Wire Boom Deployment and Attitude of Spinning Free Falling Units in Sounding Rocket Experiments

Abstract: The SPIDER experiment conducted in February 2016 made it possible togather measurements in an aurora and is likely to bring a better understandingof instabilities occurring in it, especially of the Farley-Buneman instability.To exploit properly these measurements, the attitude of the Free-Falling Units(FFUs) that gather the measurements must be well known. However the attitudereconstruction process is made harder as the camera included in the FFUfor that purpose failed to provide usable data. Using raw GPS data and datafrom the Inertial Measurement Unit, and knowing the magnetic field’s behavioroutside of the electrojet, the attitude of one FFU can be determined with anacceptable level of precision. This could extend to other scientific projects andprovide an inexpensive alternative to the use of star trackers.A re-flight by 2019 is scheduled for the SPIDER experiment. Improvementson the Boom Deployment Unit (BDU) are being investigated so their mechanismis more robust, as well as easier and faster to assemble. Getting a betterunderstanding of it through functional analysis helped finding directionsfor improvement on the pin release mechanism, on the solutions to ensure therotational guiding, on making the hardware resistant to vibrations during thelaunch, and on the connections between the measurement probes and the electronicsto process the measurements acquisition. A BDU including the modificationsproposed should be assembled and tested in the perspective of includingthe new design in the re-flight.