1、Lessons Learned Entry: 1481Lesson Info:a71 Lesson Number: 1481a71 Lesson Date: 2004-06-02a71 Submitting Organization: JPLa71 Submitted by: David OberhettingerSubject: Take CM Measures to Control the Renaming and Reuse of Old Command Files (2002) Abstract: The Nav Team renamed a lighttime file (LTF)
2、prepared for a previous mission for use on a current mission without changing the file creation time recorded in the file header. This error caused the new file to be repeatedly recognized as an “old” file, and required operations personnel for several months to manually specify the correct file. Im
3、plement CM measures to assure adequate oversight when renaming old command sequence resources for reuse.Description of Driving Event: During the Mars Odyssey mission, the Operations Team had been executing a “get-all-files” software script for several months when they discovered that the script had
4、been returning an incorrect version of the light time file (LTF) (Reference (1). The LTF contains data on spacecraft-to-Earth or Earth-to-spacecraft transmission time that is used to build Mars Odyssey sequences that command the mapping of Mars. If the LTF is not specified by the user, the autogen s
5、cript searches the project database (PDB) for the latest LTF that covers the time period needed by the sequence (Reference (2). It was determined that the script was operating properly, but that the Navigation Team had taken an old Mars Global Surveyor (MGS) LTF file and renamed it. This created a “
6、new” LTF file with an erroneous creation time recorded in the file header that was earlier than that of the previous, outdated LTF. Hence, autogen always recognized the old, unneeded file as being the most recent. The error required operations personnel to manually edit the environment file that spe
7、cifies which files should be included in the Sequence Generator (SeqGen) run. This editing occurred for several months following initial discovery of the erroneous LTF version. The error was eventually corrected by wrapping the LTF with a new SFDU (Standard Formatted Data Unit) header indicating an
8、updated creation time that flags it as the latest file created. The data content of the LTF did not Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-change.References: 1. JPL Incident Surprise Anomaly (ISA) No. Z74432, March 12, 2002.2. “Using autogen
9、 to Build Odyssey Mapping Sequences,” Roy Gladden, May 15, 2002, p. 3. http:/mgsw3.jpl.nasa.gov/seq/Autogen_Mapping_Guide_020515.pdfAdditional Key Words: command data integrity, SQA, software quality assurance, configuration control, spacecraft commanding, Command and Data Subsystem (CDS), File Titl
10、e, File Text Name, File Data, SFDU Field Specification Table, Command File Element Lesson(s) Learned: N/ARecommendation(s): Establish a Interplanetary Network Directorate (IND) policy and software configuration management (CM) procedures that will preclude the renaming of old command files, paramete
11、r files, or any other command sequence resources as “new” files without adequate oversight. Evidence of Recurrence Control Effectiveness: Corrective Action Notice No. Z84126 was opened by JPL on June 16, 2004 to initiate and document appropriate Laboratory-wide corrective action on the above recomme
12、ndation.Documents Related to Lesson: a71 JPL Procedure: Mission Planning-Operations, JPL Document 31912, March 05, 1999.a71 NPR 7120.5B, NASA Program and Project Management Processes and Requirements, November 21, 2002.a71 JPL Procedure: Mission Operations System Engineering, JPL Document 26912, Jul
13、y 11, 2002.a71 JPL Process Description: Engineer Mission and Navigation Systems, JPL Document 57492, May 07, 2002.a71 JPL Procedure: Operation of Uplink Process, JPL Document 27232, July 19, 2002a71 JPL Flight Project Practicesa71 JPL Design PracticesMission Directorate(s): Provided by IHSNot for Re
14、saleNo reproduction or networking permitted without license from IHS-,-,-a71 Exploration Systemsa71 Sciencea71 Aeronautics ResearchAdditional Key Phrase(s): a71 Communication Systemsa71 Configuration Managementa71 Flight Operationsa71 Ground Equipmenta71 Information Technology/Systemsa71 Policy & Pl
15、anninga71 Safety & Mission Assurancea71 Softwarea71 SpacecraftAdditional Info: Approval Info: a71 Approval Date: 2004-07-13a71 Approval Name: Carol Dumaina71 Approval Organization: JPLa71 Approval Phone Number: 818-354-8242Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
