1. Mission Operations Requirements
Data Capture and
Mission Operations Requirements
Manfred Bester
THEMIS Mission Operations Manager

2. Data Capture & Mission Operations
Overview
Operations Concept
Data Capture and Delivery Requirements
Ground Station Requirements
Mission Operations Center Requirements
Mission Operations Requirements

3. Operations Concept Summary
Space Segment
5 Spinning Probes in High Earth Orbits
Simultaneous Release from LV
Initial Orbits Close to Final Mission Orbits of Probes 3, 4 and 5
Probes 1 and 2 Move to Their Final 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
Universal Space Network as Secondary
TDRSS (SSA) and Wallops GN for Ascent, Maneuver and Contingency Support
Operations Centers
Mission and Science Operations Centers Co-located at U.C. Berkeley

4. Orbit Geometry Prior to First Year Tail Season
Mission Orbits
PCA
x Re at 9.0°
5 Re / div
Probe
Orbital Period
Orbit Geometry Prior to First Year Tail Season 1
4 d
x Re at 7.0° 2
2 d
x Re at 7.0° 3
1 d
x Re at 9.0° 4 5
4 / 5 d
x Re at 4.5°

5. Ground System Overview

6. Data Recovery 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 2 Prior to Transmission to the Ground
Apply 12% Overhead for CCSDS Formatting, 14% for RS Code Symbols
Resulting Science Telemetry Data Volume 480 Mbits / Orbit / Probe
Required Downlink Time 16 min Orbit / Probe at Data Rate of 512 kbps
Each Probe Bus Accumulates Up to 87 Mbits of Engineering Data per Orbit
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 1030 Passes / Year of 30 min Duration
USN−AU (Universal Space Network, Perth) as Secondary with 340 Passes / Year
Additional BGS Tracking Passes Scheduled for Orbit Determination
Contingency Passes Available (60 − 100 % Margin at Each BGS and USN−AU)

7. Ground Station Compatibility
GS.STN-1. The THEMIS ground stations shall be RF and data compatible with the space segment on both the telemetry and the command link.
Rationale: Ensures telemetry can be recovered and probes can be commanded.
GS.STN-2. The THEMIS ground stations shall perform Viterbi decoding and Reed-Solomon error correction on the telemetry stream.
Rationale: With the appropriate link margin, error detection and correction will ensure a telemetry bit error rate of 10-6.
GS.STN-3: The THEMIS ground stations shall be able to close the telemetry link at various data rates commensurate with probe range with a link margin of at least 3 dB.
Rationale: Maximize probe bus and instrument data recovery as function of probe range out to 31.6 Re. Allow for telemetry reception at low data rate to support maneuvers and contingency operations.

8. Telemetry Data Rates Stored Science and Engineering Downlink
Downlink Mode
Schedule
Duration
Range
Modulation
Data Rate
Stored Science and Engineering Downlink
1 x / Orbit / Probe
30 min
700 – 14,000 km
BPSK
1,024 kbps
700 – 20,000 km
512 kbps
14,000 – 30,000 km
256 kbps
20,000 – 40,000 km
128 kbps
Real-time Engineering Downlink with Ranging
1 x / Day / Probe
40,000 – 50,000 km
PCM/PSK/PM
1.024 MHz S/C
64 kbps
50,000 – 75,000 km
32 kbps
75,000 – 200,000 km
4 kbps
Real-time Engineering Downlink via TDRSS
30x During Entire Mission for All Probes Combined
5,000 – 42,500 km
1 kbps

9. Probe Telemetry
GS.STN-4. The THEMIS ground stations shall recover a telemetry data volume of 591 Mbits / orbit / probe.
Rationale: Ensures that sufficient telemetry bandwidth is available to recover both science and engineering data.
GS.STN-5. The THEMIS ground stations shall split received telemetry data by Virtual Channel ID, record all data locally and route real-time data to command and control workstations via network connections.
Rationale: Data stream is split for probe bus and science data processing as well as real-time command and control.
GS.STN-6. The THEMIS ground stations shall buffer recovered telemetry data for at least 10 days.
Rationale: Temporary backup storage in case network links are down.

