Jammed radar boom on Jupiter-bound Juice probe finally freed

A graph showing the Juice probe’s wobbles after a non-explosive actuator – NEA 6 – was fired in a bid to jar loose the jammed RIME radar antenna boom. The trace shows the resulting back-and-forth oscillations as the boom rotated open and locked in place, followed by a brief spike when the spacecraft’s orientation control system restarted. Image: ESA

After three weeks of intense analysis and troubleshooting, European Space Agency flight controllers have finally succeeded in freeing a jammed 16-metre (52-foot) boom critical to the Jupiter-bound Juice probe’s ice-penetrating radar instrument.

The Jupiter Icy Moons mission – Juice – was launched on 14 April atop an Ariane 5 rocket. On its way to the first of several gravity assist flybys, the spacecraft successfully deployed its over-size solar arrays and a 10.6-metre (35-foot) magnetometer boom.

But a long antenna boom needed by the Radar for Icy Moons Exploration, or RIME, instrument, designed to peer beneath the frozen crusts of Ganymede, Callisto and Europa, failed to unfurl when first commanded, raising concerns a major element of the long-awaited mission could be in jeopardy.

Engineers at ESA’s mission control center in Darmstadt, Germany, concluded the jammed boom was being held by a small pin. They attempted to shift the pin slightly by re-orienting the spacecraft so the mechanism could warm in the sun. They also fired thrusters to rock the probe back to add a bit of force. Engineers noted increased movement, but the boom remained held in place.

On 12 May, commands were sent to fire a non-explosive actuator, or NEA, located near the jammed bracket assembly. The resulting shake apparently moved the pin by a few millimetres, just enough to allow the antenna boom to unfold and lock in place.

“The Flight Control Team then commanded the release of the final remaining part of the RIME antenna boom, which extends in the opposite direction,” ESA tweeted. “Confirmation of a successful deployment arrived shortly after.”

The news prompted widespread relief among Juice scientists and engineers, along with a bit of now-relaxed tweeting.

“We thought about celebrating with a rhyme, but it’s Friday evening, who’s got the time?” the operations team tweeted. Added Daniel Scuka, a control center communications officer: “T’was happy hour time, so having a little juice – when I heard the good news that rime was loose!”

Good news indeed.