themis mission operations peer review mission operations − 1 ucb, november 4, 2003 themis mission...

THEMIS Mission Operations Peer Review Mission Operations − 1UCB, November 4, 2003

THEMIS Mission Operations

Manfred BesterTHEMIS Mission Operations Manager


Mission Operations

Overview− Mission Operations Concept− Ground System Requirements− Lessons Learned− Ground System Design− Mission Operations Center− Software Tools− Berkeley Ground Station− Mission Operations− Staffing− Telemetry Recovery− NTIA License− IT Security


Mission Operations Concept

Space Segment− 5 Spinning Probes in High Earth Orbits− Simultaneous Release from LV− Initial Orbits Close to Nominal Mission Orbits of Probes 3 and 4− Probes 1, 2 and 5 Move to Nominal Mission Orbits Prior to First Tail Season− Store and Forward Strategy for Science Data Recovery− All Probes Share Same Frequency − Contact One Probe at a Time

Ground Stations− Berkeley Ground Station as Prime Facility− Wallops GN or Universal Space Network as Secondary− TDRSS SSA for Ascent, Maneuver and Contingency Support

Operations Centers− Mission and Science Operations Centers Co-located at U.C. Berkeley


Ground System Requirements

Requirements for the THEMIS Ground System− Support of Simultaneous Mission and Science Operations for 5 Probes− Complete Flight Dynamics Support Including Maneuver Planning− Automated Pass Scheduling Functions− Secure Network Links to Local and Remote Ground Stations− Completely Isolated Network Link for TDRSS Support− Real-time Command and Control Functions− Generation of Command Loads− Databases for Probe Configuration & Status and Telemetry History− Web Based Tools for Probe Status Displays and Trend Plots− Detection of Limit Violations and Anomalies− Emergency Notification via Pagers and Email


Lessons Learned

Lessons Learned from Previous Berkeley Missions− EUVE, FAST, RHESSI, CHIPS

Lessons Learned from Existing Constellation Missions− Globalstar− Iridium− Cluster− Consult with Operations Personnel− Find Out How Other Constellation Missions Operate− Consult with Scientists Working with Cluster Data

Take Advantage of Ideas and Concepts and Lessons Learned− THEMIS Ground System Design− THEMIS Mission and Science Operations


Constellation Operations

Questions for Globalstar / Iridium / Cluster Operations Personnel− How are operations of a satellite constellation organized?− How many engineers and other support staff are required and what are their team roles?− Which software tools are used operationally?− What types of databases are used and what are their benefits and shortfalls?− How are individual spacecraft monitored and commanded?− How are operational status and configuration of each spacecraft maintained?− How are ground images of the flight software organized?− How is the overall constellation organized and maintained?− How are orbit maneuvers planned and executed?− Are spacecraft grouped operationally, e.g. by functions or by orbit plane or otherwise?− How are data flows organized?− How are individual spacecraft distinguished for telemetry and commanding?− Which spacecraft designators are used and how are they used?− What types of communications are used between control centers and ground stations?− Which operations functions are automated and to what extent?− How are anomalies reported and tracked?− How are contingencies handled?− What is planned for end-of-life operations?− What pitfalls or sources of confusion were encountered and how should they be avoided?− What lessons were learned and what should be done differently?


Globalstar Lessons Learned

Globalstar Lessons Learned− Test Each Spacecraft Carefully Before Launch

− Assembly Line Approach Led to Multiple Wrongly Wired Magnetometers− Test Flight Software Patches Carefully Prior to Uplink

− Assembly Line Approach Caused Multiple Spacecraft to Lose Attitude Control Before Automated Uplink Process Could Be Stopped

− Employ Modern Automation Techniques− Save Operations Costs and Enhance Reliability

− Provide Diagnostic Tools− Flexible Tools Allow Engineers and Scientists to Compare Trends Between Different

Spacecraft− Some Great Engineering Ideas Turned Out to NOT Be Useful

− Plan for Contingencies on Routine Basis in Daily Pass Schedules− Plot Trends for Multiple Spacecraft on Top of Each Other− Allow Operators to Set Their Own Limits− Sophisticated Database to Track Anomalies Across Satellites


Operations Org Chart

All Aspects of THEMIS Operations Are Performed at UCB / SSL NASA / GSFC GNCD Provides Support in Form of Consulting


Ground System Block Diagram


MOC Expansion

Expanded 900 ft2 MOC Facility at SSL


Mission Operations Center

BGS Antenna, Equipment Racks and FOT Workstations at the Mission Operations Center


