1、Lessons Learned Entry: 0484Lesson Info:a71 Lesson Number: 0484a71 Lesson Date: 1996-12-12a71 Submitting Organization: JPLa71 Submitted by: C. GuernseySubject: Adoption of an Earth-Orbital Propulsion System Design for a Planetary Mission (1993) Abstract: To reduce costs, the Mars Observer propulsion
2、and other subsystems followed design practices more common to earth-orbiting satellites than to planetary missions. Consider contractor experience in bipropellant spacecraft propulsion system design in source selection. To manage risk on one-of-a-kind developments, assure thorough technical oversigh
3、t of contractors with limited experience in the design of interplanetary spacecraft.Description of Driving Event: The Mars Observer propulsion system, like much of the Mars Observer spacecraft, followed design practices more common to earth-orbiting communications satellites than to planetary missio
4、ns. This was consistent with the plan to reduce costs by mandating maximum use of industry practices.A significant weakness of the Mars Observer propulsion system was in the design of the pressurization system, which regulates propellant tank pressures during main engine maneuvers. For conventional
5、earth-orbiters, where the pressurization system is used for apogee boost to establish the proper orbit, the pressurization system is required to function for only a few days following launch. Typically, the pressurization system is then isolated from the propellant tanks. This mission duty cycle mak
6、es such spacecraft essentially impervious to regulator leakage and the effects of propellant vapor diffusion within the pressurization system. This is not true of planetary missions such as Mars Observer, which require high propellant flow rates years after launch. With the Earth-orbital design, the
7、 Mars Observer propulsion system had inadequate flexibility in pressurization system isolation and marginal control of propellant vapor migration.This design limitation may have contributed to the loss of the Mars Observer mission. Of three likely propulsion-related scenarios identified by the JPL M
8、ars Observer Special Review Board, two could Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-be attributable in part to inadequate review and consideration of the differences between earth-orbiting and planetary propulsion applications. These potenti
9、al causes were (1) propellant reaction leading to pressurization system line rupture and (2) tank rupture due to regulator leakage.Reference(s):1. “Report of the Mars Observer Mission Failure Investigation Board,“ (Coffey report), December 31, 1993.2. “Mars Observer Loss of Signal: Special Review Bo
10、ard Report,“ JPL Publication 93-28, November 1993.Lesson(s) Learned: 1. The differences in the operating environment between Earth-orbiting and interplanetary missions may be very significant and must be considered very early in the project design.2. It is unrealistic to assume that contractor exper
11、ience with earth-orbiting spacecraft is directly applicable to design of interplanetary spacecraft.Recommendation(s): Consider contractor experience in bipropellant spacecraft propulsion system design in source selection. To manage risk on one-of-a-kind developments, assure thorough technical oversi
12、ght of contractors with limited experience in the design of interplanetary spacecraft.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): a71 ScienceAdditional Key Phrase(s): a71 Energetic Materials - Explosive/Propellant/Pyrotechnica71 Environmen
13、ta71 Safety & Mission AssuranceProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-a71 SpacecraftAdditional Info: Approval Info: a71 Approval Date: 1997-01-24a71 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-,-,-
