1、Lessons Learned Entry: 1771Lesson Info:a71 Lesson Number: 1771a71 Lesson Date: 2006-10-27a71 Submitting Organization: JPLa71 Submitted by: David Oberhettingera71 POC Name: Robert Manning / Don Sweetnam / Francis.H.Taylora71 POC Email: Robert.M.Manningjpl.nasa.gov / Donald.N.Sweetnamjpl.nasa.gov / Fr
2、ancis.H.Taylorjpl.nasa.gova71 POC Phone: 818-393-7815 / 818 354-7771 / 818 393-5885Subject: Ensure That Items Separated In Flight Will Not Collide Abstract: The potential for separated items to regain contact and damage the spacecraft has posed a significant risk to recent, current, and planned JPL
3、missions, and it may have been a factor in the Beagle 2 mission failure. Conduct flight tests or analyses to verify that items separated from a lander or return capsule during the descent phase of a mission remain separate by a substantial margin.Description of Driving Event: No signal was ever rece
4、ived from the joint British/European Space Agency Beagle 2 lander, carried on the Mars Express spacecraft, after its scheduled landing time in December 2003. The following year, the Beagle 2 Commission of Inquiry identified a number of lessons learned. One lesson (Reference 1) stated the need for po
5、sitive means of assuring that separated items (e.g., covers, main parachute) do not collide. The potential for separated items to regain contact and damage the spacecraft has also posed a significant risk to recent, current, and planned JPL missions. The system and mission designs have responded to
6、this concern with positive measures to assure that items separated in flight will not regain contact: Genesis The Genesis Sample Return Capsule (SRC) design (Figure 1) was subjected to extensive analysis to ensure that separated items would not regain contact. When Genesis returned to Earth, SRC des
7、cent was to be arrested by a sequence in which a small aluminum mortar disk (sabot), a Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-drogue chute, and then the main parachute were expelled from the SRC (Figure 2). Flight testing of this sequence an
8、d analysis of the resulting video demonstrated an adequate separation that increased with time, and showed that the deployed components could be tracked with ground cameras and radar. A change in the helicopter loitering duration further helped to ensure the safety of the mid-air helicopter capture
9、of the SRC. Because the sabot follows in the wake of the rapidly inflating drogue chute, analysts also had to determine that the risk of the sabot penetrating and damaging the drogue was acceptable (Reference 2). Although the drogue parachute on the SRC failed to deploy during the mission due to an
10、unrelated system failure, prior testing and analysis had successfully verified that there was little chance of collision. Figure 1 is a color diagram of the Genesis SRC that depicts the rough outline and shape of major SRC components within a roughly oval or diamond shaped capsule. On the outer port
11、ion of the top of the capsule are the Backshell TPS and the Backshell Structure. Within the capsule, near the top, are packed the Main Parachute, Drogue Chute, and DACS R vertical descent. This risk was taken into account in the Phoenix and MSL designs. They feature a backshell avoidance maneuver in
12、 which a 6-axis descent control system will allow the descent stage to scoot sideways and avoid contact with the descending backshell/parachute. Like a skycrane helicopter, the MSL descent stage will also use a tether to lower the lander to the Martian surface and then fly away from it. References:
13、1. “Beagle 2 ESA/UK Commission of Inquiry, Joint United Kingdom/European Space Agency Beagle 2 Commission of Inquiry,“ April 5, 2004, p. 30 (Recommendation No. 18).2. “Sabot Recontact with Drogue Chute and SRC, JPL Incident Surprise Anomaly (ISA) No. Z84100,“ Jet Propulsion Laboratory, June 11, 2004
14、.3. “Off-Nominal Separation System Performance and Clearance Analysis, Systems Engineering Report No. DI-IMP-MEC-005,“ Ball Aerospace & Technologies Corp., June 14, 2002, p. 1.4. “Report on the Loss of the Mars Polar Lander and Deep Space 2 Missions: JPL Special Review Board, JPL Document D-18709,“
15、March 22, 2000, p. 43.Lesson(s) Learned: Unless specifically proven by design analysis or test, it cannot be assumed that flight hardware items deployed or separated during the cruise or descent phase of a mission will not regain contact and pose a significant risk to mission success.Provided by IHS
16、Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-Recommendation(s): Conduct flight tests or analyses to verify that items separated from a lander or return capsule during the descent phase of a mission, or from the spacecraft during cruise, remain separate by a subs
17、tantial margin. Perform separation verification as an integrated process in which simulation and analysis is melded with testing that measures the gap.Evidence of Recurrence Control Effectiveness: JPL will reference this lesson learned as additional rationale and guidance supporting Paragraph 4.2.3.
18、4 (Use of Kick-Off Springs for Assured First Motion) in the JPL standard “Design, Verification/Validation and Operations Principles for Flight Systems (Design Principles),“ JPL Document D-17868, Rev. 3.Documents Related to Lesson: Click here to download document. Mission Directorate(s): a71 Space Op
19、erationsa71 Sciencea71 Exploration SystemsAdditional Key Phrase(s): a71 Missions and Systems Requirements Definition.a71 Missions and Systems Requirements Definition.Planetary entry and landing conceptsa71 Systems Engineering and Analysis.a71 Systems Engineering and Analysis.Engineering design and p
20、roject processes and standardsa71 Systems Engineering and Analysis.Level II/III requirements definitiona71 Engineering Design (Phase C/D).a71 Engineering Design (Phase C/D).Entry Systemsa71 Engineering Design (Phase C/D).Lander Systemsa71 Engineering Design (Phase C/D).Roboticsa71 Engineering Design
21、 (Phase C/D).Spacecraft and Spacecraft Instrumentsa71 Integration and Testinga71 Additional Categories.a71 Additional Categories.Flight Equipmenta71 Additional Categories.Flight OperationsProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-a71 Additional
22、 Categories.Hardwarea71 Additional Categories.Payloadsa71 Additional Categories.SpacecraftAdditional Info: a71 Project: Genesis, Deep Impact, Mars Exploration Rover, Mars Science Laboratory, PhoenixApproval Info: a71 Approval Date: 2007-02-01a71 Approval Name: ghendersona71 Approval Organization: HQProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