Overview of Software Tools

Tool Developer Function Platform Comments

GTDS GSFC Ephemeris Generation, Orbit Determination

Solaris In Operation at MOC Already

GMAN GSFC Maneuver Planning Solaris, Linux In Operation at MOC Already

MSASS GSFC Attitude Determination Windows In Operation at MOC Already

SatTrack BTS Orbit Analysis, Pass Scheduling, Networking, Visualization

Solaris, Linux In Operation at MOC Already

ITOS Hammers Probe Command and Control Solaris, Linux In Operation at MOC Already

MPS GSFC Command Load Generation Solaris In Operation at MOC Already

BEARS UCB Emergency Response System Solaris, Linux Under Development at SSL

APGEN JPL Task and Event Scheduling Solaris In Operation at MOC Already

GMSEC GSFC Data Mining & Paging Solaris Option to Be Investigated

TAPS GSFC Trend Analysis Solaris (?) Option To Be Investigated

TeamTrack TeamShare Anomaly Tracking Windows Option To Be Investigated


Operational Databases

Probe Configuration and Status Database− Relational Database− Complete State-of-health History in Raw Telemetry Units for Each Probe− Complete Probe Configuration History (Tables, ATS Loads, FSW Versions)− Support of Trend and Command History Analysis

Pass Scheduling Database− SatTrack Provides Automated Pass Scheduling Functions− Ingests Confirmed Schedules of Remote Facilities (NASA/GN, USN, Others)

Interfaces Between Databases− Scheduling System Needs to Know Various Probe Status Parameters


Probe Identification

Type of Probe IDAssigned

ByPurpose

Assignment Type

Location Where Stored at MOC

Location Where Stored on Probe

CCSDS V1 Command SCID

(e.g. 0x151)

WDC-A-R&S

Command Verification

Permanent With Probe Bus

Probe Specific ITOS & MPS Configuration

Probe Uplink Card(Jumpers)

CCSDS V1 Telemetry SCID

(e.g. 0x151)

WDC-A-R&S

TelemetryVerification


Probe Specific ITOS Configuration &

Ground Station FEPs

Probe BAU EPROM

Satellite Catalog Number(e.g. 29501, Assigned

after launch)NORAD

Identification of Orbital Elements


Flight Dynamics Object Database N/A

International Designator(e.g. 2006-001A,

Assigned after launch)

COSPAR/ WWAS & NORAD

International Reference


Flight Dynamics Object Database N/A

Probe Bus Name(e.g. THEMIS 1 and

Red Probe)UCB Constellation

ManagementPermanent With

Probe BusGround System

Database N/A

Constellation Designator(e.g. P1) UCB Constellation

Management

Dependent on Probe

Assignment in Constellation

Ground System Database N/A


Probe Identification Matrix

Probe Bus Name CCSDS V1 Command SCID

CCSDS V1 Telemetry SCID

Satellite Catalog Number

International Designator

Constellation Designator

THEMIS 1Red Probe 0x151 0x151 29501 2006-001A P1

THEMIS 2Yellow Probe 0x152 0x152 29502 2006-001B P2

THEMIS 3Green Probe 0x153 0x153 29503 2006-001C P3

THEMIS 4Blue Probe 0x154 0x154 29504 2006-001D P4

THEMIS 5Purple Probe 0x155 0x155 29505 2006-001E P5

THEMIS SIMWhite Probe 0x156 0x156 N/A N/A Simulator

Note: Only the Constellation Designator in the last column will change as a result of a probe replacement.


Usage of Probe Identifiers

Telemetry File Naming ConventionsFormat:− FACILITY.PROBE_BUS_NAME.TLM_VCN.YYYY_DDD_HHMMSS.datExamples:− BGS.THEMIS_1.TLM_VC0.2007_028_060312.dat− BGS.THEMIS_1.TLM_VC1.2007_028_060312.dat− BGS.THEMIS_1.TLM_VC2.2007_028_060312.dat− BGS.THEMIS_1.TLM_VC3.2007_028_060312.dat


ITOS Requirements

General ITOS Requirements− Same as with FAST and RHESSI (See ITOS Standard Documentation)

Performance Improvements− Configuration Monitors Built Into ITOS

Implementation of New Features− Collected Suggestions from Flight Controllers and Other Missions− New Desirable Features for Constellation Operations

− Batch Mode for Telemetry Processing (May Be Possible Already Via Scripting)− Telemetry Server for Distribution of Data Streams to Multiple ITOS Clients− Joined Status Displays for Multiple Probes

