1、Lessons Learned Entry: 1480Lesson Info:a71 Lesson Number: 1480a71 Lesson Date: 2004-06-21a71 Submitting Organization: JPLa71 Submitted by: Mark Boyles/David OberhettingerSubject: Provide In-flight Capability to Modify Mission Plans During All Operations (2004) Abstract: The Mars Exploration Rover (M
2、ER) flight system had the ability to update EDL parameters during Approach, and the mission design furnished an operational plan, process, and tools for performing the updates. These capabilities permitted JPL to respond to new data on the Mars atmospheric density by modifying the timing of the MER
3、parachute release, assuring mission success. Maintain an operational capability to code critical parameters in flight software and to update them during the latter stages of encounter/EDL.Description of Driving Event: Both the Mars Exploration Rover (MER) flight system and mission designs had the fl
4、exibility to react to unexpected events. The MER flight system provided an in-flight capability to revise Entry, Descent and Landing (EDL) parameters by coding them in flight software. The MER mission design provided an operational plan, process, and tools permitting JPL to perform EDL parameter upd
5、ates over a span of several days during final approach to Mars and up to six hours before landing.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-DThe ability to update EDL parameters was critical to the success of the MER mission. Updated data on Ma
6、rtian atmospheric pressure received from the Thermal Emission Spectrometer (TES) instrument on the Mars Global Surveyor (MGS) spacecraft during final approach (see figure) indicated a lesser atmospheric density than expected. Left uncorrected, the actual lesser atmospheric density could have caused
7、MER to sense its dynamic pressure target at a lower altitude than planned, and to trigger its parachute deployment too near the ground. Because the flight team had the processes for changing EDL parameters, and the ability to modify these parameters after launch, the timing of the MER parachute rele
8、ase was successfully accomplished.References: 1. “Mars Exploration Rover (MER) Flight Operations Report,” NASA Engineering and Safety Center Report No. RP-04-04/03-004-I2. 2003 Mars Exploration Rover Final Navigation Peer Review, February 3, 2003Additional Key Words: Mars lander, Mars probe, mission
9、 failure, signal loss, flight constraints, communications lag, continuous telemetry Lesson(s) Learned: Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Critical parameters coded in flight software and the ability to alter them within hours of critical
10、 events in response to unexpected data on flight characteristics can save a planetary mission or deep space encounter.Recommendation(s): For spaceflight missions- particularly landers- ensure that the flight system and mission designs have flexibility to react to unexpected events: 1. Code critical
11、parameters in flight software.2. Maintain an operational capability to update these parameters during the latter stages of encounter/EDL.Evidence of Recurrence Control Effectiveness: Corrective Action Notice No. Z84232 was opened by JPL on July 6, 2004 to initiate and document appropriate Laboratory
12、-wide corrective action on the above recommendation.Documents Related to Lesson: a71 JPL Procedure: Mission Planning-Operations, JPL Document 31912, March 05, 1999.a71 NPR 7120.5B, NASA Program and Project Management Processes and Requirements, November 21, 2002.Mission Directorate(s): a71 Explorati
13、on Systemsa71 Aeronautics ResearchAdditional Key Phrase(s): a71 Communication Systemsa71 Environmenta71 Flight Equipmenta71 Flight Operationsa71 Hardwarea71 Payloadsa71 Risk Management/Assessmenta71 Safety & Mission Assurancea71 SpacecraftProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Additional Info: Approval Info: a71 Approval Date: 2004-07-13a71 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-,-,-
