1、Lessons Learned Entry: 0424Lesson Info:a71 Lesson Number: 0424a71 Lesson Date: 1996-07-10a71 Submitting Organization: JPLa71 Submitted by: J.A. RobertsSubject: Voyager Unbalanced Attitude Control System and Thruster Impingement Effects on Navigation (1977) Abstract: Shortly after the launch of Voyag
2、er, unexpected dynamic effects necessitated additional orbit determination analysis, testing, and modeling to ensure an accurate trajectory. Perform careful coordinated pre-flight analysis to determine the impact of such effects as torques induced by solar pressure and gas impingement on the spacecr
3、aft structure. Design and test to avoid impingement problems.Description of Driving Event: (Relevant Historical Lesson(s) Learned)Shortly after Voyager launch, unexpected translational velocity increments and large non-gravitational acceleration effects were observed in the orbit-determination proce
4、ssing of tracking data. These velocity increments and accelerations were traced to the unbalanced translational accelerations produced by the attitude control system, its response to torques induced by solar pressure, and to the impingement of gas from the pitch thrusters onto other parts of the spa
5、cecraft structure. The magnitude of these dynamic effects required that they be modelled in the orbit determination process throughout the flight. This involved additional orbit determination processing and analysis, and necessitated a new operational interface between the Spacecraft Team and Naviga
6、tion Team. A special in-flight impingement test was performed to provide data for modelling. The pre-flight analysis to recognize or predict the effects and uncertainties from both the unbalanced thrusters and the impingement was inadequate. The result was incomplete flight operations planning by bo
7、th the Spacecraft and Navigation Teams.Additional Keyword(s): Trajectory AccuracyProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Lesson(s) Learned: Orbit determination complexity is increased significantly when translational accelerations from the at
8、titude control system must be accounted for.Recommendation(s): Careful coordinated pre-flight analysis by both the Navigation and Spacecraft areas is needed to estimate the size and uncertainties of these effects, to establish the necessary operational interfaces, and to estimate the scope of the op
9、erations task. Spacecraft designs must be reviewed with an eye to avoiding impingement problems. If impingement is suspected, a test similar to the Voyager impingement test should be planned and executed early in the flight.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson
10、 N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Hardwarea71 SpacecraftAdditional Info: Approval Info: a71 Approval Date: 1995-10-16a71 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-,-,-
