Stored Command

Sequence on Hi-fidelity Probe Simulator

Turn On Gyros and Catalyst Bed Heaters (Pre-heat)

Downlink On-board

CMD Buffer

Compare Flight and Ground

Reference Image to

Verify Load

Verify CMD & TLM Link Via BGS, WGS or

TDRSS

Verify Current

Attitude Via Sun Sensor

Data

Verify Gyro Performance,

Catalyst Bed Heater Functionality,

Propellant Tank Pressure, Valve and

Fuel Line Temperatures and States, and Pre-

Maneuver Attitude

Turn Off Catalyst

Bed Heaters

Execute Burn Sequence

Monitor Key Temperatures, Tank Pressure,

Attitude and State Vector

On-board Failure Detection &

Correction (FDC) Logic (Gyro Rates,

Sun Sensor Attitude Limits, etc.) Aborts

Sequence if Anomaly Detected

Turn Off

Gyros

Verify Tank Pressure, General Probe Health and

Safety, and Perform Two-way

Ranging

Turn Off Transmitter

Determine New Orbit

and Attitude,

and Calibrate Maneuver

Typical Maneuver Sequence

Perform Long-term Calibration of Pulse

Timing and Thruster Efficiency


Maneuver Types

Maneuver Type

Thrusters Involved

Purpose, Requirements and Fuel EfficiencyOrbit Position for Maneuver

GMAN Compatibility

Orbit Maneuver

A1 and A2 Continuous

Firing

Perigee or Apogee ChangePreceded and Followed by Attitude Maneuver

High Fuel EfficiencyArc Limited Near Perigee to Minimize Cosine Loss

Apogee or Perigee

Yes

Orbit Maneuver


Firing

Inclination Change with or without Arg Per Change

Preceded and Followed by Attitude ManeuverHigh Fuel Efficiency

Apogee Yes

Orbit Maneuver


Firing

Combined In-plane and Out-of-plane Orbit Change

Preceded and Followed by Attitude ManeuverHigh Fuel Efficiency

Arc Limited Near Perigee to Minimize Cosine Loss

Apogee or Perigee

Yes

Orbit Maneuver


Firing Alternating with T1 and T2 Pulsed Firing

In-plane and Out-of-plane Orbit Tweak in Mission Attitude

Large Beta Angle LossSunlight on Sun Sensor Required

Arc Limited Near Perigee to Minimize Cosine Loss

Apogee or Perigee

Yes

Attitude Maneuver

A1 and / or A2 Pulsed Firing

Attitude Change to or from Mission or Maneuver Attitude

High Efficiency Prior to Spin-plane Boom DeployLow Efficiency after Spin-plane Boom Deploy

Sunlight on Sun Sensor Required

Any Yes

Spin Up or Spin Down

T1 or T2 Pulsed Firing

Spin Rate AdjustmentSunlight on Sun Sensor Required

Any Yes


Maneuver Sequence

Earth

Precession Maneuver to

Normal Attitude

Upload: Thruster Enable

Precession Maneuver to Axial Thrust AttitudeAttitude Monitoring

(MSSS / IRU)

Ground-Based Attitude

Determination(MSSS / FGM)

Upload: Thruster Commands




Mission Orbit Placement

Mission Orbit Placement for P1• Accelerated Maneuver Sequence Modeled with GMAN

– Apogee and Perigee Raises– Inclination Adjustment

• Goals of Study– Determine Communications Coverage


Communications Coverage


Maneuver Details

Spin-up and Spin-down Maneuvers • Spin Rate Limits: 2 - 25 rpm

Timing of Pulse Maneuvers• Ensure Pulse Frequencies Do Not Coincide with Probes’

Fundamental Frequencies (Nutation, Spin-plane Booms, Axial Booms, Propellant Slosh)

Flight Rules Related to Maneuver Operations• RCS Configuration• Maintain Spin Rate Within Allowable Limits• Select Pulse Timing to Avoid Exciting of Resonances


Real-time Maneuver Support

Real-time Maneuver Support• Communications Requirements

– Ground Station Contact– TDRSS Contact

• Real-time Monitoring– Tank Pressure– Thruster Temperatures– Probe Attitude Vector– Doppler Profile