− New Features Hammers Is Planning to Incorporate− Arrays of Mnemonics (1-D or 2-D)− Event Displays


ITOS Configuration

Dedicated Workstations− Basic Configuration Is One Dedicated ITOS System per Probe− Additional Flexibility Built Into System for Dynamic Allocation of Workstations − TLM/CMD Connections Initiated from ITOS to Ground Station Supporting Probe− Multiple Backup Systems

Future Options for System Automation− Envision Upgrade Path Towards More Complex Future Missions− ITOS Connects to SatTrack Gateway Server (SGS)− ITOS Specifies Mission (e.g. THEMIS) and Leaves Individual Object and Facility

Unspecified− SGS Assigns Individual ITOS System to a Particular Pass Support− Routing of Telemetry and Command Connections Via FrameLink or Netcat− ITOS in Turn Loads TLM/CMD Databases and Procs and Supports Pass


ITOS Page Layout

Rules for ITOS Telemetry and Status Page Layout− Uniform Page Header

− Probe Identifier with Unique Color Coding− UNIX System Time− Probe System Time

− Uniform Page Layout (Sub-headers, Data Columns, Grouping of Parameters)− Usage of SI Units Only (V, A, s, m, kg, G, N, …)− Assigned Button Colors for Particular Functions− Usage of Templates− Incorporate Feedback from Flight Controllers


Sample ITOS Page

Standard Features:− Color Coding for Probe

Identification− UTC and Spacecraft Clocks− Telemetry Update Status− Unified Color Scheme− Color Coding for Green,

Yellow and Red Limits− Button Control to Start

Additional Pages− Button Control to Start

Configuration Monitors


TLM & CMD Naming Conventions

Rules for Telemetry & Command Naming in ITOS Database− Identify Subsystems in Telemetry Mnemonics and Commands− Use CLEAR Commands Only to Clear Counters or Status Flags− Use RESET Commands Only to Power Cycle or Reboot Subsystems


Mission Control Network

Network Architecture

All Ground Stations Connect to Different Ports on IP Router to Establish TLM and CMD Socket Connections

Router Patches Socket Connections Through to ITOS Systems, Process Controlled by Automated Scheduling System


Pass Scheduling

Advanced Pass Scheduling Functions− SatTrack Generates View and Link Access Periods for All Satellite / Ground

Station Combinations− Population of Scheduling Database with View and Link Access Periods− Scheduling Engine Calculates Support Priorities by Maximizing a Figure of Merit− Interfaces to Remote Scheduling Offices Allow for Automated Schedule

Exchange− Submission of Proposed Straw Man Schedule− Reception of Confirmed Pass Supports− Iterative Procedure to Satisfy As Many Constraints As Possible− Freeze Committed Passes− Extraction of Confirmed Multi-mission Schedule from Database− Generation and Distribution of Schedule Files (SMEX Schedule, SGS Timeline

File)− Real-time Scheduling of Passes via SGS Client Connections


SatTrack Scheduling Engine

SatTrack Scheduling Engine Calculates Support Priorities− Conflict Resolution Will Be Based on Calculated Priorities− Operators Have Override Privileges for Emergencies

Calculated Priorities Based on Various Constraints− Geometric View and Dynamic Link Access Periods− Interference Avoidance When Using Multiple Ground Stations Simultaneously− Probe Status (Memory Fill, Anomalous Conditions, Emergencies)− Time Since Last Contact for Each Spacecraft or Probe− Minimum Number of Contacts Per Day and Per Orbit− Maximum Time Between Contacts for Each Spacecraft or Probe− Maximum Transmit Time Per Pass, Per Day and Per Orbit− Data Replay Requests− Assignment of Fixed Priorities in Special Cases− Ground Station Availability (Other Spacecraft Supports, Downtime, Staffing)


Pass Scheduling System

Multi-mission Pass Scheduling System


Remote Probe Status Monitoring

SatTrack Interface to ITOS Data Point Server (DPS)− SatTrack DPS Client Program Connects to SatTrack Gateway Server− One Instance of DPS Client Can Handle Multiple Probes Simultaneously− Receives Pass Schedule Information in Real-time− Connects/Disconnects to/from ITOS Supporting a Pass for a Given Probe− Connects/Disconnects Can Be Interleaved for Multiple ITOS Systems− Polls Values for List of Mnemonics and Saves Values in Local Database− Periodically Updates Probe Specific Web Pages− Generates Constellation Overview Page with Hyperlinks to Pages for