10. Probe Commanding
GS.STN-7. The THEMIS ground stations shall provide command capabilities to allow closure of the command link out to 31.6 Re with a link margin of at least 3 dB.
Rationale: Ensures that sufficient effective radiated power is available to close the command link at a data rate of 1 kbps with a bit error rate of 10-7.
GS.STN-8. The THEMIS ground stations shall acquire the command link using a STDN compatible acquisition sweep procedure.
Rationale: Driven by probe transponder and common ground station characteristics.
GS.STN-9. The THEMIS ground stations shall support the COP-1 protocol for command verification.
Rationale: Ground stations receive telecommands from ITOS in form of CLTUs and forward these to the probes. Likewise, real-time telemetry transfer frames are forwarded from the probes to ITOS to close the command verification loop.

11. Tracking Data
GS.STN-10. All THEMIS ground stations shall provide two-way Doppler tracking data in Universal Tracking Data Format (UTDF).
Rationale: Two-way Doppler tracking data are required for orbit determination.
GS.STN-11. The THEMIS ground stations shall transfer all tracking data to the THEMIS Mission Operations Center post-pass for orbit determination.
Rationale: Primary orbit determination will be performed at the MOC using GTDS.
GS.STN-12. The Berkeley Ground Station shall be the primary ground station for THEMIS and shall be equipped with additional hardware and software systems to provide two-way digital range tracking data.
Rationale: Technology demonstration of enhanced orbit determination capabilities for future constellation missions. SatTrack Orbit Determination Tool will be used to process two-way Doppler and two-way ranging data simultaneously.

12. Pass Support Requirements
Baseline Pass Support Requirements
Day Number Modulo 4
Probe 1
Probe 2
Probe 3
Probe 4
Probe 5 1
Data Recovery
30 min
Data Recovery 30 min 2
Tracking 3 4
Blue: Required Passes for Recovery of All Telemetry Data at a Rate of 512 kbps
Red: Additional Passes Available for Tracking and Probe Monitoring

13. BGS Requirements RF Compatibility Data Compatibility
Close 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 Elevation
Transmit Power 200 W (EIRP > 66 dBW)
Two-way Doppler Tracking
Digital Range Measurement System as Technology Demonstration
Data Compatibility
Viterbi Plus Reed-Solomon Decoding and Error Correction
CCSDS Transfer Frame Processing
Telemetry Data Routing by Virtual Channel IDs
Command Forwarding
BGS 11-m Antenna

14. Mission Operations Center
GS.MOC-1. All aspects of THEMIS Mission Operations shall be performed at the Mission Operations Center, located at UCB / SSL.
Rationale: Integrated Mission Operations Center reduces overall ground systems complexity.
GS.MOC-2. The Mission Operations Center shall provide hardware, software and IT networking systems to support all mission operations functions.
Rationale: Provides infrastructure to perform all tasks required to operate the five probes and to recover all science and engineering data via primary and secondary ground stations.
GS.MOC-3. The Mission Operations Center shall interface with other THEMIS ground system elements such as the ground stations, the TDRSS Ground Terminal and the Science Operations Center.
Rationale: Ensures seamless data flow from the probes to all required ground system elements and vice versa, and exchange of all required data products.

15. Mission Operations Center
GS.MOC-4. The Mission Operations Center shall provide secure data interfaces to allow for remote probe operation and end-to-end data flow testing during mission integration.
Rationale: Allow for end-to-end data compatibility testing, telemetry page development, simulations and operator training.
GS.MOC-5. The Mission Operations Center shall provide two SCAMA voice loops to allow for communications with other facilities supporting the mission.
Rationale: Provide voice loops for end-to-end data flow test coordination, pre-launch simulations, launch and ground station support.
GS.MOC-6. The Mission Operations Center shall adhere to NASA IT Network Security standards.
Rationale: Ensures that space and ground systems are protected against unauthorized physical and network access (applies to THEMIS and other supported missions).