• Compare Observed Against Predicted Performance– Real-time Trend Plots for Observed Minus Calculated Attitude

and Doppler Residuals– Plotting Doppler Residuals Requires Real-time Data from

Ground Stations– Plotting Attitude Angle Residuals Requires Data from Probe

Telemetry Via ITOS


Attitude Control Plan

Attitude Control Plan• Probe Release from Launch Vehicle, Nominally at 15 rpm• Optional De-spin to 15 rpm, in Case of Off-nominal Release• Attitude Maneuver to Place Spin Axis Perpendicular to

Probe-to-sun Line at 15 rpm• Deploy of Magnetometer Booms at 15 rpm• Spin-up to 20 rpm• Attitude and Orbit Maneuvers at 20 rpm• Attitude Maneuver to Point Spin Axis Towards Ecliptic South

pole at 20 rpm• Spin-up to 25 rpm Prior to Spin-plane Boom Deploy• Spin-plane Boom Deploy at Variable Spin Rate 5 - 25 rpm• Spin-up to 20 rpm After Last Spin-plane Boom Deploy Step• Axial Boom Deploy at 20 rpm


Instruments

Instruments


IDPU Power Modes

IDPU Power ModesMode IDPU & Instrument Status Power Consumption

Shut Down Mode IDPU OffAll Instruments Off

0.0 W

Safe Mode IDPU OnAll Instruments Off

7.8 W

Low Power Mode IDPU OnFGM OnAll Other Instruments Off

8.0 W

Engineering Mode IDPU OnInstrument States Vary Depending on Activity

N/A

Science Mode IDPU OnAll Instruments On

11.8 W

IDPU Power Modes• Launch Configuration: Shut Down Mode• FGM Operation: Requires at Least Low Power Mode


Instrument Commissioning

Instrument Commissioning1. IDPU Turn-on As Soon As Probe Power System Is Stable and Temperature

Within Operating Limits, Verification of Nominal Voltages and Currents, Command Communications and DCB Functionality

2. FGM Turn-on, Power Verification and Uplink of Parameter Load for 32 Hz Bx, By and Bz, Verification of Sensitivity Control on Each Axis, Select Sensitivity

3. EFI Turn-on, Power Verification and Configuration for 32 Hz E & B Sample Rates

4. SCM Turn-on, Power Verification and Activation of Calibration Sequence5. Magnetometer Boom De-spin to <15 rpm and Deployment With FGM at 32 Hz

Real-time Science TLM; Cross-calibration of Magnetometers While Probe Separations Are Still Small

6. SST Turn-on After Initial Outgassing Phase, Power Verification, High-voltage Ramp-up and Attenuator Functional Test

7. ESA Turn-on After Initial Outgassing Phase, Power Verification, Cover Release and High-voltage Ramp-up

8. EFI Spin Plane Boom Deployment − Procedure Controlled by IDPU9. EFI Axial Boom Deployment − Procedure Controlled by IDPU


EFI Deployment Details

EFI Deployment Overview• Initial On-orbit Check-out

– EFI SOH Determined Using Stowed DC and AC Functional Test Capability

• Booms Deployed After Completion of Initial Orbit Placement– Attitude Maneuvers with Deployed Booms Too Expensive

• Deployment Sequence– Spin-plane Boom Deployment

– 5 to 6 Intermediate Deploy Lengths with Interleaved Spin-up

– Axial Boom Deployment– 1 Step to Deploy Both Axial Booms

• Primary Constraints for Deploy and Commissioning– Transmit Time Limited to 30 min– Required Transmitter Cool-down Period of 3.5 h– Desire to Gather Science Data at Intermediate Deploy Lengths

and in Different Plasma Regimes


EFI Deployment Sequence

EFI Deployment Sequence Per Probe• Deploy SPB-X

– Deploy Boom Section– Wait for Transmitter to Cool Down– Run Slow Sweep and Take Diagnostic Mode Data

• Deploy SPB-Y– Deploy Boom Section– Wait for Transmitter to Cool Down– Run Slow Sweep and Take Diagnostic Mode Data

• Spin Up to 20 rpm– Prepare for Next Deploy Cycle

Slow Sweep• Large Parameter Space to Be Explored

– 4 Braid, 3 Usher, 3 Guard and 32 Bias Settings– 1152 Steps, 1 Step / Spin– Sweep Duration Approximately 1 hour


EFI Deployment Order

EFI Deployment Order• P3 and P4 Deploy First

– 2-day, 2-orbit Cycle:– P3 Deploying and P4 Pausing– P4 Deploying and P3 Pausing

