Aurora, Substorms, and THEMIS D. G. Sibeck NASA/GSFC THEMIS Project Scientist.
THEMIS : RESOLVING THE PHYSICS OF ONSET AND EVOLUTION OF SUBSTORMS OBJECTIVE: Study energy releases...
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Transcript of THEMIS : RESOLVING THE PHYSICS OF ONSET AND EVOLUTION OF SUBSTORMS OBJECTIVE: Study energy releases...
THEMIS: RESOLVING THE PHYSICS OF ONSET AND EVOLUTION OF SUBSTORMS
OBJECTIVE: Study energy releases from Earth’s magnetosphere known as substorms (magnetic phenomena that intensify auroras near Earth's poles)
RATIONALE: Provide scientists with important details on how the planet's magnetosphere works, specifically:
• better understanding of the physical instability (trigger mechanism) for magnetospheric substorms
• comprehensive look at the onset of substorms and how they trigger auroral eruptions
Fundamental to our understanding of space weather
Mission Science
Mission ArchitectureConstellation of 5 satellites (probes), each carrying identical instrumentation
• fluxgate magnetometer (FGM)
• electrostatic analyzer (ESA)
• solid state telescope (SST)
• search coil magnetometer (SCM)
• electric field instrument (EFI)
Line up in magnetosphere every 4 days
• launched into “cruise phase” 33 hr orbit
• maneuver into 1, 2 and 4 day orbits for winter season 2008
Conjunction with ground based instruments
• 20 northern sites with all sky imagers and magnetometers
January 5, 2007 THEMIS Mission Readiness Review 3
Standard Delta 10 ft. Fairing Static Envelope
3712 PAF
Probe Carrier Assembly (PCA = 5 Probes + Probe Carrier) on L/V
Probe Carrier Assembly (PCA = 5 Probes + Probe Carrier) on L/V
THEMIS Launch Configuration
THEMIS Launch Configuration
Probe Carrier Assembly (PCA) on Delta 3rd StageProbe Carrier Assembly (PCA) on Delta 3rd Stage
Launch ConfigurationDedicated launch
accommodated within standard Delta 7925-10 vehicle configuration and services
10’ Composite Fairing required to accommodate five Probes on the Probe Carrier in the “Wedding Cake” configuration
PC stays attached to Delta 3rd stage after probe dispense
Each probe dispense from the PCA is coordinated with but independent of the other probes
No single probe anomaly precludes dispense of remaining probes
Star 48 3rd Stage
January 5, 2007 THEMIS Mission Readiness Review 4
Launch Vehicle Overview• Vehicle Configuration: Delta 7925–10C• Launch Site: Eastern Range (ER), SLC-17B at
Cape Canaveral Air Force Station (CCAFS)• Mission Specifics:
– Perigee: 435 km, Apogee: 91845 km– Orbit Inclination: 16 degrees– Spacecraft (SC) Mass (will not exceed)
» 829 kg (2832.94lb) 775.60 kg actual– STAR 48B Motor
» Nutation Control System» Yo-Yo de-spin system
• Spin rates: – During Third Stage operation - max 70 rpm– S/C after spin-down and separation - 162 rpm
• Mission Unique– 3712 Bolted PAF– Sep System (at PAF/PC Interface)
• Non-Standard Services– Category 1 Analysis
» (1st 7925-10C ER)– Five - 24” Doors– Two 61 pin connectors– Fairing Cleaning to VC 6
• Separation System provided by THEMIS Spacecraft, contracted through Launch Services Program (LSP)NASA Launch Service (NLS) Contract
January 5, 2007 THEMIS Mission Readiness Review 5
Depletion Burn:Removes Stage 2 fromvicinity of spacecraft,while lowering Stage 2 perigee altitude andorbit inclination
Flight Profile
Liftoff
