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Command & Data Handling
October 31st, 2008
Tyler TraceyTommy YuenKarim Barakat
October, 31st 2008
Presentation Outline• Subsystem Overview• Top Level Requirements• LP-1 C&DH Operational Phases• Descent Phase• Science Phase• Data Budget• Derived Requirements• Future Work
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October, 31st 2008
Subsystem Overview• The Lunar Penetrator Command and
Data Handling Subsystem Shall:
– gather, process, and format spacecraft housekeeping and payload data for downlink or onboard use
– determine and distribute commands to other spacecraft subsystems
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October, 31st 2008
Top Level Requirements• The C&DH subsystem shall:– Be capable of acquiring and processing
all “required” data generated by spacecraft sensors at a given time.
– Be capable of commanding all subsystems “necessary” at a given time.
– Store “important” data generated by spacecraft sensors until it can be reported to the orbiting spacecraft.
–Use COTS components wherever feasible
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October, 31st 2008
LP-1 C&DH Operational Phases
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Descent Phase[40 minutes]
Penetration Phase [1 sec]
Science Phase[120 hours]
Attitude determination and control will dominate Processing Power [Instructions per Seconds]
Payload’s accelerometer feeds data to DSU at high frequency [1 KHz]
-Provide control functions for onboard drill-Provide processing power for thermal & power
control- Store science & engineering data
- Telemetry formatting
Report Phase[TBD]
-Receive & Store image data from camera [dominate Data Budget]
-Receive & store engineering data [health of all components]
-Store science data with regards to the penetration phase
-Telemetry formatting - Wait for downlink order from relay satellite
October, 31st 2008
Descent PhaseProcessor
EPROM
Data Storage Unit
Data Bus e.g. -CAN bus -RS 422
Accelerometers
RAM
GyroscopesDigital to Analog
Converters
Multiplexers
Main Booster Feedback
Engine/BoosterON/OFF Control
[0 V – 5 V]
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Analog to Digital
Converters
Multiplexers
October, 31st 2008
Digital to Analog
Converters
Multiplexers
Science Phase
Feed to Analog components for
control functionsON/OFF
Control (0 V , +5 V)
[Multiplexers required]
Processor
RAM
Data Storage Unit
Data Bus e.g. -CAN bus -RS 422
Subsystem health sensors and payload analog components (Analog Outputs)
Digital Sensors and components
Camera
Analog to Digital
Converters
Multiplexers
EPROM
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October, 31st 2008
Science Data [Payload] Raw Data [bits] Sampling Rate (Hz) Word Size
[bits] Quantity Sampling Time Camera 640*480 resolution (8 bit depth) 2457600 N/A N/A 1 N/A
Camera 1024*1024 resolution (8 bit depth) 8388608 N/A N/A 1 N/A
Mass Spectrometer 3528000 1 8 1 441000 Thermocouple 7056000 2 8 1 441000 Accelerometer 8000 1000 8 1 1 Gas analyzers / sensors 3528000 1 8 1 441000 Drill 3528000 1 8 1 441000
Engineering Data [Thermal]
Thermocouple 35280000 1 8 10 441000Engineering Data [Propulsions & ADCS]
Accelerometers 108000 0.5 8 3 9000Gyroscopes 108000 0.5 8 3 9000Main Booster Feedback 36000 0.5 8 1 9000
Engineering Data [Power]
Battery Discharge Sensor 3528000 1 8 1 441000Bus Voltage 3528000 1 8 1 441000Bus Current 3528000 1 8 1 441000Engineering Data [Communications]
Subsystem Health Data 3528000 1 8 1 441000
Total with 640*480 resolution 69749600 In Kbits: 69749.6 In Mbits: 69.75Total with 1024*1024 resolution 75680608 In Kbits: 75680.7 In Mbits: 75.68
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October, 31st 2008
Derived Requirements• The C&DH system shall – Survive impact and the effects of the
environment thereafter for at least 5 days
– Store 75.69 Mbits for at least 5 days
– Provide [TBA] MIPS processing power for ADCS control algorithm
– Fit into a compartment of [TBD] size
– Consume less than [TBD] watts
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October, 31st 2008
Future Work• Command budget • ADCS processing algorithm (Kalman
Filter)• Continue to refine our Data Budget
(Space Packets)• Study and compare existing
technologies
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Thank you
Questions?