– Full deploy and commissioning takes 14 days• P1 and P2 Deploy Next

– P2 on 2-day (1-orbit) Cycle– Deploy on Outbound, Quiescent on Inbound; 14 Days Total

– P1 on 4-day (1-orbit) Cycle– Deploy on Outbound, Quiescent on Inbound; 28 Days Total

– P1 Deploy Cycle May Be Accelerated– Depends on Experience Gained and Data Gathered During P3 and P4

Deploy and Commissioning

• P5 Deploys Last– 1 or 2-day cycle

– Full Deploy and Commissioning Takes 7-14 Days


EFI Normal Science Operations• EFI Instrument Mode

– Slow Survey, Fast Survey, Particle Burst, Wave Burst and Diagnostic Mode

– Set by ~30 Registers on BEB– Configurable Data Rates Via DFB Mode Commands– Typical Mode Specified with ~200 Commands– Valid Over a Typical One-month Period, Once Deploy and

Commissioning Completed• Slow Sweeps and Diagnostic Data

– Taken Several Times per Year– Upon First Entry into New Plasma Regime– After Long Shadows

– Maintain Optimal Bias Settings– Monitor EFI State-of-health

EFI Science Operations


Flight Rules

Flight Rules• Preliminary Collection for All Subsystems

– Power System– Telecommunications Subsystem– Reaction Control System– Attitude Control System– Flight Software– Command & Data Handling– Instruments

• Detailed List Developed During I&T


Power System Flight Rules

Power System Flight Rules

Activity Flight Rule Potential Impact of Violation

Subsystem power-on Subsystems must be powered on only when their temperatures are within the specified limits.

Damage to flight hardware.

Load shedding Bus voltage must be kept within specified operating limits.

Load shedding will occur autonomously on-board when under-voltage condition is detected.

Battery state-of-charge too low.


Telecom Flight Rules

Telecom Flight Rules


Transmitter operation Transmitter on-time limited to 30 min.

For nominal science operations planning and analyses, transmitter on-time is limited to 30 min per day.

Overheating of transmitter.

Transmitter operation Minimum transmitter off-time of 3 hours between transmitter on-times.

Current thermal analyses show that transmitter needs to be off for 3 hours to cool down completely.

Overheating of transmitter.

Transmitter operation Minimum period of transmitter off-time prior to entry and after exit of long shadows.

Exact times are driven by operational activities and overall power management.


Transmitter operation Transmitter on-time during shadows limited to less than 30 min.

Allowed transmitter-on times for a given shadow period are driven by overall power management.



RCS Flight Rules

RCS Flight Rules


Thruster operation Catalyst bed heaters must be turned on 60 min before thrusting to heat up, and turned off before thrusting.

Damage to catalyst beds.

Thruster firing Thrusters must not be fired unless ESA HV is ramped down and SST attenuators are closed.

Damage to ESA and/or SST.

Thruster firing Maneuvers must not be performed in shadow. Erroneous maneuver execution.

Tangential thruster firing Tangential thruster T1 (spin-up thruster) must not be fired until SCM boom is deployed.

Damage to SCM sensor by thruster plume.

Pyro valve operation Pyro valve used to repressurize fuel tanks must not be opened until pressure in fuel tanks has dropped to 580 kPa.

Bursting of fuel tanks. Destruction of probe.

Latch valve operation Latch valves must be configured to allow for equal depletion of fuel tanks in case mass properties are off-nominal.

This situation may occur if the spin-plane booms do not deploy symmetrically.

Gas migration into fuel lines due to unequal depletion of fuel tanks.

Load shedding Both RCS heater services must not be turned off simultaneously.

Freezing of fuel and bursting of fuel lines.

Thruster monitoring Limits for allowable thruster sum current must be set prior to thruster operation.

Erroneous limit violations.


RCS Flight Rules - Cont.

RCS Flight Rules - Continued


FDC management Maximum angular rates measured by IRUs must be set according to planned attitude maneuver.

Premature or late maneuver abortion.

FDC management Maximum thruster on-time must be configured for expected duration of thruster operation.

Premature maneuver termination.

Pulsed thruster firing Pulsed operation of thrusters must not be performed at pulse rates at or near natural frequencies of nutation, spin-plane booms, axial booms and propellant slosh.

Loss of dynamic stability.


