Lesson Info:

• Lesson Number: 0691
• Lesson Date: 1999-02-01
• Submitting Organization: GSFC
• Submitted by: Wil Harkins

Subject:

Description of Driving Event:

This Lesson Learned is based on Reliability Practice Number PD-ED-1232 from NASA Technical Memorandum 4322A, NASA Reliability Preferred Practices for Design and Test.

Benefit:

The Spacecraft Orbital Anomaly Report (SOAR) System provides a single uniform, effective, and efficient computer data base for in-orbit reliability studies to identify performance trends for use in design reviews, flight readiness reviews, and in the evaluation of test, reliability, and quality assurance policies.

Implementation Method:

Anomaly Reporting - Immediately after the occurrence of an anomaly, the orbiting spacecraft's control center initiates the procedure shown on the SOAR Flow Diagram, Figure 1, by notifying the cognizant Project Operations Director (POD) or other cognizant NASA/government representative. The originator then enters all known information onto a SOAR reporting form (GSFC Form 4-29), Figure 2 and sends it to the POD. The POD assigns a person to be responsible for determining the cause of the anomaly, corrective actions to be taken, etc. The responsible person conducts an anomaly investigation and analysis with the help, as required, of control center personnel, the system or instrument representative, the system integration contractor, the subsystem fabricator, and the Flight Assurance Manager (FAM) or the SOAR System Manager. The cause of the anomaly is determined, if possible, and corrective action is proposed, agreed to and approved by project and Center management, as appropriate. This information is entered onto the SOAR form by the responsible person. The FAM or SOAR System Manager assures that the agreed-to corrective action indicated on the SOAR form takes place. When all the SOAR corrective actions have been completed, the FAM or SOAR System Manager is responsible for entering the information onto the SOAR reporting form and closing out the SOAR. The completed SOAR form is distributed to the appropriate project, Flight Assurance, and other interested personnel by the SOAR System Manager. The SOAR System Manager enters information from the SOAR report into the SOAR computer data base and distributes a printout.

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Yearly Summary Reports - These reports present a summary of the in-orbit reliability and performance of active spacecraft built under the management of the Goddard Space Flight Center and collectively form a continuous, published record of this performance. These reports provide a variety of statistical summaries including the total number of anomalies, the number of spacecraft over which the anomalies were distributed and a comparison with the anomalies of the previous year. A brief discussion is included of the condition and performance of each active spacecraft. The yearly SOAR reports contain a complete list of all anomalies that occurred during the year, each with the subsystem identified that caused each anomaly, the criticality, effect, and a description of the anomaly, and any corrective action that was taken. In addition, graphics show the distribution of anomalies among spacecraft and subsystems and comparisons of levels of criticality, effects, failure categories, and types of anomalies. Anomalies are classified and described in these summaries, lists, graphics, etc. as shown below. These classification categories are defined on the SOAR Form along with instructions for their use.

An appendix of the yearly SOAR report also presents a table of spacecraft lifetime data. Table 1. is a sample sheet of spacecraft lifetime data from a yearly SOAR report.

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Technical Rationale:

The SOAR System provides a positive feedback system for reporting, documenting, collecting, analyzing, and closing orbital anomaly information. The timely recognition and analysis of anomalies can lead to corrective measures that can restore performance and, in some cases, protect the safety of the spacecraft and its payload instruments.

The yearly SOAR reports provide GSFC management, spacecraft projects and designers, as well as flight assurance personnel with both short term and long term in-orbit performance and reliability trends which can indicate areas where design improvements should be made on follow-on spacecraft programs. They also can be used to evaluate the effectiveness of the prelaunch integration and environmental test programs.

References:

1. Procedure for the Spacecraft Orbital Anomaly Report (SOAR) System GSFC Report No. 303-PROC-013 (Rev C)
2. Individual Yearly Reports --- "Orbital Anomalies In Goddard Spacecraft"

Lesson(s) Learned:

If the practice is not followed, in-orbit anomalies may not be recognized, analyzed, and possibly corrected in a timely manner leading to continued degraded performance and possible damage to the spacecraft. Additionally, deficiencies in designs may not be recognized and corrected in new or follow-on flight missions.

Recommendation(s):

Implement a positive feedback system for reporting, documenting, collecting, analyzing, and closing orbital anomaly (A departure from normal operation. An abnormality in the mission operations of a spacecraft (in orbit)) information on spacecraft. An example of such a system is currently managed by Goddard Space Flight Center.

Evidence of Recurrence Control Effectiveness:

This practice has been used on Sampex, COBE instruments and electronic boxes, ISTP instruments, etc.

Documents Related to Lesson:

Mission Directorate(s):

• Exploration Systems
• Science
• Space Operations
• Aeronautics Research

Additional Key Phrase(s):

• Emergency Preparedness
• Flight Operations
• Hardware
• Payloads
• Policy & Planning
• Risk
• Management/Assessment
• Safety & Mission Assurance
• Spacecraft

Additional Info:

Approval Info:

• Approval Date: 2000-03-13
• Approval Name: Eric Raynor
• Approval Organization: QS
• Approval Phone Number: 202-358-4738