Individual Probes− Probe Status (Overall Green/Yellow/Red Condition, Battery Charge, SSR Fill,

Tank Pressure, Various Temperatures, Attitude, Spin Rate, Instrument Status)− Last and Next Contact (Via Facility X, Schedule Obtained from SGS)

− Performs Yellow and Red Limit Checking with FOT Notification


Probe Clock Adjustment

Proposed Probe Clock Adjustment− ITOS Compares Frame Transmit and Receive Times and Adjusts Clock Delta in

Real-time During Pass Supports: ΔT = Tframe received − Tframe transmitted − Trange delay

− ATS Loads Include Commands to Periodically Adjust Clock Drift in Small Steps− Requires Time Stamping of Telemetry Transfer Frames on Probes and by All

Ground Stations (Ideally with Accuracy of 1 ms)− Requires Range Information from SatTrack Gateway Server for Specified Time

(e.g. Frame Receive Time at Ground Station) When Requested by ITOS− Requires Certain Flight Software Features

− Capability to Set Coarse UTC Offset to Mission Elapsed Time− Capability to Set Fine UTC Offset (Small Delta to Coarse Offset)− Capability to Add Small Delta Offsets from ATS Load to Eliminate Clock Drift

− Scheme with Both Ground Controlled and ATS Controlled Options Allows for Maintaining Probe Clocks Well Within Required Absolute Accuracy of ± 500 ms


Ground Controlled Clock Adjustment


Attitude Determination

Real-time, Ground-based and On-orbit Attitude Determination− Slew Monitoring During Maneuvers for Fault Protection− Data Provided by Sun Sensor and Inertial Reference Units− Sensor Data Processed in Real-time− Cross-calibration of Sun Sensor with FGM Near Perigee

Post-pass, Ground-based Attitude Determination− Required for Science Data Analysis− Data Provided by Sun Sensor and FGM− Determine Attitude Accurately for Selected Orbit Arcs and/or Back Orbits− Attitude Solution Obtained with MSASS


Attitude Determination

Pre-flight Testing and Validation− Representative Command Profile Required to Perform End-to-end Tests for All

Operational Scenarios for Each Probe− Post-test Analysis of VirtualSat Archive Files and Captured Telemetry Used to

Validate ACS Flight Software for Thruster Control, On-orbit Attitude Determination and Fault Protection

− Captured Telemetry from VirtualSat Used to Validate Ground-based Attitude Determination Software

On-orbit Calibration− Test Fire All Thrusters and Assess Attitude and Spin Rate Changes− Align Magnetometer to Probe Spin Axis With 0.5 deg Accuracy− Average IRU Measurements to Determine Bias− Perform Trending Analysis to Determine Precession Versus Time


Orbit Determination

Orbit Determination Based on Two-way Doppler Tracking− Ground Stations Provide Tracking Data in Universal Tracking Data Format

(UTDF)− One Station Sufficient to Provide Required Accuracy

(10 km at Perigee, 100 km at Apogee)− Data from Multiple Stations Yield Better Solution− UTDF Files Processed with GTDS to Obtain New Orbit Solutions− New State Vectors Used in Turn to Generate Updated Planning Products

Digital Range Measurement System− Technology Demonstration During Second Year− Measures Round-trip Delay of Digital Data Stream− SatTrack/ODT Performs DRMS Based Orbit Determination Functions


DRMS Design


DRMS Implementation

DRMS Hardware Implementation− Use Dual PTP NTs for Simultaneous Probe Commanding and DRMS Operations− Uplink Uses Two Subcarriers at 16 kHz and 128 kHz− Downlink Uses Two Subcarriers at 1024 and 128 kHz− Pseudo-random Sequence of 216-1 Bits Transmitted at Rate of 32 kbps− Unique Range Determination to 300,000 km or 47 RE

DRMS Software Development− Simultaneously Read Outgoing and Incoming Data Streams− Perform Automated Shifting of Delay to Find Maximum Correlation− Restrict Delay Search Once Delay Found with High Confidence

Required BGS System Upgrades for DRMS− DRMS Hardware (Linux Computer) for Signal Analysis− Upgrade of Existing Backup PTP (Subcarrier Demodulator and Bit Synchronizer)− Additional Matrix Switch for Baseband Signal Routing− DRMS Software for Determination of Range Delay


BGS Requirements

RF CompatibilityClose S-Band Forward and Return Link with Any Probe at Any Range, Using Appropriate Data Rates