16. MOC Facility Requirements
Expanded, Secure 900 ft² Operations Facility at SSL

17. Operations Environment
NASA / GSFC GNCD Provides Support in Form of Consulting
Software Tools: GTDS, GMAN, MSASS, SatTrack, ITOS, MPS, SERS
Implement Database to Track Probe Configuration, Status & Anomalies

18. Mission Operations & Planning
GS.OPS-1. THEMIS Mission Operations shall support all phases of the mission.
Rationale: Mission operations include pre-launch, launch and early orbit, normal, contingency and end-of-life operations.
GS.OPS-2. A complete set of ephemeris and mission planning products shall be generated to support all mission planning functions, ground contact scheduling and generation of command loads for all probes.
Rationale: Generate all products based on latest state vector for each probe.
GS.OPS-3. Mission planning functions shall ensure that all probes are configured and operated according to specifications, and yield optimum science data while preserving fuel and maintaining adequate margins and probe health.
Rationale: Maintain optimum operational status of all probes and ensure that science requirements are met.

19. Probe Monitoring & Commanding
GS.OPS-4. Probe state-of-health shall be monitored during real-time pass supports. Post-pass telemetry playback shall be used to examine back-orbit data for limit violations.
Rationale: Monitor probe state-of-health throughout the entire orbit.
GS.OPS-5. Mission operations shall include data trending to establish baseline parameters and to uncover any developing anomalous conditions early on.
Rationale: Provide operational baseline and prevent risk to flight hardware due to out- of-limit operation.
GS.OPS-6. Command loads generated on the ground shall be verified prior to upload.
Rationale: Ensure correct probe operation and reduce operational risk.

20. Orbit Determination & Maneuvers
GS.OPS-7. All critical commands, table loads and flight software patches shall be verified on the probe simulator prior to upload.
Rationale: Minimize risk to flight hardware and software.
GS.OPS-8. The orbit of each probe shall be determined with an accuracy of 10 km at perigee and 100 km at apogee based on two-way Doppler tracking data.
Rationale: Adequate accuracy for ground antenna pointing and science requirements.
GS.OPS-9. All orbit maneuvers shall be carefully planned and validated prior to execution.
Rationale: Ensure that critical maneuver commands are correct and yield the desired orbit change at minimum fuel consumption.

21. Attitude Determination & Maneuvers
GS.OPS-10. Attitude determination of all probes shall be ground based and shall be based on raw Sun sensor and FGM data. FGM data recorded near perigee shall be used to cross-calibrate the Sun sensor on each probe.
Rationale: Ground based attitude determination is part of the Attitude Control System.
GS.OPS-11. All attitude maneuvers shall be carefully planned and validated prior to execution.
Rationale: Ensure that critical maneuver commands are correct and yield the desired attitude change at minimum fuel consumption.
GS.OPS-12. Probe anomaly resolution shall be conducted in consultation with pertinent subsystem engineers, instrument scientists and project management personnel.
Rationale: Recover probe bus and instruments to a safe operating state as quickly and efficiently as possible.

