1、Lessons Learned Entry: 0200Lesson Info:a71 Lesson Number: 0200a71 Lesson Date: 1992-11-04a71 Submitting Organization: KSCa71 Submitted by: Lisa L. MusgraveSubject: Adverse Environmental Conditions During Launch Description of Driving Event: Ice debris created by the STS 51-L launch was greater than
2、predicted by pre-launch analysis. The trajectories of wind-driven ice falling from the Fixed Service Structure/Rotating Service Structure (FSS/RSS) were predicted using aerodynamic analysis methods. These methods accounted for drag retarding the fall and wind velocity imparting a lateral velocity co
3、mponent. The effects of plume aspiration and particle rebound off the mobile launch platform were not included in the analysis. Launch films show that the vehicle rising off the launch pad caused considerable aspiration. This effect drew ice toward the Solid Rocket Booster (SRB) PLUME, with some ice
4、 striking the left hand SRB. The actual FSS/RSS ice movement, as observed on the photographic documentation, did not conform to the predictions in two important respects: 1) the ice generally did not release until after main engine ignition, and 2) the ice translated further toward the vehicle than
5、predicted.Lesson(s) Learned: Ice debris created by the STS 51-L launch was greater than predicted and resulted in impact with flight hardware.Recommendation(s): Prior to launches in icy conditions, thoroughly analyze predicted ice trajectories, effects on plume aspiration, and ice release times.Evid
6、ence of Recurrence Control Effectiveness: N/AProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Documents Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 EnvironmentAdditional Info: Approval Info: a71 Approval Date: 1994-06-06a71 Approval Name: James G. Klinea71 Approval Organization: KSC/HEIa71 Approval Phone Number: 407-867-7614Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