Circular Polarization (RHCP or LHCP)Figure of Merit (G/T) > 24.0 dB/K at 5 º ElevationTransmit Power 200 W (EIRP > 66 dBW)

Two-way Doppler TrackingDigital Range Measurement System as Technology Demonstration

Data CompatibilityViterbi Plus Reed-Solomon Decoding and Error CorrectionCCSDS Transfer Frame ProcessingTelemetry Data Routing by Virtual Channel IDsCommand ForwardingBGS 11-m Antenna


Apogee Labs Doppler Tracking System− Carrier Doppler Measurement System (CDMS) and Track Data Formatter (TDF)− Time Code Generator Needs 10 pps Output

ACU-21C Hardware and Software Upgrades− Parallel Interface for Fast Angle Readout

Transmit Chain Upgrade− SSPA Upgrade to 250 W− Low-loss Transmit Coax Cable− Additional Fiber-optic Cables

Optional Receive Chain Upgrade− Replace LNAs to Improve G/T

Pedestal Environment Monitor Backup Power Via Existing Generator and UPS

BGS Upgrades


BGS Control Software Upgrades

SatTrack/MCS Software Upgrades− Control Apogee Labs Model 7701 CDMS− Control Apogee Labs Model 2208 TDF− Control DRMS System Via Network Sockets− Control Dual SSPAs via RS-232 Interfaces− Read-out Second Environment Monitor in Pedestal− Read-out Status from Multiple UPS


Doppler Tracking Tests

Rationale for Doppler Accuracy Tests− THEMIS Orbit Determination Based on Two-way Doppler Tracking− Doppler Accuracy Difficult to Predict for THEMIS Ground System Configuration− Doppler Signal Extracted from 2nd Local Oscillator in Telemetry Receivers− Perform Tests to Establish Baseline to Predict Accuracy of Range Rate

Measurements as Function of CNR for BPSK and PSK/PCM/PM Modulation− Predicted Accuracy Will Tell How Many Tracking Arcs Are Needed to Perform

Orbit Determination for the THEMIS Mission− Required Accuracy 10 km at Perigee and 100 km at Apogee

Test Sequence− Functional Checkout of Equipment− Long Loop RF Tests with Unmodulated Carrier and Telemetry Playback− On-orbit Tests with FAST Spacecraft


Test Schematic

Schematic Diagram for Doppler Accuracy Tests


Sources for Doppler Errors

Potential Sources for Doppler Errors− Synchronization of Timing Signals Is Very Critical− All Reference Signals Need to Be Generated By the Same Source

− 5 MHz RF Reference for Phase-lock Loops− 10 pps Clock for Triggering Measurements− IRIG-B Time Code for Time Tagging Measurements

− Lack of Synchronization Causes Errors− Lack of Synchronization Between 5 MHz Reference and 10 pps Clock Causes

Doppler Bias and Large Fluctuations in Doppler Signal− Lack of Accuracy in IRIG-B Time Code Causes Doppler Bias

− Receivers Need to Lock Cleanly− Receiver Firmware Can Cause False or Imperfect Lock Under Certain Conditions

Related to Remote Control Functions− False Lock Causes Large Doppler Bias


Loop-back Doppler Tests

Initial Loop-back Tests Performed− Unmodulated Carrier Signal− Transmitted at Low Power from Test Dipole at Apex of 11-m Reflector− RHCP Receiver in BPSK Mode, 3 kHz Loop Bandwidth− AGC Level in Receiver 20 dB− Recorded Tracking Data for 6 min− Measured Average Range Rate: −0.00000470 km/s− Measured Range Rate Error (1-σ): 0.00012869 km/s


Loop-back Doppler Tests


On-Orbit Doppler Tests

Initial On-Orbit Test Performed With HESSI Spacecraft− HESSI Has a Transceiver – Two-way Doppler Tracking Not Possible− TDF Was Configured for Two-way Mode in Preparation of Tests with FAST− Graphs on Following Slides Are Therefore Not Scaled Properly− Test However Demonstrates Functionality of System− Brief Data Drop-out Occurred When Spacecraft Switched Antennas (2nd Graph)


Mission Operations Phases

Launch & Early Orbit Operations− Probe and Instrument Checkout− Maneuver Operations for Initial Orbit Placement− Contingency Operations

Normal Operations− Science Data Acquisition− Maneuver Operations for Orbit Optimization− Contingency Operations

Mission Termination Operations− Maneuver Operations to Initiate Re-entry− Instrument Shutdown