MECOt = 263.3 secAlt = 69.0 nmiVI = 20,060 fps
Second Stage Ignitiont = 276.8 secAlt = 72.9 nmiVI = 20,068 fps
Fairing Jettisont = 281.0 secAlt = 74.1 nmiVI = 20,103 fps
SECO 1t = 593.5 secAlt = 101.9 nmiVI = 25,923 fps
ORBIT:100 x 304 nmi28.50 deg inclination
Second Stage Restartt = 3859.4 secAlt = 282.7 nmiVI = 24,662 fps
SECO 2t = 3915.1 secAlt = 280.6 nmiVI = 25,778 fps
ORBIT:280 x 825 nmi26.58 deg inclination
TECOt = 4091.6 secAlt = 305.2 nmiVI = 33,975 fps
Separate Probe At = 4380.1 secAlt = 658.6 nmiVI = 32,368 fps
Orbit:235 x 49,592 nmi16.00 deg inclination-40.00 deg arg of per
SRM Impact SRM Impact
SRM Jettison (6)t = 66.0 / 67.0 secAlt = 9.9 / 10.2 nmiVI = 3,231 / 3,269 fps
SRM Jettison (3)t = 131.5 secAlt = 31.3 nmiVI = 8,018 fps
Third Stage Ignitiont = 4005.1 secAlt = 281.0 nmiVI = 25,775 fps
Note: Values shown are for 15-28 Feb 2007 launch
Simple, Robust, Fault Tolerant System: • Power positive in all attitudes with
instruments off (launch, safe hold modes)
• Passive spin stability achieved in all nominal and off-nominal conditions
• Passive thermal design using MLI and thermostatically controlled heaters tolerant of longest shadows (3 hours)
• S-Band communication system always in view of earth every orbit at nominal attitude. In view for greatest part of orbit in any attitude
• Monoprop blow down RCS (propulsion) system is self balancing on orbit
Probe Bus Design
PAF Adapter Ring/Tube & Attach to Launch Vehicle
PAF Adapter Ring/Tube & Attach to Launch Vehicle
Main DeckMain Deck
Center SpoolCenter Spool
(4) Lower Probe
Standard Separation
Fittings
(4) Lower Probe
Standard Separation
Fittings
(1) Upper Probe Standard Separation Fitting(1) Upper Probe Standard Separation Fitting
(8) External Struts(8) External Struts Probe Carrier (PC)Probe Carrier (PC)
• Simple probe carrier utilizes– Machined aluminum structure– Standard heritage payload attach fittings
utilize pyro- actuated clampband– Straight-forward umbilical interconnect
harness
• Detailed design supported by analysis and full system test– NASTRAN model to recover material
stresses and fundamental frequencies– Base drive analysis used to verify
strength and recover component loads– Coupled Loads Analysis– PCA Vibration/Acoustic Test
• Probe layout on carrier maximizes static and dynamic clearances– Design is the best balance between
deployment clearances and probe mass
First Axial Mode: 48.27 Hz
First Lateral Mode:18.29 Hz
Probe Carrier Fundamental Natural Frequencies:
Displacements Not to Scale
Probe Carrier Design
Probe Bus SystemsProbe Structure
• Carbon Composite, Total Mass 126 kg
Payload Interface• Single, simple RS-422 Interface between UCB
Instrument Data Processor (IDPU) and Swales Bus Avionics Unit (BAU)
RF Communications• S-band Transponder, 5 W• Hexagonal Microstrip Patch Antenna• Toroidal Antenna Pattern, LHCP• 10 Telemetry Rates: 1.024 - 1048.576 kbps• Command Data Rate: 1.0 kbps
Thermal Subsystem• Passive Hot Biased System with Local
Radiators• Thermostatically Controlled Heaters
Power System• Total Power: 40 W• Solar Panels: 6 Sets, Body Mounted• Solar Cells: GaAs Triple-junction• Battery: Lithium Ion, 28 V, 11.8 Ah• Charge Control: Direct Energy Transfer
Propulsion System• Hydrazine Blow-down System• 4 Thrusters
2 Axial, 2 Tangential, 4.4 N• 2 Propellant Tanks
Total Fuel Load: 49.0 kgMEOP: 2750 kPa at 40 C