ACS Flight Rules

ACS Flight Rules


Spin rate control Spin rate must be maintained within 2 - 25 rpm. Loss of dynamic stability. Damage to booms.


FSW / C&DH Flight Rules

FSW / C&DH Flight Rules


RTS operation FDC algorithms and ATS loads must be set up such that not more than two RTSs operate at the same time.

Erroneous command execution.

FDC management Turn off Data Monitors when components are turned off.


FDC management Disable Data Monitors that use delta time before setting the clock.


FDC management Reset time before enabling Data Monitors that use delta time.


Clock adjustment Clock adjustments must not be performed during critical operations such as maneuvers.

Erroneous maneuver execution.


Instrument Flight Rules

Instrument Flight Rules


IDPU power power-on IDPU temperature must be within allowed operational limits prior to powering up.

Damage to IDPU electronics.

ESA HV power-on ESA HV must not be turned on until initial outgassing is completed.

Damage to ESA.

ESA HV ramp-down ESA HV must be ramped down prior to thruster operations.

Contamination of ESA.

SST HV power-on SST HV must not be turned on until initial outgassing completed.

Damage to SST.

SST attenuator operation

SST attenuators must be closed prior to thruster operations.

Damage to SST.

Boom deployment Booms must be deployed only when their temperature is within allowed range.

Probe attitude may have to be adjusted to bring temperature into allowed range.

Unsuccessful boom deploy. Damage to boom deployment mechanism.

Magnetometer boom deployment

Magnetometer booms must be deployed at spin rates from 2 to 15 rpm.

Damage to magnetometer booms.

EFI radial boom deployment

EFI radial booms must be deployed at spin rates from 2 to 25 rpm.

Unsuccessful boom deploy. Damage to boom deployment mechanism.

EFI axial boom deployment

EFI axial booms must not be deployed unless spin-plane booms are deployed to their nominal distance.

Loss of dynamic stability.


Instrument Flight Rules - Cont.

Instrument Flight Rules - Continued


EFI axial boom deployment

EFI axial booms must be deployed at spin rates from 2 to 25 rpm.

Damage to axial booms.


Normal Science Operations

Mission Planning• Pass Schedule and Command Load Generation

Probe Command and Control• Probe Health and Safety Monitoring• Recovery of Science and Engineering Data• Command Load Uplink Twice Per Week• Probe Clock Adjustments• Instrument Configuration and Data Trending

Orbit and Attitude Determination• Routinely Performed Multiple Times per Week

Maneuver Planning and Execution• Orbits of P1 and P2 Adjusted Few Times Per Year to Optimize

Conjunctions and Annually to Avoid Shadows• Orbit of P5 Adjusted for First Year Dayside and Second Year

Tail and Dayside Seasons


Weekly Operations Schedule

Week Operations Schedule for the ConstellationMon Tue Wed Thu Fri Sat Sun5 Pass

Supports

FOT On Console

5 Pass Supports

FOT On Console

5 Pass Supports

FOT On Console

5 Pass Supports

FOT On Console

5 Pass Supports

FOT On Console

5 Pass Supports

Lights-out Operation

5 Pass Supports

Lights-out Operation

Generation and Uplink of

ATS Loads

Pass Scheduling

Uplink of Table Loads

(If Required)

Pass Scheduling

Generation and Uplink of

ATS Loads

Telemetry Recovery

Telemetry Recovery

Telemetry Recovery

Telemetry Recovery

Telemetry Recovery

Telemetry Recovery

Telemetry Recovery

Data Trending and Limit Checking







Tracking Data Pre-

processing

Attitude Validation

Maneuver Calibration

Tracking Data Pre-

processing

Attitude Validation

Orbit Determination

Attitude Determination

Maneuver Planning

Orbit Determination

Attitude Determination

Ephemeris and Product Generation







Delivery of IIRVs and

PSATs


PSATs


PSATs


PSATs


PSATs


PSATs


PSATs


Probe Safing Operations

Probe Safing Operations• Power System

– Automatic Load Shedding• Attitude Control System

– Spinning Platform• Reaction Control System Shutdown

– Various Fault Detection Mechanisms– Time-out for Thrusting– Rate Monitoring Via IRUs

• Instrument Safing– HV Ramped Down and Attenuators Moved into FOV for Thruster

Operations

themis fdmo cdr peer review − l&eo and normal operations 1june 1-2, 2004 l&eo and normal...

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