L&EO Operations

Launch & Early Orbit Operations− Delta II Launch Sequence with Release of Probes− Round Robin State-of-Health Monitoring− Initial Attitude and Orbit Determination− Uplink of First Set of Command Loads to Each Probe− IDPU and FGM Power-up With Pre-deployment Calibration− Deployment of Magnetometer Booms− Cross-calibration of Magnetometers While Probe Separations Are Still Small − Systematic Instrument Power-up and Check-out− Test Fire and Calibrate Each Thruster on Each Probe− Spin Up to 30 r.p.m. with Calibration of Tangential Thrusters as Byproduct− Decision of Probe Placement− Discrete Pairs of Apogee and Perigee Maneuvers for Placement into Final

Mission Orbits (Reorientation – Continuous Burn – Reorientation Sequence)− Maneuvers Performed While in Contact with Ground Stations and/or TDRSS


Launch & Early Orbit Profile

13-Oct-2006

23-Dec-2006


Maneuver Planning and Execution

Maneuver Planning and Execution− Determine Pre-maneuver State Vector and Probe Attitude− Perform Maneuver Analysis with Current and Target State Vectors− Verify Delta V Budget− Develop Detailed Thruster Firing Sequence− Perform Contact Schedule and Shadow Analysis− Validate Probe Configuration and Maneuver Sequence on Probe Simulator− Establish Two-way Communications with Probe− Turn off ESA and SST High-voltage Supplies, Place SST into Attenuated Mode− Uplink Command Sequence to Perform Reorientation and Orbit Maneuvers− Download and Verify Command Buffer− Verify Firing Attitude− Monitor Maneuver Execution in Real-time (Tank Pressure, Attitude, Temps.)− De-configure Probe Systems and Monitor Health and Safety− Determine New Orbit and Attitude


Flight Operations Functions

Ground Operations Functions

“Look Ahead” Orbit Propagation Indicates

Upcoming Maintenance Maneuver is Desired

Current/Desired Orbit/Attitude

used in GMAN

Specific Maneuver

Events, Attitudes, and Durations

Formulated

Discrete Thruster Profile and Pulse Sequence Formed

Discrete Stored Command Sequence Generated via MPS

Upload TLM Table, Firing Sequence, &

Downlink Rate Selection

Offline Validation of Entire Stored Command

Sequence Performed on Probe Hi-Fidelity Test-bed

Power-up Gyro’s,

Catalyst Bed Heaters (Pre-

Heat)

Downlink On-Board CMD

Buffer

Compare Flight to Ground Reference

Image to Verify Proper

Sequence Load

Verify CMD & TLM link via GN, TDRSS, USN, or DSN

Verify Current Attitude via Sun Sensor

Data

Verify Gyro Performance, Catalyst

Bed Heater Functionality,

Propellant Tank Pressure, Valve/Fuel Line Temperatures &

States, and Pre-Maneuver Attitude

Power-off Catalyst Bed

Heaters

Execute Burn Sequence

Periodic Long-Term Calibration of Pulse Timing and

Thruster Performance

Monitor Key Temperatures,

Attitude, and State Vector

On-Board Failure Detection/Correction

(FDC) Logic (gyro rates, sun-sensor attitude limits, etc) Aborts Sequence if

Anomaly is Detected

Power Down Gyros

Verify Tank Pressure, General

Probe Health & Safety, 2-

Way Ranging

Turn Off Transmitter

Determine New Orbit and New Attitude

Typical Maneuver Sequence


Instrument Commissioning

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

Maximum Operating Limit, 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 Rates4. SCM Turn-on, Power Verification and Activation of Calibration Sequence5. Magnetometer Boom Deployment With FGM at 32 Hz Real-time Science TLM6. SST Turn-on After Initial Outgasing Phase, Power Verification, High-voltage Ramp-

up and Attenuator Functional Test7. ESA Turn-on After Initial Outgasing Phase, Power Verification, Cover Release and

High-voltage Ramp-up8. EFI Spin Plane Boom Deployment − Procedure Controlled by IDPU9. EFI Axial Boom Deployment − Procedure Controlled by IDPU


Normal Operations

Mission Planning During Normal Operations− Preparation of the Conjunction Season− Ground Station Contact Schedules

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

Attitude & Orbit Determination− Routinely Performed Multiple Times per Week

Maneuver Planning and Execution− Orbits of Probes 1,2,5 Adjusted Few Times Per Year to Optimize Conjunctions− Orbits of Probes 1 & 2 Adjusted Annually to Counteract Lunar Perturbations


