1、Lessons Learned Entry: 0422Lesson Info:a71 Lesson Number: 0422a71 Lesson Date: 1996-07-10a71 Submitting Organization: JPLa71 Submitted by: J.A. RobertsSubject: Particles Generated by Pyrotechnic Events (1967/76) Abstract: Following a Viking Orbiter pyrotechnic-actuated event, debris was viewed by th
2、e star tracker as numerous bright objects, initiating a command to change the spacecraft roll position. During and following a pyrotechnic event, place the spacecraft in roll inertial and disable any Canopus-loss fault protection software.Description of Driving Event: (Relevant Historical Lesson(s)
3、Learned)At the time of Mariner 6 scan platform unlatching, which was effected by firing a pyrotechnic squib, several bright objects were seen by the Canopus tracker. This caused the tracker to lose lock on Canopus, causing a roll search to be initiated.For 25 minutes following the first opening of t
4、he Viking Orbiter-1 propellant pressurant supply (a pyrotechnic-actuated event), the spacecraft roll axis was commanded to roll inertial hold and the Canopus-loss fault protection software was disabled. During the first part of this period, numerous bright objects were seen by the Canopus tracker. W
5、ithin a few minutes after completion of the inertial hold period, another bright particle was seen by the tracker, this time causing the spacecraft roll position to change and the on-board software to execute the Canopus-loss fault protection response.Additional Keyword(s): Attitude Control, Science
6、 ViewingLesson(s) Learned: Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Always take the precaution of placing the spacecraft in roll inertial and disabling any Canopus-loss fault protection software at and following a pyrotechnic event. At these t
7、imes particles are shocked loose from parts of the spacecraft, from whence they drift through the Canopus tracker field of view.Recommendation(s): Provide at least an hours protection period following these events before returning the spacecraft to normal roll control.Bright objects resulting from a
8、 pyro event may also adversely effect other devices such as science instruments. A one-hour delay in operating these devices should be considered.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Energetic Materi
9、als - Explosive/Propellant/Pyrotechnica71 Flight Operationsa71 SpacecraftAdditional Info: Approval Info: a71 Approval Date: 1995-08-10a71 Approval Name: Carol Dumaina71 Approval Organization: 125-204a71 Approval Phone Number: 818-354-8242Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