• Repressurizing Tank, He• Latch and Solenoid Valves
Attitude Control System• Spin-stabilized Platform• Open Loop Spin Control, 20 rpm• Miniature Spinning Sun Sensor• Flux Gate Magnetometer• Inertial Reference Units (2)• Attitude Control Via Propulsion System
Command and Data Handling• ColdFire Processor, 8.388 MHz
• RTEMS Operating System
• Bulk Memory, SDRAM, 64 MBytes
• CCSDS V1 TLM and CMD Formats
Fuel Tank
ESA
EFI SPB
Thruster T1
EFI Axial Booms (2, Stowed)
BatteryBAU
Repress Tank
Miniature Sun Sensor
Transponder
Thruster T2
IDPU
Fuel Tank
Antenna
EFI SPB
EFI SPB
Thruster A1
Thruster A2
AEB
Gyros
Probe Configuration
Probe Block Diagram
DirectPower
ShuntRegulation
UmbilicalSAS
Interface
PowerDistribution
UplinkCommandInterface
CommandVerification
LVPS5V, 3.3V,
2.5V
DiscreteCommandGenerator
DownlinkTelemetryInterface
TelemetryProcessor
HardwareCmd
Interface
TelemetryLogic /FIFO
RSEncoding
+28V to IDPU,XPNDR,&Heaters
BatteryOff Cmd
PowerControlModule
LVPS+5V
SepInterface
HardlineTlm
+28V Bus
To SunSensor
LVPS+/-5V
ToGyros
HardlineCmd
Cmd/Status
Interface
Cmd/Status
Interface
SeparationCommand
SeparationInputs
33.554MHz
FPGA
inst tlminst status
8.388 MHz
512 KBEEPROM
PowerSwitch
Refresh
Baud Clk
4/25/04
Ctrl/Status 1
Ctrl/Status 2
Reg Reg
P-S
Reg
P-S
RS-422
Clock1PPS
ColdFireProcessor
512 KBRAM
64 KBPROM
64 MBBulk
Memory
CommunicationInterfaceModule
ProcessorModuleRS-422RS-422
D/L TLM
32-8
Reg
2.1Mbps
RS-42254AC
IDPUSun
Pulse8.388MHz
RS-422
S-P
Reg
Clock/TimerCircuitry
inst cmdss/c statustime
RS-422
UARTXMitter
InstrumentData Processing
Unit (IDPU)
Solar Array
SunSensor
TransmitterReceiver
DiplexerThrusters &
Latch Valves
PressureTransducers
S-BandAntenna SST
SCM
ESA
FGM
EFIEFI EFIEFIEFIEFI
+28V
Thermistors& PRTs
LV Hardline Command
+28V
+5V
+28V
SolidState
Gyro(2)
+5V -5V
RS-422RS-422
Battery
BatteryRelay
BatteryOn Cmd
Attitude Control System
ACS Sensors
Actuators
Bus Avionics Unit (BAU)
Flight Software
Ground Data System
SS Interface Electronics
IRU Interface Electronics
Sun Sensor
Three-Axis Magnetometer
(FGM Instrument)
Y-Axis Angular Rate
Sun Crossing Pulse Sun Sensor Processing
at sun crossing
TAM Processing at 1 Hz
3-Axis Magnetic Field
IRU Processing at 1 Hz
w/ 20 Hz IRU dataACS
Telemetry Processing
at 1 Hz
Thruster Output
at 20 Hz
Thruster Operations Monitoring
GTDS Orbit Detemination
MSASS Attitude
Determination
GMAN Maneuver Planning
Disable Thrusters
Thruster Commands
Limits
Thruster Control Electronics
Start Count, Stop Count
ThrusterThruster
ThrusterThruster (2 Axial, 2 Side)
Rate Gyro
Thruster Valve
Open/Closed
IRU (2 single-axis)
X-Axis Angular Rate
Spin rate, Sun Aspect Angle, Sun Crossing Time
Instrument Data Processing Unit
(IDPU)
Sun Aspect Angle
Status Bit
Status Bit
Spin Rate
Limit Monitoring at 1 Hz
Thruster Command Processing
at sun crossing
Start & Stop Buffer
Spin Axis, Cone Angle
Reaction Control System• Four 4.4-N Thrusters for maneuvers -2 Axial, 2 Tangential
• Latch valves opened right after launch, prior to first maneuver
• Redundant Cat-beds used prior to all firings to avoid cold starts
• Isolation valve opened right before pyro valve is fired at specific pressure for system repress:
Two axial thrusters (A1, A2) for major orbit changes and attitude control
Two tangential thrusters(T1, T2) for spin control
