Juice’s wriggling RIME antenna

Juice’s stuck but moving RIME antenna is captured by the Juice Monitoring Camera on board the spacecraft. This animation shows the radar’s movements in five photos taken across 17–21 April, as teams on Earth work through steps in Juice’s deployment.

Four segments of the RIME antenna are visible here, folded on top of each other. This ‘stack’ of antenna elements is one half of the full antenna, next to the other half also in a folded stack. The other half has not yet begun deployment and becomes visible through the widening gaps between antenna segments.

The RIME deployment process is a bit like unfolding single segments of a folding ruler. Teams at ESA’s mission control centre in Darmstadt, Germany, activate the release mechanisms for each individual stage, causing the stack of radar segments to gradually move upwards.

In order, the images in the animation show the RIME antenna:

• Before launch lock release
• After launch lock release
• After deployment of the first segment
• After deployment attempt of second and third segments
• After deployment of the magnetometer boom

Each of these stages show a change in the RIME antenna’s position. For scale, this part of the RIME moves about 5 cm from the first to the last image.

In the first two images, the RIME moves as the launch lock is released. This mechanical lock holds the two halves of the antenna steady during launch and must be released before deployment.

In the third image of the sequence, the top segment appears to disappear but has in fact correctly unfolded, turning by 180 degrees as it was successfully deployed.

The fourth image in the sequence shows the moment after teams attempted to deploy the second and third segments, which are thought to be held back by the mounting bracket on the other side of the antenna, not in the field of view.

The successful deployment of Juice’s magnetometer boom also created a jolt across the spacecraft, further nudging the radar as shown in the final image.

The small moving dot at the top right of the animation is, in fact, the Moon, from a distance of initially about 1 million then 2 million km away.

There are two months of planned commissioning still ahead, and engineers, scientists and industry partners have lots of ideas to free the stuck antenna.