MOC Staffing

MOC Staffing During Launch & Early Orbit Operations− UCB Flight Operations Team− 24 Hour Staffing with Prime and Secondary Shifts− Critical Commanding During Prime Shift Only− Swales and UCB Engineering Team on Console During Prime Shift− Instrument Scientists on Console During Instrument Commissioning

MOC Staffing During Normal Operations− THEMIS Follows FAST / RHESSI / CHIPS Model− Normal Operations Eventually Run with 8 x 5 Staffing− Lights-out Operations During Off-hours Successfully Demonstrated− Transition to Autonomous Operations After First Tail Season− Attitude & Orbit Maneuvers Always Treated as Special Operations


Telemetry Requirements

Baseline Requirements for Instrument and Probe Bus Data Recovery− Each Probe Accumulates Up to 750 Mbits of Instrument Data per Orbit− Data Compressed by Factor of 1.5−2.0 Prior to Transmission to the Ground− Apply 12% Overhead for CCSDS Formatting, 14% for RS Code Symbols − Resulting Science Telemetry Data Volume 480−640 Mbits / Orbit / Probe− Required Downlink Time 16−21 min Orbit / Probe at Data Rate of 512 kbps

− Each Probe Bus Accumulates Up to 87 Mbits of Engineering Data per Orbit− Apply 12% Overhead for CCSDS Formatting, 14% for RS Code Symbols− Resulting Engineering Telemetry Data Volume 111 Mbits / Orbit / Probe− Required Downlink Time 4 min / Orbit / Probe at Data Rate of 512 kbps

− BGS as Primary Ground Station with 1070 Passes / Year of 15−30 min Duration− Additional Secondary Network Stations Support 300 Passes / Year− Other BGS Tracking Passes Scheduled for Orbit Determination and Probe Monitoring− Contingency Passes Available (60−100 % Margin)


Science Modes & Data Compression

Science Modes− Slow Survey (SS)− Fast Survey (FS)− Particle Burst (PB)− Wave Burst (WB)− Mode Control Via ATS and/or On-board Triggers

Data Compression− Selectively Enabled / Disabled− Applied Prior to Downlink− Segmentation into 64 Byte Input Blocks− Output Blocks Are Variable in Length− Relatively Short Block Size Minimizes Impact from Bit Errors− Compression Factor of 1.5-2.0 Achievable− Depends on Instrument Data Type


Link Analysis

Telemetry Link

Frequency 2234.0 MHz

Modulation BPSK

Probe Antenna Gain -3.0 dBic

Probe EIRP 2.5 dBW

Range 20,000 km

Path Loss 185.5 dB

Polarization and Pointing Losses 1.0 dB

Ground Station G/T (11-m Antenna) 24.0 dB/K

Data Rate 1024.0 kbps

Bandwidth 2048.0 kHz

Coding Gain RS + Rate-1/2 Convolutional 8.0 dB

BER 10-6

Required Eb/No 2.5 dB

Predicted Eb/No 9.5 dB

Implementation Loss 2.5 dB

Link Margin 4.5 dB

Command Link

Frequency 2057.141667 MHz

Modulation PCM/PSK/PM

Ground Station Antenna Gain 45.5 dB

Ground Station EIRP (11-m Antenna) 66.5 dBW

Range 197,000 km

Path Loss 204.6 dB

Polarization and Pointing Losses 1.0 dB

Probe G/T -38.6 dB/K

Data Rate 1.0 kbps

Bandwidth 1.0 kHz

Coding Gain 0.0 dB

BER 10-6

Required Eb/No 10.5 dB

Predicted Eb/No 19.2 dB

Implementation Loss 2.5 dB

Link Margin 6.2 dB


Telemetry Rates

Downlink Mode Schedule Duration Range Modulation Data Rate

Stored Science and Engineering Downlink 1 x / Orbit / Probe 30 min 750 – 15,000 km BPSK 1,024 kbps

Stored Science and Engineering Downlink 1 x / Orbit / Probe 30 min 2,500 – 20,000 km BPSK 512 kbps



Real-time Engineering Downlink with Ranging 1 x / Day / Probe 30 min 30,000 – 60,000 km PCM/PSK/PM

