MONTHLY PROGRAM STATUS REVIEW

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Section 3 Overview of the FMEAs
. . . Robert Prince Swales Aerospace, Inc.
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Contents

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

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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)

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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

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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)

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FMEA Baseline Considerations

• The spacecraft and ALI FMEAs have been performed
  post-IT
• 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

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FMEA Overview - Spacecraft Segment
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FMEA Overview - Spacecraft Segment (continued)
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FMEA Overview - Spacecraft Segment (continued)
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FMEA Overview - Spacecraft Segment (continued)
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FMEA Overview - Spacecraft Segment (continued)
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FMEA Overview - Spacecraft Segment (concluded)
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FMEA Overview Launch Vehicle Segment,
Mission-Unique Elements
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FMEA OverviewGround System Segment

• No ground system failures of severity category
  worse than 4
• EO-1s 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

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Redundancies Work-Arounds OverviewSpacecraft
Segment
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Redundancies Work-Arounds OverviewSpacecraft
Segment (Continued)
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Redundancies Work-Arounds OverviewSpacecraft
Segment (Continued)
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Redundancies Work-Arounds OverviewSpacecraft
Segment (Continued)
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Redundancies Work-Arounds OverviewSpacecraft
Segment (Concluded)
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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
• CDH 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