and minor orbit changes
Thruster Placement
RCS Operational Modes
Maneuver Type
Thrusters InvolvedDepiction of
Operational ModePurpose of Maneuver
Axial ThrustA1 and A2
Continuous Firing
Perigee or Apogee Change or Combined In-
plane and Out-of-plane Orbit Change
with Stowed EFI Booms
Side ThrustT1 and T2 Pulsed
Firing
Perigee or Apogee Change
with Deployed EFI Booms
Beta Thrust
A1 and A2 Continuous Firing Alternating With
T1 and T2 Pulsed Firing
In-plane and Out-of-plane Orbit Change with
Deployed EFI Booms
Attitude Precession
A1 or A2 Pulsed Firing Attitude Change
Spin-up / Spin-down
T1 or T2 Continuous or Pulsed Firing
Spin Rate Adjustment
Instrument SystemsElectric Field Instrument (EFI)
• Three dimensional experiment• Measures electric field• 4 spin-plane spherical sensors mounted on
20m deployable cable • 2 axial tubular sensors mounted on 4m
deployable stacer element• Experiment and booms built at UCB
Fluxgate Magnetometer (FGM)• Single triaxial fluxgate magnetometer• Mounted on 2 meter deployable boom• Measures low frequency magnetic field• Sensors built by TUBS (Germany)• Electronics built by IWF (Austria)• Boom built by UCB• Magnetic cleanliness led by UCLA
Search Coil Magnetometer (SCM)• Single unit, three orthogonal u-metal rods• Mounted on 1 meter deployable boom• Measures high frequency magnetic field• Sensor, Electronics built by CETP (France)• Boom built by UCB
Electrostatic analyzer (ESA)• Single unit, mounted to IDPU• Measures thermal plasma; electrons and
ions in the range 5-40 KeV • Built by UCB, nearly identical to the ESA
Instruments on the FAST Spacecraft
Solid State Telescope (SST)• Two double-ended telescope units• Measures super-thermal plasma; electrons
and ions in the range 30-300 KeV • Built by UCB, similar to WIND
Instrument Data Processing Unit (IDPU)• Provides the electronic interface between
the Probe and the Instrument sensors • Collects and formats all instrument data,
and controls instrument operations • Multi-slot 6U VME chassis• Consists of 6 boards (LVPS, PCB, DCB,
FGE, DFB, BEB, DAP)• 8085 Processor• 256MB SDRAM Storage• ~2x loss-less compression
Instrument Configuration
Deployed Configuration
Instrument Suite −Stowed Configuration
January 5, 2007 THEMIS Mission Readiness Review 17
Mass Status
• < 2% mass deviation between Probes (requirement)• Dry Mass Margin: 4.5% (Worst case)
Power Status• Probe CBE: 38.7 W• Probe Capability: 40.60 W• Probe Margin: 8.8% (First 3-hour Eclipse Season)
4.9% (Second 3- hour Eclipse Season)
Resources
Mass(Kg) F1 F2 F3 F4 F5Measured 78.04 77.62 76.72 76.72 78.08NTE 81.80 81.80 81.80 81.80 81.80Margin 3.76 4.18 5.08 5.08 3.72% 4.6% 5.1% 6.2% 6.2% 4.5%
Mass History• Mass
– Probe Dry Mass was limiting mass resource – Probe Dry Mass Current Best Estimate (CBE): 77.5 kg– Probe Dry Mass Not to Exceed (NTE) due to Delta-V requirement: 81.8 kg– All Probes measured during spin balance, <1% variability between Probes– Probe Dry Mass Margin: 5.6%
SPACECRAFT MASS
0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
90.00
Ph
ase
A
8/0
3
10
/03
12
/03
2/0
4
4/0
4
6/0
4
8/0
4
10
/04
12
/04
2/0
5
4/0
5
6/0
5
8/0
5
9/0
6
Date
Mas
s (
kg)
Probe Dry Mass NTEProbe Dry Mass CBEProbe Bus CBEInstrument CBE
Power History• Power
– Late increase in Probe power was from additional heater power predicted from updated thermal model.
