# Presentation: 111068

##  SuperNova / Acceleration Probe(SNAP)

**28 June 2001**

**Flight Software**

** ****SuperNova / Acceleration Probe****(SNAP)**

## C&DH Flight Software
ACS Flight Software
ACE Flight Software
SI Flight Software
Development Testbeds & Simulators

**ACS Flight Software**
**ACE Flight Software**
**SI Flight Software**
**Development Testbeds & Simulators**

**Flight Software Overview**

## Flight SoftwareC&DH 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

**ACS 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**

## Flight SoftwareSI 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**

## Flight Software C&DH Development & Test Bed

**C&DH**
**(ACS)**

**Dynamic**
**Simulator**

**Spacecraft External Data Bus**

**Ground System**
**or Simulator**

**R-T raw data**
**simulator**

**Development**
**Workstation**

**Serial**
**Interface**

**SI simulator**

**High-speed**
**serial I/F**

## Flight Software

**ACS Development & Test Bed**

**ACS**
**(C&DH)**

**Dynamic**
**Simulator**

**Spacecraft External Data Bus**

**Ground System**
**or Simulator**

**R-T raw data**
**Simulator**

**Development**
**Workstation**

**Serial**
**Interface**

**ACE**

**Guider**
**Simulator**

**High-speed**
**serial I/F**

## Flight SoftwareSI Development & Test Bed

**C&DH**
**(ACS Stubs)**

**Instrument**
**Processor**

**Spacecraft External Data Bus**

**Ground System**
**or Simulator**

**Development**
**Workstation**

**Serial**
**Interface**

**FPE Interface**
**Simulator**

**High-speed**
**serial I/F**

##  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**

##  Flight SoftwareIssues 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.**