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?