– Late increase in capability was based on measured S/A LAPSS performance data for F2 S/As, coupled with BEAST time history analysis.
SPACECRAFT POWER
0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
45.00
PhaseA
8/03 10/03 12/03 2/04 4/04 6/04 8/04 10/04 12/04 2/05 6/05 8/05 10/05 12/05 2/06
Date
Po
wer
(W
)
P1 Capability - Daylight Pow er
P1 Probe CBE
Probe Bus CBE
Instrument CBE
Probe CBE: 36.6 W
Probe Capability: 40.35 W
Probe Margin: 10.2%
Ground Based Observatories
Ground Based Observatories • 20 GBO (GMAG and ASI) units• Automatic Data Collection and Archiving• Remote Commanding and Diagnostics• Expect to be Fully Functional at Winter 2008
Courtesy H.Frey, UCB
GeographicLongitude 324°
Geographic Longitude 195°
GeomagneticNorth Pole
GeographicNorth Pole
Ground System Diagram
Ground System Elements•Ground Stations
•Ground Network
•Space Network
•Mission Operations Center
•Science Operations Center
•Flight Dynamics Center
Including•Mission Design
•Orbit & Attitude Determination
•Maneuver Planning
•Limit Detection and Notification
•Network Security
January 5, 2007 THEMIS Mission Readiness Review 22
Ground Stations
Ground StationStation
DesignatorFigure of
MeritLocation Function
Berkeley, CA BGS 11-m 24.0 dB/K37.879° N 122.243° W
Primary TLM/CMD/TRK
Wallops Island, VA WGS 11-m 23.0 dB/K37.925° N75.476° W
Secondary TLM/CMD/TRK
Merritt Island, FL MILA 9-m 1/2 21.6 dB/K28.508° N80.693° W
Secondary TLM/CMD/TRK
Santiago, Chile AGO 9-m 21.6 dB/K33.151° S70.668° W
Secondary TLM/CMD/TRK
Hartebeesthoek, SA HBK 10-m 20.4 dB/K25.883° S27.708° E
Secondary TLM/CMD/TRK
Mission Supported by 5 Ground Stations• Ground Stations: BGS, WGS, MILA, AGO, HBK• GN, SN and FDF Support Documented in PSLA• All Stations Have Successfully Flowed Data with MOC
January 5, 2007 THEMIS Mission Readiness Review 23
Mission Operations Center
BGS Antenna, Equipment Racks and FOT Workstations at the Mission Operations Center
January 5, 2007 THEMIS Mission Readiness Review 24
UCB MOC
Integration and Test Flow• Instruments delivered to UCB for Instrument Suite Integration
– Integration to IDPU (BAU simulator is used)– Interface tests and self-compatibility, complete functional testing before/after environments– Environmental Test Sequence on Instrument Suite
• Probe Buses delivered to UCB for Probe/Instrument Suite Integration– Component-wise integration of Instrument Suite with Probe Bus– Interface tests and self-compatibility– RF Performance and End-to-End Mission Operations Center testing– Comprehensive Performance Tests, Mission Simulations