1.024 MHz S/C 64 kbps









Real-time Engineering Downlink via TDRSS

Contingency & Real-time Maneuver Support 30 min 5,000 – 42,500 km PCM/PSK/PM



Pass Support Plan

Baseline Probe Contact ScheduleDay Number

Modulo 4Probe 1 Probe 2 Probe 3 Probe 4 Probe 5

1 Data Recovery30 min

Data Recovery30 min

Data Recovery 30 min



2Tracking & Monitoring

30 min

Tracking & Monitoring

30 min





30 min






30 min

Tracking & Monitoring

30 min




Blue: Required Passes for Recovery of All Telemetry Data at a Rate of 512 kbpsRed: Additional Passes Available for Tracking and Probe Monitoring at Lower Data Rates


Ground Station Support

Ground Station Support Options− Option 1:

− Berkeley, CA, 11-m (Primary)− Wallops Island, VA, 11-m (Secondary TLM/CMD))− Poker Flat, Alaska, 11-m (Possible Back-up TLM/CMD)− Santiago, Chile, 9-m (Secondary TLM Only)− Hartebeesthoek, South Africa, 10-m (Secondary TLM Only)

− Option 2:− Berkeley, CA, 11-m (Primary)− Dongara, Australia, 13-m (Secondary TLM/CMD)− South Point, Hawaii, 13-m (Secondary TLM/CMD)− North Pole, Alaska, 13-m (Back-up TLM/CMD)


Pass Requirements

Pass Requirements Per Mission Phase− L&EO 4 Months− First Year Science− Second Year Science

THEMIS Probe L&EO Passes First Year Passes Second Year Passes

1 120 92 922 120 183 1833 120 365 3654 120 365 3655 120 365 365

Total 600 1370 1370


Pass Schedule BGS & NASA/GN


Pass Schedule BGS & USN


NASA GN and SN Resource Requirements in PSLA− THEMIS PSLA Reviewed by GSFC/Code 450− PSLA Under Code 450 Configuration Control− Compatibility Test Van for GN/SN End-to-end Testing

Additional Documentation Requirements− Detailed Mission Requirements – Draft at CDR− RF ICD (Ground to TDRSS) – Draft at CDR

Data Flows and Scheduling for Ground Testing & Mission Operations− Supported and Coordinated by GSFC/Code 450

Ground System Development− Support of Experiments with Berkeley Ground Station to Determine Accuracy of

Two-way Doppler Tracking

GSFC/Code 450 Support


NTIA License

NTIA License Status− Frequencies Tentatively Assigned by GSFC Spectrum Management Office− Identical Frequencies for All Probes

− Telemetry: 2234.0 MHz− Command: 221 / 240 ∙ 2234.0 = 2057.141667 MHz

− DoD Currently Reviews Frequency Assignment− BGS Interference Survey Has Been Performed – No Offending RF Sources− NTIA Forms Have Been Provided by All Ground Stations− Formal NTIA Stage 2 License Application Under Development− Application Will Be Submitted in Mid November 2003− Stage 2 Approval With Confirmed Frequencies Expected by August 2004− Transponders Are Long-lead Items and Need to Be Procured Sooner− Risk Is Tentatively Assigned Frequencies May Be Denied by Non-U.S. Members


Network Plan & IT Security

NASA Network Security Requirements Driven by NPG 2810.1, Security of Information Technology

− GSFC IT Security Outlined in Document 290-004, IONet Access Protection Policy and Requirements

− Establishes IT Network Systems Security Measures and Controls for Access to Critical NASA Resources

Documentation Requirements− Information Technology Security Plan, Risk Analysis and Contingency Plan

Closed IONet Security Compliance− Dedicated, Isolated Network and Workstations for TDRSS Access− Configuration Control by System Administrator− Network Certification and Scanning− Personnel Screening


Acronyms

ATS Absolute Time SequenceBEARS Berkeley Emergency & Anomaly Response SystemBFDS Berkeley Flight Dynamics SystemCDMS Carrier Doppler Measurement SystemCOSPAR Committee for Space ResearchDRMS Digital Range Measurement SystemFGM Fluxgate MagnetometerGMAN General Maneuver ProgramGMSEC Goddard Mission Services Evolution CenterGTDS Goddard Trajectory Determination SystemIRU Inertial Reference UnitMSASS Multi-mission Spin Axis Stabilized SpacecraftRTS Relative Time SequenceSSPA Solid State Power AmplifierTAPS Trending and Plotting SystemTDF Track Data FormatterUTDF Universal Tracking Data FormatWDC-A-R&S World Data Center A for Rockets & SatellitesWWAS World Warning Agency for Satellites

themis mission operations peer review mission operations − 1 ucb, november 4, 2003 themis mission...

Documents