Ed Greville

28 June 2001

Flight Software

SuperNova / Acceleration Probe(SNAP)

Flight SoftwarePage 2

SNAP June 28, 2001Goddard Space Flight Center

C&DH Flight Software

ACS Flight Software

ACE Flight Software

SI Flight Software

Development Testbeds & Simulators

Flight Software Overview

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SNAP June 28, 2001Goddard Space Flight Center

Flight SoftwareC&DH Functions

Command Ingest Receive CCSDS code blocks and distributeStored Command Processing Relative and Absolute time driven command sequenccesTelemetry Output Downlink data device driver, realtime protocol stackData Storage Manage all stored data as CCSDS packetsPayload Manager Science Instrument Telemetry/Command I/FPower Control Solar Array Control, Battery State of Charge, Switching, MonitoringHousekeeping Engineering telemetry from C&DH, ACS, other S/C subsystemsHealth & Safety Monitor Critical subsystemsTelemetry & Monitoring Telemetry limit checking & statisticsFile Manager Manage data filesTask Manager Task monitoring & ControlScheduler Coordination of time driven activitiesSoftware Manager Table load I/O peek and poke, Mem load and dumpSystem Tables General repository for S/C and operational parameters Software Bus Software task intercommunicationExternal Bus I/F External Bus DriversChecksum Detect changes in critical data or codeMemory Scrub Memory error correctionSelf Test Check InterfacesS/C Clock Time mangement & distributionOperating System

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Flight SoftwareACS Functions

Propagate Spacecraft Ephemeris

Validate Ephemeris Update Compute Solar Ephemeris Compute Lunar Ephemeris Process HGA Data Generate HGA Commands Correct For Velocity Aberration Process DSS Data Process CSS Data Process Thruster Data Process RW Data Process IRU Data Process ST Data Process Fine Guidance Data Select Sun Vector Compute Total Momentum Estimate State Vector

Execute H/W Safemode Execute Sunpoint Mode Execute Slew Mode Execute Science Mode Select Guide Star Acquire Guide Stars Identify Guide Stars Compute/Check Target

Quaternion Check For Occultation Generate RWA Commands Generate Hydrazine Thrust

Cmds. Generate ST Commands Generate Fine Guider Commands Detect ACS Fault Process ACS Faults ACS Utilities

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SNAP June 28, 2001Goddard Space Flight Center

Flight SoftwareSI Software Functions

On/Off Read out CCD Extract event data Mechanism control Mode Management Read out alignment data Exposure control State data collection (housekeeping,

telemetry) Save dark current readings Dump dark current table SI thermal control External Data interfaces

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SNAP June 28, 2001Goddard Space Flight Center

Flight Software C&DH Development & Test Bed

C&DH

(ACS)

DynamicSimulator

Spacecraft External Data Bus

Ground Systemor Simulator

R-T raw data

simulator

Development

Workstation

SerialInterface

SI simulator

High-speedserial I/F

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SNAP June 28, 2001Goddard Space Flight Center

Flight SoftwareACS Development & Test

Bed

ACS

(C&DH)

DynamicSimulator

Spacecraft External Data Bus

Ground Systemor Simulator

R-T raw data

Simulator

Development

Workstation

SerialInterface

ACE

Guider

Simulator

High-speedserial I/F

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SNAP June 28, 2001Goddard Space Flight Center

Flight SoftwareSI Development & Test Bed

C&DH(ACS Stubs)

Instrument

Processor

Spacecraft External Data Bus

Ground Systemor Simulator

Development

Workstation

SerialInterface

FPE Interface

Simulator

High-speedserial I/F

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SNAP June 28, 2001Goddard Space Flight Center

Flight Software Risk Assessment

No new concepts or technology

Early C&DH development supports ACS

and SI software development and eases

integration

Typical software risks apply Good industry practices Adequate test time Adequate test resources Adequate documentation

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Flight SoftwareIssues and Concerns

Overall flight software system engineering including testbeds can benefit cost and schedule in the long run.

Instrument software estimate may be low because there are several instruments and the functions and commonality between them has not been studied.