• 1st Integrated Probe to JPL for Environmental Tests (Pathfinder)– Magnetics, EMI/EMC– Vibration– Thermal Vacuum (Cycling and Extended Balance)
• Remaining 4 Probes and Probe Carrier (PC) to JPL for Environmental Tests– Probe Carrier Assembly (PCA - PC and 5 Probes) Vibration and Acoustic Test– Mass Properties and Spin Balance– Thermal Vacuum– Magnetic Survey
• Probes and Probe Carrier to Cape– Probes Fueled, mass properties– Final PCA build-up and spin balancing
Environmental Test
Environmental Test Matrix (ETM):
NOTES: A = Analysis Q = Qualification unit only
T = Test I = Inspection
TS = Test on 1st unit only, rest by similarity W = Weigh
TL = Limited Test
OTHER
COMPONENT (ITEM)
QU
AN
TIT
Y
SU
PP
LIE
R
ALI
GN
ME
NT
MO
DA
L S
IGN
AT
UR
E/S
UR
VE
Y
SIN
E B
UR
ST
RA
ND
OM
VIB
RA
TIO
N
SIN
E V
IBR
AT
ION
AC
OU
ST
IC
PR
OO
F T
ES
T
CLA
MP
BA
ND
SH
OC
K
VE
NT
ING
/PR
ES
SU
RE
PR
OF
ILE
MA
SS
PR
OP
ER
TIE
S
ME
CH
IN
TE
RF
AC
E
SP
IN B
ALA
NC
E
INT
ER
FA
CE
VE
RIF
ICA
TIO
N
CO
ND
UC
TE
D E
MIS
SIO
NS
CO
ND
UC
TE
D S
US
CE
PT
IBIL
ITY
RA
DIA
TE
D E
MIS
SIO
NS
RA
DIA
TE
D S
US
CE
PT
IBIL
ITY
TH
ER
MA
L V
AC
UU
M
TH
ER
MA
L B
ALA
NC
E
# O
F T
HE
RM
AL
CY
CLE
S
ES
C A
ND
GR
OU
ND
ING
DC
MA
GN
ET
ICS
AC
MA
GN
ET
ICS
BA
KE
OU
T
RA
DIA
TIO
N
Instrument Suite 6 UCB T TS TS T 6 TS TInstruments and IDPU 1 TUBS T T A T T A W I T T 2 T M T AProbe Subsystems SAI T T A T/A A/T A T Q/A A W I T TS TS TS TS T 8 T M T A Integrated Probe F2 1 UCB T T T T T T W I T T self self T T T T 4 T M T T Integated Probes F1, F3-5 4 UCB T T T T T W I T T self self TS TS T TL 4 T M T TProbe Carrier 1 SAI T T A W IProbe Carrier Assembly 1 SAI T T A W I T
CONTAMINATIONHARDWARE MECHANICAL ELECTRICAL THERMAL
Environmental Test• Thermal Vacuum
• Instruments: 2 cycles Instrument level, 6 cycles Instrument Suite level. • Probe Bus: 8 cycles component level.• Probe System: 4 cycles on all probes. Extended thermal balance completed on 1st Probe. Limited
Thermal Balance on subsequent probes.
• Vibration/Shock/Acoustics• Instruments: Qualification vibe on ETUs, Acceptance vibe on all flight units• Probe Bus: Qualification/Acceptance vibe on ETU/flight or Protoflight vibe on 1st flight unit• Probe System: Protoflight vibe on 1st Probe. Sine vibration and acoustics on PCA. 2 shock tests on
1st Probe (1 complete, 1 after PCA acoustics), 1 shock test on subsequent probes after PCA acoustics. 1 sep test on ETU sep system after PCA Mass Dummy Vibration.