22. Launch & Early Orbit Operations
L&EO Operations
Launch & Early Orbit Operations
Delta II Launch Sequence with Release of Probes
Round Robin State-of-Health Monitoring
Attitude and Orbit Determination
Uplink of First Set of Command Loads to Each Probe
IDPU and FGM Power-up
Deployment of Magnetometer Booms
Systematic Instrument Power-up and Check-out
Decision of Probe Placement
Spin Up to 30 r.p.m. with Calibration of Tangential Thrusters as Byproduct
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

23. Mission Profile
13-Oct-2006
23-Dec-2006

24. THEMIS Maneuver Summary
Probe
Maneuver ID
Purpose of Maneuver
Maneuvers 1
P1-1 − P1-5
P1-6 − P1-13
P1-14
Initial Mission Orbit Insertion
Fine Tuning for Optimization of Conjunction Science
De-orbit 8 2
P2-1 − P2-5
P2-6 − P2-13
P2-14 7 3
P3-1 − P3-3
P3-4 − P3-6
P3-7 − P3-8 4
P4-1 − P4-3
P4-4 − P4-6
P4-7 − P4-8 5
P5-1 − P5-2
P5-3 − P5-7
P5-8
Total 57

25. TDRSS Support Requirements
TDRSS Shall Be Used to Support Launch and Maneuver Operations
Command and Telemetry Data Rate Via TDRSS Shall Be 1 kbps
TDRSS Support Summary
PCA
Probe Monitoring During Ascent Phase
6.0 h
Probe 1
4 Apogee Raise Maneuvers Performed Near 1.25 h Each
5.0 h
Probe 2
3 Apogee Raise Maneuvers Performed Near 1.0 h Each
3.0 h
Probe 3
1 Apogee Trim Performed Near 1.0 h Each
1.0 h
Probe 4
Probe 5
4 Period Change Maneuvers Performed Near 0.7 – 1.7 h Each
Total Support
Entire Mission
21.0 h

26. 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

27. 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 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

28. Science Operations Requirements
Tim Quinn
THEMIS Science Operations Manager

29. Science Operations Overview Data Acquisition and Processing
Data Access and Analysis
Data Archiving and Distribution
Instrument Commanding

30. Data Acquisition and Processing
Science Operations
Data Acquisition and Processing
Spacecraft Data –
Spacecraft data (Virtual Channel – VC) files are delivered from the ground stations to the SOC server over the Internet and Local Area Network (LAN) via FTP
Initial checks for data gaps and missing frames are performed
VC files (Level 0) -> Level 1 data files
Packets are stripped out of Virtual Channels and are filed by Application Identifier (APID)
Level 1 data files -> Summary Plots
IDL routines produce GIF and Common Data Format (CDF) files for viewing and downloading from WWW
Ground Based Observatory (GBO) Data -
Image data are mirrored from University of Calgary site

31. Data Acquisition and Processing
Science Operations
Data Acquisition and Processing
Ground Based Observatory (GBO) Data -
Magnetometer data mirrored from University of Alberta
GBO data combined with spacecraft data into integrated summary plots

32. Data Access and Analysis
Science Operations
Data Access and Analysis
Complete spacecraft data set is accessible from local disk array
WWW access to summary data
GBO data accessed from Canadian sites
Imager data from University of Calgary
Magnetometer data from University of Alberta
Data validated on a daily basis by designated operations scientist (TOHBAN)
Assures data quality
Monitors housekeeping data trends
Identifies and tabulates geophysical events of special interest
Software tools include include
Extensive library of IDL programs
Science Data Tool (SDT)

33. Data Access and Analysis
Science Operations
Data Access and Analysis
Software distributions will be made available to the Co-I’s
Training sessions at UCB for Co-I’s and Guest Investigators

34. Data Archival and Distribution
Science Operations
Data Archival and Distribution
Raw and processed data (Level 0 & 1) are archived to disk array and DVD
Data volume ~100 GBytes/Year (All Spacecraft)
Summary Plots (GIF plots and CDF files)
Data Volume ~100 GBytes/Year
GBO data sets are mirrored from University of Calgary and University of Alberta
Data volume 5-10 TBytes/Mission (All sites)
DVD’s are distributed to NSSDC and Co-I institutions

35. Instrument Commanding
Science Operations
Instrument Commanding
Stored command loads produced using modified version of existing FAST system
Loads transferred to MOC for integration into overall spacecraft load and uplink to spacecraft