A small pin attached to ESA’s Juice spacecraft may be preventing engineers from deploying its 16-metre antenna as it approaches Jupiter. Launched two weeks ago, the probe has just begun its eight-year journey to the largest planet in our solar system to take a closer look at Jupiter’s moons first spotted by Galileo Galilei: Europa, Callisto, Ganymede and Io.

Juice will not begin its scientific observations until it approaches its target, the Jupiter system, in about 2031, and is currently unpacking equipment previously removed for launch. But dispatchers are having trouble expanding their Radar for Icy Moon Exploration (RIME), a tool designed to analyze the surface of Jupiter’s moons and discover what may lie beneath.

Astronomers are particularly interested in finding hidden liquid oceans flowing under the icy crusts of Europa, Callisto, and Ganymede. RIME is designed to probe up to nine kilometers below the surface and test whether theories about vast underwater resources are correct and how useful they can be.

“RIME Juice’s ice penetrating antenna has not yet been deployed as planned,” ESA said in a statement. “During the first week of commissioning, an issue occurred with the 16m RIME antenna preventing it from being removed from the mounting bracket.”

Engineers believe the problem could be caused by a small pin that is stuck and preventing the antenna from fully extending. According to rough calculations, this pin only needs to be moved a few millimeters to fix the problem. RIME’s antenna is currently only extended by a third of its full length, according to an image taken by a camera on the spacecraft. Flight control plans to start the engine and rotate the Juice to push its components and heat the RIME to encourage pin loosening.

“After successfully deploying and operating the mission-critical solar arrays and medium-gain antenna, as well as the 10.6-metre magnetometer burst, Juice is doing great,” ESA said.

The European Space Agency says it has plenty of time to fix the antenna issue, with the spacecraft still two months away from its planned launch. Juice is expected to arrive at Jupiter within the next ten years and begin exploring its moons in the next four years; The mission is expected to last until 2035.