JUICE antenna deployment
An image from a camera on ESA's JUICE spacecraft captured the radar antenna snapping into place after a stuck pin finally came loose May 12. Credit: ESA

WASHINGTON — A radar antenna on a newly-launched European mission to Jupiter has finally deployed after weeks of effort to loosen a stuck pin.

The European Space Agency said May 12 that controllers had successfully deployed the 16-meter-long antenna on its Jupiter Icy Moons Explorer, or JUICE, mission. The antenna was supposed to deploy in the first week after its April 13 launch, but had extended only a third of its intended length as of late April.

Engineers suspected that a pin used to hold the antenna in its stowed configuration for launch had not separated as planned. They planned a series of measures to shake the spacecraft through a thruster firing, then orient the spacecraft so the antenna was in sunlight and would warm up, as ways to loosen the pin.

While those efforts showed some signs of progress, the antenna did not deploy until controllers fired a non-explosive actuator in the jammed bracket. The shock of the firing loosened the pin enough for the antenna to unfold. Another actuator fired later to complete the antenna’s deployment.

The antenna is part of an instrument called the Radar for Icy Moons Exploration (RIME), one of 10 on JUICE. RIME is designed to probe below the surfaces of the large icy moons of Europa, Ganymede and Callisto to depths of up to nine kilometers.

The timeline for the troubleshooting effort for RIME’s antenna matched what Olivier Witasse, project scientist for JUICE, said at a May 3 meeting of NASA’s Outer Planets Assessment Group (OPAG). “Don’t expect news until the end of next week” on deployment efforts, he advised at the meeting after discussing the plans to shake and warm the antenna. “We cross our fingers for good news for our radar team.”

JUICE will arrive at Jupiter in 2031, a year after NASA’s Europa Clipper mission, slated to launch in October 2024. Europa Clipper has its own radar instrument, called Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON), that also features deployable booms.

Tim Larson, deputy project manager for Europa Clipper at NASA’s Jet Propulsion Laboratory, said at the May 3 OPAG meeting that the project had been following the RIME antenna issue. The RIME antennas use a “very different design and deployment” than REASON, but he said the hold-down mechanisms for RIME might be similar to those used by Clipper’s solar arrays.

“We are looking into it and making sure we understand the details, and seeing whether or not it has any impact on us,” he said.

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...