NASA/LARC HAS A REQUIREMENT TO CONDUCT ARCJET TESTING OF AN ABLATIVE THERMAL PROTECTION SYSTEM (TPS) MATERI…

Public award description

NASA/LARC HAS A REQUIREMENT TO CONDUCT ARCJET TESTING OF AN ABLATIVE THERMAL PROTECTION SYSTEM (TPS) MATERIAL. THE MARS SCIENCE LABORATORY ENTRY, DESCENT AND LANDING INSTRUMENTATION (MEDLI) PROJECT HAS BEEN APPROVED TO INCORPORATE AN ATMOSPHERIC DATA SYSTEM INTO THE MARS SCIENCE LABORATORY HEATSHIELD, FOR COLLECTING VALUABLE ENVIRONMENTAL DATA DURING THE MARS ENTRY. THIS DATA SYSTEM INCLUDES A SERIES OF PRESSURE PORTS, THROUGH THE TPS, WHICH FEED TO PRESSURE TRANSDUCERS MOUNTED INSIDE THE AEROSHELL. THE MEDLI PROJECT IS ON A VERY AGGRESSIVE SCHEDULE, AND AN EARLY DETERMINATION OF THE PROPER PORT CONFIGURATION IS CRITICAL TO SUCCESSFUL INTEGRATION WITH THE MSL SCHEDULE. A MATRIX OF ARCJET TESTS IS NECESSARY TO FIND THE PORT DIAMETER THAT CAN BE SUSTAINED UNDER PYROLYSIS AND ABLATION, PROVIDING A GOOD PRESSURE MEASUREMENT WITHOUT COMPROMISING HEATSHIELD INTEGRITY. A SERIES OF 14 TEST RUNS WERE PERFORMED AT THE BOEING LARGE CORE ARC TUNNEL (LCAT) FROM FEBRUARY 19 TO MARCH 1, 2007, TO EVALUATE VARIOUS SIZE PRESSURE PORTS IN THE SUPER LIGHTWEIGHT ABLATOR (SLA) 561V HEAT SHIELD MATERIAL AT MSL-RELEVANT ENTRY HEATING LEVELS. DURING THIS TEST SERIES, SOME OF THE DATA REQUIREMENTS WERE COMPROMISED BECAUSE OF THE SMALL MODEL SIZE (2 INCHES), CHOSEN TO MEET THE TEST CONDITIONS. THE TEST RESULTS SHOWED A NEED TO PERFORM FURTHER TESTING TO IMPROVE THE DATA FIDELITY BY USING A LARGER MODEL SIZE (3 TO 4 INCHES). BOEING PERFORMED A SERIES OF EXPLORATORY CALIBRATION RUNS FROM MARCH 26 TO MARCH 30, 2007, TO ASSESS THE POTENTIAL OF THE LCAT FACILITY TO MEET THE REQUIRED CONDITIONS WITH A LARGER NOZZLE, TO ACCOMMODATE 3 TO 4 INCH SAMPLES. THIS CALIBRATION SERIES CONFIRMED THAT THE CONDITIONS CAN BE MET IN THE LCAT FACILITY, ON SAMPLES OF 3 TO 4 INCH DIAMETER. THE NEXT TEST SERIES AT LCAT IS REQUIRED, TO RECOVER DATA COMPROMISED IN THE PREVIOUS TEST EFFORT DUE TO THE SMALL MODEL SIZE, AND TO ACQUIRE ADDITIONAL DATA TO EVALUATE PRESSURE PORT SIZE EFFECTIVENESS. FOR THE NEXT TEST SERIES, EXPECTED CONDITIONS AT THE PRESSURE PORT LOCATIONS RANGE BETWEEN 100 AND 140 W/CM2 IN HOT WALL HEAT RATE, AND 0.15 TO 0.25 ATMOSPHERES IN PRESSURE. THE TEST MATRIX CONSISTS OF 9 POINTS SPANNING THESE CONDITIONS, WITH 2 PORT DIAMETERS TO BE COMPARED AT EACH CONDITION. THESE TESTS WILL REQUIRE UP TO EIGHT THERMOCOUPLE AND FOUR PRESSURE TRANSDUCER ACCOMMODATIONS PER SAMPLE.