Europa Clipper Mechanical Subsystem Response to Canary Box and Plume Impingement Late Findings

The Europa Clipper mechanical team had to respond to two significant and late findings on the project. The first was the addition of what is referred to as the Canary Box; an entire subsystem added to address the late revelation that certain electrical components throughout the spacecraft were not sufficiently radiation-shielded for the mission. The second was the discovery of a thruster plume impingement on the stowed magnetometer instrument. The Canary Box involved the addition of an electronics box to the exterior of the spacecraft top panel. The box itself is designed with unique thermal and radiation shielding properties to mimic different environments within the spacecraft in support of triaging the health of the plagued electronics. From a system perspective, the box is mass added after finite element model correlation, system test, and final coupled loads analysis. Thus much precaution had to be taken in order to ensure the box and necessary harnessing did not cause inadvertent harm to the spacecraft and its dynamics. The thruster plume impingement was addressed by the addition of a plume shield mounted on the canister which supports the deployable boom that hosts the magnetometer. There were severe constraints on the design and implementation of the plume shield. The shield itself had to be sufficiently sized and placed to protect the instrument yet could only be mounted to existing fastener locations on nearby structure. It must survive extreme temperature swings; both the heating from deflecting the thruster plume as well as the cold of deep space at the outer planets. It had very specific structural stiffness requirements given how it is mounted and it had to be simple to install onto the fully-populated spacecraft. This paper will discuss the solutions from the mechanical subsystem in addressing these two issues and how they were satisfactorily implemented respecting the principle of “do no harm” to the spacecraft.