Sener’s work consist of the design, manufacture, verification and integration of the magnetometer boom for the main Spacecraft under JUICE Mission. The purpose of this magnetometer boom is to place five of the ten instruments carried by JUICE for scientific experiments away from the magnetic disturbances of the spacecraft. These five instruments are required to perform two wave characterisation experiments, one for magnetic waves, named J-MAG, and another for radio waves, named RPWI.
The boom is a structure consisting of three segments of composite material (CFRP) and the corresponding titanium hinges, whose deployed length is 10.6 m (with an undeployed length of 3.8 m).
The boom features non-explosive release and hold-down mechanisms that keep it secured to different satellite panels during launch and until deployment, thus guaranteeing the required stiffness.
Moreover, the boom has a deployment mechanism based on torsion springs which includes a viscous damper to control deployment speed. The movement of the boom”s different segments is synchronized with a pulley and cable system so that only one deployment mechanism is required, with the corresponding savings in terms of mass.
In the final deployment phase, once the required angle has been attained, the position of one of the segments is secured by means of a system of latches.
The boom houses five of the instruments that are required for the scientific experiments, and which are located in the third segment in order to maximize the distance from any magnetic element in the satellite. The instrument supports are made of titanium, and even of composite material for those instruments that are more susceptible to the presence of metals.
The instrument wiring is routed through the boom, including the hinge area in each segment, where routing is helical in order to reduce resistive torque during deployment.
Main features
The boom must withstand a temperature range of more than 500ºC (from -229 to +278ºC).
The temperatures reached by the tubes of composite material require the use of materials and sheets that are optimised in comparison with similar projects. Similarly, the cryogenic temperatures require specific installations for the performance of the thermal vacuum tests, an added difficulty due to the booms actual dimensions.
The booms total mass (without wiring or instruments) is 30 kg.
This is a particularly demanding requirement due to the total length of 10.6 meters. In order to achieve this, the weight of all the metal parts had to be reduced.
Minimum stiffness without deployment is 55 Hz and 0.1 Hz when deployed.
The required deployment time is 180 seconds (maximum).
The deployment angle precision required is 0.1 degrees.
Magnetic cleanliness requirements are particularly high,
since the boom holds the magnetometers for the performance of the scientific experiments. This not only limits the use of magnetic materials, but also calls for unprecedented magnetic cleanliness requirements throughout the boom’s manufacturing, integration and test processes.
Due to the length of the mission, the dose of ionising radiation received is in the order of 7.4E8 Rads.
This calls for the implementation of suitable protection for elements that are susceptible to degradation by these levels of radiation.
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