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Description of Driving Event:

The Terrain-Relative Navigation and Employee Development (TRaiNED) project was a Class D (i.e., low cost, high risk) mission employing a sounding rocket to capture exoatmospheric and low-altitude imagery. Using the imagery to refine navigation algorithms, the payload developed by the NASA/Caltech Jet Propulsion Laboratory (JPL) for the 41.087 mission (Dr. Martin Heyne, Principal Investigator) was intended to advance the technology for autonomous terrain-relative navigation and hazard detection, providing aerial and surface access to key sites in the solar system.

The launch of the 41.087/Heyne Terrier-Improved Orion sounding rocket (Figure 1) from White Sands Missile Range (WSMR) on December 6, 2010 was nominal, but no data was received from the JPL-furnished cameras located in the exoatmospheric section. The camera field of view was blocked by a blow-off door, which did not release early in the flight as planned. The sounding rocket for the "Heyne" mission employed a legacy design in which the door (Figure 2) is held in place by tabs and by a single brass screw that is severed in flight by a pyrotechnic guillotine cutter. Rotational acceleration forces then act on the released door, which rotates away from the payload.

Review of telemetry records, inspection of the remaining door hardware, and material analysis, established that the blowoff door release (Figure 3) was actuated at the proper time in flight, but the deployment screw was only partially severed by the cutter (Reference (1)). A more common industry practice is to use high strength fasteners with an extremely high pre-load, so that the cutter only need weaken the screw to the point that the tensile load induces failure in the remainder of the material.

Although the Heyne mission failed to capture camera imagery at 120 km altitude from its exoatmospheric experiment section, the JPL payload did succeed in capturing the requisite descent imagery.