• EMI/EMC• Instruments: Conducted EMC on FM1 Instrument Suite, self-compatibility on all Suites• Probe Bus: Conducted and radiated EMC on 1st BAU and transponder• Probe System: Radiated EMC completed on 1st Probe at JPL. EMC comparison checks and self-
compatibility tests during probe integration.
• Magnetics• Instruments and Probe Bus: Measurements and deguass (if necessary) prior to Integration• Probe System: For 1st Probe, DC Magnetics in JPL coil facility (powered and un-powered probe
states), AC magnetics during EMC. For all Probes, final DC magnetics check.
Thermal Vac Test Plan
January 5, 2007 THEMIS Mission Readiness Review 29
Environments
Thermal Vacuum
Acoustics
Spin Balance
EMC
VibrationMagnetics
January 5, 2007 THEMIS Mission Readiness Review 30
Probe Carrier Assembly during Vibration
Installation of Thermal Vacuum Shrouds
Probe on GSFC Spin Balance Miller Table
Two Probes Ready for TV Testing
Environments
January 5, 2007 THEMIS Mission Readiness Review 31
Probe Processing
Bolt Cutter Installation
Performance Tests
Solar Array Illumination
Delivery to ASO
January 5, 2007 THEMIS Mission Readiness Review 32
Probe Fueling Preps
FM2/FM3 Thermal Vacuum
Vibration
Thermal Vacuum
Acoustics Spin Balance
Storage
Dry Weigh & Pressurize
Ready for Fuel
January 5, 2007 THEMIS Mission Readiness Review 33
Carrier Processing
Vibration Acoustics Spin Balance
Storage
PC Unload
SSS Installation
Ready for Probes
January 5, 2007 THEMIS Mission Readiness Review 34
THEMIS Probe Carrier Assembly (PCA) in Launch Configuration
Launch Configuration
January 5, 2007 THEMIS Mission Readiness Review 35
THEMIS was originally scheduled to launch on October 19th, 2006:
– delays caused by workmanship problems with Delta II second stages delayed launch to Feb 15th, 2007
– weather conditions on Feb 13th delayed fueling of the second stage, launch pushed back 24 hours
– on February 16th, launch was scrubbed in a hold at the T-4 minute point in the countdown due to the final weather balloon reporting a no-go condition for upper level winds
– 24-hour turnaround procedure was initiated, targeting a new launch window between 23:01 and 23:17GMT on February 17th
Launch Delays…
January 5, 2007 THEMIS Mission Readiness Review 36
THEMIS successfully launched at 6:01 pm EST, February 17th, 2007:
– Probes separated from the launch vehicle approximately 73 minutes after liftoff
– 8:07 p.m. EST, mission operators at the University of California, Berkeley, commanded and received signals from all five spacecraft, confirming nominal separation status
– (then didn’t hear from Probes for 33 hours… )
Launch!
January 5, 2007 THEMIS Mission Readiness Review 37
LEO Acquisition
LEO AcquisitionMultiple Ground Assets Had Good View Following LaunchProbe Attitude Around 1:30 MET is Poor for Telemetry Probes Contacted at 4Kbps for 5 Minutes each from 1:20 to 1:40
January 5, 2007 THEMIS Mission Readiness Review 38
LEO Operations
LEO Operations• State Vector Delivered to UCB via email @ SECO-2 (65min)• Monitoring of Probe Separation via TDRSS
– Top Probe was commanded to transmit at T+70 mins– Separation occurred at T+73 minutes – All Probes were recording Engineering Data– Separation was recorded by each Probe individually– Engineering Data dumped in later passes
• Probes Are Released at Good Sun Angle, Power Positive– 43 degrees Side to Sun
Probe A Released First
Probes B−E Released Simultaneously 3 s Later
All Probes Independent of Each Other
January 5, 2007 THEMIS Mission Readiness Review 39
Mission Profile