Juice’s RIME Antenna Breaks Free

More than three weeks after efforts began to deploy Juice’s ice-penetrating Radar for Icy Moons Exploration (RIME) antenna, the 16-metre-long boom has finally escaped its mounting bracket.

During the first attempt to extend the folded-up antenna, only the first segments of each half were deployed. Flight controllers suspected that a tiny stuck pin jammed the other segments in place.

Fortunately, the flight control teams at ESA’s mission control centre in Darmstadt had lots of ideas up their sleeves.

To try to shift the pin, they shook Juice using its thrusters, then they warmed Juice with sunlight. Every day the RIME antenna was showing signs of movement, but no full release.

On 12 May RIME was finally jolted into life when the flight control team fired a mechanical device called a ‘non-explosive actuator’ (NEA), located in the jammed bracket. This delivered a shock that moved the pin by a matter of millimetres and allowed the antenna to unfold.

The image below shows the mechanical shock delivered by the firing of the actuator in the mounting bracket. The actuator was fired at the moment labelled ‘NEA 6 Release’. The resulting damping oscillation indicates that the antenna is released and then wobbles back and forth before stabilising into an extended, locked position.

But a final part of the antenna remained folded. Confirmation that the RIME antenna was successfully deployed came only when the flight control team fired another actuator in the bracket, causing RIME to fully stretch itself out after months spent folded up for launch.

Once ESA’s Jupiter Icy Moons Explorer (Juice) arrives at Jupiter, it will use RIME to study the surface and subsurface structure of Jupiter’s icy moons down to a depth of 9 km. RIME is one of ten instruments on board Juice set to investigate the emergence of habitable worlds around gas giants and the formation of our Solar System.