# Presentation: 704630

## Section 3

_***Section 3***_
***Overview of the FMEAs***

*** ******. . . Robert Prince***
*Swales Aerospace, Inc.*

## Contents

***Contents***

***Spacecraft Segment***
***Advanced Land Imager Instrument***
***Ground System Segment ***
***Launch Vehicle EO-1 Mission-Unique Segment***

## Assumptions For All FMEAs

***Assumptions For All FMEAs***

***One failure at a time***
***All required inputs are nominal***
***All consumables are present in sufficient quantities***
***Nominal power is available (except when the availability of power is part of the failure(s) being considered)***
***Only the launch separation and on-orbit phase of the mission has been treated***
***Connector failures are not treated***
*(Adapted from GSFC P-302-720 and GSFC S-302-89-01)*

## Failure Severity Criticality Categories for FMEAs

***Failure Severity Criticality Categories for FMEAs***

***Severity Criticality Category codes for these FMEAs are defined as follows: ***
***1 =******	******Effective loss of the Mission (non-recoverable complete loss of ALI data) ***
***2 =******	******Loss of the Hyperion Mission (non-recoverable complete loss of Hyperion data)***
***3 =******	******Serious degradation, but still meets some of the Level I ALI and/or Hyperion requirements***
***4 =******	******Some degradation or operations impact, but still achieves the baseline mission***
***5 =******	******Little or no impact to mission success or mission operations***
***Some examples are:***
***Category 1:  Power System, ACS, WARP, or ALI instrument dying completely***
***Category 2:  Hyperion instrument failing by itself***
***Category 3:  A Hyperion ASP failure, or an X-Band Phased Array failure***
***Category 4:  Heaters***
***Category 5:  PPT, GPS, AC, etc.***
***These Criticality Categories are specific for the EO-1 Mission and should NOT be confused with the NMP Technology Categorizations***

## EO-1 Redundancy & Treatment of Redundancy for FMEAs

***EO-1 Redundancy & Treatment of Redundancy for FMEAs***

***EO-1 by “ground rules” is “single-string”***
***Redundancy was included where practical and affordable***
***In some cases, multiple identical functions***
***Different functions with “more-or-less” equivalent results***
***Multiple channels***
***Failure modes with partial or full redundancy are identified with an “R” modifier***
***With redundancy the failure effects indicated in these FMEAs give the results of the failure ***_***as if there was no redundancy available***_
***Redundancy means that with one failure, the indicated “failure effects” do not actually occur***
***If the redundant function were then to fail (a second failure), the indicated “failure effects” would be observed (excepting the third category mentioned in the above paragraph where there are many parallel channels)***

## FMEA Baseline Considerations

***FMEA Baseline Considerations***

***The spacecraft and ALI FMEAs have been performed post-I&T***
***The spacecraft and ALI FMEAs were in general conducted at the first level below system “box” or major functional level***
***That first “sub” level is either an identifiable circuit card or system function***
***The launch vehicle FMEA looked ***_***only***_*** at mission-unique elements***
***The ground system FMEA looked ***_***only***_*** at hardware system units and data paths***

## FMEA Overview - Spacecraft Segment

## FMEA Overview - Spacecraft Segment (continued)

## FMEA Overview - Spacecraft Segment (continued)

## FMEA Overview - Spacecraft Segment (continued)

## FMEA Overview - Spacecraft Segment (continued)

## FMEA Overview - Spacecraft Segment (concluded)

## FMEA Overview Launch Vehicle Segment, Mission-Unique Elements

***FMEA Overview ****Launch Vehicle Segment, Mission-Unique Elements*

## No ground system failures of severity category worse than “4”
EO-1’s robust Safe Hold Mode will keep the spacecraft unharmed during any credible Ground System outage
All ground system equipment is commercial
Maintenance contracts exist for all ground system equipment
Spares and/or alternative data flow paths exist for all ground system equipment
The one exception is a tape drive in the MOC (Building 14) used to read science tapes
For this case, the tapes can be re-read after maintenance – no data loss
Consideration is being given to obtaining a back-up tape drive

***No ground system failures of severity category worse than “4”***
***EO-1’s robust Safe Hold Mode will keep the spacecraft unharmed during any credible Ground System outage***
***All ground system equipment is commercial***
***Maintenance contracts exist for all ground system equipment***
***Spares and/or alternative data flow paths exist for all ground system equipment***
***The one exception is a tape drive in the MOC (Building 14) used to read science tapes***
*For this case, the tapes can be re-read after maintenance – no data loss*
*Consideration is being given to obtaining a back-up tape drive*

***FMEA Overview****Ground System Segment*

## Redundancies & Work-Arounds OverviewSpacecraft Segment

## Redundancies & Work-Arounds OverviewSpacecraft Segment (Continued)

## Redundancies & Work-Arounds OverviewSpacecraft Segment (Continued)

## Redundancies & Work-Arounds OverviewSpacecraft Segment (Continued)

***Redundancies & Work-Arounds Overview****Spacecraft Segment **(Continued)*

## Redundancies & Work-Arounds OverviewSpacecraft Segment (Concluded)

## Final Summary of FMEAs

***Final Summary of FMEAs***

***Spacecraft Systems FMEA***
***Solar Array:  Loss of a string can be tolerated***
***Solar Array Drive:  Not required for Minimum Mission***
***PSE:  Some internal work-arounds available***
***S-Band Comm:  Non-redundant Command & Control Receiver***
***1773 Data Bus:  Redundant fibers, Star Couplers, and Transceivers***
***C&DH:  Mostly non-redundant***
***ACS:  Mostly non-redundant***
***Propulsion:  Not required for Minimum Mission***
***WARP:  Some internal partial redundancies***
***X-Band Transmit:  Not required for Minimum Mission***
***ALI: Some internal partial redundancies***
***Other Hardware and Instruments:  Not required for Minimum Mission***
***Launch Vehicle Mission-Uniques FMEA***
***EO-1 Separation from DPAF:  Bolt Cutters and Wiring are redundant***
***Ground System FMEA***
***Spares and alternative data paths***
***Safe Hold will keep EO-1 unharmed during Ground System outages   ***