REG NASA-LLIS-0376--1995 Lessons Learned - Galileo Spacecraft Transporter Excessive Humidity (2007 Revision).pdf

1、Lessons Learned Entry: 0376Lesson Info:a71 Lesson Number: 0376a71 Lesson Date: 1995-01-30a71 Submitting Organization: JPLa71 Submitted by: R.F. CollinsSubject: Galileo Spacecraft Transporter Excessive Humidity (2007 Revision) Abstract: The Galileo spacecraft sustained water damage when its environme

2、ntally controlled shipping container was left open at the launch facility, allowing humid air to enter throughout a holiday weekend. Controlled environment containers should have continuously visible indicating recorders including an alarm feature. Novel operational modes require hazard analysis.Des

3、cription of Driving Event: The Galileo Spacecraft was shipped to the launch site in a custom made transporter with the RHUs (Radioisotope Heating Units) installed. Removal of the heat from the RHUs required external cooling to an ambient air temperature between 48 degrees and 59 degrees F., which wa

4、s provided by the transporter air conditioning system. The spacecraft also had an internal purge system which protected sensitive elements from uncontrolled humidity and airborne contamination during shipment.Upon arrival at The Cape, the transporter was placed indoors under guard in environmentally

5、 controlled conditions. Once inside the transporter air conditioners were transferred to facility power and the purge gas supply was transferred to facility nitrogen. The pressurized enclosure seal of the transporter door was relieved. Since the S/C was not to begin processing until after the year-e

6、nd holiday interval at KSC, it remained in the controlled environment under guard with periodic monitoring until after the holidays when the mechanical crew arrived and commenced KSC operations. When the transporter was opened, puddles of water were noted on the floor of the transporter and external

7、 spacecraft surfaces exhibited corrosion, characteristic evidence of excessive humidity. The conclusion after intensive inspection and extensive additional analysis by all subsystem cognizant personnel was that only external and cleanable damage occurred.Provided by IHSNot for ResaleNo reproduction

8、or networking permitted without license from IHS-,-,-Additional Keyword(s): Environmental ControlLesson(s) Learned: If the humidity inside the transporter had been monitored, the super saturation condition produced by 70 degree room air entering the 50 degree transporter environment would have been

9、detected early and negligible damage to the spacecraft would have occurred.Recommendation(s): 1. Whenever environmental conditions are specified for a container, the specified parameters should be provided with continuously visible indicating recorders including an alarm feature if limits are exceed

10、ed.2. When a device is operated in a mode which was not contemplated, analysis should be conducted to determine whether this new operational mode could be hazardous to the device or personnel.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): N/A

11、Additional Key Phrase(s): a71 Environmenta71 Packaging Handling Storagea71 TransportationAdditional Info: Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Approval Info: a71 Approval Date: 1986-05-30a71 Approval Name: ghendersona71 Approval Organization: HQProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-